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Well I finally gathered up all the parts, and the warm weather to do the repair. I know there is already several posts about rebuilding the rear diff in our cars, but I wanted to start from scratch with an organized initial post containing all of the info, so future DIY'ers won't have to read though miles of posts to get all the answers.

This work was completed on jack stands in front of my garage. I will list tools and equipment needed as best as possible, and also a list of parts I used/replaced.

Symptoms: Leaking pinion seal along with whine noise from the rear at certain speeds and loads.

Time: Friday night, all day Saturday, all day Sunday {all day meaning morning until dinner time, taking breaks along the way... its not like I'm getting paid to do the work :) }

Hands: 4 hands needed at some points in the removal/installation process, so it's good to have a buddy there or on call - can be done soley but it will take you longer.

Tools/equipment: 4-6 jack stands, 1 or 2 floor jacks, metric sockets and wrenches [mostly 13, 16, 18mm], inverted torx socket set [E8 or E10 I think], air tools [if available] make some of the work go faster, pry bars, hammers, the usual :D. 10 ton (or so) press for the bearings

Parts List:

TIMKEN BEARINGS: HM89410 HM89448 HM803110 HM803149 JLM104948 (x2) JLM104910 (x2) I sourced these from eBay, total cost $120

Crush sleeve: 33-12-1-204-657 $9.92 from dealer

Output shaft seals: 33-10-7-510-289 (x2) size - 76x50x10mm $11.00 ea from AutohausAZ (Victor Reinz)

Pinion seal: 33-12-1-213-949 size - 50x80x9mm $41.50 from AutoHausAZ (OEM)

Cover gasket: 33-11-1-211-679 $1.49 AutoHausAZ (Victor Reinz)

Royal Purple 75w-140 diff fluid, suitable for LSD $36.00 for 2 quarts, local


Operation:

Get the car jacked up high enough to safely work under it. Remove exhaust, I have a Tubi Catback, but couldn't get the pipes to separate for the life of me, so I dropped the whole system. It is VERY HEAVY and is a PITA to do. Recommend 2 people job. It is a time consuming scope of work.

Next, unbolt the halfshafts from the unit, using the E-torxs.

Unbolt the driveshaft from the unit, leave setting in place for now.

Now, support the diff and remove the 3 bolts securing it to the car. Start with the front mount and manipulate the jack to tilt the diff to allow more space to get at the top bolts, if needed.

TIPS FOR REMOVING TOP BOLTS
-grind 2 flat spots onto a cheap 18mm short well socket, or heat and bend an 18mm box end wrench

-Grip the socket with vise-grips or use the wrench to hold the passenger side nut. You will know what I'm talking about when your under there.

Slowly begin to lower the unit from the car. You will have to use your pry bars here, and an extra person is helpful once again. - both for steadying the unit and for prying. dislodge each halfshaft one at a time, then continue to lower enough to pull the unit backword and/or angle it out of the driveshaft bolts. Its hard to describe, but can be done.

Bring unit to a work bench.

FROM HERE ON YOU NEED PRIOR DIFFERENTIAL REBUILD EXPERIENCE, OR A FRIEND WHO HAS.

For everyone else I recommend bringing all of your parts and the unit to a qualified shop that can do the rebuild for you. Make the arrangements before hand and confirm they can do the right job for you.

Remove half shaft "stubs". Use a small pry bar to pop them out.

Remove rear cover

Unbolt the 2 side covers that hold the carrier in place. Tap these out.

Now you can easily knock the seals out from the back side with a punch and hammer. TIP - use a scribe to mark the inside edge of where the seal should sit, to reference when installing the new seals.

R&R the bearing cups in the covers.

Install the new seals.

NOTE: Clean everything nicely during the whole process, you should know what to do to have a good project.

Scrape old cover gasket, ready for new gasket and gray silicone sealant

Remove old bearings from the carrier. - use whatever method your used to. I find it too hard to fit a bearing splitter, so I use a cut-off wheel and cut the bearing off. - it is a flat-rate mechanic technique, only do it if your confident you wont grind into the parts. The tip here is cut it down as far as you can and then use an air hammer to crack it open. This relieves enough pressure to slide it off.

Take diff housing with pinion to your press, set up and press pinion from the housing.

R&R the bearing cones from the diff housing.

Again, choose your method and remove the inner pinion bearing. If you use my method, DO NOT CUT/GOUGE INTO THE PINION GEAR! This creates a stress point and could cause the related tooth to break off in that area. If you nick the "shaft" part, it is OK, but be careful to not nick anything.

Install all the new bearings, don't forget to slide the new crush sleeve on before pressing the pinion back into the housing.

Reinstall carrier, side covers, half shaft "stubs", rear cover, and input shaft seal and "stub". Torque nut to set preload. Be careful here. The crush sleeve "crushes" really hard, but it is easy to tighten too far. Go slow and use your previous experience. I have seen 15 in lbs thrown around as the target torque spec.

INSTALL TO CAR:

NOTE: This is a good time to replace the front mount bushing. Mine was completely shot and made a clunk every time I shifted or put load on/off the diff. It can be replaced using a balljoint press with the proper adapters.

I prefilled the diff with a quart of fluid before putting it under the car, makes for a little less hassle later. After the job was done I realized I probably could have filled it up as long as I had the right angle on the diff. (Proper fill level)

Use a helper to get the diff back "onto" the driveshaft and halfshafts. Jack into place and reinstall the 3 mount bolts. I believe the TIS says to mount everything loose, tighten the top bolts first, then the front mount.

Finish installation reverse of removal. The exhaust will again be a time consuming PITA!!!

Check fluid level, double check everything looks tight, properly aligned, etc. Make sure you don't have any extra bolts :nono:

Job done! Now clean up, sit back and crack open a 12 pack with you helper.

Next post will have some pics.
 

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Discussion Starter #2
Here are a few photos. I forgot to take after shots installed in the car. I will get some though. It looked great having a clean diff and those Tubi resonators shine brightly after being cleaned off!

Also a neat thing I found in the diff. As you can see in the pics below, someone has been in my diff before. There were 2 markings on the pinion. I have no idea what they mean. I counted the teeth on the gears and I have "stock" gearing... so? any ideas?
 

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I assume you're talking about the yellow paint marks on the pinion end?
Somebody has either:
changed the front pinion seal before, or pinion shaft bearings.

The marks were to prevent relative movement of the pinion shaft to nut, so that the nut was not over-torqued. (meaning somebody used an air tool to r+r the nut.
You'll know in about 200-500 miles, if that nut is over-torqued by too much when the rear diff explodes. Ask me how I know. (That was a rhetorical question, please don't. bad memories)

-Pat
 

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This is very timely, I just took apart my spare 2.93 diff apart today and was looking for the last remaining bearing part numbers.

FWIW, RockAuto has the bearings very reasonably priced ($79.60 plus shipping for all of the Timken parts).

Anyone have info on where to source replacement LSD clutches??
 

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Rao I bought my clutch plates from Jim at performance gearing. Very nice guy to deal with. Tell him Robert from MN sent you if you go that route.
 

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Discussion Starter #7
I assume you're talking about the yellow paint marks on the pinion end?
Somebody has either:
changed the front pinion seal before, or pinion shaft bearings.

The marks were to prevent relative movement of the pinion shaft to nut, so that the nut was not over-torqued. (meaning somebody used an air tool to r+r the nut.
You'll know in about 200-500 miles, if that nut is over-torqued by too much when the rear diff explodes. Ask me how I know. (That was a rhetorical question, please don't. bad memories)

-Pat
No, there isn't any yellow paint. I have used that method many times when I was "in the business". I am referring to the "x" and "y" scribed into the top of the pinion, and the letters and numbers on the side, right around where the crush sleeve goes. The divot mark in the top of the pinion was from me slipping my air hammer a bit. I thought the diff was the same as every other domestic rear diff I've done, in that the pinion needs a little assistance breaking free from the bearing to pop out. I quickly realized this wasn't the case and pressed it out the proper way.
 

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Discussion Starter #10
The marking are from BMW. When gears are lapped, they are marked to identify them as a pair and to help with initial pinion shim selection.

You learn something new everyday! Thanks
 

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Install all the new bearings, don't forget to slide the new crush sleeve on before pressing the pinion back into the housing.
I am looking into switching out my ring and pinion and this thread is very helpfull. Do I need to press fit bearing back on the pinion or does it get pressed in the diff housing?

Thanks
 

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I am looking into switching out my ring and pinion and this thread is very helpfull. Do I need to press fit bearing back on the pinion or does it get pressed in the diff housing?

Thanks
If my memory serves me right, the bearing sits in the cone which is tapped into the housing and you press the pinion onto it from the other side. This essentially holds it in. The pinion has to be pressed out of the housing during removal.

So you will need to buy new pinion bearings if you plan to replace the pinion. I would anyways even if this wasn't the case.
 
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If my memory serves me right, the bearing sits in the cone which is tapped into the housing and you press the pinion onto it from the other side. This essentially holds it in. The pinion has to be pressed out of the housing during removal.

So you will need to buy new pinion bearings if you plan to replace the pinion. I would anyways even if this wasn't the case.
Thanks for the quick reply. I saw the part numbers posted so I'm guessing it is only 1 bearing to replace.
 

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ADAM!?!?

Are you paying attention?
 

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I doubt it - he still thinks I am going to fly out and rebuild his for free :rofl:
 

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It's best to use a new crush sleeve and measure the turning torque ;) , but marking the pinion nut and putting it back together the way it was before is what most people do.
 

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It's best to use a new crush sleeve and measure the turning torque ;) , but marking the pinion nut and putting it back together the way it was before is what most people do.
Ok cool then,I will be replacing the crush sleeve. How is the turning torque measured? What kind of tool?

See im paying attention
 

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