Is it the Clutch?
Thread Starter
Intermediate
Joined: Oct 2011
Posts: 27
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Is it the Clutch?
I have just recently purchased a 1989 Corvette convertible 6 speed manual transmission. When I first drove it everything seemed fine, but now I am having problems. Once in awhile when shifting from 1st to 2nd gear it will come out of 1st hard and I will end up in 4th gear. Also, when I am in reverse backing up a grade the clutch will chatter. The clutch pedal is at the top of its travel. One repair shop said that he would start by replacing the clutch master cylinder and if necessary adjust the arm to get more pedal. Is that a good idea or should I just replace the clutch and get it over with? Also, can the clutch replacement be done from underneath the car or does the engine and transmission need to be removed to get this job done. I've done a clutch once on a Mustang will the Vette be more difficult?
Melting Slicks
Joined: May 2007
Posts: 2,075
Likes: 109
From: Longmont Co
The later 6 speeds have a 1st to 4th feature that prevents shifting to
2nd under certain circumstances (speed , RPMs, etc.). I think an 89 would have it too. Details should be in the owners manual. A plug is available to override this annoying feature.
2nd under certain circumstances (speed , RPMs, etc.). I think an 89 would have it too. Details should be in the owners manual. A plug is available to override this annoying feature.
Last edited by markKlein; Oct 14, 2011 at 02:34 PM.
Melting Slicks
Joined: Jul 2006
Posts: 2,151
Likes: 0
From: Strongsville Ohio
its called CAGS- skip shift eliminator. Ecklers.com, ebay all have them on there. It connects inbetween a line on the tranny. EASY fix. 1 to 4 is a GM way to save gas. Engine stays in while taking clutch out.
Melting Slicks
Joined: Apr 2007
Posts: 2,616
Likes: 111
clutch chatter in reverse gear especially on upgrades is not uncommon...my car has a fairly new SPEC 2 clutch system in it and it is just "grabby" especially when slipping the clutch in reverse gear on an inclined surface (putting a load on it).....you may already have an aftermarket clutch in that thing already it sounds like.....very common on these cars as they are aging.....I would be surprised if you have the original clutch parts in there......also, clutch travel sounds good actually....it should release high, not as soon as you start to lift up on the pedal.....usually when the clutch starts to engage as soon as you lift your foot up, you have a leak of fluid somewhere....check the fluid level in the master cylinder, if it is full, you are good to go......
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Thread Starter
Intermediate
Joined: Oct 2011
Posts: 27
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Thanks for your reply. The fluid in the clutch master sylinder was full on inspection. One transmission shop suggested replacing it and adjusting the clutch rod to give me more clutch pedal. At $360 and not a foresure cure I thought that was too much just to experiment. Anyways, I bought the part for $45 and I think I will do that job myself. As far as chattering in reverse, would that be because of a bad aftermarket clutch?
Melting Slicks
Joined: Jul 2006
Posts: 2,151
Likes: 0
From: Strongsville Ohio
No, reverse chattering is caused by the flywheel and clutch rubbing together. It is normal really. I JUST bought a spec stage 1 with xtra mass aded to the flywheel and I still have chatter. I called spec and they said it is normal to see some chatter. Some say it will go away, some say it wont. If its not driveable then I would think the chatter is too much. You will learn to live with it. Big cause of chatter is oil or anything getting in between the two.
Thread Starter
Intermediate
Joined: Oct 2011
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Is there an inspection plate to remove to see if there is any oil on the flywheel? I didn't look for the clutch slave cylinder as yet. Where is that located? If that is leaking onto the clutch I suppose that could be a big problem.
Melting Slicks
Joined: Jul 2006
Posts: 2,151
Likes: 0
From: Strongsville Ohio
Yes, about 1/4 of the flywheel is hanging out the bottom for you to see. there is a tin almost cover that has about 4 small bolts that you can take off. Whats going to leak onto the flywheel is a rear main oil gasket from the block that would be going bad...Ask me how I know. Remember, clutch chatter is pretty normal to some degree. Mine was so bad, I could let the clutch out of reserve, it would just sit there and shake the car horribly.
Race Director
Joined: Jan 2002
Posts: 12,263
Likes: 86
From: O'Fallon Missouri
Thread Starter
Intermediate
Joined: Oct 2011
Posts: 27
Likes: 0
One more question. Since I will be under the car, I hope in my garage on stands, I plan to change the transmission fluid. It was recommended I use Lucas Transmission fluid. All I have seen so far is automatic transmission fluid. Is there a different one for a manual transmission?
Burning Brakes
Joined: Aug 2006
Posts: 878
Likes: 2
From: BC
Yes very much so.
The ZF6 is a little strange when it comes to is recommendations but one of the following will be fine.
GM Syncromesh
Castrol TWS 10W-60
Amsoil Sycromesh
A good website with ZF Info - http://www.zfdoc.com/faq.htm
The ZF6 is a little strange when it comes to is recommendations but one of the following will be fine.
GM Syncromesh
Castrol TWS 10W-60
Amsoil Sycromesh
A good website with ZF Info - http://www.zfdoc.com/faq.htm
Thread Starter
Intermediate
Joined: Oct 2011
Posts: 27
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OK...I had the fluid changed in the transmission and installed CAGS - skip shift eliminator. I have taken only a short ride since being serviced, because the weather is crummy today, and had no shifting problems. Seems to have fixed it. Now I have another problem to address. The speedometer is not working correctly. When the Vette was in the shop, I had them check to make sure there is a signal from the speed sensor up to the dash and there is. The gage reads a signal, but only the first diget is readable. I had, a while ago, ordered just the speedometer lense off of ebay, because the rest of the dash is working. I had started to replace the lense, but stopped when I realized that I need to drop the steering wheel to get the dash out. Can anyone give me some help and or some ideas on this project?
Team Owner
Joined: Oct 2004
Posts: 81,241
Likes: 3,063
From: altered state
St. Jude Donor '05
Think Agent86 has a good lnk for that fix
No adjustment or clutch rod on your trans.
Keep doing the work yourself
A lot of chatter is NOT normal at least on the factory clutch setup.
In fact they almost never should if all is right.
new cars dont?!
Could have some glaze/oil on it
Unless it slips keep driving it. Make sure your Cbeam bolts are good and snug, too.
No adjustment or clutch rod on your trans.
Keep doing the work yourself
A lot of chatter is NOT normal at least on the factory clutch setup.
In fact they almost never should if all is right.
new cars dont?!
Could have some glaze/oil on it
Unless it slips keep driving it. Make sure your Cbeam bolts are good and snug, too.
Safety Car
Joined: Dec 2009
Posts: 4,363
Likes: 429
From: Birmingham Al
clutch chatter in reverse gear especially on upgrades is not uncommon...my car has a fairly new SPEC 2 clutch system in it and it is just "grabby" especially when slipping the clutch in reverse gear on an inclined surface (putting a load on it).....you may already have an aftermarket clutch in that thing already it sounds like.....very common on these cars as they are aging.....I would be surprised if you have the original clutch parts in there......also, clutch travel sounds good actually....it should release high, not as soon as you start to lift up on the pedal.....usually when the clutch starts to engage as soon as you lift your foot up, you have a leak of fluid somewhere....check the fluid level in the master cylinder, if it is full, you are good to go......
Race Director
Joined: Sep 2003
Posts: 16,838
Likes: 341
From: Database Error Indiana
You dont have to drop the steering to get the instrument panel out. I think (its been a while) I tilt it down and unscrew the tilt lever to get it out of the way. I lay a towel over the column so I dont scratch the lenses going across it.