One quick Q.. at the last track event I had a massive coolant leak, had vapors of coolant everywhere and even the guys following me were loosing traction because of my coolant all over. The coolant seemed to go somehow to the drivers rear wheel, my coolant pipes are welded and if driving normally the car it looses the level pretty fast now but we are unable to locate where the leak is located or what is the problem.

Were thinking to replace some common hoses, the coolant tank, the coolant valve from the tank, etc... Anybody had this problem ? drives me crazy... missed a very nice event at the track, travelled 500miles each way to race 35-40 supercars and wasnt able to complete even one clean lap. Seems the coolant gets hot, pressure is climbing through the roof and its getting out somehow..

On another note, is there any racing thermostat available for our cars, something to trigger way sooner the fans and keep everything happy ?

 

Yeah, we were all pretty shocked that the same hub (left rear) broke again. The 7GT hub had 2402 track miles (110 sessions = 45.8 track hours) when it broke. Same exact spot as the first hub.

I agree that Porsche put a lot of margin in parts but GT3s or Cups do not put down anywhere near the torque that these modded cars do. The metallurgist told us the failure is a result of the combined lateral loads and the high torque twisting the hub at the same time. I would imagine that running a full monoball suspension with relatively high spring rates of 1400/1500 puts a lot more stress directly into the suspension components compared to someone with a squishier softer suspension set up. I also run an aggressive motorsport LSD which may really put a lot of load on the outside loaded wheel. I discussed the failure at length with Chris Cervelli who set up my car and he basically told me that once you start pushing these cars beyond a certain level you really start to discover where to weak links are. I think were are doing just that unfortunately.

Yes, my gearbox is fully built. I have the 7GT3RS 1-3 mainshaft with the taller RS gears including the wide 3rd gear. I also have a gearbox cooler which keeps the temps in the low 200s even on hot day extended sessions.

Ride height is 96/125 (96/119 when transposed to a 996TT) with 25.5"/26.4" tall tires.

 

Hi Fadi,

don't just change parts when you don't know which one is broken. Do a pressure test on the coolant system, just like you would on the air system. Check your water pump housing and the heat exchanger on top of the engine, behind the throttle plate .

When filling the car with coolant, you use a vacuum system. This is also good for checking for leaks.

Different thermostats won't do anything for you, except extending the time it needs to get you car to operating temperature. Do you have a problem with temps?

Andreas

 

Hi Andreas, no problem with temps as long as the coolant level is normal. When starting to loose coolant obvisously the temps are raising, had once only at 120C but normally when loosing 2-3L of coolant the temps are normal or in the 90s C

I will follow your advice, didnt pressure test the system yet

 

Once the coolant pipes expand from pressure thats when you have a leak. I found my leak when pressure testing from both radiators.

 

I have bought almost all parts form the engine bay related to coolant system, new hoses, sealsm new water tank, etc... Got to the track without testing before as car was ready the night before the track event.

Was able to run 4 laps, when got back I have seen some steam and was AGAIN from the cooland system, engine bay was wet all over but nothing like before.. and no coolant low level, temps on the engine were ok.

After a short break of maybe 30min got back at the track and right after the warm up lap, the hose from the front right radiator was out and wooowwwwwww I was blind at 130mph on the straight line just before the turn... dangerous.... continued the lap with a lot of coolant steam in the back of my car, got to the pits, water was like 100C..

Bought some distilled water, put back the hose and just started the engine at idle... after 2 mins the water was 100C... this was the FIRST TIME I have seen this happening at idle, temps were warm but not hot, maybe 23C or so

Now... I remember this happened for the first time December 2014 when I did 2.2bar on my car, both my oem radiators cracked that night !!! Replaced them with some cheap radiators and at the same track from the yesterday event, at the same spot one of the radiators blew up, thats at the end of a long straight line of 1/2mile (maybe 600m or 1/3mile is the exact spot) when I am keeping the acceleration for a long time

I guess the problem is elsewhere and I am fixing the effect and not the cause... the problem might be the huge pressure in the coolant system.

Now as I did 2.2bar (first time problems) and the high pressure might mean a headgasket problem, what do you think ? I will check the headgasket anyway, but interested if anybody else had this problem and what the fix was, it is driving me crazy already

Just before dropping it to the shop I tried my first set of slicks (pirelli 245/645/18 and 305/680/18) in the parking lot, car was already cold for some time, did just maybe one mile very very easy on the car and it seemed to stay at 90C temps or so...

Also seems the tall 680 fit inside my car, I have aggressive rolled fenders and still no inside plastic liners

 

Before this track event I have replaced all parts from the pics, found some damaged parts and the pic with the rear of the car is made before changing all these parts

 

You got PM.

 

Thanks for the PM

I went in the end with the OEM stuff
-Gt3 4.0/Gt2RS clutch plate
-964 LWFW
-New Sachs pressure plate, rated up to 1040Nm
- all the minor stuff involved
and
- gt3rs engine pulley

Looking forward to having them on the car, going to do 1.8bar max on gt28s on the highway but 99% of the time going to run 1.3bar street and road racing

 

Also ordered new Raceware studs 10mm and Cometic HG and will replace the old ones, my guess is I am running with lifted heads for some time already (December 2014)

Will do also (again) straight pipes and lighter battery + half Cromo rollcage, hope car will be 100% in May

Looking to buy some 997 turbo/gt3 calipers + brake pump and guess should be done for this year

 

What's the part number on that Sachs 1040Nm pressure plate Fadi? 487?

 

You want the GT calipers, not the Turbo ones...

 

Seems that part number is missing from everywhere, bought the pressure plate from FVD Germany and asked them to send me the PN, unfortunately they didnt have the Sachs PN opnly their internal PN, that is

FVD 116 928 1

Pressure Plate - ZF SACHS Racing - 1,040 NM Max., cost was 604Euros+VAT(20%)

 

The number should be on the pressure plate case.

Ok, just looked it up. They list is as a clutch for 964/993 cars. The 1040NM rating is based on using a sintered puck racing disc. With a normal organic street disc like the 4.0 it should be basically the same as the 764 plate. My understanding is that the 487 plate should be the legit 1000 Nm plate. It's bolted instead of riveted. It's about $1200

 

When delivered will look it up for you. Hope I didnt take worng decision with this one, had the alternative to use the classic 764 plate

I remembered from you 427 not 487, obviously wasnt able to find the plate