XJ Pinion Seal Replacement

A

akorna

New member
Re: Biggest jeep wave ever!

Just purchased a '99 Cherokee Classic 4WD - my first Jeep!

Noticed some minor leaking from both the front and rear differential pinion seals (109K on the clock). The AllData subscription that I have shows a very elaborate method to replace the seals which includes a lot of special tools and removing the brake drums/rotors!

I've read some tech articles that just describe using an impact wrench to remove and replace the pinion nut/yoke and simply replacing the seal. Any advice on replacing the seals?

Also I gather that I have Dana 30 differentials fron/rear. Is there a way to tell if they are Track Loc other than removing the cover?

Thanks for any responses.
 

You have a D30 front, and either the D35 or the Chrysler 8.25" in the rear, the 8.25" came with the factory tow package.

Here's the FSM directions on changing the rear D35 pinion seal:
http://www.sija.org/bounty/Misc/D35PinionSeal.pdf

Correct me if I'm wrong, but the front D30 will be easier as it doesn't use a crush sleeve. Remove the yoke, change the seal, and slap the yoke back on.
 
A little seepage at the seal, doesn´t mean much. Keeps the seal lubed and helps fight rust. Really not worth the aggrivation, if it´s just a little moist around the seal and there is no large area of oil or dripping. Just wash it off occasionally, when washing your underbody at the wash and spray. Check the diff. oils every so often.
If the yoke is loose, when pushing it sideways, you can feel a little click. It´s probably time for pinion bearings, an adjustment and seals rarley holds for long, when the pinion bearings are worn.
Another little tip, mark the yoke and shaft (like mentioned in the FSM also record the inch pound readings) and also the shaft and nut (a small cold chisel notch works and doesn´t rub off). When loosening the pinion nut, use a big torque wrench, as soon as the nut starts to move, record the reading. That nut is usually really on there tight (like 150 ft pounds) cleaning the threads with a wire brush and oil helps.
The object is to get it back together as close as possible to how it came apart. Then, if there is a little to much play in the bearings, to take up the extra slack, without putting to much pressure on the bearings (which may overheat them). If you tighten up the pinion nut, until it starts getting tight, then line the notch up with the mark on the shaft, with a torque wrench and watching the readings, you can get back to what you had pretty easy. Then if needed, do some fine adjustment, with the inch pound torque wrench and pre load adjustment.
One thing they didn´t mention, is removing the brake drums, helps when trying to get an accurate inch pound measurement and the proper bearing preload. Even better if you pull the axles, but not really necessary most times.
When you get done, you should be able to turn the yoke (without the drivedhaft) with one hand (close to the same inch pound torque, it took to turn it before removal), without too much effort. If you need a big wrench to turn it, it´s too tight and won´t last. Too loose and your pinion/ring gear may start to howl and make noise, after awhile.
 
Thanks for the great advice. Looks like just the front differential is leaking from the pinion seal, makes a a drop or two every time it's driven, the case is pretty oily.

If the goal is to get the yoke tighted down to where it was originally, maybe it would be worthwhile to measure the length of the pinion exposed past the nut with a vernier caliper. Even a small amount of rotation would register I would think.
 

A dial gauge could probably be used, but a thin sharp notch or dot made with a punch will work just a good. Mark the shaft, the nut and the yoke. If you read the FSM they suggest putting it back together again and adding 5 inch pounds of additional pressure on the bearings. This is to account for wear and is kind of an approximation or close enough. The final test is to try and turn it with one hand, without really forcing anything. I usually do it by feel and haven´t had any problems yet.
Too tight can heat up the bearings, to loose can cause noise and affect the way the gears mesh.
 
If your diff. oil is really black, it may be time for a change. Might be the original oil. After 5-6 years, was used to be 90 wt. could be closer to 30 wt. due to shear. I´ve seen seeps, mostly dry up and stop, with an oil change.
The only way to really tell, how much you are loosing, is through periodic checks. A very little gear oil, often looks like more than it is.
 
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