Vladimer

My rear seal start to leak suddenly so naturally another write up was in order! Normally I just post them on the local clubs forum but seems JK-Forum doesn't have one on the rear pinion seal yet.

There seems to be numerous schools of thought for the rear pinion. All have decent reasons which are valid. The longest and most accurate of the ways involves pulling the axles to measure the rotating resistance of the pinion, the preload. The shortest is simply removing the pinion nut and then re-torquing it to 160 foot pounds. I decided to meet in the middle and go off of what the service manual states which doesn't involve pulling the axles, but does measure your before and after resistance.

The first two pictures are backwards and simply depend on how high you are lifting the Jeep. I only put it an inch off of the ground so I drained the oil afterwards. If you are lifting it higher (makes the work easier) then it would be better to drain the oil first.

So for starters, get a drain pan and pull the lower and upper plugs on the rear differential.


Once drained, put the drain bolt back in enough so it doesn't leak. Lift the Jeep up and prop it up on jackstands. Put the transmission into neutral and leave the ebrake off.


Now for the underneath portion. Mark the driveshaft and pinion flange with a permanent marker or some paint for reference when we reassemble it.


Once marked, remove the eight 8mm bolts holding the drive shaft to the pinion flange.


Depending how old your drive shaft is, this step can by time consuming. If it is new, you can remove it with your hands. If it is rusted together then you are going to need a hammer. Looking at the flange from the rear and towards the front of the vehicle, there will be two non threaded holes. These holes are used to help punch the drive shaft out of the pinion flange. A small punch can be inserted and hit a few times to unseat the driveshaft. Mine required a bit more persuasion and I didn't want to keep holding the punch as the blows were getting to be pretty big. I simply wrapped the punch in place so allow solid hits without the risk of sore fingers.


Once the driveshaft is free, you can secure it to the crossmember directly above to allow your self room to work. The two circles are the holes mentioned from the previous step.


At this point I measured the pinion torque to rotate. You cannot use the click style torque wrench for this as it will not give you an accurate reading. The reading should be accurate to one inch pound. My reading was 19 inch pounds to rotate the pinion. If you do not record this number you do run the risk of over, or under tightening the pinion nut and the crush sleeve not having the correct amount of force on it. With all the wrenching on the shaft, be sure to rotate the pinion a few times before taking the reading.


The pinion nut is 1 5/16". Mine came off within a second using an impact only. If yours only spins then putting a few of the bolts that secured the driveshaft back in and putting a pole in place to prevent the rotation might be required. Once the pinion nut is removed a puller will be needed to remove the pinion flange. I used a 3 jaw puller.


At this point you are left with culprit that started this. The pinion seal. I have a small 3" puller but it did not work due to the large pinion shaft in the middle. If you have a puller of some kind that would work it would be considerably easier. It took me a good 15-30 minutes to remove the old seal. It has an orange sealant along the edge and is pressed in there pretty good. I took a screwdriver and hammer and started chiseling away at it and after working the edge enough it did come out.

The old one in all its glory.


The new one: much nicer. Orange sealant on the outside and it comes pre-greased with pink grease in the middle.


Using a rubber deadblow, I pressed the new seal into the housing. Be sure to feel all the edges to make sure it is all flush.


Torque down the pinion nut to the minimum 160 ft-lbs.


Measure the torque require to spin the pinion nut. The reading should what you recorder earlier, plus 5 inch pounds. If your reading is less, torque down the pinion nut in 5 foot pound increments until your reading is 5 inch pounds greater then your recorded reading at the start. Mine took 175 ft lbs before I got that reading.


Reattached your driveshaft with the eight bolts. Take note of the reference line drawn at the start and line them up.


Now is a good time to open the diff and do a clean/inspection of everything inside. Afterwards, tighten up the drain plug and fill the differential with 2.375 quarts of your favorite 75w-90 synthetic gear oil.


Take the Jeep of the jack stands and go for a test drive. If nothing has burned up or blown up, everything has gone according to plan and you just changed your rear pinion seal.

Morris4x4Center

Excellent post ! :-)





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lowendrider

Very good write up..

ronjenx

It's good that you did the before and after torque-to-rotate readings. There are so many "experts" that say 160 ft/lbs on the nut is all it takes.

I have to ask, though, as long as you chose the factory service manual procedure, why didn't you remove the wheels, brake calipers, and rotors to eliminate their inertia and drag from your torque-to-rotate readings?

Vladimer

Thanks guys!

Honestly, I was waffling the idea a few times. I spun the shaft a few times before taking the reading and each time it was the same. I figured as long as I was only working on the seal area of the pinion and didn't change anything else the same amount of drag would be present before and afterwards. The wheels were the same distance off the ground and all of the other factors were basically identical. That was my thought on it at least. The service manual does state to remove the drag as you mentioned.