I've had a Sachs clutch, flywheel & slave cylinder fitted at the same time as everything needed to run 400bhp from my 2018 f/l vrs230. As soon as I hit 6000rpm & change gear my clutch pedal takes a few seconds to pop back up. I've had a new clutch master cylinder, ecs bleed blocker & braided clutch hose to solve the problem & though improved the problem is still there. Any ideas to help fix the problem?! 

On a previous car (Audi RS4) this problem was caused by a restriction in (or too small a diameter) pipe to the clutch slave cylinder.

I had a similar setup put in recently (Sachs 550Nm kit, DMF, and slave) and am having no such issues, pedal snaps back right away (as expected with how firm it is). The lines, bleed block, etc are an unknown....previous owner has modified the car and I don't know what work was performed other than it's running more power than stock!

 

Does this only happen above 6,000RPM, or is that kind of spirited acceleration just the only time you're trying to get off the clutch fast enough for it to be an issue?

Literally between 1000 & 5500rpm theres 0 problem. Between 5500 & 5900 theres some clutch slippage because the clutch pedal is slow to return but hit 6000 rpm & you can count just over 2 seconds for the clutch pedal to return. My partner has filled it & the car is now booked back in to the workshop for further investigation--i believe to replace the clutch slave cylinder & see what happens. 

It sounds like something in the clutch pressure plate is acting like a James Watt governor and impeding the plate from re-engaging at high revs.

 

That it's a non standard clutch makes it the primary suspect.

Edited 16 November, 20205 yr by J.R.

Only 2 things would prevent that as I see ot which is the clutch plate itself being weak or not strong enough to handle the 400+BHP 500+lbft torque or the clutch slave cylinder. 

10 minutes ago, J.R. said:

It sounds like something in the clutch pressure plate is acting like a James Watt governor and impeding the plate from re-engaging.

 

That certainly makes sense from a physics perspective, though I can't imagine how/why a clutch would do it - not an engineer however!

 

@Niomi can you confirm it is the Sachs street kit with 550Nm organic disc?

 

Does it still happen if you're just revving the car to 6,000RPM in neutral? (I've read the idle limiter is disabled with TC off, yet to test that)

 

So I tested this yesterday with a few aggressive redline upshifts - no issues. Also revved up while coasting in neutral and clutch always engaged as fast as I could lift my foot off the pedal.

 

Certainly points to something being not quite right with your setup.