Dana 25/41 "Setup Bearings"

The inner "race" of the bearings used for ring and pinions and differentials is extremely hard steel. You will not be able to machine it or drill it.

The steel can be ground using a die grinder. It could be ground on a lathe with a tool post grinder.

When I operated a driveline shop several years ago, I took a brand new Timken bearing cone that was used for the outer pinion bearing and enlarged the bore with a die grinder being very careful to remove material evenly throughout the bore. I stopped after each pass and checked a pinion for fit and when I obtained a snug slip fit I stopped. I also did this with a pair of new differential bearing cones.

Because I had ownership of factory pinion depth tooling, I did not need the inner pinion bearing modified in such a manner. The setup tooling did not use the pinion itself for the setup of pinion depth, but used a precision fixture of a known precise dimension to obtain the required pinion depth, modified only by the + or - markings on the pinion. Even though the tooling gave me the required shim pack thickness for setting the pinion, I always installed the pinion using the dummy outer pinion bearing and set the pinion preload without a seal installed. After I determined the differential offset (Trial and error), I always pulled a pattern the check my work. It was then just a matter of removing the differential and installing the differential bearings with the shims that I had already determined would fit. Replace the outer pinion dummy with the new outer pinion bearing cone and cup and preload shims, install the pinion seal and yoke and torque it down to specs. Install the differential. Pull a final pattern and button things up. The last step was to put the tooling and dummy bearings away with a light coat of oil; ready for the next time they were needed.

The only thing that would have to be done differently for what you propose would be that a inner pinion bearing would have to be modified to slip fit and put as part of the test set.

If you were going to do this, I would start with a set of new bearings OF ONE BRAND, and stick with that brand of bearing for each installation. I sold Timken bearings exclusively in my shop so for the temporary tooling I used Timken bearings. Timken bearings have extremely close dimensional tolerances and can be relied on the set up the same time after time.

I can't speak for other brands of bearings but I am certain that they also extremely very close dimensional tolerances but I would not mix brands of bearings in any setup. Different brands of bearing use the same part numbers for tapered roller bearings, but there could be minor differences in dimensions or even very small differences in the angles of the taper in the bearing cones or cups and this could cause differences in the setup.

Always use the same brand of bearing cone and cup together. Never run a SKF cone, for example, with a Timken cup. Both are reputable manufacturers of bearings...just don't mix them.

Maybe this helped...?

Edited by SE Kansas 46 CJ-2A - 17 Apr. 2017 at 10:11pm

Thanks guys, this is exactly what I'm looking for.

I believe a cylinder hone would be the best solution to opening up the bore of the bearing.

Les, if the cylinder hone doesn't work you can buy a cheap sanding drum from HFT for the drill press. You don't need to buy an oscillating sander...unless you need an excuse for one

Here's a drum I got at HFT; it's too big of course, but they have smaller ones that should work.

both good ideas! I have a dremel and a drill press. I'll probably be next week before I can make them though. The electronics card on our furnace went up in smoke this morning.

Ol' Unreliable wrote: LesBerg wrote: The electronics card on our furnace went up in smoke this morning. That just doesn't sound right.  Electronics on a furnace, when a couple relays worked out perfectly for many decades?

Modern furnaces have all kinds of electronics in them. Manufacturers of furnaces that are better than 90% efficient are all dependent on electronics to make them operate more efficiently and economically. Furnaces of a couple of decades ago only operated at 80% efficiency where now days efficiencies of 98% are possible using electronic controls. This cuts way down on the gas bills and even more if you have to run propane.

After I got out of the driveline business, I installed HVAC equipment until I retired.


Les: If it weren't for bad luck you wouldn't have any luck at all. I hope this doesn't end up costing you too much. Sorry this happened to you.

it seems that my caliper is good, but the thickness of the various blades on the feeler gauge may not be correct. I need to buy better tools...