1963 Chevrolet Biscayne Positraction Differential Overhaul - Part 3 - Problems

[@Ademann]

You can try to dismantle the whole thing again and carefully clean the differential housing and the ring gear. Then tighten the housing screws in several stages. Do the same with the screws from ring gear. I have had great success with it many times!

[@WeberAuto]

Thanks

[@AddictedtoProjects]

Hi, I have left a similar comment in Part-2, so just for context's sake; You could have put this inner gear housing (fully assembled, so that both halves mate together) into a lathe and turn it between centers, as they call it. It involves setting up the inner case on two cones in the lathe, and dialing everything in to eliminate runout. Then you machine the mating surface for the ring gear to remove any runout. Not much material needs to be removed to achieve this. I suspect you would have enough adjustment left in the side bearings to make up for the 0.007" removed to get a clean, straight surface.

[@WeberAuto]

+mictho100 Good thought! Thanks for the feedback!

[@geojor]

thanks for sharing...

[@flineman]

If the run out doubled when you added the ring gear then have you tried rotating the ring gear 180 degrees to cancel out the runout

[@WeberAuto]

Hi, thank you for your comment. The .007" lateral runout was in the differential case before installing the ring gear. I should have stopped at that point without installing the ring gear to address the problem.

[@geojor]

thanks again...

[@SGags001]

How did you fix the problem? I didn’t see a video of the fix. Thanks

[@rockabilly229]

Hello, I have probably a similar issue with 1958 Chevy Impala, too? The "problem": If I check my new Eaton-Posi as you did, I measure an axial runout from max. 0,0016". That's possibly not too much for a brand new part? In accordance with the manual 0,003" would be acceptable. With the installed ring gear on the Posi, I measure an axial runout from max. 0,0026" on the outer edge of the ring gear. To be honest, I'm a little bit disappointed of these values with brand new parts. Especially, if I compare these values with the 57year old stock differential. It runs with nearly no play, 0,0008", measured on the ring gear! What is your opinion? Can I stay calm with that results? Is my expectation too high and I can go on with the new parts? Or should I rework the new Posi? Thanks in advance!

[@WeberAuto]

Hi, new parts are not necessarily good parts; however, you should be okay with that amount of lateral runout as long as your backlash does not vary more than 0.002" across all the ring gear teeth.

[@SS-U23]

I thought that the graduations were 6-7 of 0.0005 of an inch. They are actually 12-13 Graduations or marks of 0.0005 of an inch. Thank you