I have a 95 dana 30 out of a cherokee that i am rebuilding for my 4wd conversion. I have done almost everything but rebuild or work on diffs. This is my first time taking the internals apart and i would like to learn and do the install myself. I have the axle completely taken apart and am ready to put it back together. I have the new inner bearing pressed on the pinion and have the cup put into the inside of the diff. Now where im getting confused is how to put everything back together. I have the original shims, a new baffle, new outer bearing and cup, outer oil seal, yoke and nut ready. What is the order i put everything in? I see the baffle can only go in one way and do not want to mess that up. Also i am still trying to figure out what pinion depth or preload is that i need to set before i put in the carrier. I simple explanation will help. Thank you, Mike.

 

The thing is, it is not simple to explain. I did this years ago, and you have to have patience, precise tools and the factory specs to all the torques and clearances. There are some threads that are very good and cover the process start to finish.

 

If you google “XJ Diff gear change” you’re going to get tons of good videos on the process. Unfortunately it involves using a “sacrificial” set of pinion bearings to set the pinion up, then install the permanent bears only after all pinion dimensions and preloads are set.

As stated above, it’s a tedious process of prepping “fit up” bearings for the pinion, install and torque the pinion, verify pinion depth with a caliper (have to know spec), this usually takes a few tries to get the right shims in there, then pull it all apart and press on the permanent bearing, reassemble with seal, set preload using a dial indicating torque wrench. All that is just for the pinion, haven’t even started on the carrier yet!! It’s very doable, but do some reading and research before you go any further. The next step (carrier) is going to involve using a dial indicator to set backlash....very important to get right!!

 

Basically, the pinion gear and the ring teeth have to engage one another at a certain way or else they will fail. The range for them to engage is very tight, like thousands of an inch. At the factory they measure the pinion, and casting and know exactly how to adjust, with shims, the depth of the pinion so that it engages with the ring in the required way.

If you had taken it apart, cleaned everything and then put it back together with the same bearings, races and shims, no problem, because they would mate the same way as before. But the new inner bearing is probably going to change the contact pattern and you are going to have to play with the shims to get close to the old contact pattern or an acceptable one.

I did it with trial and error, using the yellow gear paint. I used a throw away jam nut to tighten the pinion, then check the contact pattern with the paint. Once I got to an acceptable pattern, I tightened it all with the real pinion nut. You can do it the other way, using calipers and measurements and math. I wasn't smart enough for that but maybe you are.

 

This thread helped me a lot

https://www.jeepforum.com/forum/f8/c...art-i-1121189/

 

You need to measure the old shims first with a digital caliper then set the new ones at the same thickness and use that as your baseline. You need to make setup bearings for the carrier and a setup race for the pinion. I had to assemble and take apart my Dana 30 4 or 5 times to get the pinion depth correct when I regeared.

 

Thank you guys so much. I will use everything and start with that. Kinda sucks i already pressed on new bearings onto the carrier with the old shims installed. I did one side at a time not to mix up the shims. Is there a way not to use set up bearings and be able to do the work. Or will i be messing up these brand new bearings i already installed?

 

You may get lucky and have the correct backlash using the old shims.

 

If you never did this, know you are getting in way way over your head. Not to discourage you but just know this is a big project for a skilled person, and a really big one for someone that never did it. My 2c.

 

I've called around and all the 4x4 shops want 400-500$ to do it. That seems ridiculous. Rather learn and do it my self.

 

Careful...you got to have torque wrenches ft lbs and inch pounds, dial indicators, a way to press bearings and the specs (pinion preload,backlash,torque to turn and how to read a contact pattern ) to do it correctly. I work at a plant (well was until the dang corona virus hit now were are laid off ) that makes diffs for MB,Chrysler and GM trust me to do it correctly takes correct tools. If you do decide to do it just take your time and do it correctly do not take short cuts.

 

4-500 is cheap, me thinks. I called around for pinion bearing replacement once and was quoted the book number of hours all the same at 3 shops x the hourly rate was in the 11-12oo range.

 

$1100-1200 for a pinion bearing replacement? That is ridiculous, about 4x what it should be.

 

Had a camero got it rebuilt back in 86 for 250. Think my 67 stang back in 90 got rebuilt for about the same price. figured today should be around 400-500?

 

That is ridiculous, isn't it. Figure shop gets 100/hr, most reputable ones do. Then go look it up hourly, add the cost of the bearings, shims, side bearings, crush sleeve etc and see what you come up with.