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Hi all,
I've got an '80 Vette, and the other day while I was driving it something happened to the clutch. When I push the pedal to the floor, the clutch doesn't engage at all. I'm thinking it's a broken cable or something came unhooked. I'm wondering what the best way to troubleshoot this would be.
it is a straight-out mechanical linkage. look at the pivot bar on left side of engine near steering while somebody moves clutch pedal. no movement at all? something came unhooked at the pedal.
2020 Corvette of the Year Finalist (performance mods)
2019 C3 of Year Winner (performance mods)
2016 C3 of Year Finalist
If you can get it in the air and secure it so you can safely be under it, have someone move the clutch pedal and you will be able to figure it out from underneath
Unfortunately, I don't have any way of getting it up in the air to get under it but I did squeeze under it and could see the engine fork moving when my son pushed the clutch in. How much travel is there supposed to be in the engine fork? I took a little video, hopefully it shows up.
Is that a flattened brake line it is pushing against?
I'd think that would be enough movement. The proceedure to adjust the clutch is in the Shop Manual (which I don't have handy, or I'd post an image). If I can find a link to it, I'll edit this post. That would give you the maximum throw, if that's all the issue is. Can you see the linkage at the Z-bar?
Congratulations on the 80 4-speed! They are the best C3s ever made.
EDIT: Here is a thread with some diagrams/instructions. I am worried that @71 Green 454 is correct, though (below).
How hard is it to fix a broken pressure plate spring? I'm guessing I'll have to drop the tranny and pull the clutch apart? (Sorry, not a mechanic. I didn't even stay at a Holiday Inn last night so I'm doubly screwed.)
Looking at the video - dang it's upside down!!! Suggestion, and relatively easy. There is an 'inspection plate' on the front of the bell housing. It's held on by a few bolts, and will be hald captive by the starter. Remove the bolts and pull the plate away from the bellhousing and see what, if anything. falls out.
Looking at the video it appears to me that the clutch release fork is going straight back, not pivoting.
you said clutch doesn't engage. i think you mean clutch doesn't disengage. if you step on the clutch, does the car still wanna go? or when you take your foot off the clutch in gear does the car sit there as if in neutral. if the car wants to go with clutch pressed, the linkage is most likely culprit and trans may be able to stay in the car. . if car stays still when it is supposed to go, the trans has to come out. you say you have no way to get the car in the air. time to change that. a harbor freight jack and stands is cheaper than getting it fixed by a shop. and you still have the jack and stands. cuz this ain't the last time you are gonna want to get it up in the air. even if just to clean, inspect and paint. i don't think it is the throw out bearing inside the bell housing in front of the trans. when they go, it is rather noisy...
In addition to the jack and jackstands, I'd suggest RaceRamps for some simple tasks, like getting under to take a look, oil changes, looking for play in your steering, etc.
From this position, I can raise the rear onto jackstands, followed by the entire car, if needed. Or I can safely do a fluid change as is. 54" 2-piece ramps work for both of my cars, but check your approach angle if your car is very low.
Did you find anything in the clutch linkage? Is your Z-bar correctly aligned, with both ends intact?
Quick answer to, "How hard is it to replace a broken pressure plate spring".
Your looking at replacing the clutch assembly complete.
Major pain in the butt on a C3.
I did mine at home on jackstands. I am a mechanic.
I seriously doubt that anything will fall out of the dust cover when removed as the flywheel is right there. About all he will see is the back of the flywheel.
Clutch fork is moving, but Clutch is not disengaging.
It's pull the transmission time. Remove the bell housing and then everything will be seen.
I seriously doubt that anything will fall out of the dust cover when removed as the flywheel is right there. About all he will see is the back of the flywheel.
Clutch fork is moving, but Clutch is not disengaging.
It's pull the transmission time. Remove the bell housing and then everything will be seen.
Correct, when my pressure plate spring broke nothing fell out, it was all internal. I replaced mine when I was 25 using ramps and jack stands. No transmission jack required....I was a lot younger and stronger 46 years ago. Removing the drive shaft, transmission, bell housing, and clutch assembly is the easy part. It's all the preliminary stuff that's tedious.
Could not disengage clutch, clutch pedal was spongy and did nothing. It happened 46 years ago after I backed out of my driveway, I was lucky that I was able to get it back in. I asked a couple of guys at work and they thought it was a broken pressure plate spring and they were correct. Not knowing much back then, they explained to me about the pressure plate fingers and how the throwout bearing presses against the pressure plate fingers to disengage the clutch.
Interesting. I would have expected some unusual noise, not to mention the clutch slipping.
I remain of the opinion not to spend a lot of money on non-returnable new clutch bits until you know the whole story, and take the inspection plate off first. It will have to come off anyway.
(I need to point out that I remain on a 'High' after correctly diagnosing why the wipers didn't work and buying a replacement switch before taking things apart, AND correctly diagnosing my neighbor's (heaven help him) ratty MGB. I said there's a number of aspects to this that I don't understand, but the problem is the fuel pump. I know he bought a new battery (likely needed, but it didn't make a whit of difference), and was going to replace the starter until told by another that he lacked the skills and tools needed. At the shop the problem was pinned on the fuel pump.)
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No More Clutch
