I need some help with differential

[homer41]

I have a 41 P-12 that is stock.  I am working on putting disc brakes on it and I noticed the endplay on the rear axles is excessive. I read in the maintenance manual about adding or subtracting spacers but for the life of me I don't see how this affects endplay when nothing touches the bearing to stop it from moving axiially. I got a 37 diff and pulled the hubs and it is the same. Any help would be greatly appreciated.    Dave

[PT81Jan]

On 4/24/2019 at 4:43 AM, homer41 said:

I have a 41 P-12 that is stock.  I am working on putting disc brakes on it and I noticed the endplay on the rear axles is excessive. I read in the maintenance manual about adding or subtracting spacers but for the life of me I don't see how this affects endplay when nothing touches the bearing to stop it from moving axiially. I got a 37 diff and pulled the hubs and it is the same. Any help would be greatly appreciated.    Dave

 

The spacers are supposed to adjust the outer bearing race in relation to the inner race / rollers.

With the original differential installed, the outer wheel bearing races protudes slightly out of the flange. Then one or more flange spacers are needed (pic.1)

If there is another ring and pinion (different ratio) installed, it might be, the wheel bearing race is slightly recessed. In that case a spacer ring is necessary (pic.2 no original equipment).

Watch out to check left and right at the same time, adjustment has got effect each on the other side, since the axle shafts can move in the center area.

I hope my explanation attempt is understandable (if not, pic.3 might help)

pic.1

pic.2

 

pic.3

 

Edited April 25, 2019 by PT81Jan

[keithb7]

I uploaded a  few videos with some explanations, when I serviced my rear wheel bearings. 

 

Grease and future service topics are discussed too. 

 

https://youtu.be/2TlQvMxLeEY

Edited April 24, 2019 by keithb7

[MarkAubuchon]

10/4  that's what you need to do.  also make note of the grease fittings for the bearings.

[greg g]

you could swap in a later unit with disc brakes or upgraded drums.  Likely donors include ranger explorer, mopar B bodies, early jeep Cherokees not grand, 5 bolt Dakota.  there will be some surgery deeded on spring perches and shock mounts but they are doable at home if you have the skills and a good welder.

[homer41]

I got schooled!  I thought the bearings were lubricated from the gear oil in the differential. Now I need to do more investigation. This forum is great! I still have a lot of endplay that I need to deal with, I might have to change the bearings. I still need to get it straight in my head as to what comes in contact with the bearing to set the endplay because I just don't understand it. I am going to dig deeper.   Dave

[keithb7]

If you watched my video I posted earlier, you’ll see a tapered roller bearing pressed on to 1 axle shaft. I am feeding grease into it. This bearing is cone shaped. It has no outer race yet on it. Also known as the cup part of the bearing. 

 

The axle shaft with outer bearing pressed onto it is placed inside the axle housing. It is held snugly at the diff end by the inner bearing and splines.  The outer end, tapered bearing cone pointing outward, needs a home to rest and support the axle. The tapered bearing cup gets pushed into place and seats nicely against the cone roller bearing. How tight you push the cup in, or not, is restricted by the shims. You are pushing the cup into its final resting place against the cone when you bolt down the brake backing plate. 

 

After everything is bolted down, the play you feel on the axle when you push/pull on it is the clearance between the bearing cone and cup. 

 

Pull you axles. Clean an inspect the outer bearings. You’re in that far, I’d replace the bearings with new.  New inner & outer seals too. New brake backing plate dust seals too. 

 

Well, then you’re  in that far. Hows the brakes? Lol.  How about the diff housing gasket?...All a great learning opportunity. 

 

Edited April 25, 2019 by keithb7

[Merle Coggins]

The two axle shafts but up against a thrust block in the middle of the differential. When you set the preload/end play of the bearings you are pressing the two bearing cups against the bearing cones, which push the axle shafts against each other, against the thrust block. When you set your end play with shims you have to do both sides together.

[homer41]

You folks are the best! I am a little thick in the head sometimes, BUT now I have it figured out! I was told when I put the disc brakes on I did not need the backing plate, WRONG, that is my issue, I will have to cut out the center of the backing plate and install it. THEN I should be able to make the proper adjustments. Thank you so much.    Dave