Aug 28, 2015 update to the BMW M3 project car

Use the BMW, Abuse the BMW

Our Bmw E36 M3 has seen a fair amount of use.
The combination of a sticky track, 4000 rpm launch and healthy dose of wheel-hop caused our driveshaft to twist itself in two.

Our poor E36-Chassis BMW M3. It never asked for this sort of abuse.

During the $2014 Challenge’s fun runs, our M3 suffered a catastrophic failure at the drag strip. The combination of a sticky track, 4000 rpm launch and healthy dose of wheel-hop caused our driveshaft to twist itself in two. The usually sturdy metal shaft underneath our BMW now resembled a Twizzlers. This was not good.

While we were replacing the driveshaft with one sourced from Redline BMW Performance, we noticed that our rear camber angles looked a bit wonky. Further inspection revealed that our rear trailing arm bushings were worn. This was hardly surprising as they were the original rubber pieces, and our 170,000-mile BMW is now 18 years old. It was clearly time for a refresh.

Fortunately aftermarket choices abound for this very popular chassis, and our friends at Condor Speed Shop had what we were after. As we drive more aggressively than the average BMW owner, we decided to forgo the stock rubber bushings and instead chose their solid Delrin replacements for $90.

The Delrin bushings are very dense, theoretically allowing just enough compliance to keep NVH levels at a reasonable level. Their lack of deflection will also control the rear suspension better than the squishy rubber originals.

While we were underneath our car, we also noticed that our differential bushings and rear subframe bushings were worn. With our Speedfest at the Classic Motorsports Mitty presented by Hagerty only days away, we decided to postpone replacing these bushings until after the event. After all, BMW was the featured marque and our M3 was scheduled to act as chase car during the weekend’s parade and touring laps.

Throughout the Mitty weekend, our M3 performed well. The new Condor Speed Shop bushings were immediately noticeable, keeping the car secure and planted in all circumstances.

Remember that decision to hold off on repairing the car? That turned out to be a mistake. As the weekend rolled on, we began noticing an occasional clunk. It seemed to be coming from the rear suspension, but repeated checks didn’t reveal the culprit.

After one last look, we convinced ourselves that the clunk and rattle were the result of the worn subframe and differential bushings. We decided to hit the road, leaving Road Atlanta for home in Daytona Beach with our fingers crossed. We’d replace the bushings once we returned home. This plan almost worked.

Just 30 miles from home, the rattle revealed itself to be the differential mounting bolt. The worn suspension bushings had allowed the bolt to loosen and it finally sheared. Our beloved M3 would make the final leg of the journey on the back of a flatbed.

As we later learned, high-mileage E36-chassis BMWs tend to shear the differential bolt. We’ve since ordered a differential support mounting bracket from Active Autowerke. This $275 part should fix this problem.

While we have the car apart, we will freshen all the suspension bushings. This will be a massive undertaking, but one that will no doubt make our M3 safe and enjoyable for years to come.

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Comments

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jsquared
jsquared Reader
8/28/15 10:34 a.m.

Have you reinforced the subframe mounting points yet?

Joe Gearin
Joe Gearin Associate Publisher
8/28/15 11:54 a.m.

M3's have factory reinforced subframe mounting points. At least by 1997 they did. I think the 95's didn't but I'm not positive on that one. In any case, they are in good shape.

Jamey_from_Legal
Jamey_from_Legal Reader
8/28/15 1:09 p.m.

Sorry for your troubles on the road.

I don't think of a full bushing swap job on these cars as a massive effort. I think of it as inevitable routine maintenance. But it is a tedious bit.

I'm betting the E36 chassis will become a popular grassroots platform for the next several years. It's cheap, it handles well, and there's plenty of available info on what they can do for you once you "do for them." If you publish an overview of the process, I think it will do the community a service. We see a lot of this type of question popping up here, every other week.

Joe Gearin
Joe Gearin Associate Publisher
8/28/15 1:35 p.m.

Thanks Jamey--- I'll be heading down to Redline BMW in mid-September to do the bushing install with help from longtime GRM friend Rennie Bryant. I plan on detailing the entire process to give other E36 owners (or prospective owners) an idea of what is involved. These wonderful cars are getting older now.....so most will need this done--- sooner rather than later. I'm looking forward to driving the car again....it's been too long!

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