There can be a lot of different problems with these old BMW's, but one of the most common seems to be a shimmy when going at a certain speed, 50-65 mph (80-100 km/h). Does that sound familiar?

The message boards (check the Links section) are filled with different solutions to this problem, but the solution for my car was new to me. Here's the story..

When I got this car, the 525i, it had a set of old tires on. I had them balanced twice to remove some of the shimmy and while in the balancer, I had the chance to see them spin slowly. They were bouncing all over the place, up and down, up and down. No wonder the car had the shimmies...
When at the service center, I checked the steering parts to see if something needed replacing. On both occasions I asked the mechanic to see if he could find something, but everything seemed fine.

The time came to put on a new set of tires, and I was sure that was gonna remove the shimmy, since everything else was OK. I kept a close eye on the wheels while being balanced and they were rock steady. No bouncing up and down as with the old tires.
The rims are an old set of OZ's, which doesn't look very fashionable, but they are very high quality. Perfectly round. Only took a single 0.35 ounce (10 gram) counterweight to balance each wheel. Very nice.

The wheels got on and I drove home. The shimmy was worse than ever! That didn't make any sense to me, now that everything was seemingly OK. So what to do, where to go?

I had a chat with fellow 525i owner Gene H. about this. He knows quite a few things about BMW's and cars/motorcycles in general, so his input can be very valuable. We got to the simple conclusion that something was keeping the wheels from getting balanced right, maybe the balancer itself. Only thing was that the tire shop were using two different balancers to speed things up. Could they both have a problem?
Then it hit me: what if some dirt was caught between the wheel and the hub (brake disc), on the joining surfaces?

I removed the wheels one by one and found there indeed was a lot of buildup, maybe 0.05 inch (1 mm) in all on each wheel. Dirt, brake dust, rust... Everything imaginable. This of course made the wheels go on slightly askew, thereby causing an imperfection in balancing..
I removed the brake discs too and cleaned everything very thoroughly. Here's a few 'before' pictures...

The result? For the first time ever, I am driving a BMW without a shimmy!

I am not saying that this kind of buildup is the cause of every shimmy, but if your wheels are the original ones or kinda old anyhow, then check this out before spending a fortune on replacing control arms, rims and tires. It's a dirt-cheap fix :-)