Topic: Pinion bearings


thirtysixford    -- 07-25-2015 @ 7:39 PM
  I,m rebuilding a '37 differential.
Vanpelts instructions say the pinion bearing next to the pinion gear is a press on fit. It says the outer pinion bearing is a slip on fit.

I have a new set of gears and the new bearing surfaces for both gears are the same size.... they would have to be pressed on.

The bearings are both the same, both new and old pinions are same OD where bearings seat
???


40 Coupe    -- 07-26-2015 @ 5:08 AM
  In order to adjust the pinion bearing preload the bearing next to the adjustment nuts has to be able to move. It can not be a press fit. The bearing next to the gear is indeed a press fit. Suggest you use a micrometer on the pinion shaft. The difference is only a couple of thousands. The ID of the bearings is identical.


pauls39coupe    -- 07-26-2015 @ 8:29 AM
  The original bearings did have two different ID's. One was marked with a suffix P to indicate press fit.
One is pressed on, the other slides for adjustment.
It takes some time and effort but the shaft can be turned slightly undersize by polishing it with crocus cloth till the bearing will just slide on.
Heat the housing in an oven or gas grill for about an hour. This will allow the assembled pinion to drop in place. Allow it to cool then follow the adjustment procedures.


thirtysixford    -- 07-26-2015 @ 4:22 PM
  Upon very close inspection, I do see a small P stamped into one of the original bearings.

The Green Bible only shows one part number 48-4621-B, but does note the one marked p is to be installed next to pinion. This seems to indicate they were sold as a set, however it states 2 required.

Seems to me it would have been easier to machine the shaft to 2 different od's, but what do I know.

Thanks for the help


thirtysixford    -- 08-06-2015 @ 2:06 PM
  Just a follow up... used abrasive cloth for hours, no good.
Went to machine shop was told the shaft is hardened would have to be ground.
Was told to try Euro Precision in Mission Viejo. Once there, Bryan took a look at it and we walked to a nearby shop. He chucked it in a lathe and in 5 minutes the bearing slipped on. When I asked what I owed him, he said nothing..... I gave him $10 anyway. hope I didn't insult him.


thirtysixford    -- 08-06-2015 @ 2:17 PM
  Check out the difference between a 4.44 and 3.54 pinion.


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