Any suspension engineers out there?

[mcorbin]

The E34 factory service manual says that the bushings for upper control (thrust) arms should be centered in the arm, i.e. there should be an equal amount of bushing sticking out on either side of the arm once the bushing is pressed in.

The bushings on the new arms I got for my '92 535 are off a little bit, however. The bushing sticks out 2-3 mm more on one side than the other.

It's not much, but of course, on a few things, suspension geometry has to be precise. Does anybody out there know the suspension well enough to know whether that asymmetry will be a problem, and lead to premature wear or the suspension not working quite right, or something?

If I was to do it again I'd just go ahead and have a shop press the bearings to the center position, but unfortunately I didn't notice until too late and the arms are already installed on the car.

Thanks for any thoughts,

Marcus

[Kalevera]

I'm no engineer, but it makes sense that the bushing should be centered in the arm so that the load is applied as evenly as possible on the bushing. Because of the nature of thrust arm bushings and operating conditions that they work under, I wouldn't worry about it.

Just out of curiosity...who did the pressing? Was it BMA?

best, whit

[mcorbin]

I'm no engineer, but it makes sense that the bushing should be centered in the arm so that the load is applied as evenly as possible on the bushing. Because of the nature of thrust arm bushings and operating conditions that they work under, I wouldn't worry about it.

Just out of curiosity...who did the pressing? Was it BMA?

best, whit

Yes, BMA, that is, a place they use. Thanks for your good-news, though qualified, response.

Marcus

[632 Regal]

yep, these things sometimes last only 10-20k and at other times they can last 100k...luck of the draw. I cant really see anything detrimental with them being slightly off center, probably not even enough to raise an alignment issue.

[infinity5]

mine from BMA are off center. well one is. probably 5mm. i'm not going to mess with it.

[Robin-535im]

Not a suspension engineer... but a mechanical engineer in a previous life. :) Things like suspensions have to be built to operate well over a wide range of adjustments because of the harsh working environment, as Lowell said.

IMHO, there is absolutely no difference in performance for bushings off by a few mm. Especially for the front, where the alignment process will correct any gross errors. As long as the front end as a unit is properly aligned and nothing is bent or way out of whack, you're all set.