I rebuilt the rear in my '27 touring a year or two ago and the ring and pinion clearance was a tad under 15 thou. Rear was nice and quiet. I am now fitting a Planetor transmission to the rear which I though would only entail changing the drive shaft/torque tube assembly on the car for the assembly that includes the Planetor transmission. When I did that I found a lot of play so I pulled one side of the rear housing out and found that the clearance is now 80 thou using the pinion gear on the Planetor drive shaft assembly even though the ring and pinion gears line up perfectly. It seem like my only option is to shim the ring gear and/ or the thrust washers on one side while shaving them on the other side to move the whole assembly over. What is the best way to correct this problem and how do I ever make up the 65 thou difference without a ton of shims. Could it be that the pinion gears are cut so differently that this is what is causing the difference? Both the old pinion gear and the one on the Planetor assembly appear to have little or no wear and the ring gear is nos. I should add that the Planetor assembly came out of another car of mine and the ring and pinion clearance on that car was less than 20 thou.
Are both the pinion gears the same diameter?
If you end up moving the whole assembly over, double check that the brake drum doesn't end up to close to the diff backing plate on one side, I would be trying the pinion change first.
I will check the diameter of the two pinions and swap them if the Ford standard pinion is bigger. If not I guess I will have to go the shim route but I am reluctant to shim that much. I had new axles for the rebuild a year ago and they are slightly longer than the originals so I hope the brake drum interference wont be a problem.
If you decide to shim, 16 gauge sheet metal is .0625" and 15 gauge is .0703", so you may get away w/one of them, or use one shim of 16 gauge and another thin one.