c2 driveline vibration

[Larry T.]

I have replaced main drive shaft, both half shafts. No rear wheel bearing problems (?) Still I have a severe vibration problem that comes in at around 72-73mph and progressively gets worse. No vibration in steering wheel, vibration in seats. No bent wheels, tires/wheels are balanced. Can't figure out where vibration is coming from.


SUGGESTIONS/EXPERIENCE!!!!!

[Joel T.]

Re: c2 driveline vibration

Larry;

The main drive shaft and the front yoke/universal should be balanced as an assembly. I would do that before I do anything else. I had a similar problem on my 1963.. and found that the way I matched the yoke to the shaft (0 degrees or 180 degrees; i.e 1/2 rotation) made all the difference. There are folks out there who build and balance drive shafts.. I would check this out next. A "quick and dirty" thing to try is just to remove the front "U" bolts, pull the yoke forward and rotate it 1/2 turn, then re-assemble. Joel

[Edward J.]

Re: c2 driveline vibration

Larry, sometimes its best to look at whether the vibration is caused by the engine or driveline. The way I test is drive the car to the speed at where the vibration is worst and note the RPMS, Then put car into neutral and repeat that RPM range , increase RPMS slowly. If it is there while in neutral the problem is engine. if not head to the drive line components.

[Gene M.]

Re: c2 driveline vibration

Larry,
Give us some history. Is this a fresh restoration, a daily driver, all original, anything recent change,...... what?

[Larry T.]

Re: c2 driveline vibration

daily fair weather driver, pleasure (?) vehicle. Don't have substantial history on the vehicle. I have owned the car for 3 1/2 years. I originally thought the vibrations might be inherent to the 1966 Corvette, however after conversing with others - I have concluded I have a problem. The banjo head on the passenger side has been replaced (frozen bearing) the main drive shaft has been replaced along with universal joints, the short shaft on the passenger side has been replaced. Tires and rims have been speed balanced, none are warped.

During all these replacements we have noticed there has to be three (3) washers put on top of the carrier that mounts to the rear end and frame (about 3/4" thick), if the washers are not there the yoke on the rear end hits the underside of the body. According to all schematics in parts books this should not be the case. This is the was the vehicle was when I bought it. I'm wondering why these washers were put there in the first place?

[Edward J.]

Re: c2 driveline vibration

Larry can you post a pic. of the area? It might make it easier to see what your talking about.

[Gene M.]

Re: c2 driveline vibration

Larry,
Yes, photos could help as Ed says. The front of the rear end is secured to a brace that is then mounted to the frame via a pair of rubber cushion and a bolt goes thu it all. If this area is loose that could allow contact with the bottom of the body. Compare illustrations in parts cataloge to verify your car is complete in this area.

[John H.]

Re: c2 driveline vibration

During all these replacements we have noticed there has to be three (3) washers put on top of the carrier that mounts to the rear end and frame (about 3/4" thick), if the washers are not there the yoke on the rear end hits the underside of the body. According to all schematics in parts books this should not be the case. This is the was the vehicle was when I bought it. I'm wondering why these washers were put there in the first place?

Larry -

You may have a "Bubba" system there instead of the correct/original rubber cushions; one has a big flat washer bonded to it, and the other one has a tubular steel spacer in it. If a previous owner has messed with it or replaced the original rubber cushions with hot-rod "poly" bushings (which are way too thin), it will allow the diff nose to rise, the U-joint can hit the underbody, and the angle change in the U-joint that results will cause a driveline vibration. First thing I'd do is to replace whatever's there now with the correct OEM bonded rubber bushings, oriented as shown in UPC 4, sheet B3 in your Assembly Manual.