Weird Hollow Noise in my 62

[John O.]

Hi All

This is hard to explain but here goes. On my completely redone 62, I have noticed a weird noise when I let off the gas pedal.Can't hear it while accelerating cause of engine noise. But it sounds like if something is out of round or unbalanced. It's a low muffle type noise that definatly sounds like something is off balanced.I'm thinking it's coming from the bellhousing area. Pressure plate, clutch etc. Everything is new and the original flywheel was resurfaced. Any thoughts? I was told it could possibly be a broken spring on the clutch disk or the pessure plate. Your help is greatly needed and appreciated before I tear into this. (The noise is not coming from the engine..Only when i'm moving and letting off the gas is when I hear it.)

Thank you....John

[Terry D.]

Re: Weird Hollow Noise in my 62

John

Sounds like you are going to have to tear into it. Was the assembly balanced after flywheel was resurfaced? I'm assuming you tried going down a hill and shuting off the engine to listen to the noise. Might help to have a passenger with you to try and isolate the noise. Keep us informed
Terry

[Chuck R.]

Re: Weird Hollow Noise in my 62

Hi John,

If you had something off balance, I would think that you would be getting a serious vibration through both the floor boards and especially the clutch pedal.

How many miles were put on the drivetrain before this issue surfaced?

Chuck

[John O.]

Re: Weird Hollow Noise in my 62

Hi Chuck

The car has 2000 miles on it since restoration. I have noticed it since I put it on the road. The flywheel was resurfaced and I hoped they balanced it. But i'm not sure. The clutch assembly was new from corvette central. This was done in the beginning of 1999. The car sat till 2003. I finished the car in 2006 because of a major set back. I put it on the road in July of 2006 and I have had the odd wallowing out of round type noise and can't figure it out. But like I said, you hear it mainly when you let up on the throttle and slowing down. It's not the engine it self. I feel it's in the bellhousing area. I'm trying to get some idea's before I tear into it.

Thanks for your reply....John

[Wayne P.]

Re: Weird Hollow Noise in my 62

My experience has been that noise when letting off, comes from the rear end when it unloads. Could also be the transmission. Doesn't really sound like out of balance. That would be there all the time and probably more pronounced under load.

[Terry R.]

Re: Weird Hollow Noise in my 62

I'm like Wayne a noise in the rear end will travel right up the driveshaft. Slide under the car and see if you have excessive backlash on the pinion.Good Luck

[John O.]

Re: Weird Hollow Noise in my 62

Thanks Wayne and Terry

The rear end was rebuilt and all is snug.The tranny was rebuilt too. A friend is going to ride shot gun to help hear the noise. Is it possible for a noise like that to come from the tranny or rear end? Is there any way you can think of to isolate the tranny, rear end to figure out if it,s either one of them?

Thanks....John

[Chuck R.]

Re: Weird Hollow Noise in my 62

Are you getting any kind of vibration along with this noise John?

I'll probably catch heat for this but.......I'm not convinced that balancing of the complete clutch assembly is necessary unless your turning 10K or greater rpms racing.

Other than balancing the flywheel, once the rest of the clutch assembly is centered and bolted into place, it's pretty much right where it needs to be and at the 6K or less RPMs that these cars may see, that should be plenty tru enough.

Anything beyond the flywheel is money in the shredder as far as I'm concerned.

Chuck

[Verle R.]

Re: Weird Hollow Noise in my 62

Chuck,

No heat on the balance question, just my experience.

I have made it a practice to have any new clutch balanced and the flywheel should be after it is surfaced. My experience has been that they are all out of balance to some extent, many enough to cause vibration problems. Just experienced it again, a guy didn't balance the flywheel and clutch and complained about significant engine vibration about 2000 RPM. Finally pulled the clutch and flywheel and both were out of balance, the clutch in particular. These were not cheap parts, they were good quality.

I have seen this enough times before that I consider it just part of the process. It will cost a lot of aggravation, work and money to pull it out later.

It does not cost much to get them balanced. While the engine is out/apart, go ahead and balance them.

Verle

[John O.]

Re: Weird Hollow Noise in my 62

Hi Chuck

No i'm not getting vibration. Just this type of out of round hum noise as I let off the gas.A friend of mine is going to help me with it. I'll let you know what we find.

John

[Wayne W.]

Re: Weird Hollow Noise in my 62

Exhaust harmonics?