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Steve190E 2.3 01-14-2003 06:30 AM

Question about differential seal replacement?
Is there a special socket to loosen the axle nut on the rear diff on a 1988 300E? I have read that you need to mark the nut before you loosen it. I have a 2 different torque wrenches. Should I use the one with the handle that flexes to show torque reading or can I use the one you set and it clicks?

Any other tips?


stevebfl 01-14-2003 08:03 AM

This is really tricky. A torque wrench is of no use. The important thing is to place the nut in exactly the same position it came off.

The problem is that the pinion bearings are set up by crushing a special spacer between the bearing inner races till it takes a certain small torque to turn the tightened bearings only (totally unlike the way you do front wheel bearings). This original tightening is done with only the pinion installed in the case and the measurement can not be retested with the gear set in place.

So, what you have to do is retighten the nut to the exact point it was before removal. it should be tightened to a torque only if it won't go farther. if it will go farther then there is already wear on the pinion bearings and they are probably the reason for the original leak.

Steve190E 2.3 01-17-2003 07:16 AM

Thanks stevebfl.

I think I read a previous post by you regarding this replacement. It mentions marking the nut and the shaft with a sharp chisel to reference where it originally was tightened to. How do you know you are going back to that same postition when tightening? I am not totally clear. Is there only a few turns and then it is tight? I am nervous about the bearings and the crush washers.

P.S. What size of socket is it? It looks like a 30mm deep 12 point.


Steve190E 2.3 01-22-2003 08:09 AM

I finished replacing the seal on the weekend. The socket that is needed is a 30mm deep 12 point socket. I could not use the chisel to mark the shaft that comes out of the differential. (Maybe my chisel was too cheap.) ;) I ended up using a grinding tool and made a small notch to mark the relationship between the shaft and the nut. Once you feel is start to get snug, all you have to do is take the socket off and make small movements till the marks line up.

I hope this helps someone and thanks for the pointers stevebfl.


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