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Old 12-18-2010, 03:30 PM   #1
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Default Help me troubleshoot my clutch before I buy a new setup

Help me diagnose possible causes of the clutch slipping. I really don't want to buy a new setup and find out after the swap that it was something else entirely


The clutch has been adjusted according to FM, SS lines bled, new 6 puck clutch, slave cylinder was rebuilt, and no fluid when you pull the boot back. I have not messed with the master cylinder, but I always thought that a bad master would cause the clutch to not disengage. The trans shifts perfectly. I'm going to double check again to make sure that i can physically push the slave piston in so that I know it is adjusted properly. I'm using motul brake fluid






I was able to get a good run in 5th up a hill and I watched the oil pressure needle bounce around while it felt like it was slipping.

I now have some decisions to make.

1.) Try to find a good used pressure plate (this has me gunshy since a used system has gotten me to this point.

2.) buy a new xtreme pressure plate and run with the 6-puck

3.) buy a HD pp and run with six puck

4.) buy a FM stage 2 organic disk and pp

5.) buy another brand of pp and run it with the ACT 6 puck clutch.

The setup needs to handle up to 300 ft lbs at the wheels

I don't see what else it could be at this point. Thanks

Last edited by miatauser884; 12-22-2010 at 12:18 AM.
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Old 12-18-2010, 04:47 PM   #2
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A side note, it's easy to measure clutch slip via datalogging. Just compare the ratio of speed to RPM in a given gear. It should remain constant. Also, make sure you are not running into any wheelspin at the time...
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Old 12-19-2010, 08:19 PM   #3
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Bump for title change, and request for more help
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Old 12-20-2010, 11:26 AM   #4
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I wish you the best. I know I am not making near your power, but at 15 psi on my churbo, I have a XTD pressure plate with a rebuild clutch disk from some clutch place and it is holding surprisingly well. Anyways, I was weary about putting that in and it worked, so I would get something proven depending on your budget.
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Old 12-20-2010, 01:17 PM   #5
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Quote:
Originally Posted by djp0623 View Post
I was able to get a good run in 5th up a hill and I watched the oil pressure needle bounce around while


Sure it wasn't detonation?
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Old 12-21-2010, 08:31 PM   #6
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i was running the same amount of timing that i was when it was tuned, so im pretty sure that it wasnt. the oil pressure dropped at the same time as the suspected slipping occured. it is also the same experience at the track, which turned out to be the clutch. i guess i can pull a couple degrees of timing and try again. wouldnt be pretty audible if knocking that bad to make oil pressure drop from 60 to 30 and back to 60?
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Old 12-21-2010, 08:46 PM   #7
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When your clutch slips, engine speed increases. Why do you think that a slipping clutch would cause your oil pressure to drop? Oil pressure generally increases with engine speed.
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Old 12-21-2010, 08:53 PM   #8
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Originally Posted by crashnscar View Post
When your clutch slips, engine speed increases. Why do you think that a slipping clutch would cause your oil pressure to drop? Oil pressure generally increases with engine speed.
The rpm increased a little, but the clutch didn't let go like it did while at the track.

I figured the oil pressure dropped because the load on the engine decreased. If that doesn't make sense, then I guess I may be lucky that I haven't blown up my engine due to knock.

Ok, after doing a bit of research and thinking. This idea is stupid. The pump is connected to the crank which should flow the same volume at whatever rpm no matter the load.


I should be able to check. I have a scope that is used to check inside the bladder by going thru the urethra. (ouch) I should be able to shine a light down there and look for any detonation damage.

however, this happened last time and I immediately pulled the plugs to look for signs of det. Clean plugs, and the appropriate color. No signs of being lean. Of course I was unable to check the piston tops.

What does det feel like when it happens under boost? Loss of power?

EDIT: Could the oil pressure drop and rise fluctuation be due to the oil bypass spring. Opens (pressure reduces, closes and pressure increases, continue cycle)

I'm left thinking that maybe the oil pressure fluctuation is not a symptom of my clutch problem. I was going up a pretty steep incline, and I did not compensate engine oil volume for the turbo and lines. Maybe the pickup was really running out of oil due to the uphill angle, possible shortage of oil, and acceleration.

I'll test the detonation theory by pulling a few degrees of timing. That will be easy enough.

Last edited by miatauser884; 12-22-2010 at 12:20 AM.
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Old 01-08-2011, 06:00 PM   #9
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Originally Posted by BenR View Post
Sure it wasn't detonation?
I was tuning today with my new clutch and the oil pressure needle started bouncing like it did before. I pulled a little timing, and it seemed like it got better. I pulled some more and it went away.

Det??????

How bad is the det if it shows on oil pressure gauge, but isn't audible?
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Old 01-10-2011, 06:49 PM   #10
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If it's bad enough to make the needle move then it's enough that it's pushing back on a piston during a compression stroke, and definitely hurting your motor.


Your ears might not be tuned into what det sounds like, my brother can't hear it either. It may be time to get some det cans like hustler uses.
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Old 01-10-2011, 08:18 PM   #11
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I have a set. I'll put them back on. I had them when it was dynoed at didn't here anything. I'ved dialed it back now and the needle doesn't move. Yay
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