In my 64 Elky, what is the correct pinion angle? Exactly how/where is it measured? How do I adjust it??
Any tech articles or sites with this info ???
Didn't find any when I looked. Thanks.

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283v8, If you dont have an assembly manual you should get one as it address's the pinion angle in there. On a 64 car the upper control arms on the rear have eccentric's at the differential housing that are used to adjust the pinion angle. I dont have the information with me as I'm at work. A chevy service manual of the correct year would also be useful.

Thanks, I have a service manual and will do some more research.

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As a rule of the thumb, the pinion shaft should be parallel in both planes with the transmission output shaft. Get the car up in the air with the weight on the wheels and start measuring and checking. The actual offset between the input and output of the driveshft is not critical up to a certain point. When the two shafts are parallel the drive shaft speed varies to allow both shaft to run the same speed without vibration. If you find anything different, please come back and post, I'm very interested in this. tom

Another way of wording it is that the output shaft of the transmission should be parallel with the pinion shaft.

The angle of the transmission will dictate the angle of the pinion.

I've heard that 64's had the excentric washers, but I've never seen them (time to look real close under my 64 wagon!). I believe that it was unique to the 64's.

On all others, you have to use an adjustable upper arm like the one that Hotchkiss sells.


This is the "simplistic" explanation and the angle may be set different if you were doing extreme drag racing.

Wes

[This message has been edited by Wes V (edited 04-03-99).]

I've never seen a good explination of this subject either...so I'll be watching here for more info.

When drag racing, you want the pinion angle set a bit lower than normal, so that under power, when the natural torque reaction twists the pinion "up", everything aligns.

According to Spicer the correct settings are to match the rear angle to the trans yoke to driveshaft angle so that both u-jionts are on the same plane. There are no standard angles.

I guess I have a similar concern -

I recently purchased a '68 Elky - the rearend ratio is 2.76?, which I think is too low (numerically). Anyway, I notice that the angle of the rearend appears to be approx 10-15 degrees down. It is definitely not aligned with the output of the tranny. In fact, when making a left turn I hear a clunking noise, like I'm getting some binding of the u-joints, etc.

So, are the trailing arms allowing too much slop, etc? Or is the rear-end not the correct one for this A-body? I'm not sure how to check, or how to correct.

I also get vibrations when letting up off the gas.


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Sounds like alot of us are in the dark here. I will do some measuring and post another reply with "how it is now".
Still need to know how it should be.

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rkenly - it sounds like your bushings need to be replaced. Mine was about 9 degrees out so i picked up a new set of adjustable upper arms and new lower arms. once i installed the new arms i was only 1 1/2 out. The bushings made the difference not the arms but i also had a bent lower

To all, I have an assembly manual at home for my 64SS Conv and i'll look it up and yes it was a one year thing with the eccentric's on the upper trailing arms my bro-in-law's 65 does not have it this way.

Well I will add my 2 cents, here is what my manuals stats. I could not get the gragh to print out.

The rear universal joint angle is adjusted by means of the cam-type adjuster provided at each rear upper control arm-to-differential carrier attaching. This cam-type adjuster controls the pinion angle; that is, it rotates the axle assembly, thereby changing the pinion shaft centerline in relation to the propeller shaft centerline. (No method is provided for adjusting the front universal joint angle.)

1. Raise vehicle so weight is supported on axle.

2. Check engine angle, propeller shaft and spring condition to make sure riding height is satisfactory.

3. Measure distance from top of axle housing to frame kick-up. Record this measurement for future reference.

4. By use of a bubble protractor, measure propeller shaft angle.
Record this reading for future reference.

5. Rotate propeller shaft until one of the four machined surfaces of the pinion shaft drive flange is parallel to floor. Measure this angle.

6. Referring to graph, (this graph would not print, I listed the numbers below) select angle applicable to the axle-to-frame dimension recorded in Step 3.

7. If the result obtained in Step 6 is not the same (plus or minus 1/2°) adjust pinion shaft as follows:

8. Loosen cam nut, and rotate cams as required. Rotate each cam an equal amount to maintain correct suspension-to-frame relationship. NOTE: Each index mark on cam represents about 5/16-degree change in joint angle. If proper angle cannot be obtained, inspect engine mounts, transmission support and drive line to determine faulty parts.

Not sure if the graph showed up, here are some of the angles:

Axle to frame height Rear joint angle
6" 1 3/4-degree
7" 1 3/4-degree
8" 2 1/4-degree
9" 3 1/2-degree

The way I always did it was to make the tailshaft of the transmission was parallel to the pinion shaft as you can.