Slackdaddy

While my Chrysler 8.25 (3.73) was out of the 2001 XJ, I did a truss and KJ disc brake conversion, new axle shaft bearings and seals.
While it was out I dropped it, from about 2' off the stands and it his the concrete shop floor. I think pinion hit 1st
When I was re-assembling the carrier/axles, etc,, I noticed the pinion had some "noise" spinning it by hand (carrier was out),, but I "ignored it"

So, axle is in, new U bolts, E-brake cables, everything bled and tightened up.
Took it for a test spin and it makes a pretty good grinding sound starting at about 5 mph,, deff coming from the pinion area, not axle bearings.

So,,
Pull the axle and do the pinion bearings with the axle on an axle stand,, or try to do it with the axle in the XJ,,
It is in a nice clean, conditioned shop, I have the floor jacks, heavy duty jack stands, deadman safety blocks, etc,, But no lift,, so this would be a "on my back repair"

Can not decide if all the effort of pulling the axle is worth it to have the axle out in the open.
Also,, 2000 XJ FSM (Page 3-119, Pinion install) says that if reusing the pinion and ring gear that factory pinion shims should not need replacement.
Anyone have experience replacing the pinon bearings? did the factory shims work out ?

Slackdaddy

So,,
I ended up pulling the rear.
I pulled the axles and carrier
This is spinning the pinion and the noise it makes. There is no end play or tightness, just a rumbling sound, full of 90W and driving 10 mph it is audible. (no carpet in xj yet)

Is this normal pinion bearing noise??

Saudade

Looks and sounds like your pinion preload is off. It shouldn't spin that freely.

Pinion bearing preload should be:

Original Bearings . . . . . . . 1–2 N·m (10–20 in. lbs.)
New Bearings ......... 1.5–4 N·m (10–30 in. lbs.)

From the 2001 FSM:

Slackdaddy

Yeah, the pre load was not really moving the pointer on the 1/4 beam torque wrench. I'd say 1-3 in/lb

Moral of the story,, don't drop the rear end on the pinion when moving it around the shop.

Slackdaddy

Quick question,,
what are my chances that I will get a good pattern just replacing the pinion bearings and re-using the factory pinion shims ?

Old Man Minimalist

Can't answer directly to the 8.25 but I just finished setting up my Dana 30. I used set up bearings to get my pinion depth and preload set up. Since I was reusing the ring and pinion and carrier I used the factory shim for the depth. That was fine. I could not use the original shims though for the preload. The new bearings I installed must have been enough different that I had to use different shims.

I even had to make a slight adjustment once I pressed on the permanent bearings.

For me, I'd take the axle out from under the Jeep. As many times as I had the pinion and carrier in and out, my back would have been screaming at me much more than it is now, lol.

OldTires

I wonder if when you dropped it, the crush sleeve went out of sorts and let go of the preload. I would try a new crush sleeve before redoing the pinion bearings. Though, if you have it out already, may as well go all the way.

BwanaBob

I recently redid my 8.25 and used the factory pinion shims. It had Timken
pinion bearings before so I put new Timkens in, same dimension.

If you get a new crush sleeve and Timken bearings, I think you can get
the preload set easily enough. Then you should be in good shape to get
the pattern you had before.

Slackdaddy

So I did pull the pinion,, The front pinion bearing race is quite "scuffed"

So if re-assembling with new pinion and carrier bearings,,
I could use the original pinion shims and press on the new bearing and assemble, IF the new bearing was the same spec as the original bearing.
I could use a "set-up" pinion bearing and check the original shims, if that is good then press on the new bearing,,, BUT who is to say the "set-up" bearing is the same as the new perm bearing ?
The new perm bearing has as much chance of being the same as the original bearing,, as the perm bearing being the same as the set-up bearing.

I understand using a set-up bearing on new gears, but is it needed with the old gears in the same housing ?
Now if the new race was slightly different, that would show up on the set-up AND the new perm bearing.

here is a pic of the front pinion bearing race,,

Old Man Minimalist

I took key measurements from my set up bearings and my permanent bearings. The idea was to match them perfectly if possible. As it turned out, they were basically spot on.

BUT, I did have to adjust the shims with the new bearings over the old ones. And I have been told that usually once you set it with the setup bearings, the permanent bearings should produce the same specs.

Mine was close like I may have mentioned above.

Slackdaddy

The Motive Gear master bearing set I am getting has Koyo bearings,, from some reading online, They have a solid reputation. Same parent company as Timken,, even some "claiming" they ordered Timken and Koyo bearings were in the Timken box.
I guess I should get a 2nd Koyo bearing to make a set-up bearing out of?

Old Man Minimalist

I'm no expert in setting up differentials. This recent one is only my second though I believe I got it right (knock on wood). Buying and making set up bearings is a process and extra money for sure. But you can keep them for future use or maybe share with someone else that may need to do theirs.

It is a risk I suppose. On one hand you could just go ahead and press new bearings and hope everything lines up correct. If it does, you are golden. If it doesn't, you will most likely ruin the bearing pressing it off and now you are where you would have been if you had used a set up bearing. Plus, given that I had mine out at least a half dozen times from start to finish, it paid off well for me to have set up bearings.

The nice thing is, if I am correct, you won't need setup bearings for the carrier. That carrier should have adjusters for the backlash. So only one set up bearing for pinion depth.

Slackdaddy

I ordered a USA Gear master kit with Koyo Bearings -$85
I ordered a 2nd Koyo M802048 bearing (found an open box bearing only, no race for $18 on ebay)

I'll let you all know how it goes.

Old Man Minimalist

Perfect! All you need for set up purposes is the cone(bearing). Cup can be installed.