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ID Why My Clutch Started Slipping

 
Old 07-20-2018, 06:56 PM
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Default ID Why My Clutch Started Slipping

Just looking to learn a little why my clutch started to slip and how to read a used clutch disk. To me it looks "glazed" but I also couldn't find any very good articles on what to look at with a used clutch.

FM level 1 clutch has 20k miles and started to slip in high gears no matter how I adjusted it.













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Old 07-20-2018, 07:10 PM
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Check to flywheel and make sure the step height ( the difference between the clutch mounting surface and the friction surface ) is within spec . Alternatively , too much power or poor clutch skills are the other choices. Fredb
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Old 07-20-2018, 07:38 PM
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Sadly I sold the flywheel, however it was new FM so I hope it would have been within spec when it went in. Only ran a max of 14psi on a gt2560, that is when it started to slip but it should have been well within the power limit of the disc. The driving was 95% me so I dont think it was that.
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Old 07-20-2018, 08:34 PM
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only thing I can think of is adjustment out of spec causing it to not fully engage

did you just remove that? I was just about to send you the next revision lol
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Old 07-20-2018, 09:06 PM
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No haha, carry on with the revisions! This happened before we started tuning, we started right when I got the fresh clutch in. I just finally got around to cleaning the garage and it reminded me to try to figure out what happened to this one.

Adjustment was in spec. I also replaced the master and slave with new oem to be sure. I tried adjusting it the FM supplied way and according to the FSM: both netting different engagment points but the same slipping and weak grab.
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Old 07-20-2018, 10:00 PM
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I'm running a FM stage 1 clutch bolted to a 10lb Findenza flywheel and its hanging on to 18 psi and 300+ hp , just... I do think my step height is tighter than it should be though . I had to resort to extreme measures to get the clutch to fully disengage. I know I'm at the ragged edge of what it should be able to hold though. Fredb
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Old 07-21-2018, 09:31 AM
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Am I reading your pics correctly in that the flywheel side of the clutch is tapered? The inner half of your pressure plate looks heat/friction blued, yet it's the outside of the clutch friction material that's worn. Weird.
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Old 07-21-2018, 10:35 AM
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You're really only looking at the final symptom, not the root cause. Clutch life can be significantly reduced by a lot of factors, like improper installation, too much grease/antiseize, misadjustment, poor driving habits, along with any leaks from your valve cover, cam angle sensor (or plug), rear main seal, oil pan, or input seal.

You can usually look at a flywheel or pressure plate to see a poorly machined piece, look for cracks in the friction disc for poor shifting or bad adjustment, but without the rest of the picture, I don't know how much you can say about that one.
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Old 07-21-2018, 10:42 AM
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Did it feel like it always engaged pretty high?
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Old 07-21-2018, 11:08 AM
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Hues- yes the side with the protrusion contacts the flywheel.

Curly- Thanks for that info, it was kind of what I was gathering as well. I was just hoping maybe something about the disc really stood out.

There are no oil leaks and all the associated seals and gaskets were replaced with OEM. I was very conservative with grease and only in the places where FM showed. Everything was assembled and torqued exactly how FM instructed.

Concealer- It did always seem to engage in the upper half of the pedals range of movement. There was still plenty of travel after engagement though.


Also to clarify: I'm not really upset with FM or looking to hold them accountable for the failure. Just looking to learn.
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Old 07-22-2018, 02:48 PM
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Originally Posted by BBro View Post


Originally Posted by BBro View Post
Hues- yes the side with the protrusion contacts the flywheel.
Waitaminute. Are you saying this pictured side was contacting the flywheel?
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Old 07-22-2018, 03:49 PM
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Yes, that’s backwards, highly unlikely he’d be able to bolt it down without noticing that
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Old 07-22-2018, 06:23 PM
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No bad explanation by me. It’s the opposite of the picture.

It was definitely in the right way. I dont think it would even work backwards.
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Old 07-31-2018, 09:14 PM
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Originally Posted by concealer404 View Post
Did it feel like it always engaged pretty high?
Mine has always seems to engage ~1/2" higher than i'd like. Any thoughts about leaks which could degrade the friction? Any "easy" ways to check these?
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Old 07-31-2018, 09:46 PM
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Originally Posted by btfu1869 View Post
Mine has always seems to engage ~1/2" higher than i'd like. Any thoughts about leaks which could degrade the friction? Any "easy" ways to check these?
For the most parts leaks only cause the clutch to not disengage. Sounds like your adjustment is just off. Quoted from another thread on here: FM advice "If you’re able to disengage the clutch properly with less than full pedal travel, back off on your adjustment until 100% pedal = 100% disengagement."

After you adjust the rod that goes into the MC to make 100% pedal= 100% engagement you will have basically turned the beginning part of the pedals travel into free play. Decrease the total pedal travel to get rid of excess free-play until you have free-play within spec.
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