Hello everyone and thanks in advance for any help. I have an all stock 1972 convertible 350 with a 4 speed manual transmission (Muncie). I took the car for a quick ride and the car was operating perfectly. When I returned home I parked the car in the driveway and it sat for a few hours. When I went to put the car back into the garage, it started normally (it was in neutral) but I could not get the car into first gear to pull into the garage. The clutch pedal felt normal but it was as if the shifter was locked out of 1st (or any other gear which I tried). I shut the car off and the shifter went into each gear smoothly. I pushed in the clutch, put the shifter in 1st gear and restarted the car. It did not jump forward or make any unusual noises. It drove normally in 1st but would not shift into any other gear. I have to shut the car off to change into any other gear and then cannot shift again unless engine is off. It drives normal in any chosen gear but I cannot change into another gear. I am leaning towards a throwout bearing or shift linkage problem causing the clutch to drag slightly. I don't think the clutch plates are stuck because the car does not jump forward when started in gear. The clutch also does not seem to be slipping when in gear and driving forward/reverse. Both springs are intact on the linkage that runs close to the engine. Has anyone experienced this problem? Thanks

 

I haven't experienced this with my Vette, it's an automatic. But, I have with my wife's Ford and a pickup I had a while ago. The clutch is definitely dragging, and the synchros can't do their job, preventing you from shifting. The car doesn't go forward when started in gear because it's a 3,500 lb car and the clutch would really have to be dragging to move it.
I seem to remember the fingers on a diaphragm clutch not coming back all the way, meaning the clutch isn't fully releasing, and this could be your problem.
Before I started taking things apart, I would double check the linkage adjustment, and have somebody watch the release fork pivot while you're pushing the pedal up and down to make sure it's moving far enough, and freely.

 

Thanks. Yes, I'm going to take a look at all of the linkages and adjustments tomorrow. I'm hoping it's something simple so that I do not have to drop the transmission and change out the clutch, throwout bearing, etc.

 

Does the Clutch engage the moment the Pedal comes off the Floor ?

 

I don't think so but I will check tomorrow. The pedal seems to be adjusted properly with about 1.5 inches of freeplay at the top then you can feel resistance as you continue to push the pedal down. The clutch pedal itself does not feel any different from when the car was operating properly. It seems like the same amount of resistance and feels just as smooth as it did when it worked before.

 

There's a clutch adjustment procedure in the shop manual. I was having similar issues (grinding going into gear). I adjusted my clutch per the manual, and the problem went away.

I don't have my shop manual handy, but the adjustment is on one of the threaded bars attached to the Z-bar.

 

Thanks. Going to try adjusting tomorrow. Hopefully it is a simple fix like an adjustment.

 

Well I adjusted the clutch today per the manual and unfortunately it did not resolve the issue. With the engine running there is a distinct groaning noise when the clutch pedal is depressed and goes away when the clutch pedal is let out. I'm 99% certain that it is the throwout bearing. Time for a new clutch, pressure plate, throwout bearing, and u joints while I'm at it.

 

Too bad it wasn't something easy.

Please let us know how it goes, and good luck!

 

? Does trans have plenty of gear oil in it?

 

Read member Lars clutch engagement thread.......some good info there:

https://www.corvetteforum.com/forums...and-specs.html

Jebby

 

I believe the manual calls for 1 1/2" free play but the thread above in the link mentions a smaller value, 1/2". Try reducing the free play before doing anything else.

 

Thanks for all the help. Yes, checked the transmission fluid and level was correct. Tried adjusting the clutch a bit more but still did not work. It's the groaning noise when I press the clutch that's making me think it's the bearing. I'm in the process right now of dropping the transmission.

 

Yes, definitely a great thread. I try to read all of Lar's posts. He rebuilt my Quadrajet and fixed a number of problems with it last year and did a great job.

 

Ok so I was able to get the transmission out today (still working on the bell housing and clutch, hopefully will have time tomorrow). I had difficulty getting a socket or wrench on the middle side bell housing bolts. The old throwout bearing is very noisy (spins around fast/easily and sounds like it's full of rocks). I'm going to install a LUK clutch kit but will be scrapping the plastic throwout bearing (ordered SKF N1488 as a replacement) and will also be scrapping the magnetic pilot bushing (replacing with National PB656HD). I am also going to order a new clutch fork and ball stud. I was wondering if the Corvette America manufactured ones are any good. Thanks

 

I experinced this exact phenomena about 35 years ago. Turned out the pilot bearing/bushing in the flywheel had siezed (hope I spelled it right) on the input shaft.
The input shaft will then not release completely from the flywheel no matter how you adjust the clutch. So check the pilot bearing and the front part of the input shaft for any damage.

 

Thanks for all the replies and advice. It looks like this is the problem (I hope that is it anyway and not an additional issue). Waiting on parts to arrive and then I can get back to installing new clutch, pilot bushing, clutch fork, Ball, throwout bearing.