LT4 Clutch -- again
Thread Starter
Burning Brakes
Joined: Aug 2001
Posts: 797
Likes: 2
From: Westminster MD
LT4 Clutch -- again
After about 3-4000 miles, my clutch is slipping again. :banghead:
I installed a new one (Disk/Plate/TO from Carolina Clutch - "Valeo" components just like the factory) this time last year after the 50th kickoff in Bowling Green - 13 trips down the strip and I got to baby it home to MD...
Anyway - is there anything outside the obvious that I should be checking? Last time I didn't do the flywheel - it looked to be in good shape; no burns or scores, and I took a sanding disk to it just lightly to break any glaze on the surface.
Car hasn't been on slicks or drag radials; only occasional trips to the strip. I mostly autocross which isn't normally hard on a clutch.
So far I'm not seeing any obvious leaks - I have no reason to believe that the rear main seal is bad, or the tranny seal. Garage is dry underneath...
The clutch has always felt normal and my understanding is that it's not adjustable in any way.
Right now it's only slipping in 1st and 6th gear (last time it would slip in most any gear) so I figure it's not as bad this time.
Any ideas on things to check when I get around to changing this thing again? I really hope to avoid doing the flywheel if I can - lots of $$.
Thanks!
-travis
Le Mans Master
Joined: Oct 1999
Posts: 9,713
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From: Sachse Texas
Cruise-In I Veteran
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Re: LT4 Clutch -- again (TravisD)
Did you properly break in the clutch to let it seed in? Generally a 500 miles break in period of city driving is suggested prior to beating on it.
Thread Starter
Burning Brakes
Joined: Aug 2001
Posts: 797
Likes: 2
From: Westminster MD
Re: LT4 Clutch -- again (TravisD)
I seem to recall that I did about 500 miles of street driving (daily commute) after changing it last time. Those were highway mostly though.
Melting Slicks
Joined: Apr 2001
Posts: 2,474
Likes: 1
From: Drive it Like You Hate it Cincinnati OH
Re: LT4 Clutch -- again (TravisD)
I put a stock clutch in my LT4 (see sig)last may... about 5,000 miles ago. I drive it Hard:smash: , including about 50-60 passes at the strip. It grabs perfectly so far. maybe it didn't get seated properly... :crazy:
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Instructor
Joined: May 2003
Posts: 104
Likes: 0
From: Ocean City MD
Re: LT4 Clutch -- again (TravisD)
I have heard some rumors about the piston in the slave cylnder moving out a little during a clutch change due to residual pressure......I took mine off and with bleeder cracked open shoved piston as far in as it could go.....Then reinstalled and blead system thru....It solved my problem, which was close to yours. I say rumor because a few people claim this does not matter....but again it is way more easy than changing that clutch again.....With the piston out more it engages the fork just a little letting you never fully engage the clutch....I would be interested if you try this if it fixed the problem......
KDD
KDD
Thread Starter
Burning Brakes
Joined: Aug 2001
Posts: 797
Likes: 2
From: Westminster MD
Re: LT4 Clutch -- again (buell_freak)
Hmm.. interesting theory. Can't hurt to try it. I guess that just cracking it open might be enough? (and bleeding of course...) Not too had to pull the
cylinder though.
Odd though that it would take so far to surface.
cylinder though.
Odd though that it would take so far to surface.
Instructor
Joined: May 2003
Posts: 104
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From: Ocean City MD
Re: LT4 Clutch -- again (TravisD)
Odd though that it would take so far to surface.
KDD
Thread Starter
Burning Brakes
Joined: Aug 2001
Posts: 797
Likes: 2
From: Westminster MD
Re: LT4 Clutch -- again (buell_freak)
Maybe it finally wore to the point where it caught a "groove" or something?
Hmm...
We'll be in OC for the Corvette weekend later in the year. Had a great time last year.
Hmm...
We'll be in OC for the Corvette weekend later in the year. Had a great time last year.
Thread Starter
Burning Brakes
Joined: Aug 2001
Posts: 797
Likes: 2
From: Westminster MD
Re: LT4 Clutch -- again (TravisD)
Finally got around to calling Tom @ Carolina Clutch. He thinks it's likely the flywheel. Apparently the dual-mass doesn't show hot-spots very much, and can be bad even when it "looks" good.
So, now the decision is replace with stock, or go for the single-mass aluminum flywheel conversion. :confused: Supposedly the Al flywheel will be better for Autocross...
So, now the decision is replace with stock, or go for the single-mass aluminum flywheel conversion. :confused: Supposedly the Al flywheel will be better for Autocross...
Race Director
Joined: Apr 2000
Posts: 15,344
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From: Texas
Re: LT4 Clutch -- again (TravisD)
Finally got around to calling Tom @ Carolina Clutch. He thinks it's likely the flywheel. Apparently the dual-mass doesn't show hot-spots very much, and can be bad even when it "looks" good.
So, now the decision is replace with stock, or go for the single-mass aluminum flywheel conversion. :confused: Supposedly the Al flywheel will be better for Autocross...
So, now the decision is replace with stock, or go for the single-mass aluminum flywheel conversion. :confused: Supposedly the Al flywheel will be better for Autocross...
Just something to keep in mind.
Thread Starter
Burning Brakes
Joined: Aug 2001
Posts: 797
Likes: 2
From: Westminster MD
Re: LT4 Clutch -- again (96GS#007)
I decided to go the stock route for now - basically because I got lucky (I hope) and won an auction for a new Flywheel and Clutch. The lighter flywheel was pretty appealing but the cost difference (vs. the auction price) said go with it for now.
Maybe when this one goes I'll be ready for the single-mass and kevlar set up...
Maybe when this one goes I'll be ready for the single-mass and kevlar set up...
Instructor
Joined: Jun 2003
Posts: 101
Likes: 0
From: West TX
Re: LT4 Clutch -- again (TravisD)
I think my clutch is going out, but I'm really not too sure. I rarely drag, but when I do a couple of passes in a row, and then try a third, it slips. Also, I recenly noticed that when it is disengaged (pedal depressed) a whirring noise coming from it. The release seems to be getting higher and higher. The clutch is original with about 60000 miles on it, and plenty of smokey burnouts and 2500 RPM drops. I already know it will cost an arm and a leg to replace, but how much $$$ will I be looking to spend with labor included for a good performance street clutch???
Thread Starter
Burning Brakes
Joined: Aug 2001
Posts: 797
Likes: 2
From: Westminster MD
Re: LT4 Clutch -- again (LT4 2 Fast)
Yeah, you probably need a new clutch.
The whirring noise when the pedal is depressed sounds like a throwout bearing -- usually the ZF's only whirr when the pedal is up...
I would expect it to not be cheap to have a shop do it -it's a pain pulling the tranny. It took me two days with a friend doing it in the driveway, and was the first time doing it (inexperience). I would guess that you're looking at 6-8 hours shop-rate to have someone do it.
Parts -- I paid $300 for the disk/pressure-plate/TO from Carolina Clutch; I've seen a price of $650 for the flywheel on-line. I have no idea what a shop will charge you for the parts - I'd guess you'd be at close to $1000 in parts to have a dealer do it.
That's with stock parts.
Expect to add more in parts for a performance model. Tom@CC quoted me $795 I think for his "Stage II" single-mass setup - Fidanza Al flywheel, and kevlar disk. I would imagine that a similar setup is available from others as well if you check. For a stock motor I can't justify a more advanced clutch setup than that.
The whirring noise when the pedal is depressed sounds like a throwout bearing -- usually the ZF's only whirr when the pedal is up...
I would expect it to not be cheap to have a shop do it -it's a pain pulling the tranny. It took me two days with a friend doing it in the driveway, and was the first time doing it (inexperience). I would guess that you're looking at 6-8 hours shop-rate to have someone do it.
Parts -- I paid $300 for the disk/pressure-plate/TO from Carolina Clutch; I've seen a price of $650 for the flywheel on-line. I have no idea what a shop will charge you for the parts - I'd guess you'd be at close to $1000 in parts to have a dealer do it.
That's with stock parts.
Expect to add more in parts for a performance model. Tom@CC quoted me $795 I think for his "Stage II" single-mass setup - Fidanza Al flywheel, and kevlar disk. I would imagine that a similar setup is available from others as well if you check. For a stock motor I can't justify a more advanced clutch setup than that.
