C2 Proper Drive Shaft Alignment

[James W.]

I am going over my 1964 Corvette to get it ready for the trip to Salt Lake City in a few weeks. One of the things I did tonight is grease the drive shaft U-joints and in the process of removing the drive shaft at the differential I got to looking at the balance weight position on the pinion flange and the balance weight position on the drive shaft. My question is are they suppose to be aligned with each other or opposed 90 degrees? Does it matter in terms of eliminating vibration? They were in-line with each other when I took them off. I have had some vibration between 60 and 70 mph.

Just thought I'd ask before I put the drive shaft back on.

Thanks,

James West

[Duke W.]

Re: C2 Proper Drive Shaft Alignment

There is nothing in the '63 AIM that indicates a specific or even preferred installation orientation.

Check your '64 AIM (Section 4) and see what it says. If nothing is indicated, I'd suggest installing the drive shaft 180 degrees from the orientation you found it in and see if that mitigates the vibration, however, vibration at 60-70 is usually due to static wheel unbalance or tire out of round/radial stiffness variation.

Duke

[Michael H.]

Re: C2 Proper Drive Shaft Alignment

James,

Duke is correct. The balance weights on each component have nothing to do with the other. The prop shaft is balanced as an assembly and weight added where necessary. The diff companion flange is also balanced as a unit, with weight added where necessary. Each component is balanced to within a specified amount (can't remember the amount) so each would have a heavy side and a light side. The heavy side of the drive shaft is marked with a swash of paint and the light side of the companion flange is also marked. On assembly at St. Louis, the shaft was to be assembled to the flange with the paint marks clocked in the same position so any imbalance in one would be canceled by the other.

If your car is at all rusty and these paint marks are no longer visible, there's no way to determine the original position. However, as Duke suggested, if you suspect the shaft is the cause of a vibration, try rotating 180 deg.

I agree on the probility of drive line vibration also. Typically, drive line imbalance problems will first show at roughly 30 MPH, then smooth out at higher speeds. Wheel/tire imbalance problems typically come in around 60 MPH, although a second wave of drive line imbalance can reoccur at that speed also.

Michael

[James W.]

Re: C2 Proper Drive Shaft Alignment

Duke,

Thanks I'll lookagain in the AIM. I think there is a statement about alignment of paint marks on the prop shaft and pinion flange. I suspect it is the cheap General 205/75-15 tire I installed to have the car judged. I'm looking at going with the 205/70-15 or 215/70-15 Goodyear Triple Tread tires if the current tires will not balance. I have a local shopthat will road force balance them to determine if there is a problem.

Thanks again,

James West

[James W.]

Re: C2 Proper Drive Shaft Alignment

Michael,

I suspecting that it is the tires. I'm planning to heve them road force balance checked this weekend.

Thanks,

James West