Differential question for the experts

'89 Jeep Comanche 4 banger, 134K miles, son-in-law ran diff dry and locked it up. On disassembly it was found that the pinion bearing welded to the shaft. Replaced ring and pinion, pinion bearings and carrier bearings. Tehnperature was over 105 that day so I used new spacers the same thickness as the old with the intent when it cooled down going back in if it wasn't setup correctly.

Needless to say rearend developed typical pinion noise at 40-55 MPH when under load. It's starting to cool off so I'm getting ready to work on it again.

Questions:
1. In generic Dana 35 rearend procedures they refer to a crush sleeve in the pinion area. I never saw one. Is there one?

2. The setup procedure is quite extensive with putting it together and taking it apart. That is probably why the shops charge mega bucks. They want more than the truck is worth. Are there any shortcuts to shorten this?

3. The vehicle is used for short trips in town only and rarely at speed. Other than the irritation from the noise, is any damage occuring?

Any help appreciated.

Tnx Fred

Yes, it uses a crush sleeve to set the pinion bearing preload. If you didn't see it, it's probably because it was already crushed and you didn't recognize it. How DID you set the preload?

What some of the gear vendors suggest (and I think a few even sell) is a pair of setup bearings for the carrier. These have the inside bore honed out slightly so that they can be slipped on and off by hand. That makes it much easier and quicker to shift shims around until you have the correct carrier bearing preload and backlash. Once you have it dialed in, then you take off the setup bearings and press on the actual bearings you'll run.

Take a look at your wear pattern. If it's not way off from what it should be I don't think short, low-speed trips will hurt anything. Might help to run 75W140 gear lube, and maybe log onto Mr. Moly's web site and order a can of molybdenum disulfide additive to help things keep sliding instead of rubbing. I don't have a URL but I found him once through Google, so you probably can also.

1,2,3 ... sounds like and old Jackson 5 song...


1: YES - there should be a sleevebetween the two pinion bearings - it'll set/hold pre-load

2: The Mega-Buck thing is all you imagination -- it's actually quite affordable! -- HOWEVER, for the D35 and similar diffs, if you have a set of new pinion bearings that have the ID's opened-up a little bit and the old pinion nut, you can set everything from the gear pattern, the open ID's will allow you to slip the bearings on and off with impunity -- try what shims you think are close first under the pinion head, get it tight (don't go nuts just tight) with the bearings in place - set the ring and carrier in and get the backlash shimed, the bearing caps tight and run a pattern -- (remember to add some loading to the carrier to resist turning so you'll get a real parttern!

Decreasing backlash moves the ring gear closer to the pinion.
- Drive pattern (convex side of gear) moves slightly lower and toward the toe.
- Coast pattern (concave side of gear) moves lower and toward the toe.

Increasing backlash moves the ring gear away from the pinion.
- Drive pattern moves slightly higher and toward the heel.
- Coast pattern moves higher and towards the heel.

Thicker pinion shim with the backlash constant moves the pinion closer to the ring gear.
- Drive pattern moves deeper on the tooth (flank contact) and slightly toward the toe.
- Coast pattern moves deeper on the tooth and toward the heel.

Thinner pinion shim with the backlash constant moves the pinion further from the ring gear.
- Drive pattern moves toward the top of the tooth (face contact) and toward the heel.
- Coast pattern moves toward the top of the tooth and slightly toward the toe.

You're looking to get something like this:

3: Wear is also work hardening the R&P once the pattern is run farr off for a while (a few hundred to a thousand miles) you'll get some hard spots that'll give you noise forevermore ... a poorly centered pattern will have you working the ring in less than it's strongest places and stuff does break and a small wear areas loads/heats/wears that little area much faster than a large wear pattern...


[edit] moved some typos around, added some new ones, and tried a smaller pic[/edit]

Pinion setup

I wouldn't mind paying $100-150 for it to be setup. I would even pull the diff and deliver it if could be in that range. Local shop where I got the spacers quoted $350. Truck is barely worth that!

Wonder if noise is due to not replacing crush sleeve? I used a micrometer to measure the old spacers. Hard to diagnose, might change it first.

Really appreciate the information, it is really helpful!

Tnx Fred

Re: Pinion setup

fgcox1 said:

Wonder if noise is due to not replacing crush sleeve? I used a micrometer to measure the old spacers. Hard to diagnose, might change it first.

Click to expand...

Doubtful. The crush sleeve does not affect any spacing or the wear pattern -- it affects the preload on the pinion bearing. Pinion depth -- which DOES affect the pattern -- is controlled with shims. Bearings are manufactured to close enough tolerances that you should not have to change the shim pack when replacing bearings. However, in your case I think you said you had to replace the pinion, so the depth should have been checked when installing the new one.

Usually they have a mark on the end that gives you a starting point -- if both the old one and the new one are marked the same, they should be the same length and install with the same shims. But the FSM tells you to use that only as a starting point and to measure with the jig to verify.

Back to my previous question: If you didn't use a new crush sleeve, how did you set the pinion bearing preload?