Bearing Race Fit 2

[zcoker]

Question: I have a Porsche transmission pinion bearing race going into an aluminum housing. On top of this roller style bearing is a four point ball bearing and then a steel retainer plate. The problem with these transmissions is that the pinion race creeps over time and sooner the pinion race becomes real loose. Mine had .002 clearance. Some have quite a bit more and can wobble in the bore. The common fix is to machine the housing and press fit a sleeve and then the race. This takes a lot of meat away from the upper bearing, the main shaft bearing. The other alternative is to electro-plate the OD race and then sneak up on a clearance, which is the route I've taken because it was cheap (nickle plating). My question is fit. My housing is 3.151". My bearing was 3.149" OD and is now 3.154" OD. This bearing is FAG, special bearing, impossible to get information, $600 list ala Porsche -- basically a black hole. I believe this bearing takes the radial load from the pinion and the other takes the axial. The bearing race is .904" wide. The other smaller main shaft bearing appears a tight press fit, and I am not touching it to see how tight. The pinion bearing race (to the best of my knowledge) is not a slip fit by design because the factory manual says to heat up the aluminum to 120c to get it out. I think that I have covered all the information needed for the pros to give some advice on the matter. Any info on fit is appreciated.

 

[pontiacjack]

Pat- You've confirmed my worst fears- that I'm invisible and voiceless...

 

[Tmoose]

That old bearing tech publication "Ask Walt" had a picture of a bearing that had reportedly been run in a housing that had been "repaired" by knurling. The knurled pattern had shivered and fretted right into the race, most likely because the forces that made the micromotions or creeping and wore out the housing the first time were opposed by about 1/10 as much metal after knurling. The accuracy (location, roundness and circularity) of the surface provided by knurling if "sized" by pressing in the bearing in is pretty poor too.