What size gasket for transmission, Another method to set pinion depth Options

[adolimpio]

I decided to rebuild an extra transmission that I had, but since it was in pieces I did not know what size gasket/shim should be installed on the intermediate plate. I had this issue once before and successfully used dye on the crown and pinion gear to set the proper depth. It took a couple of tries, but I eventually got the proper mesh pattern and the transmission worked nicely.

I decided to use the same procedure on this transmission, but the result was noisy. So I added 0.005 and tried again without success. I then subtracted 0.005, again without success.

So I dug out the shop manuals and read up on the recommended procedure, which is to set the proper distance between the face of the pinion gear and the centerline of the crown gear. The proper distance is determined as follows:

The original design dimension is 63.20mm, but this must be tweaked for quietest operation on each individual transmission.
When the quietest operation is determined at the factory, they etch the variance from the design dimension on the end of the pinion gear, which in my case was 16, (see pic #1 below) so the target distance from face of pinion gear to centerline of crown for my transmission was (63.20 + 0.16), or 63.36mm.

The challenge is accurately measuring this distance, but I came up with this method which seems to work great:

I noticed that the main body of the differential, right above the crown gear had a few machined surfaces, so I chucked it up on a lathe and checked for consistency. Although I don’t recall what the exact runout was, it was very consistent.

The diameter of the machined area was 108.24mm, which meant that from the outside to the centerline is (108.24 / 2), or 54.12mm. (see pic #2 below)

I them assembled the transmission without a gasket and took a machined steel bar and shim stock (see pic #3 below) to measure the distance from the face of the pinion gear to the machined surface, which was 8.75mm. This meant that the distance between the face of the pinion gear and the centerline of crown gear was (54.12 + 8.75), or 62.87mm. (see pic #4 below)

So the required gasket/shim is (target distance, 63.36 – distance without shims, 62.87), or 0.49mm, or 0.019 inch.

I reassembled the transmission with a 0.020 gasket/shim and it performed beautifully.

I hope you find this helpful!

Pic#1


Pic#2


Pic#3


Pic #4