Hi Guys.  Didn’t know a better place to list this. I have a rotational squeak coming from the front of the transmission. Raised the car and got 5 pair of experienced ears on it and all agreed “Yup. I hear it from the front of the transmission where it connects to the crank.”

77 C3, original 350, Th350 transmission, shifts fine, no noticeable leak. Not the brakes, not the suspension, rule those out. Not a grinding noise, just a squeak, squeak continuous when driving. Does not get worse with acceleration, deceleration or braking. No squeak when cold, squeak starts after 3 miles of driving  

Maybe something with the input shaft seal?

Unless there’s an additive that might lube the input shaft seal, don’t know what to do other than pull the tranny. What do you guys think?

Sounds like a torque converter, or fly wheel hitting on something. Maybe a bent cover on the bottom. How bout a bolt falling out somewhere, and rubbing. Pull the cover and see if it still squeaks. 

Click on image for full view

Cracked flywheel would be my #1 bet. Does the noise change with rpm? Does it make noise in gear, forward and/or reverse, in park, or all the time? I agree with Mark that it may be the dust cover rubbing, or possibly the starter bendix not fully returning to rest after starting. Park it with the nose of the car downhill on an incline, and see if it stops or not. If it stops, turn the car around and see if the noise gets worse. If so, the bendix is making the noise. 

Never in 50 years of transmission work have I ever heard a seal make a noise. 

Last thing....I HAVE heard distributors make squeaks/squeals....just a thought.

Joel Adams
C3VR Lifetime Member #56    
My Link


(click for Texas-sized view!)             NCRS

"Money can't buy happiness -- but somehow it's more comforting to cry in a CORVETTE than in a Kia"

Thank you for the insights, Vette(s). That's a great intermediate step before pulling the transmission is to just remove the cover and see what I can see. The car had sat for perhaps 15 years not started before I got it. I got it roadworthy again and it is a dependable and safe driver now. But it's not a full rebuild. The original engine has never been torn down other than the quadrajet carb rebuilt. The valve covers have not even been removed. So, I'll inspect what I can. Thanks for the reasonable advice.

Patience is a virtue with these old cars. Do the easy stuff First. The sound can be evaluated by listening. A high pitch may be tin, or lower dull scrape could be aluminum or cast iron. 

Click on image for full view

Hey manchestershark, you and I are starting to think alike, perhaps the torque converter? Did you see my last post when I said I am asking myself what turns and squeeks in the transmission when the car is moving that doesn't turn and squeek when the car is sitting at idle? Don't know what is inside the torque converter, but maybe something in there? It's a high pitched squeek, not a low pitch or grinding or scraping noise.

If it is the torque converter, might be a good justification for swapping to a 5spd manual conversion which I have always desired. The TH350 has no lock up, rpm's are too high at freeway speeds (3,000+ at 65 mph), but it still shifts and drives fine.

Ah, well a conversion may be a desire, but DO your homework first. If RPMs are a concern, I agree. My O.E.M. M20 with 336 rear is equal to yours. Consider a different route. It will be Very costly to convert. If you have ever taken a 4 speed out, or installed one, you'll know the space is Very limited, and NO picnic to accomplish. You will NEVER recoupe your money on gas savings. A good 350 will run fine at 3 grand. Rowing gears is fun, and exiting, but consider a Vette already set up for it. You won't regret it. 

Click on image for full view