C-2 Driveline vibration

[Richard Hayes]

I have a 65 4-speed car that the driveline starts vibrating/shifter buzzing at 60MPH or so and really doesn't get worse(just buzzes w/ a higher pitch) as I increase in speed. As I started my investigation- I'm thinking it's coming from the driveshaft. As I was unbolting the shaft from the diff- I found three original bolts and one "ace hardware" bolt- that looked like it had Bubba's fingerprints on (see pic). The bolt is lighter and shorter- would this be the culprit or should I look deeper?

Thanks-

Richard

[Richard Hayes]

Re: C-2 Driveline vibration

Try the link...




Driveshaft

[Rich G.]

Re: C-2 Driveline vibration

I'm not an expert, but in aviation we dynamically balance propellers that turn typically 2400-2700 RPM and the weights are measured in tens of grams. Sometimes a small nut, bolt and washer on the edge of the spinner bulkhead is all it takes. So, could be.

Rich Giannotti

[Mike S.]

Re: C-2 Driveline vibration

Richard -

I was unable to open the picture in your post or your linked page, so I may misunderstand your question. Are you saying your driveshaft is connected to the differential with four bolts? Unless I am mistaken (and I seem to be with increasing frequency), your driveshaft and universal joint should connect with the differential with two u-bolts and four nuts.

Mike S
#33053

[Craig S.]

Re: C-2 Driveline vibration

Richard - this definitely is not a good situation, I would search for a correct GM fastener, or at least insure you have a high grade fastener of equal length in the trunion. You may also have additional balance issues in the shaft, but this is the first step. Since the shaft is out, I would take it to a local driveshaft shop and have it checked for balance, bend, and phasing (they can twist, not likely, but could be off). All of these can affect this situation. Also, check the yoke for wear on the rear of the transmission, and the bushing in the tailshaft housing for play, there should be none. Wear here can worsen any driveline balance issues.....Craig

[Michael S.]

Re: C-2 Driveline vibration

Check your driveshaft and see if it has been out recently for new U joints, clutch etc. It could be installed backwards! Look for the factory paint marks if still visible and then check the assembly manual. There is a front and rear to the driveshaft. If you install the driveshaft "backwards" with the "correct front" of the shaft hooked to the rearend and the "correct rear end" of the driveshaft hooked to the transmission, you can develop a vibration that will effect the car and shifter as noted.

Mike #11202

Something else to check.

[Richard Hayes]

Re: C-2 Driveline vibration

Yes- it does have newer u-joints and yes -it does look like it was installed backwards. And I thought I've done some not so intelligent things working on cars! So- folling everyones recommendations. I'm getting it balanced and getting matching hardware.

Richard