Repair of Differential Carrier Bushings (archive)

I wanted to pass along a repair technique that I used to repair a couple of differential carrier bushings (the ones just under the rear doors that secure the rear suspension subframe to the chassis) in the hope that it will help someone facing this job.

Not having the proper tools to remove/replace the bushings, I was looking at either purchasing the tools ($350+), making them myself (a lathe would be nice), or sending the car to a dealer ($500+). There are ways to do the job without the tools, but none are particularly fun or easy (removal of the entire subframe, for instance).

I settled on attempting to repair the bad bushings using a urethane rubber product made by Devcon called "Flexane." It's a pourable two-part urethane that hardens to 80 Durometer urethane rubber. It is an industrial product intended for really heavy duty repairs and manufacture (casting of heavy duty parts).

I simply lowered the carrier by removing the lower locating plate (13mm headed bolts plus the large nut that retains the bushing), and allowed the subframe to drop down about an inch or so. Using the Devcon primer (for improved adhesion), I coated the interior of the rubber bushing and the metal sleeve (the bushings fail when the sleeves pull free of the rubber itself). I then jacked the subframe back into position, placed a 4" round cardboard gasket under the bushing (to prevent the urethane to running out before curing), and loosely secured the locating plate with the large nut finger tight only.

Then I mixed the Flexane according to directions (about 3:1) and poured about 4 oz into the top of each bushing, roughly filling it to the top.

You have to leave the parts in position for about 48-72 hours for the Flexane to fully cure.

The result is a bushing that appears stronger than new that requires less than 2 hours of very easy effort to accomplish. The cost is about $50 initially for the materials($20 for the primers and $39 for the Flexane), of which only about 5% of the primer and 50% of the pound container of the Flexane is used.

The remainder has already come in handy repairing many items around the shop.

It is also suitable for making "new" e28 thrust arm bushings bullet proof (pour them solid before installation and they should be as good as 750iL bushings).

Bob
(Absolutely NO connection to Devcon)

Devcon Web Site

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