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quattrosedan
11-23-2009, 02:35 PM
Hey guys, looking for some input on kind of a random problem.
I replaced my clutch about 2 months ago with a custom Spec clutch, rated for over 500 ft*lbs. I have a fidanza lwfw (replaced the inserts on it at the same time) and replaced the pressure plate with an oem sachs. I also replaced the master cylinder with the one out of my parts car and replaced the slave cylinder (new). I am fairly familiar with clutch break in (done in many times before) and I know there was no problem there. So here is the strange problem.
When I am accelerating, the car will pull hard and for a split second, the rpms will creep up faster than they had been, for no apparent reason. A way to think about this would be if you were driving your car at wot and you barely depressed the clutch pedal, so that the car would still accelerate hard, but the clutch would start to slip. I have only seen it happen in 3rd gear, not in 4th or 5th where the higher loads are. I really am not sure.
Does anyone know if the clutch pedal has an adjustment? Or does the slave cylinder have one? Anyone with any thoughts, lemme know! Thanks.

Oceanside
11-23-2009, 09:38 PM
Im confused. Why did you use a stock pressure plate with a performance disk? I dont see how the stock PP could hold the disk to achieve the results its advertised at

biketsai
11-23-2009, 09:46 PM
Im confused. Why did you use a stock pressure plate with a performance disk? I dont see how the stock PP could hold the disk to achieve the results its advertised at

X2, how can it hold that pressure now?

Kyle H
11-23-2009, 09:54 PM
Spec clutch
I think I found your problem. [>_<]



Are you sure you did the install right? The only way a bad adjustment would make it slip is if it didn't release the pressure on the pp, which I doubt.


My friend with a turbo volvo put a clutchmasters 6-puck disk in his car with his original ~170k mile pressure plate and it's held ~200whp for like 6 months just fine. Which spec disk did you use?

Oceanside
11-23-2009, 10:49 PM
My friend with a turbo volvo put a clutchmasters 6-puck disk in his car with his original ~170k mile pressure plate and it's held ~200whp for like 6 months just fine. Which spec disk did you use?

From my experience with my stg2 a4 and 200whp I can see this feasible. But look at his mods and hes running a 50 trim, So Im guessing at least 300whp. Thats alot more clamping capacity required

BlackLock_A4
11-23-2009, 11:17 PM
... I have only seen it happen in 3rd gear, not in 4th or 5th where the higher loads are...

Lower gears (1 &2) would be a much higher load than 4th and 5th under acceleration. That doesn't make sense to me that it only slips in 3rd gear. You WOT all the way through 1 and 2? And it doesn't slip then?

Weird.

Kyle H
11-23-2009, 11:20 PM
How are first and second gears higher load? I thought the torque multiplier of the transmission made it easier on the clutch in those gears. Which puts more load on your legs on a bike, first gear or 7th gear? [;)]

BlackLock_A4
11-24-2009, 12:27 AM
http://www.ramclutches.com/Clutch%20U/cl_u_10.htm

Your right, Kyle H. Should have done research before posting...

[headbang]

quattrosedan
11-24-2009, 11:02 AM
Okay, here's some answers.
1. The stock pressure plate should have plenty of force to withstand nearly 400 awhp. I SERIOUSLY DOUBT that that is a problem at all. I had my gt28 elim with a stock pressure plate and stock clutch running 275 awhp and it NEVER slipped.

2. In most cases, the higher the load will be on the clutch/pressure plate. This situation follows this case.

3. As far as power, I am running around 14 psi on my megasquirt setup and I am still in the tuning stages. The car is running around 12.0:1 when this slipping occurs, so maybe ~240-260 awhp?

4. The clutch is a Spec 2027-2400.

VMRWheels
11-24-2009, 12:50 PM
how many miles do you have on the clutch? is it still within the break in period? My friend's clutch slipped a bit when he got on the throttle during break in, after that it held fine.

Scotty@Advanced
11-24-2009, 02:13 PM
I think I found your problem. [>_<]

I second that emotion.. Southbend FTW!

adr3naline fix
11-24-2009, 03:22 PM
Take it on the hwy. Get into 5th at a low speed (45-55) and then gun it. If your rpms rise quickly and your speed barely moves, something is slipping. I find it very weird that you say it only has this problem in 3rd.

quattrosedan
11-25-2009, 07:37 AM
I cannot understand why this doesn't happen in 4th or 5th either. I can only get it to do it *sometimes* in 3rd. It seems like the colder out it is, the more it does it. And it doesn't happen until around 6k. The turbo makes 14 lbs by ~3700, and I would think that the 3500-5000 rpm range would be a higher torque than at 6k, but I don't really know.
As for the clutch not being strong enough, I don't think it is a problem. A good friend has a 97 fwd a4 with ~300whp and it has held up for over 10k miles, with NO slipping. And he drives his car harder than anyone I have met. This is the same clutch as that. It was purchased from competition clutch, in GA, which is who makes Spec clutches.

If it would be better, i can post the megasquirt log, or a print screen, and show where it happens.