Rear Differential Pinion Seal Leaking

[Jimvr4]

Title says it all. I have a leak at the pinion seal of my VR4 rear diff. I checked the manual and I have to mark and disconnect the propeller shaft from the companion flange. Then using a special tool (end yoke holder) remove the lock nut and pop out the seal.

It looks like pressing in a new seal (MB569924, to be confirmed) requires a special tool which appears to be a spacer. I believe you just use the flange and lock nut to press the seal in and the spacer pushes it in far enough to seat properly. Then the spacer is removed and companion flange is reinstalled and lock nut tightened. It appears it may be possible to do all of this without removing the rear differential carrier.

Has anyone done this? What are the tips and tricks? Can it be done without the special tools?

Thanks for any help you can provide.
Jim :)

[J. Fast]

Check the torque, runout, and backlash before you pull the locking nut on the rear diff companion and write it down for futurde ref.

To break the locking nut pull the rear tires and reset the lug nuts (so you don't strip the threads). Get two 3' prybars/crowbars and slide them thru the lugs so they bind on the ground when you rotate the rear axles. Set the locking bars in opposite directions thru the wheel studs so they work against eachother and wedge/lock the rear diff. Once you lock the rear diff in place with the bars mark the bar angles on the rotors and the locking positions of the bars on the ground (when you reset the flange later you will want to reposition the bars in the same position they locked before so the locking marks will come in handy). Check the freeplay and mark your lines. You're ready to go after the locking bolt on the companion flange.

Once you break the companion free, pull your bars and check the spacers at the flange union to see if they're cracked and need to be replaced. Pull the seal and check the bearing and make sure it's not burned or grooved into the race. If the bearing is good, grease it and set the seal with a flange spacer and a piece of 1 1/2" schedule 80pvc/abs pipe and a rubber mallet. Use the lines you drew on the rear rotors to reset the bars and lock the rear in position to re-torque the rear. Check the rotation tq and the backlash before you put the driveshaft back on just incase you need to set shims.

Have fun :)

[Jimvr4]

Thanks Jeremy. I was out of town so just getting around to reading your reply and assessing the task. I've ordered the pinion oil seal which does appear to be MB569924 as it is priced the same if you drill down through the online catalog at Cherry Hill Mits. I'm new to working on gears so had to read what backlash is and checked the manual for the procedure. For torque measurement I would need a spring balance, correct? I see a 2.6 lbs spec for rear wheel bearing resistance (measured with drive shaft disconnected) in the manual and assume this figure includes the resistance of both rear wheels as well as the differential. Is this the torque measurement you refer to? Still don't know what runout is and how to measure.

I followed your breaker bar idea for locking up the rear diff. Cool - I just need to get a couple more bars as the only one I have would be needed on the lock nut. I don't get why the position of the locking bars would be critical and need to be marked though.

I don't have much reason to suspect an issue with the bearing as the leak has recently developed and I know the fluid was topped off when I changed it a few months ago. I'm trying to imagine how this looks apart. The pinion front bearing just slides on the shaft and seats against the pinion, correct? To install the oil seal you call for a flange spacer, a piece of schedule 80 and a rubber mallet. Where do I get the flange spacer?

Sorry for all the stupid questions.
-Jim

[Jimvr4]

Found some time today to work on this. I jacked the car up and checked the backlash with the handbrake on and it measured about 0.2 inches which is in the range. Disconnected the drive shaft from the companion flange. The lock nut measures around 28mm. Can you confirm this is the correct size? I still need to pick up a couple of breaker bars and a 28mm socket assuming that's the correct size.

[J. Fast]

Can't confirm that size, I didnt use a metric, I believe it's 1 1/4" or 1 1/8"

[Jimvr4]

Thanks. My measurement was right about 1.1 inches so I'll go with a 1 1/8 socket. 28mm is probably going to be too tight.

[Jimvr4]

Picked up a 1 1/8 and it was too big. Tried to find a 28mm but must be a non-standard so I went with a 1 1/16 and it fits perfect. I need to raise the car further to get some room with my 25 inch breaker bar. Also thinking about bolting an angle iron to the companion flange to lock it instead of trying to lock the wheels (won't the LSD allow the flange to turn anyway?) Also need to pick up some 1 1/2 ABS pipe and another pack of latex work gloves.

[Jimvr4]

Still trying to get the locknut out. Having trouble getting enough room to work. I raised the car a few more inches but still can't move my breaker bar very far. I picked up a 1 1/16 12 point socket to get a little more range to work with. Wedging crowbars against the lug nuts still allows a little play in the companion flange so I tried to bolt a metal strip across the flange so the end would bind on the frame. The strip tore at the mounting hole so it needs to be thicker in that area. Thinking about trying my impact driver as well as pulling the E-brake or having someone stand on the brake pedal.

Seal came in and looks good
http://jns.jimnshar.com/2c380a90.jpg

[J. Fast]

You use PB Blaster? In cases like yours I have several pieces of 1" rigid gas pipe. I believe the one I used for that is about 6' long and I put a 10 degree bend in it about 2 1/2 feet out. You can slide it under the car and sleeve your breaker and extend it for leverage.

[Jimvr4]

You use PB Blaster? In cases like yours I have several pieces of 1" rigid gas pipe. I believe the one I used for that is about 6' long and I put a 10 degree bend in it about 2 1/2 feet out. You can slide it under the car and sleeve your breaker and extend it for leverage.

No need for PB Blaster. No rust whatsoever in there, just a tight locknut.

I made a special tool to remove the flange out of a piece designed for gates. It was pre-drilled but I had to drill another hole and notch out the side to allow my socket to fit in the center:

http://jns.jimnshar.com/2c580a90.jpg

http://jns.jimnshar.com/2c780a90.jpg

With this strap bolted on the flange I used my impact driver and gave it a few whacks. Then I went to the 1/2 inch breaker bar and it did the trick. The flange pulls right off the splines at this point. I pulled out the old seal and inspected the bearings for damage and found nothing wrong. Great news! That meant the leak was just the old rubber failing and nothing more:

http://jns.jimnshar.com/2c980a90.jpg

Here's a shot taken after I pressed in the new seal using a 1 1/2 inch piece of ABS plastic:

http://jns.jimnshar.com/2cb80a90.jpg

At this point I just reversed the tool on the flange so I could turn the breaker bar clockwise for tightening. Got it all back together, filled with 1.2 quarts of 75W90 and checked for leaks. All looks to be OK now.