The Stovebolt Site Forums The Shop Area Driveline 1951 3/4T Pinion Rebuild stiff

If this still is an HO52 Eaton axle, last I looked those pinion bearings were somewhere between unobtainable and very expensive NOS. It bears being careful as it seems you are doing.

It sounds like the bearing preload is too tight. Could you have mixed up the spacer no.5 with spacer no.7? No. 7 will set the bearing preload. No. 5 provides a seat for the u-joint yoke and tightening that nut should have no effect on preload. This is a much better setup than the crush sleeve used on various light duty axles like the open driveline half-ton and car ones.

Did you give the end of the pinion shaft a good whack with a brass drift to release the stress on the assembly after pressing? If this was an NOS bearing I wonder if the spacer got switched with another one along the way somewhere. Did you keep track not to use the original spacer but use the new one that came with the new bearing? It probably would not be a good idea to add a shim on top of no. 7 as one wants to avoid shimming under a bearing but you may have to do that to reduce preload. Too much preload will make a high speed bearing like this run hot. In some applications, rather than preload, there is a couple thousanths clearance. However, just as a reference, the straddle-mounted tapered rollers in my 6231 Spicer gearbox specify 2-3 thousanths preload. Like a pinion bearing it typically turns up to 3500-4000 RPM.You can't directly measure that but the torque required to turn the assembled shaft will give you a good indication of preload.

Shims, no. 13 will locate the pinion depth. Assuming you are replacing only the bearings, you should use the same shims. You'll have to use a dial indicator to set the backlash when you get to that point. Check the gear pattern anyway. One I got from a boneyard had WAY too much backlash and I reduced it to spec. but I was afraid it would howl but it didn't and the pattern was correct so apparently the gears hadn't worn into the loose pattern.