Adjusting pinion on drive shaft after assembly

[Bill Goddard]

I am about to assemble my pinion to the drive shaft and then assemble that assembly to the banjo. If the gear tooth engagement needs to be adjusted later along the drive shaft how will I get the pinion/bearing assembly apart to add shims.. In my case the second (forward ) bearing is also a press fit on the pinion sleeve even with the reduced dia of the pinion sleeve. The pinion is an original part I am sure.Wouldn't it be best if the forward(second) bearing was a looser sliding fit like a piston pin? Thanks for your help here. Bill G

 

[Tom Endy]

You ask two questions:

The first, about shimming the pinion gear on the drive shaft. I have rebuilt several hundred rear ends and have never seen the need to either shim the pinion bearing or machine material off the pinion sleeve bearing stop. I have never found a shim under the bearing closest to the gear end of the sleeve on any I have torn down. I know there was an article in the Restorer about it and the same article is also in the Volume 8 of the How-To series, but I don't see where all this is necessary. Henry's design pretty much centers the pinion gear to the ring gear and you adjust the gear depth by the side to side selection of the banjo gaskets determined when the carrier pre-load was made. This is the back lash adjustment.

The second: If you are using an original R&P set the two diameter dimensions on the pinion sleeve are usually already there and correct. It is the repos you have to be concerned about. The first bearing that sits next to the gear end should be an interference press fit. The second bearing should not be. It should be a "snug" fit. You may have to tap it on with a pipe and several small hammer blows. If during the pre-load adjustment you get the pre-load too tight, you back the nuts off and tap the pinion end of the drive shaft with a hammer to move the forward bearing back slightly. If the bearing is "snug" it will move back. If it is truely an interference fit, it will not move.

The pre-load on the pinion is equally important as is the pre-load on the carrier. All four bearings are the same part number and if you get any of them too tight you will generate heat and likely spin them on their mounts.

Tom Endy

 

[Bill Goddard]

Thanks Tom for your reply.

I have a fit that will require a little tapping on the second bearing. I hope it will not be too tight. By the way, the pinion that came with the car has a 1/8" fillet radius between the back of the gear surface and the sleeve and the old bearing has a similar radius at the corner of the I D of the inner race. When I took the bearing off there was a shim crushed between the gear radius and the bearing I.D filleted corner. My replacement pinion has a more square corner and would accommodate a shim better if I needed one. Thanks again Bill G

 

[sonny30coupe]

I just started to put my rearend back together. I had the problem of not being able to get the bearing on the shaft at all. I could barely get it much past the threads. I then took a dremel to the inside of the bearing and made it a tight fit on the back bearing and a slightly snug fit on the front. There was a .005 difference in the shaft and the I.D of the bearing. I am now ready to move on with the final assembly.