Silicone Brake Fluid

911 and Porsche World

Porsche recommends that the brake fluid be replaced every two years. Porsche also goes on to recommend that we use only polyglycol, DOT 3 or DOT 4 fluids and not DOT 5 silicone fluid. Furthermore they say that we should not add or mix DOT 5 silicone type brake fluid with the brake fluid in your car as severe component corrosion may result. Such corrosion could lead to brake system failure. 

For the model year 1993 and forward the brake systems in all Porsche models were filled with an improved type of brake fluid, ATE type 200. ATE Type 200 fluid was a new improved DOT 4 fluid with a higher dry boiling point, a higher wet boiling point which extended the life of the fluid and resulted in longer change intervals (every 3 years). This same brake fluid is sold on the aftermarket as ATE Blue and is a superior normal DOT 4 brake fluids. 

Brake fluid comes in DOT 3, DOT 4 or DOT 5 ratings. The DOT standards for brake fluids were established in 1972. When the National Highway Traffic Safety Administration, Department of Transportation (NHTSA) set up the requirements for brake fluids they determined that there was a need for two grades of fluid until an all-weather fluid was developed with viscosity and boiling point characteristics suitable for all braking systems. In order to provide added protection against vapor locking and fade in severe braking service, DOT 4 fluid is recommended. But in such applications it is important to note that the same higher viscosity that helps eliminated vapor locking and fade may result in poorer system performance in very cold weather Also, it should be noted that the high boiling points are sacrificed in the DOT 3 fluid for low viscosities for use at low temperatures. These differences between the viscosities of the DOT 3 and DOT 4 fluids are necessary to cover the specified operating temperature ranges and as such make it necessary to maintain both DOT 3 and DOT 4 brake fluids. 

DOT 5 fluid is supposed to be the all-weather fluid that is mentioned in the preceding paragraph and it can be used as a replacement for both DOT 3 and DOT 4 brake fluids. They test all three fluids for a great number of different characteristics, however, the most interesting characteristics to us are the equilibrium reflux boiling point (dry boiling point), the wet equilibrium reflux boiling point (wet boiling point) and the kinematic viscosities (viscosity at cold temperatures). Dry boiling point: These are the minimum boiling temperatures allowed for the various grades of fluid (this test simulates the boiling point when the fluid is new). 

DOT 3 401° F
DOT 4 446° F
DOT 5 500° F 

Wet boiling point: These are the minimum boiling temperatures allowed for the various grades of fluid when wet (this test is a simulation of the boiling point after the absorption of moisture from air) 

DOT 3 284° F
DOT 4 311° F
DOT 5 356° F 

NOTE: These are the minimum requirements and there are brake fluids available that will exceed these minimum requirements. 

Kinematic viscosities: All brake fluids (DOT 3, DOT 4 and DOT 5) must meet a minimum viscosity test of not less than 1.5 centestokes at 100° C (212° F) and must not be more than the following to meet their various classifications (the larger numbers indicate higher kinematic viscosities just like with motor oils). 

DOT 3 1500 Centestokes at minus 40° F
DOT 4 1800 Centestokes at minus 40° F
DOT 5 900 Centestokes at minus 40° F. 

There are some advantages to silicon brake fluid over conventional polyglycol brake fluids. It is permanent, it does not absorb moisture, it does not boil, it helps prevent corrosion rather than causing it, it will not damage paint if it is spilled on the paint and it helps lubricate seals and other components in the brake system. 

The disadvantages, though minor, can still be very annoying. Silicon brake fluids are slightly compressible, or at least they appear to be because of their affinity for air, which results in a different pedal feel from that of a system which uses a conventional non-compressible polyglycol fluid. Because of silicon brake fluid's affinity for air and their surface tension characteristics they tend to cling to any air bubbles which get into the braking system making the system very difficult to bleed properly. 

The brake fluids required for our Porsches by Porsche AG are either DOT 3 or DOT 4 in new and unused condition (that means that the can should be sealed so that there is no moisture in the fluid). Porsche recommends that we changed the brake fluid every two years (three years with the new ATE type 200 brake fluid) because the conventional polyglycol fluids are hygroscopic and will absorb moisture. When the fluid absorbs moisture, two things happen: the boiling temperature goes down and the absorbed moisture is corrosive to the brake components. Minimum wet boiling point is specified for DOT 3 is 284° F and for DOT 4 is 311° F and because these fluids are hygroscopic they commonly will approach these minimum limits. In contrast DOT 5 silicon fluids have a wet boiling temperature of 356° F and because they are not hygroscopic they will never approach the wet boiling limit. 

The silicon brake fluids are DOT 5 and as such are required to be compatible with all conventional DOT 3 and DOT 4 fluids in order to comply with the federal regulations for DOT 5. There are also other DOT 5 brake fluids that while they are synthetic are not silicone based and as a result are more similar to the conventional DOT 3 and DOT 4 brake fluids that we are familiar with. 

Silicon brake fluid is inert and is supposed to be the only universally compatible brake fluid. However silicon is not miscible and will not mix with other types of brake fluids. Although the silicon fluids can be used with conventional polyglycol fluids, they will not mix and the conventional fluid still in the brake system can continue to absorb any moisture in the system components. 

To gain maximum benefits for the silicon brake fluids the complete brake system should be completely disassembled and cleaned before adding the silicon brake fluid. Then because of the silicon brake fluid's affinity for air, it is recommended that a pressure bleeder be used for bleeding the system. 

I have had personal experience with silicon brake fluid in both street and racing cars. And indeed have experienced difficulties getting the systems properly bled. Even when we were sure we had properly bled the brake system, the brake pedal always had a strange, soft feel to it. We attempted to use silicon brake fluid in a Porsche 935 race car at Daytona in 1981 for the twenty four hour race because of the problems we have in Florida with the high humidity lowering the boiling point of the brake fluid. It probably would have achieved our objective; however, the drivers didn't like the pedal feel and requested that we change it back to conventional fluid. The spongy pedal thing gets worse with heat and in our experience with it at Daytona the driver, Bobby Rahal, told us if we didn't take it out we would have to drive the car ourselves; it was scaring him to death. At that time there was no chicane on the back strait away and they would come into the braking area for Turn one at about 200 mph before braking. At that point they were committed to turn one, which was a little like threading a needle and the soft brake pedal was very unsettling to say the least. Rahal said that the pedal would get worse each lap as the brakes got warmer. We returned to conventional brake fluid and won that years 24-hour race. 

In street cars the silicon fluid has advantages which may outweigh its disadvantages, particularly for older cars that do not get driven very much. Moisture absorbed by conventional polyglycol brake fluid cause serious corrosion of metal parts and deterioration of rubber seals and hoses in the brake system. However, in order to take advantage of that attribute the brake system must be completely free of any polyglycol brake fluid. If any polyglycol brake fluid remains in the system any moisture in the system will be attracted to those small pockets of polyglycol brake fluid causing corrosion

Unleaded Fuels

911 and Porsche World

When we started to convert to unleaded fuels here in the United States in the late seventies everyone was concerned about what was going to happen to our cars with out lead to lubricate the valve guides and cushion the valves on the valve seats. 

One of the first things that I did was check with Porsche and they said that all of the cars from the SC forward had sintered iron seats made of a material that they call Pluko. They said that all of these cars would be fine and that they weren't sure about the earlier cars, but that if there was a problem the could provide Pluko seats for the earlier cars as well. 

Next I checked with a friend, Tim Wusz, who was the Senior Engineering Associate Fuels Technology, Unocal Science & Technology Division then, and who is one of the authorities here in the US on what the effect would be when they took the lead out of the gas over here in the late seventies and early eighties. Tim Wusz said that the only cars that would have problems with the removal of lead were some early American cars that used the cast iron of the blocks or the heads as the material for the valve seats and had very soft seats. Wusz assured me that our cars would run fine on the unleaded fuels that would be available and suggested that I have our valve seats tested for their hardness. 

Unleaded fuel is really no problem at all - lead was the work of the Devil. Lead did do a few things for us, but it may have actually done more harm than good. Lead in gasoline contaminated our oil, it fouled our plugs and it loaded up our oil control rings. Modern cars that run on unleaded fuels last longer, run better, and go further between services. We often see the modern Porsches of the unleaded era run for well over two hundred thousand miles without requiring major mechanical work. 

However, besides acting as an octane booster tetraethyl lead acts as a shock absorber between the exhaust valves and valve seats. The concern we enthusiasts have is for the potential of excessive valve seat recession or pound-in because of being run without leaded fuels. The reason that lead is so important to these older cars with "soft" seats is that the lead acts as a lubricant between the valves and the valve seats, cushioning the valve each time it seats to prevent exhaust valves and/or seats from recessing or pounding-in. In older Porsches, with their softer seats and valves there is some cause for concern. The newer cars, from 1977/78 on were designed so they could run on unleaded gasoline. In 1978, when Porsche started to use catalytic converters to meet the emissions standards requiring the use of unleaded gasoline, they changed the valve seat material to an sintered iron material that they call Pluko. Just how hard are "soft" seats and how hard do they have to be to prevent recession or pound-in. Really soft seats are cast iron seats with a hardness of from Rockwell 12 to 25. Seats with a Rockwell hardness of 45 to 50 are probably hard enough in most cases to provide for satisfactory protection. 

I have hardness tested the exhaust seats used in a number of our different Porsche cylinder heads. I checked the following heads with the following results:

1. 1966 911 head RA 65
2. 1969 911 head RA 54
3. 1976 911 head RA 64
4. 1.8 914 head RA 59
5. 1.7 914 head RA 44
6. 1962 356 head RA 64
7. 356C/912 head RA 58

None of these seats can be considered "soft" seats and as such they should not cause any problems with unleaded gasolines. Additionally all of the Porsche engines built since 1964 have some form of valve rotators. Their favorite is to use the ATE style keepers which do not hold the valve tightly, so that the valve is free to rotate. This has served them well and only the 924 engines had a separate valve rotator. So we should be able to use unleaded gasoline without any additional changes. However, the best way to keep track of what is happening until we are sure, will be with more frequent checks of the valve clearances. Obviously, if the valve clearance changes over a short period of time, some changes will have to be made to the exhaust valves and/or seats. 

It is also interesting to note that when lead was introduced to gasoline in 1923 there was very similar concern about the effect on the engine's valves and valve seats because of the addition of lead to gasoline as there is today with the removal of lead from the gasoline. At the time the engine designers felt that the lead caused a serious service problem with the spark plugs and exhaust valve damage caused by the corrosive effect of lead oxide. The designers forged ahead and used lead as an additive because of leads superiority over all other antiknock additives of that era. With higher octane gasoline the engine designers could use higher compression ratios to achieve major gains in both power and fuel economy. During this period of automotive history the designs and materials used in high-compression engines made tremendous improvements over a very short period of time. These included special alloy exhaust valves, and seats and sodium cooled valves all to combat valve and valve seat erosion, caused not by the removal of lead, but the addition of lead to the gasoline. With the introduction of lead to gasoline the octane number was increased from about 50 to todays 90+ for high octane unleaded gasolines making possible a boost in compression ratios from 4 to 1 up to the 9+ to 1 used by all of our modern Porsche engines. Because of advanced catalytic cracking methods and other octane boosting additives the gasoline companies find it easier to make high octane unleaded gasolines today than they did sixty years ago so the removal of lead from our gasoline hasn't caused much problems. 

Engines that are run on unleaded gasoline burn cleaner and will run much longer between tune-ups than cars that are run on leaded gasolines. All modern normally aspirated Porsches (4, 6 and 8 cylinders) have a recommended service interval of 15,000 miles including the oil change intervals and the turbocharged cars have a recommended oil change interval of 7,500 miles. Bosch has 30,000 and 50,000 mile spark plugs and the unleaded fuels are largely responsible for these extended service intervals. It also looks like engines that have been run on unleaded fuels will last longer than those run on leaded fuels, it is not uncommon for 911 SC engines to run for 175,000 to 200,000 miles without requiring any major maintenance. 

I have offered to write an article for 911 & Porsche World, which would include most of the above information, but Chris didn't seem too interested, perhaps I should ask the Post. 

Porsche never really wanted to say much beyond what I mentioned about the seat material. PCNA has never really said anything about the potential effect of unleaded fuels. Here in California the leaded fuels have been gone for most of this decade and we have really seen no negative effects are a result of the absence of lead. 

To your point about the amount of power used, my expert said that the only to examples that he could think of where people might have problems were Power boats where you run at full power for extended periods of time and possibly with one of the old VW busses heavily loaded pulling a very long very steep grade. Everyone will worry about the potential problem until sometime in the future when it dawns on everyone that everything has gone on as normal and that the cars have had no problems. Everyone will pretty much have to experience that for themselves as they have over here. Young people over here don't know any better and think unleaded fuels are just fine.

Daytona with Joel

911 and Porsche World

This year I went to the Daytona 24-hour race with a good friend, Joel Reiser, who just started racing this past year. I have known Joel Reiser for ten years or so, we met because we are both Porsche enthusiast and share the interest in modifying Porsches for more performance. He contacted me because he had read my suggestions for modifying the 911SC engines in my Porsche 911 Performance Handbook and had some questions. He contacted me to find out how to modify a 911 SC that he owned at the time and he and I became great friends. 

Over the years Joel got involved in the Porsche Club of America Drivers Education events held at the different tracks in the north eastern United States and in Canada. He has run PCA drivers education events for the past eight year and instructed for the past five. Joel kept buying newer and better cars to participate in the club events, but he also continued to modify all of his cars. I tried to talk Joel into running in some of the club races, but because of the modifications that he made to his cars they were always unfavorably classed so he never ran any of the club races.

Then last fall he ordered a factory 993 RSR which was delivered in late December 1997 as a 1998 model. His first event with this car was a test session in June, which was the first time he had ever driven on slicks. A couple weeks later he entered his first PCA club race in the RSR at Mosport July 27, 1998 where he placed second in GT2R. Joel told me he had a fantastic time an that the thrill of passing the other guy was a lot more fun that he thought it would be. He said that passing cars added a whole new dimension to cars for him. 

In early July Joel also bought Jochen Rohr’s GT1 car which he immediately started racing. He raced it in the 50/50 at Watkins Glen and four top ten finishes in the Canada Challenge Cup races at Mosport. Joel’s racing carrier was limited to these races before entering the Daytona 24-hour race in January. 

After Joel got the GT1 car he met Tony Callas who had a great deal of experience with GT1 Porsches, a lot of that experience with the car that Joel bought from Jochen Rohr, both with Rohr and the previous owner the Roock Brothers. Tony has been involved in racing since he was a kid starting with his father, racing their 910 and RSRs. Tony moved to California in 1985 working for several prestigious Porsche shops before starting his own Callas Rennsport in 1992. The past few years Callas has worked for several name teams including the New Zealand New Hardware team in 1996. I first met Tony Callas at Daytona 1996 when he was with the New Hardware team. He has also worked for Rohr Motorsport, Roock Racing and Champion racing. Tony was a member of the Rohr GT1 team that won their class at Daytona in both 1997 and 1998 and won the GT1 class at the Petit Le Mans with the Champion team. He was alto the lead engineer for the Rohr Motorsport team when they won the GT1 championship in 1997 with the Porsche GT1 car. 

Joel and Tony Callas hit it off personally and decided to do more together than just the GT1 racing. Joel shipped his car from his home in NY to Tony Callas’s shop in California with the idea that they would run the car in some of the west coast PCA club races. Instead they decided to race the car in the January 24-hour race and started making plans toward that end in November. 

They started rounding up drivers for the race and planned a test session at Willow Springs December 21, 1998. By then three drivers had been selected, Joel, Grady Wilingham and Johnny Mowlem. 

Joel is 39 years old the Chief Technical Officer of Matamor Software Solutions which is headquartered in Rochester, NY. Metamor is one of the teams sponsors. Grady Willingham is 35, from Birmingham Alabama and entering his seventh season of racing. Grady has class wins at Sebring, Road Atlanta and Road America. Grady has raced at Daytona the past three years scoring victories in all three races. He has also claimed a victory in his class in the HSR/Rolex Enduro at Road Atlanta in 1995. Johnny Mowlem was referred to Tony Callas by his friend Allan McNish. Mowlem is 29 years old from Great Britain in his ninth season as a professional racer. Most of his experience has been in formula cars, with a change to the Pirelli Porsche Cup series in 1996. In 1996 he recorded a class victory and a second overall, he was back Cup racing again in 1998 where he wan first overall. The Daytona 24-hour race was his first endurance race. 

After the test session they were lucky to add David Murry to the driver line up for the race. Murry who is 41 and lives in Atlanta, GA and is the most experienced of the driving team. Murry has been racing since 1981 and has recorded three championships, the most recent SCCA’s World Challenge drivers championship. 

This was Johnny Mowlem’s first endurance race so I was interested in his impressions of the race. He said that in the test at Daytona early in January he was impressed with being there. He said that the green grass in front of the pits is like a putting green and then behind that you see a wall with Daytona on it and all of the grandstands behind that, it really makes a big impression. He said that at most road courses like Le Mans and there is no real land mark that you can look at and say well, that’s Le Man, whereas Daytona is so obviously Daytona. Was really excited to be there. When they asked him to qualify the car during one of the qualifying sessions he said he was really honored that they would ask him with David Murry on the same team with so much more experience at Daytona. 

He said that it was nice to work with David Murry, because David was so helpful. It gave him a lot of confidence to be able to run the same sort of time as David. Johnny and David were able to work together on the setup of the cars and then to be able to go out and qualify the car was simply fantastic. Johnny told me that he never ever thought that they would finish the race, not that he didn’t’ think that they would finish, but he said he just never thought about them finishing. He said he just assumed that they wouldn’t finish, until he got back from resting read to drive again at about eleven in the morning, twenty two hours into the race and the car was second in class and eighth overall in the race. He said he remember thinking then maybe we are going to finish and do well. He didn’t realize that the car had stalled already and David had gotten it back to the pits and saved their position.

Johnny got in and drove for the last hour an a half in very slippery rainy conditions. The team wanted to leave David Murry in the car because he was used to driving the car in the rain there as he was in the car when the rain started. However, to leave Murry in until the end would exceed the four hours continuous driving allowed by the rules so the team had to change drivers. Johnny was anxious about getting in while it was raining with the car in a good position for fear he might have a problem learning the wet track. He felt that it was going to take two or three laps to get to know the track without throwing it into the wall. The O7 closing down on their second place car and he was concerned that he might loose second position while he learned the track in the wet. There was a lot of pressure on him to do well and maintain their second position. During that last hour one of the Ferraris in the CanAm class went by him that had problems earlier but was again running well and passed them for eighth overall dropping them to ninth overall. 

Johnny said that at the end of the day Joel has the enthusiasm and commitment to do the job properly, Tony Callas is unbelievably good as a crew chief, particularly when it came to dealing with the car. He said he enjoyed it so much even though he was so tired at the end of the race and had sores on his hands. It was so much to take in, but he felt so happy for Joel and Tony that he didn’t really feel any happiness for himself until he got home and had time to think about it. Afterwards he said he thought about it and thought wow that it really good for his career as a race drive. He said that when he got home people were ringing him up and telling him you have done yourself so much good. He said that at the end of the race he was just happy for the guys and happy that the race was over, because there is nothing worse than being the one that is sitting in the car when it stops.

He said it was a wonderful experience for him, it worked out absolutely perfect. It was such an adventure to start out they rang him up about the twelfth of December and two weeks later he was in California testing at Willow Springs and a month later they were finishing second in the race at Daytona. That is like the sort of stories you have in a comic books. 

He said that David Murry was very helpful. When he knew he was going to be driving with David Murry he told Allan McNish, and Allan told him that he was a perfect guy for him and that he would help him and not try to hurt him. And he will be a really good guy to learn about 24-hour races from. Johnny said that everything McNish said was true, he was a great guy and he gave him a lot of advice and helped him the whole way through. He said he told him that when he got out of the car not to hang around the pits, even if it is day time, but to go back to the motor home and lay down even if he couldn’t sleep. Lay down, relax, drink, eat bananas and don’t start getting caught up in the race because it will catch up with you. He said he was glad that he took Murry’s advice, because if he had stayed in the pits until nine or ten at night and then had to do night driving he would have been finished. He said that advice like that was very helpful for him because David Murry really knows what he is doing. He said that this was his first ever 24-hour race and that he was happy to have started with this team and David Murry. 

David Murry said that the teams plan was to qualify the primary number 02 car for the race. But that between the early January test at Daytona and the race Joel Reiser had purchased a second RSR that the team planned to qualify and then start in the race, but not run the entire race. With the two cars they would have more time for all four drivers to become familiar with the track and the 993 RSRs. They didn’t have enough time to race prepare the second car nor the crew to run the two car in the race. The new number 92 RSR is red and was fitted with basically the same spring rates and set up as theyhad on the primary car. Joel Reiser and Grady Willingham spent most of their time driving the red number 92 car to get more track experience while Johnny Mowlem and David Murry worked on setup in the number 02 car getting it ready to run in the race. Thursday was practice and qualifying so they didn’t have much time to get everything done before it was time to qualify, which is why having the two cars was a real benefit for the team. 

During qualifying on Thursday David Murry took the white number 02 car out on a light fuel load to qualify it. I took Murry awhile to get a couple of clear laps and qualify and by then he had run out of fuel, but by the checkered flag he had qualified fifth. The plan had been to have Johnny Mowlem qualify the red number 92 car, but they were experiencing ABS problems and the car did not get out during the Thursday session. Thursday David Murry said that the had a chance to change the set up on the white number 02 again and it was better. It was a two hour session and everyone got some time in the primary number 02 car during the night practice.

Friday the plan was for Johnny Mowlem to qualify the number 02 car and David Murry to qualify the red number 92 car to make sure that it was in the race just in case something happened to the primary car at the start of the race. The red number 92 car was again troubled with some brake problems and team manager Tony Callas most of the final qualifying session to solve the problem. They just got the car out at the end of the session in time for one lap of qualifying. The one lap was good enough to qualify the car for the race so both cars were qualified for the race. 

David Murry said that it is really hard to understand what it takes to do well in a long race until you have done one - or more. Joel and Johnny had never done an endurance race before and he was surprised at how quickly that they they figured it out. Murry started the race 6th in GT3 and by the end of his first driving sting he was in 4th place. Johnny Mowlem started the red car and ran it for about 20 minutes before retiring it. Then Johnny took over the primary car from Murry and when he turned it over to Grady Willingham he was 3rd in GT3. David Murry said that they were looking pretty good after the first round of driving, but it was very early. Grady drove his stint and turned the controls over to Joel Reiser. They did that same rotation again through all four drivers and were still 4th. It was going to be a tough battle. The Alex Job Porsche had led from the pole and was very strong. There car was more extensively developed than the Reiser/Callas car so they weren’t able to run quite as fast a pace as the lead car, but even so they soon found themselves 2nd in the GT3 class with the G&W #07 very close behind. 

Murry said that in the morning, around 9 AM with four hours of the race to go it began to rain. The rain came down very fast and hard, hard enough for USRRC to go full coarse yellow. David Murry knew the track conditions and drove most of the rest of the race. He couldn’t finish the race because that would put him over the 4-hour straight driving limit that USRRC has set. The plan was to put Johnny Mowlem in for the last hour plus to finish the race. The team was confident that Johnny could finish the race. He was "very" quick and would adapt to the conditions instantly. Johnny an incredible job to finish 2nd in GT3 and 9th overall. The #07 car had an axle break just before the finish but fixed it to finish 3rd in GT3. 

I spent most of my time at Daytona either out photographing the cars on the track or hanging out in the pits taking photos of the various GT3 teams doing their pit work. The Reiser/Callas Rennsport team was a well organized team with good team members and most of their stops went well. Tony Callas’ dad Mike was on the crew and about dawn I was talking with him and he said that he remembered why he had quit racing before. All of the leading GT3 teams did well, but they all had minor problems in the last few hours of the race that because the each had their own problems had little effect on the outcome of th e race. The lead Alex Job car, number 23, had and axle fail that they had to replace. The third place G&W Motorsports, number 07, car had a similar problem. While the second place Reiser/Callas Rennsport, number 02 car, had an oxygen sensor fail and the car died out on the course. Fortunately David Murry was able to get the car running again and return to the pits where Tony Callas could diagnose and repair the car and get it under way again.

Guest Speaker

911 and Porsche World

I am a third generation Californian, I was born and raised in the Santa Clara Valley in California, which you may recognize as our renowned Silicon Valley where we have had our high tech revolution. My first career was in the electronics industry where I was a technical writer. 

I was a regular at the sports car races in the early '50s when there were local tracks at the Fair Grounds, Moffett Field Navel Air Station, Golden Gate Park in San Francisco and of course the famed Pebble Beach. My interest on sports cars became focused on Porsches after a ride down Dry Creek Road, which was the only winding road within several miles of my home in 1955 in a friends 1953 Porsche normal coupe. For any of you who have had the opportunity to recently drive a pre-A 356 you may wonder why I was impressed, but that was a long time ago and that was the way it was. Up until then the only sports cars that I had ridden in were MGs and Austin Healys. 

From that first ride in 1955 I have had a love affair with Porsches every since and had an abiding interest in the advancements in Porsche technology. I can remember going to a car show in a local shopping center in 1956 and marveling at a new 356A model with its 15 inch wheels, improved suspension, and curved windshield, this was a truly advanced wonder for its time quite a technical improvement. 

I purchased my first Porsche in 1961, a shiny new ruby red Super Karmann Hardtop, from our local dealer Norm Anderson VW-Porsche in San Jose. Since then I have owned eleven more Porsches and currently own a 356 Speedster and a 944. Among the colossal errors of my life are some of the cars that I have sold including a 1959 GT Speedster and a 1964 SC GT Coupe. 

I joined the Porsche Club of America (PCA) in 1964 and have been active in the club for many year on both a local and National level. I have attended twenty of the annual Porsche Parades.which are a national gatherings of the faithful for fun and competition. I received the top score on the Technical Quiz that is sponsored by Bosch at three of the parades and won my class championship in autocross at the 1973 Porsche Parade in my 914-6. I retired from autocrossing in 1976, after 12 years of competition and several class championships in both PCA and Northern California Sports Car Council events. I like the technical aspects of Porsches and have served the club as the national Technical Chairman for PCA since 1981. 

Seriously competing in concours is a generally accepted way of proving oneself to be slightly bonkers, in case there's room for doubt. I set out to dispel any doubts by showing my 1964 SC GT from 1969 through 1971 winning a lot of shows. My favorite victories were Best of show at a Porsche Club West Coast Weekend Meet and wins at the Pebble Beach Concours and Hillsborough Concours. Since 1971 I have confined my interest in concours to just judging at local shows and the national Porsche Parades. 

In the 1960s a friend and I started a Porsche performance business at his home in his garage. We started by modifying and tweeking our own cars and our friends cars for autocrossing and club competition. This business grew into a full time business in the early 1970s as Garretson Enterprises. We had a great deal of fun with our Porsche business preparing cars for others and racing around the world. I was part owner and General manager of for about ten year before we sold the business and all went our separate ways. 

Our first racing program was for our friends the local Porsche Dealers and the distributor, Porsche Cars Pacific. We ran a 914 for them in the 1972 and 1973 seasons. Next we prepared cars for off road racing and Pikes Peak, where we won in 1976 with Rick Mears driving and Gary Lee Kanawyer in 1981. Over the years we established a winning record with the cars we prepared winning the IMSA GTU, GTX and GTO championship and the Porsche Cup, the FIA World Endurance Drivers Championship and the Porsche Team Cup. The past couple of years we have helped some friends in Show Room Stock racing with their 944s, winning the 1986 Pro-SSGT Escort series. 

I first became acquainted with 911s during the winter of 1966/67 when some friends and I bought a half a dozen engines that were badly damaged, but not lost, in a shipwreck in the Azores. These engines had started out in cars, but when the ship that they were being transported in was rammed by another ship the 911s broke loose in the flooded hold. Please note that I said engines, my first 911 experience was just with the engines. I didn't actually work on one of the cars until about a year later when we installed one of our refurbished engines into a 912 making it into a 911. By the time we had resurrected all of our engines we had all learned quite a bit about the 911 engines and cars. My Porsche education continued with my rebuilding and hot rodding 911 engines, and working on the race team. My education continues today as I help others learn about these great cars with my technical articles and books; by offering instruction in training courses on the Porsches and by giving technical presentations lectures on the 911 engines. 

Because of my love affair with Porsche and because I am racing enthusiast I am really disappointed that Porsche has strayed from their focus on the sports car racing. I feel that it was because they focused on this one form of racing that they did so well. It took Porsche more than three decades to build the reputation that they are allowing to be eroded away by their lack of focus over the past five years. First they strayed away into CART Indy car racing in the United States and more recently they have gone back into Formula 1 racing with Footwork. Both of these efforts were misguided and failures and have certainly done more to tarnish the Porsche image than build it. I am sure that if the same effort had been expended on a more modern sports car that Porsche and their racing customers would still be world contenders in sports car racing rather than the grid fodder that they have become.

Garretson's 935

911 and Porsche World

This is a special story about a very special Porsche 935 that was raced for more than 70,000 miles. The story actually starts a little earlier, but is mostly about this remarkable 935 that not only raced as a 935, but also masqueraded as a 934 and as a 930S, whatever was necessary to make this remarkable car eligible for the various racing classes in IMSA. Our story actually begins before this car was built and includes a little of the history of Porsches turbocharged 911s and some of the various different racing cars derived from those turbocharged 911s. 

A prototype 911 Turbo was first shown at the Frankfurt Auto Show in September 1973 to test the market potential of such a car. The production version of this car was introduced at the 1974 Paris Auto Show and then put into production as the type 930 Turbo Carrera in 1975. The original purpose of the Turbo Carrera was to gain homologation for the Group 4 and Group 5 cars that Porsche originally intended to race in the Manufactures Championship from 1975 on. To qualify as a Group 4 Grand Touring car a quantity of at least 400 units had to be produced over a period of 24 consecutive months. The original plan was to build the necessary 400 required for homologation and then cease production, but the car became such a success that it remained in production for fifteen years and in those fifteen model years between 1975 and 1989 over 20,640 the original 911 Turbos were built.

The change to Groups 4 and 5 classes was delayed by FIA (Fédération International de l'Automobile) from 1975 for one year until 1976. In 1976 when the rules for the World Championship of Makes were finally changed by the F.I.A. Porsche produced two new 911 based racing cars for the resulting Group 4 and Group 5 classes, the 934 and 935. The 934 was homologated as a Group 4 car and sold to Porsche's racing customers for GT (Grand Touring) racing, while the 935 was a Group 5 car and only the factory planned to race them. Although the Group 4 rules were really quite strict and restricted the 934s to very nearly to the same production configuration as the 930s the Group 5 rules were a much more liberal. The Group 5 class was based upon silhouette formula where the cars were offered a great deal of latitude as long as they resembled the basic silhouette of the car from which they were homologated. The rules stated that the aerodynamic devices not homologated for series production must fit with the cars frontal projection. What they mean by this is that when you view the car from the front the rear spoiler cannot stick out into view from the silhouette of the car, and this is in essence what they meant by the silhouette formula.

Thirty one of the group 4 934s were produced for Porsche's racing customers in 1976 and 1977. Most of these cars remained in Europe and competed in the Group 4 category. Toine Hezemans won the 1976 European GT with a 934. Only two of the 935s were built by Porsche for use by the Martini sponsored Porsche factory race team. The Martini team won the 1976 World Championship of Makes with these two 935s.

In the U.S. I.M.S.A. (International Motor Sports Association) had said no to the Porsche Turbos preferring to try to encourage Porsche to continue to build and support the normally aspirated RSRs in their series. Porsche, being a small company could not support more than one racing series at a time with customer racing cars and they had already chosen the Group 4 934 so there would be no more RSRs. SCCA (Sports Car Club of America) welcomed the Group 4 934s with open arms. Vasek Polakbought five and Al Holbert one to race in the popular SCCA Trans-Am series. Several different drivers drove the Polak cars over the year, but George Follmer drove for Vasek most of the season and was rewarded for his efforts with the 1976 SCCA Trans-Am championship. Al Holbert spent most of his time with his Chevrolet Monza winning the I.M.S.A. championship and had little time to race his 934 in the Trans-Am series.

For 1977 I.M.S.A. not only relented and let Porsche's customers race turbocharged Porsches, they also relaxed the rules letting an even more potent cross between 934 and 935 called the 934/5 or 934 1/2 compete in their series. Porsche produced a special series of ten special I.M.S.A. legal 934s which took full advantage of the more liberal I.M.S.A. rules and used many of the mechanicals from the 935. The I.M.S.A. cars were able to run with a lighter weight, wider fifteen inch wheels, tires and fenders, larger group 5 rear aerodynamic wing and the Bosch plunger- type mechanical injection instead of the CIS system. This change was to make the cars faster, more pleasant to drive, more reliable and able to produce nearer the 600 horsepower of the 935 instead of the 500 horsepower of the Group 4 version.

In Europe, over the 1976 season, a number of Porsche's racing customers had been converting their Group 4 934 racers to Group 5 specifications, so for 1977 Porsche also produced a small series of thirteen cars (Type 935/77) for their customers to race in Group 5 with. The new cars were a customer version which were in effect replicas of the two original 1976 factory single turbo 935s (Type 935/76).

For the 1977 season the factory team had a new 1977 version of the 935 for their own use. The factory 935/77 was quite different from the customers version and had new body work which had running boards, a new front end that had fared in mirrors at the edge of the fender which also served as fences to keep the air from spilling off the front end improving the downforce on the front end. They also had a raised false roof section to clean up the airflow over the back of the car making the rear wing more effective. The running boards were used to improve the air management and were the beginning of efforts to provide some ground effects for the 935. The rules said that the car had to retain its original rear window in its original location, but it did not say that there couldn't be a second rear window over the original so that's what they did. This new false roof faired into a new rear wing, and they used the edges of this false rear roof section as air inlets for the engine. This car again won the world championship of Makes for Porsche with the help of several of the customer teams racing the customer version of the Porsche 935.

I.M.S.A. decided to let people update their 934s to 935 specifications and also to let the 935s race in their series in 1978. Our story starts with the very last 935/77 built. Californian, Dick Barbour added the car to his team at the beginning of the 1978 season where it was a solo entry by the team at the first race of the season, the Daytona 24 hour race in Florida, in early February 1978. It was a good start for the team, Barbour, Manfred Schurti and Johnny Rutherford drove the teams 935/77 to second place to the German GELO team's 935/78 that was entered by Brumos Porsche and Driven by Rolf Stommelen, Tony Hezemans and for a one hour stint by Peter Greg. The next race for Barbour's 935/77 was Sebring where the car qualified second but did not finish. However, another Barbour team 935 driven by Brian Redman, Charles Mendez and Bob Garretson won Sebring so the Barbour team was improving on their good start. Barbour drove again with Johnny Rutherford at Talladega Alabama where they placed third. Barbour drove his 935/77 solo to a sixth place finish at the May Laguna Seca race in Northern California, which was the fourth time, and turned out to be the last time, he was to drive this 935/77. 

From 1978 on Porsche left the defense of the World Championship of Makes, which was based on these Group 5 cars to their customers. For the both the 1978 and 1979 seasons the Porsche customers did bring home the World Manufactures' Championship for the Porsche factory. To encourage the private teams to compete in the manufactures championship Porsche created what they called the "Porsche Team Cup" to be awarded to the private Porsche customer team accumulating the most points in races counting towards the World Manufactures Championship.

The Martini sponsored factory team only raced one 935 in 1978 "Moby Dick".The "Moby Dick"car was built with an aluminum roll cage/tube frame, the center section of the car was lowered and the floor section was raised up to regain the ground clearance. All new body work was developed to take advantage of the car's lower profile for improved aerodynamics. "Moby Dick" was created with the intention of doing well in just one race, Le Mans. At Le Mans the emphasis is more on straight away speeds rather than cornering speeds so the cars aerodynamics were compromised towards high speed rather than downforce. "Moby Dick" only raced four times and only won at Silverstone, but the concepts it established had a great influence on the future of Group 5 racing and Group 5 racing cars. Some of the features of this car were larger brakes, improved aerodynamics and its upside down transmission. The upside down transmission was utilized to reduce the severe angle of the rear drive axles created by lowering the car as much as they had with the larger diameter 19 inch wheels and tires.

For 1978 Porsche built a series of fifteen customer 935s (Type 935/78) and let their customers defend the World Championship of Makes. The cars looked very similar to the first series of customer cars, but they had some refinements and they did have a twin turbo version of the 935 engine similar to those that had been used by the factory's Martini sponsored cars in 1977. These twin turbo engines offered a big improvement in drivability and as a result reduceed lap times every where that they ran. The bodywork of these 1978 customer cars was a little different from the 1977 customer version in that the rear fenders were removable for the first time on the 935s. This made the cars much easier to work on and of course easier to repair. The rear wing was changed to a two stage wing to provide improved rear down force.

Barbour bought one of these new cars for his team in June 1978 for the Le Mans race. Barbour ran a two car team at Le Mans with Bob Garretson, Steve Earl and Bob Akin driving Barbour's old 935/77 while Barbour, Brian Redman and John Paul drove the new 935/78 in the race. Barbour's car did well and finished fifth overall and first in the I.M.S.A. class. The 935/77 did quite well for the first half of the race, running as high as 18th place. At 4:55 am, less than an hour past the half way mark, Garretson had a terrifying crash at the kink on the Mulsane straight where the cars are at their fastest, which for the 935s was 190 to over 200 mph. Garretson said that he thought he had caused the accident by getting a little off line while passing a much slower car. When the car crashed it rolled end to end and side to side until the wreckage was strewn over a quarter of a mile and left some of the body parts stuck in the nearby trees. The car was destroyed, but Garretson was only battered and bruised. 

Like the Phoenix the wrecked 935 rose again from its ashes. The team shipped the wrecked car back home to the United States for a salvage operation. The car was completely stripped of any parts that might be usable and the rest of the car was discarded. In May of 1979 a complete new chassis was purchased from the Porsche customer racing at Werke I. The made in "Mt. View, California by Garretson Enterprises" 935 was constructed from this new 935/79 chassis, the salvaged parts, and some new parts. Mountain View was the home of Garretson Enterprises so the team felt that this slogan was appropriate.

Again for the 1979 season Porsche produced an updated version of the 935 for their customers to defend the World Championship of Makes title, a series of 13 of these cars were built when you include those built from "tubs", or spare chassis. The 935/79 incorporated some of the innovations from their 935/78 "Moby Dick" and was the basis with which private teams were able to continue to develop their own more competitive versions of the 935.

The tub or chassis for the resurrected race car was one of these updated 935/79 replacement chassis, chassis number 0090030. The new car, which was built to the 935/79 specifications was completed in time for the June 1979 running of Le Mans, where Rolf Stommelen, Paul Newman and Dick Barbour drove it to second overall and first in the I.M.S.A. class. This car was but one of four cars entered by the Barbour team for the 1979 running the Le Mans race, one of the team cars failed to finish while the other two team cars placed eight and ninth. Stommelen, Newman and Barbour were teamed again In July for the Watkins Glen in upstate New York six hour race where they also placed second. The car was raced only once again by Barbour in 1979 at Elkhart Lake Wisconsin where it was a DNF with a broken rear trailing arm.

The car that had beaten Barbour's 935/79 at Le Mans was one of the Kremer Brothers 935 K3s. The Kremers had developed their K3 935 for their own use during the 1979 season. In 1979, the Kremers won 11 of the 12 races in the German National Championship in addition to their win at Le Mans. In 1980 the Kremers built replicas of their winning K3s and sold them as customer cars to anyone who wanted to win. In addition to the Kremer K3s they also sold several conversion kits so that 935 owners could convert their own 935s to K3 specifications. 

For the 1980 season Barbour bought one of the new K3s from the Kremer brothers for himself and co-driver John Fitzpatrick to drive. With Sachs sponsorship for the 1980 season Fitzpatrick was able to win both the 1980 Porsche Cup and the IMSA championship with this K3 935. The Made In Mt. View 935 remained in the Barbour Racing team, but the Bob Garretson team was the cars new owner. The old war horse's first race in the 1980 season was the 24 hour race at Daytona where Garretson finished ninth with Anny-Charlott Verney and Skeeter McKitterick as co-drivers. Before the cars next race at Sebring Florida the 935 was converted to Kremer K3 specifications using one of the Kremer's conversion kits. At Sebring, with Apple Computer sponsorship, Garretson, Bobby Rahal and Kees Nierop raced to a seventh place. The cars next race was at Riverside Raceway in Southern California where Rahal and Garretson placed second to Barbour and John Fitzpatrick in the other team car, the teams real Kremer K3 935.

That was the last time that the car did well for awhile as the car was a DNF at both Le Mans and Watkins Glen. In the July sprint race at Sears Point Raceway in Northern California Rahal again placed second to teammate Fitzpatrick. The car again DNF'd at Mosport when Garretson had an accident, and then a week later Rahal qualified on the pole at Elkhart Lake and he and Garretson drove to a third in the race.
For the 1981 season the Garretson team separated from Barbour and went off on their own. The Made in Mt. Veiw car was again modified to improve its performance, the suspension was revised front and rear and the body work was altered to provide better aerodynamics and improved intercooling for the engine. The Garretson teams engine builder, Jerry Woods, also redesigned the air-to-air intercooler system to further improve the intercooling for both more power and improved reliability. Garretson raced the car most of the 1981 season with various different co-drivers to win the 1981 World Endurance Drivers Championship and the Porsche Team Cup for the Garretson Team.

The 1981 season started at Daytona where Garretson, Rahal, and Brian Redman won the 24 hour race. With the same drivers at the Sebring twelve hour race great things were expected of this car, but unfortunately they ended up fifth in class and 17th overall. Garretson got off into the sand and flipped the car. Afterwards a great deal of time was lost because it proved difficult to make a windshield stay in the misshapen roof section.

At Riverside in Southern California Rahal and Redman finished third. The following weekend Rahal picked up a fourth at Laguna Seca in Northern California. The car's next race was Le Mans where Garretson, Anny-Charlott Verney and Ralph Cooke were sixth overall, second in the I.M.S.A. class. Rahal took the car to the July 4 race at Daytona, where an oil leak in a new engine relegated him to 18th place. Garretson co-drove with Johnny Rutherford and Rick Mears to a third place finish at Watkins Glen in upstate New York.

The car had problems at Sears Point California in 1981, breaking a crankshaft and costing Rahal another DNF. The following weekend at Portland Oregon Rahal placed third. The next race for the car was Road America at Elkhart Lake Wisconsin where Tom Gloy and Garretson drove the car to fourth. Then the car was taken to Brands Hatch for the final World Endurance Championship race where Garretson and Rahal placed second, which gave Garretson the 1981 World Endurance Drivers Championship and won the Porsche Team Cup for the Garretson Team.

Garretson and Rahal ran the car one more time in 1981 at the Daytona Finale. The car was delayed with a turbocharger failure and only placed 17th.

Because of limited finances the car was run in only a limited series of races in 1982 as a "renta-racer". When there was money and drivers to run the car it went to the races and when there was no money it stayed at home. At the Daytona 24 hour race Garretson, Jeff Wood and Mauricio de Naverez were third. At Sebring Ray Ratcliff, Grady Clay and Skeeter McKitterick placed seventh. Ratcliff and Clay were were fifth at Riverside and fourth at the Charlotte 500 Km. The car's finale race for 1982 was Le Mans where Garretson, Verney and Ratcliff placed eleventh. This was the last Le Mans where the Group five cars were still eligible and the first year of the Group C car, this was the race where the Rothmans Porsche 962 placed first, second and third.

At the end of the 1982 season, Southern Californian Wayne Baker bought the 935 from Garretson so that he could convert it to "934 specifications" and race it in the I.M.S.A. GTO class. I.M.S.A.'s GTO class was very loosely based on the F.I.A. Group 4 rules, the class where the original 934s were built to race in 1976. The I.M.S.A. GTO rules were less restrictive than the F.I.A. Group 4 rules and allowed many of the developments from the faster 935s. I.M.S.A.'s rules did, however, require that the cars physically resemble the 930 street turbos from which they were derived. This meant that all of the trick aerodynamic 935 body work had to go. The wheel size was also restricted to 12 X 16 instead of the 15 X 19 inch wheels that the car had been able to use as a 935. They also were required revert back to the single ignition and single turbocharger concept of the street 930 Turbo to comply with the rules. Baker felt that the rules had been made liberal enough by I.M.S.A. to give a well prepared 935 back dated to "934" specs a chance at the GTO championship.

Baker kept on most of the crew from the Garretson Team who had originally built the Made in Mt. View 935 in 1979 to convert the car to GTO specifications and crew the car at the races. They spent a month converting the chassis to make it more suitable as a GTO competitor. For 1983 the GTO rules required that the car weigh more than it had as a 935, so it was decided to take advantage of the additional weight to make the car stronger and to add some other features that would make the car more reliable. Baker designed and had new fiberglass bodywork made that would meet I.M.S.A. GTO requirements and still provide a reasonable amount of aerodynamic assistance.

The 3.2 liter 935 engine was modified to take advantage of as many performance opportunities possible while complying with the restrictions imposed by the GTO rules. Jerry Woods who was responsible for the engine took advantage of the fact that the body work was being completely redesigned to incorporate several improvements in the engine design. The bodywork change allowed him to design a new induction system with a very larger rear mounted air-to-air intercooler. Woods felt that the large twin inlet single turbo from the I.M.S.A. version of the 935/79 would offer performance similar to the twin turbocharged 935 engine if properly utilized. To facilitate the large twin inlet turbocharger Woods designed a pair of new equal length three-into-one headers, each with its own wastegate. The engine development program was very successful and the single turbo I.M.S.A. "934" did have performance similar to when it was a twin-turbo 935. Baker felt that it was critical to maintain engine performance at a level similar to what it had been as a 935 because the other restrictions: smaller wheels, higher weight and restricted aerodynamics were going to seriously restrict the cars overall performance.

The goals that Baker and Woods had set for the team and their converted 935/934 were to win GTO races, place well overall and win the I.M.S.A. GTO championship. At the first race of the season the Daytona 24 Hour race the car was not fully developed, but even so the car placed ninth overall and fourth in the GTO class.

The next race was the first race to be held at Miami Florida, which turned out to be more of a regatta than a road race, boy did it ever rain. Baker got tangled up with a spinning car in the rain and was a DNF. Sebring brought the success that the team was looking for and Baker, Kees Nierop and Jim Mullen won their class and first overall. This was the fourth Sebring 12 hour race that Woods had won as an engine builder and marked the first time that a GTO car had ever won that prestigious race. At Road Atlanta in Georgia, the car won its class and finished eighth overall with Baker and Mullen driving. Riverside California produced another class win for the team and a fifth overall. An accident at Laguna Seca in Northern California resulted in a ninth overall and a fifth in class finish. At Charlotte North Carolina, Baker and Mullen again won the GTO class and were fifth overall. At Lime Rock Connecticut they were second in GTO and fifth overall.

At Mid-Ohio the team had an unusual problem when the starter ring gear exploded in the last third of the race, destroying the transmission case, some of the wiring and some of the linkage for the fuel injection system. The mechanics made some quick repairs and drivers persevered to get the points and placed eighth in GTO and 24th overall. At the July 4th race at Daytona Baker and Mullen placed seventh in class.

In an effort to gain an unfair advantage over their competition the team went to Sears Point in Northern California a day early to tune-up both the car and the drivers for this tricky circuit. During their practice session Mullen had what should have been a simple off road excursion. The problem was that he came to stop in tall dry grass and the grass caught fire. By the time the fire was extinguished, most of the rear of the car had burned. The fire had been so hot that the rear view mirror melted.

The crew started working on the car Thursday night to assess the damage so that they could get the parts needed to get the car ready for the Portland Oregon race the following weekend. As they made a list of the parts needed, they discovered that most of the parts that they needed were on hand. When they discovered this they decided to attempt to get the car ready for the Sears Point race, 48 hours away.

It looked like a volunteer fire department with people showing up from everywhere at the Garretson Team shop to try to help get the car ready for the race in two days. Both drivers, the regular crew and all of their friends helped put Humpty Dumpty back together again. The minute the car was completed the crew loaded it in the truck and dashed off to Sears Point. They unloaded the car just in time to make three laps in the last few minutes of qualifying. Their efforts were not in vain; they qualified and the next day they placed third in class and eighth overall.

A week later in Portland Oregon Mullen and Baker were third in class and fifth overall. The teams last effort in the GTO class was at Elkhart Lake Wisconsin where Baker received enough points for their fifth place in class finish to win the GTO championship. Jim Mullen raced at Pocono Pennsylvania with another team and placed well enough to secure second place in the I.M.S.A. GTO standings. The team had achieved their season's goals, placing well overall in several races and winning the I.M.S.A. GTO championship.

Baker converted the old war horse back to 935 specs and returned it to its status of renta-racer for the finale at Daytona in November 1983. The conversion required putting back the 935 body work, wider 19 inch diameter rear wheels and adding the twin turbos and twin ignition to the engine. Baker, Mullen and Tom Blackaller placed 30th in the finale. The same team raced again at the Daytona 24 hour race in February 1984 when they placed fifth overall. Blackaller and Baker placed second at the second running of Miami. Baker, Mullen and Blackaller placed fifth at Sebring. Baker and Jack Newsum placed sixteenth at Riverside California. Blackaller ran solo at Laguna Seca in Northern California placing eleventh. Baker, Newsum and Chip Mead ran the old war horse once more as a 935 at the 1985 24 hour Daytona race where they placed ninth overall.

Chet Vincentz had been running a similar car in selected I.M.S.A. GTO events since 1982. Vincentz had actually showed the way for the 935 to 934 conversions when he and Baker had won the GTO class at the 1982 Mosport Canada event. In June 1985 Chet's 935/934 was badly damaged in a mid-week testing crash at Riverside California where it caught fire and burned to the ground. Vincentz bought the old war horse from Baker and again converted it back to 934 specifications so that it would be eligible to run in the I.M.S.A. GTO events. Vincentz Team used a 962 engine for their 935/934 conversion.

Their debut showed that Vincentz's teams efforts were well spent when they placed second in the GTO class at Road America at Elkhart Lake Wisconsin and twelfth overall. Their next race was Pocono Pennsylvania where they had a fuel injection problem and placed twenty sixth overall and ninth in the GTO class. Vincentz was fourth in the GTO class and fourteenth overall at the Watkins Glen Race in upstate New York. The final two races for the 1985 season were Mid-Ohio where he placed fourth in the GTO class and the finale at Daytona where Vincentz had an oil line fail and was a DNF.

For the 1986 season Vincentz was able to modify the body work back to a slope nose configuration similar to the cars original 935 body work. This had been allowed by the I.M.S.A. rules because Porsche offered a model that they called the 930S which had the front slope nose body work with pop-up head lights.

Vincentz's 1986 season got off to a slow start at Miami Florida where the car was a DNF with an electrical failure. Things got better at the next race at Road Atlanta in Georgia, however, where he placed second in GTO to Scott Pruett and beat Bill Elliott and Bruce Jenner on his way to second place. The next two races at Charlotte North Carolina and Mid Ohio were not too good for the team either with the car crashing out at the chicane at Charlotte and getting caught in a sand trap at Mid Ohio.

The next race was at West Palm Beach Florida where the car was geared wrong in qualifying and was seventeenth on the grid. Vincentz had a great race, passing cars right and left and working himself up into fourth before the checker. At Watkins Glen New York Vincentz placed fourteenth overall and fourth in GTO. The last race for the old war horse in the 1986 season was the street race in Columbus Ohio where Vincentz placed ninth in the GTO race.

Vincentz's 1987 season started off at Miami Florida where the old war horse was again the victim of another drivers accident resulting in another Miami DNF. The team placed a lowly sixteenth at Mid Ohio, but bounced back up to fifth at West Palm Beach. At Road Atlanta they placed twelfth in GTO. The team placed ninth in GTO at both Summit Point and Road America Wisconsin where they were also thirty fourth overall. Vincentz got tangled with a sloppy driver at Lime Rock Connecticut and crashed out of the race. At Watkins Glen the team started tenth and finished seventh in GTO. And at the old war horses final race at the Columbus Ohio street race Vincentz placed twelfth.

Most of the GTO races for the 1987 season had been held separately from the GT races. John Bauer a former SCCA Trans-Am champion co-drove with Vincentz for the whole year, but finally the car was just out classed by the tube frame U.S. domestic race cars running in the I.M.S.A. GTO class.

After the 1987 season Vincentz retired the old war horse to show car status,. The old war horse was run seventy two races, won two major international races, two championships and probably has well over 70,000 racing miles. Our old friend has given a great number of good people a great deal of pleasure and success and is now be given a well deserved rest after being put on display at the Vincentz business, Electrodyne Performance, Inc. in Alexandria Virginia.