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Track Day Clutch Failure
- Thread starter GlowRed
- Start date
.This is good news indeed. I had all oils and fluids changed when I bought my Vee in Aug 2011, and the brake fluid once since then. Even though the Vee has been driven properly on the road, I have not taken it on track (yet), so would be interesting to see how it behaves at Origine RS.
Well, guess I was tempting fate, but this exact same thing did happen at Origine RS (Goodwood), even though the fluid was flushed and refilled - Scott did the work.
Clutch pedal went soft on the 3rd lap of my third stint (all in the afternoon) and was completely gone half way through the 4th lap!
Clutch pedal went soft on the 3rd lap of my third stint (all in the afternoon) and was completely gone half way through the 4th lap!
Ali":2on4i6lu said:
The clutch and brake use the same reservoir, however they have independent pipework. Therefore you must drain each independently.
Scott changed the clutch fluid side of mine when I was there. He undid a nut at the back of the car at the engine. If I remember correctly it is made of plastic and he said that it was easy to break without being very careful, and an engine out job to replace
. Fluid was put through the brake / clutch reservoir at the front of the car. I had the hard job of pressing the clutch peddle 
whilst he sorted the rest out.This is exactly what was done on mine a day or two before the Vee went on track - still did not stop the issue. Carl, how was it for you after the clutch side was drained and refreshed? What fluid was used?GlowRed":218pha7j said:Ali":218pha7j said:
The clutch and brake use the same reservoir, however they have independent pipework. Therefore you must drain each independently.
Scott changed the clutch fluid side of mine when I was there. He undid a nut at the back of the car at the engine. If I remember correctly it is made of plastic and he said that it was easy to break without being very careful, and an engine out job to replace
So as I understand it, the fluid boils due to heavy braking but clutch operation is most affected due to both the brake and clutch sharing the same reservoir (and fluid), but didn't notice any brake fade at all. I also had new brake discs, pads (EBC Red Stuff), braided/steel hoses, tyres and changed the transmission oil at the same time.
Eastlmark suggested using Castrol SRF, which is a full on racing fluid with the following properties:
"- Exceptionally high dry boiling point of 590ºF (Wet 518ºF)
- Superior anti-vapor lock properties
- Safe for all non-mineral oil-based disc and drum brake systems"
Castrol SRF being used for racing - from Porsche circles:
"FWIW in my endurance GT2 race car (800+hp) i flush the brake fluid once a season and only bleed twice with SRF.."
In my experience of previously tracking Porsches, ATE Blue was widely used for track days, and was more than fit for purpose.
Kett, I have a Phase 1 clutch, which was required when switching to the TTV lightweight flywheel.
I hadn't heard of clutch-fade before but it makes perfect sense now that I've learned of the shared reservoir.
I thought Goodwood was fairly kind on the brakes as the two tightest corners followed each other.
By contrast, Pembrey near me has two hard-braking hairpins located immediately after the fastest straights.
I thought Goodwood was fairly kind on the brakes as the two tightest corners followed each other.
By contrast, Pembrey near me has two hard-braking hairpins located immediately after the fastest straights.
Goodwood is particularly kind on brakes tbh, which is what surprises me about this whole fade, I haven't experienced it before and I've had the Vee out on a number of harder braking tracks...albeit not since we changed the braking set-up...perhaps a little air? Doesn't seem likely either tbh...weird,
So, the plot thickens, but, for me, not having a reference point doesn't help. One to take away.........
Of course, one's style of driving (such as braking later, and harder) too has an impact on the way a car reacts, but IMO there were only 3 (perhaps 4) areas at Goodwood where one needed to brake sufficiently enough to scrub off speed, which shouldn't really have been an issue.
Of course, one's style of driving (such as braking later, and harder) too has an impact on the way a car reacts, but IMO there were only 3 (perhaps 4) areas at Goodwood where one needed to brake sufficiently enough to scrub off speed, which shouldn't really have been an issue.
rustedandrotten
Well-Known Member
It shouldn't be anything to do with the brakes other than the shared reservoir, problem is the clutch master or more likely slave cylinder suffering heating with either air or water creating an effective vapour lock in the clutch hydraulics. Clutch recovers once the temp drops in the engine bay. Thorough flush through and bleed, then bleed again after a run out to get the final air bubbles out. Some of the high temp silicone fluids have some strange fluid shear properties and I personally would avoid them, use top quality fluid from a new sealed container, open containers in the garage will slowly take up moisture from the atmosphere, reducing the boiling point as it invisibly emulsifies. :approve:
Simon, what you say makes this even more interesting..............so it is nothing to do with the brakes, or how one uses the brakes? The clutch certainly recovers once the temperature drops (i.e. there was no trace of the issue on the way back to the hotel after Origine RS). I thought a thorough flush through was done when the fluid was changed, a day or two before Origine RS, but of course I am not sure what fluid was used, and whether the container was sealed up until the point the fluid was used to refill #002.rustedandrotten":1mz6yv2e said:
I recall you mentioning that you too felt the clutch on your Vee going soft. Did you flush out and refresh the fluid just before the event?
Lastly, what would you consider "top quality fluid" for use in the Vee? Very keen to find a solution to this issue. Thanks.
Did you feel the temp of the shared reservoir Dulan? Shouldn't be all that hot even under constant hairpins as the heat should be fairly localised near the caliper end of the brake lines. If the reservoir was anywhere near the temp the calipers can get then you would have an almighty brake failure as the plastic would probably melt! Lmao This probably means the over heating of the clutch fluid is happening at the clutch end if it was indeed the clutch fluid boiling. Have you rested your foot on the pedal whilst going around the track? I never used to put the dearest fluid in mine but I changed it regularly and not once had any fade or fluid issues even though i cooked the discs snd pads on a fair few times. The only thing i remember getting too hot once was the PAS fluid and pump.
Brett, no, I didn't check the temp (by touch) on the reservoir. The brake discs got hot enough though, but there was no fade at all (Apec disks all round, Red Stuff pads and braided hoses - all this was done during the week leading up to the event. Not sure what fluid Scott used though).Oldskoolbaby":vseeffzj said:
"Have you rested your foot on the pedal whilst going around the track?" - nope, foot was firmly planted on the footrest when not changing gear.
