C-1 drivetrain angles

[David B.]

I searched and read the archive posts on this topic but have a question on setting up the shims correctly between the transmission mounting plate and frame on a '57:

If the "canceled angle" between the transmission output shaft and the pinion angle is set up to be close to zero degrees (or some other recommended angle?) by shimming, is that a preferred setup? Also, does it matter what the driveshaft angle is?

I am measuring off the oil pan rails and off the bottom of the rear housing to pick up my inclinations of the trans output shaft and the pinion angle (assuming the bottom of the carrier case is parallel to the pinion shaft).

After shimming the trans carrier bracket down 3/8", my measurements are:
pinion angle = 1 degree, positive
trans output angle = 1 degree, positive
driveshaft angle 9 = degrees, positive
canceled angle = (1-1) = 0 degrees
*all angles measured relative to the horizon
**positive defined as higher toward front of car
Therefore, the angle between the driveshaft and the pinion shaft is (9-1)=8 degrees with the car in its natural stance.

Does this setup sound ok, subject to a road test? Or, should I be shimming to a different angle to offset rear leaf spring travel under acceleration?

Thanks,
Dave

[Doug F.]

Re: C-1 drivetrain angles

i have never worried about degree of angle, as long as the shifter clears the tunnel and the drive shaft, yoke and ujoint also clear everything, you are good to go, some cars require spacers, others don't, if your spring arch varies greatly from original, you might have an angle issue,

[John H.]

Re: C-1 drivetrain angles

David -

C1's have defied the accepted engineering rules of U-joint operating angle limitations for 50 years; I shimmed the trans crossmember down about 3/8" from the frame on all of mine and never had an issue.

[David B.]

Re: C-1 drivetrain angles

Doug, John,

Sounds good. Thanks very much for the replies. I will button it up and see how it drives.

Dave B.

[Robert G.]

Re: C-1 drivetrain angles

You can probably check the U-joint manufacturer's website to see what they say the maximum angle should be. I seem to recall that 3 degrees was optimum and this website has some good info on it.

http://www.4xshaft.com/driveline101.html

[David B.]

Re: C-1 drivetrain angles

Robert,

Thanks very much for the link. I had not seen that site.

I see it recommends not exceeding 7 degrees u-joint angle - I have 8 degrees with no driver or passenger weight. (I think that with my overweight self in the seat, it should make 7 degrees ok).

Based on that info, it also seems that I shouldn't shim it any further down, and possibly could remove some shims, so long as I have adequate tunnel clearances.

Thanks for the information. This has been educational for me. Between you, John, and Doug, all of my questions have been answered.

Dave

[Edward M.]

Re: C-1 drivetrain angles

I just went through this with my 56. I initially had a vibration at speed. After following John Hinckley and others suggestion about getting zero cancelled angle, the vibration went away.

Mine needed to be shimmed down about 3/8 of an inch.

[David B.]

Re: C-1 drivetrain angles

Edwards,

Thanks for the info on your '56. It seems that 3/8" is the general consensus dimension, unless there is tunnel interference.

Strangely, I did not find anything in the ST-12 or the AIM on this subject when first researching this. Consequently, the info from you and the other contributors to this thread should be really helpful to others in the future as well as me.

Thanks,
Dave

[John H.]

Re: C-1 drivetrain angles

Edwards,

Thanks for the info on your '56. It seems that 3/8" is the general consensus dimension, unless there is tunnel interference.

Strangely, I did not find anything in the ST-12 or the AIM on this subject when first researching this. Consequently, the info from you and the other contributors to this thread should be really helpful to others in the future as well as me.

Thanks,
Dave

Dave -

There were several TSB's on this driveline vibration issue over the years - one in 1959 told the dealers to install tapered shims between the rear axle spring pads and the springs to change the pinion angle, and another one in 1961 told them to shim the transmission crossmember down 1/4" - 3/8".

[David B.]

Re: C-1 drivetrain angles

John,

Is there a source you know of to find a complete set of the TSB's?

Thanks,
Dave

[John H.]

Re: C-1 drivetrain angles

John,

Is there a source you know of to find a complete set of the TSB's?

Thanks,
Dave

Dave -

Not that I'm aware of.

[David B.]

Re: C-1 drivetrain angles

John,

There seems to be a solution forthcoming...

https://www.forums.ncrs.org/showthre...809#post499162

Dave