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Old 04-08-2013, 12:15 AM   #1
STi_Scott
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Member#: 191941
Join Date: Oct 2008
Location: Minnesota
Vehicle:
2007 STI
SWP

Default 07 STI Clutch slips excessively even under light acceleration

I just finished a complete engine rebuild that I performed myself, and now the clutch slips very excessively (Disappointing to say the least after this long rebuild project, but at least the engine seems to run great!). Before the tear down I thought the clutch held well, and the car drove well. I cleaned the clutch while I had it out just with compressed air and some paper towels, but I didn't use any chemicals as I didn't want to leave any residue on the clutch surfaces. Just figured getting the dust out couldn't hurt. Now it is almost not driveable. Even at half throttle the clutch will slip like crazy... I can't get into boost at all.

I think I may have installed the clutch fork wrong initially, but I fixed that.

I'm thinking the problem could be one of the following...
1. The clutch fork being installed wrong initially caused excessive slippage by not allowing full clamp force, and I may have glazed the clutch on my first test spin around the block?
2. I did something wrong installing the clutch itself?
3. The clutch is just plain wore out... seems odd since it worked fine before the tear down though?
4. Something broke during the install and I didn't realize it?

What do you guys think?
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Old 04-08-2013, 01:58 AM   #2
Uncle Scotty
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we have an Uncle

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almost sounds like something didnt get put back together right
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Old 04-08-2013, 08:49 AM   #3
STi_Scott
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Quote:
Originally Posted by Uncle Scotty View Post
almost sounds like something didnt get put back together right
What can be done to assemble it wrong? Flywheel goes on, clutch disc, pressure plate bolts on... seems like there is nothing to mess up? The car runs and drives without making any funny noises or anything, but the clutch couldn't hold the power of a Smart car.
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Old 04-08-2013, 11:23 AM   #4
FuJi K
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MY99 GF4 JDM 6spd
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First guess is to take apart and see if there is grease or whatever on the fw/pp. Second guess is pressure plate to fw bolts needs to be tighten fully.
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Old 04-08-2013, 11:32 AM   #5
STi_Scott
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Quote:
Originally Posted by FuJi K View Post
First guess is to take apart and see if there is grease or whatever on the fw/pp. Second guess is pressure plate to fw bolts needs to be tighten fully.
Both would be logical explanations, but I did not use any grease on the clutch/flywheel/pressure plate and I know that I torqued the pressure plate to Subaru torque specs.
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Old 04-09-2013, 08:45 AM   #6
STi_Scott
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As it turns out you were right! I installed the pressure plate flush and torqued it the first time I installed it, but I realized I had forgotten to align the clutch disc and it was off center. So I took it apart, aligned it and I guess I forgot to retorque the bolts when I put it back together the second time. All of the bolts were snugged just enough to flatten the lock washers, but not enough to bring it flush to the flywheel. Thankfully none of the screws fell out of the flywheel.



And to anyone wondering... the pressure plate bolts can be tightened with an open end wrench through the starter hole in the bell housing. Didn't even have to drop out the trans. Of course I wasn't able to torque it to spec with an open ended wrench, but hey tight is tight right?
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