Dana 25 pinion bearing replacement

Hey all. Went to change all the fluids on my '56 CJ5 I've been working on. Drained the front differential and found a bunch of metal flakes in the oil. Removed the cover and found a bunch of bearing pieces laying in the bottom, especially towards the rear of the case. Checked all the gears and bearings that I could see and they all looked fine. I have to assume I'm seeing what remains of the outer pinion bearing. I've found my Haynes manual to be practically useless. My question is: can I remove the front drive shaft, yolk, and seal and replace the bearing without removing the axle and tearing it down? Thanks in advance.
-Jeremy

 

if you need to ask, I would gently suggest that a specialist differential shop would be a good idea. The gears need to be set up very precisely.

On the other hand I personally (un-encumbered by knowledge) would probably want to try exactly what you are suggesting.

 

I would be tempted to replace the complete axle with another 25 or 27. What ratio is it? These axles are not desirable as anything but replacement parts, so the price should be ok if you can find one nearby.

Another - perhaps encouraging - comment. The front axles on these Jeeps are normally only used at low speeds and infrequently ... I would certainly remove the yoke and take a look with the idea in mind that I could just replace the outer pinion bearing and get away with it for quite a while. Looking at how the differential goes together, it appears that the thickness of the outer pinion bearing does not affect the pinion depth.

Once you get into a lot of new parts and extensive setup and dis-assembly, the cost and risk goes up a lot.

 

Gear ratio is 5.38. Yeah, I'm hoping I can just replace the bearing and move on. Like I said, everything else looks good. I'm hoping someone knows if this can be done. If it can't, I'll probably just clean it out, fill it with oil and use it until it pukes and hunt for a replacement axle in the meantime.

 

Assuming all other parts are in good condition; replacing the outer pinion bearing alone is a simple task.
The drive yoke must be removed.
The pinion seal must be removed.
The old bearing cup (#02820) must be removed from the carrier.
The old bearing (#02872) can then be slid off from the pinion shaft.
The bearing preload shim pack is also on the pinion shaft.
Remove, clean and inspect the preload shim pack.

Re-assembly....
Install new bearing cup into the clean carrier bore.
If servicable re-install the original preload shim pack onto the pinion shaft.
Install the new bearing onto the pinion shaft.
Technically you should re-adjust the pinion bearing preload upon re-assembly.
Install the drive yoke and tighten the old pinion nut down to 180 ft pounds.
Rotate the pinion with a wheel off ground (for open differential) to test the preload via inch pound meter.
Technically you are simultaneously rotating the carrier preload so your preload reading will be compounded higher than the standard pinion preload of 15-20 inch pounds.
I would probably adjust the compound preload by feel or you may wish to set it at about 30 inch pounds.
If not correct you should remove / re-assemble and re-adjust the shim pack.
In theory the preload should not vary but in practice it will vary due to bearing differences, wear etc.

After all that is done and adjusted you can then re-install the new pinion seal.
The pinion nut must be put on and torqued down one final time.
If you have a late design hug lock pinion nut it should be a brand new never used one.
(Use once throw away design)
If you have an early design hug lock pinion nut it can be re-used with thread locker.

 

Ken, the bearing comes out before the cup, no?

 

Correct that's my mistake...
The cup may be very hard to remove or near impossible with the differential, plus ring and pinion in place.
A puller is normally used to remove and install bearing cups but one might get by using a long thin drift.
(preferably aluminum or brass)
If the bearing cup looks good one might have to re-use it if they can't get the old bearing cup out. (not the ideal repair)

Now that I think about it there's really no way to remove the outer pinion cup without pulling the differential out.
Or just maybe one could somehow use a bearing puller with the jaws set outward.

 

FYI.......The correct Dana tools to remove and install the inside / outside cups and inner axle seals look like this.

 

These are later tools.
The early W99 Miller tools are similar but the bearing cups are pulled in and out of position as oppose to being driven.

 

That's exactly the info I was looking for! Thanks guys. I'll pull it apart and see what I got (tonight hopefully). I figured it'd would be near impossible to get the cup out, but I'll determine that once I get it apart. Thanks so much! I'll let you know how it goes!

 

Actually, no. I tried moving it around but it didn't feel sloppy. I assumed that the inner bearing and yolk seal were holding it true and doing all the work. I'll double check when I get home though.

 

Well, pulled the yoke and seal. I couldn't believe it. The bearing is in perfect shape. I double, triple, quadruple checked all the other bearings and gears. Everything is in good shape. I'm scratching my head on this one. I gueesss it's pooooossssible a PO replaced a bearing and missed some of the shrapnel. All together there were three chewed up rollers and the other chunks maybe added up to the size of a quarter. That just seems like such a huge oversight to me I'm having a hard time convincing myself.
Oh well. Guess I'll slap it back together and move on. Almost ready to hit the trails!

 

You can get by with just a bearing change most of the time. The bearings are made to very close tolerances. I did many bearing changes on diffs with same shim packs and the bearings were not even made by the same manufacturer. It can be done, but NOT always!