Would a 40-55 shimmy point towards wheel balance, and not thrust arms?

[AllanS]

I swapped out my thrust arms, and put in new Lemfoerder arms with 750 bushings. This time, I did everything by the book, replaced all hardware, torqued everything exactly.......and now I have a shimmy between 40 and 55 mph. I took it in for an alignment, and it came out exactly the same. I took it back this morning, and the shop said that they'd check out the wheel balance again.

Now, I've had thrust arm induced shimmy before, and I don't remember it starting out lower than 50mph, and mine starts to get noticeable at 40. Does this seem to be more of a balance issue than a worn suspension part? Any opinions or ideas would be much obliged!

Thanks,
Allan

[Rodericb]

Post a follow-up once you resolve your problem. I had the same problem and found that I had a bent rim and my tires needed HS balancing. This is a common occurance on the e34 and many people would be interested in hearing the results....or at least I would.



I swapped out my thrust arms, and put in new Lemfoerder arms with 750 bushings. This time, I did everything by the book, replaced all hardware, torqued everything exactly.......and now I have a shimmy between 40 and 55 mph. I took it in for an alignment, and it came out exactly the same. I took it back this morning, and the shop said that they'd check out the wheel balance again.

Now, I've had thrust arm induced shimmy before, and I don't remember it starting out lower than 50mph, and mine starts to get noticeable at 40. Does this seem to be more of a balance issue than a worn suspension part? Any opinions or ideas would be much obliged!

Thanks,
Allan

[AllanS]

Yep, I'll be picking it up tonight so I'll have a talk with the service manager about it as well.

[AllanS]

Well, they said that the wheels are fine, and the tires don't have any flat spots in them, so I'm going to take a look at adjusting the steering box as the first point of attack. I messed with it a few weeks before and was able to eleviate the shimmy, at the risk of lack of feedback above 45mph.

[Hector]

balancing but not the road force balancing. If you are really anal but any kind of vibrations (or even car noises like myself,) then even the smallest shimmy not noticeable to many people would be noticeable to us. Sometimes static wheel balancing will not eliminate the vibrations/shimmies entirely so one has to do the road force measurements. Here is an excellent link I have on the matter from a tire forum I belong to. I even have it book marked.

http://128.242.141.111/pub/technical/index.cfm

Also, keep in mind that all suspension components work in concert as stated by George M so even if you changed the thrust arms you still might experience a slight shimmy if other suspension components are worn. Was the problem worse before you changed the thrust arms? If it got better after you installed the thrust arms, then it might be something else related to the suspension or it could be related to the driveshaft which you didn't notice before changing thrust arms.

HTW

[ryan roopnarine]

after i put the spare tire on the front, my reduction in shimmy was at least 50%, even with totally dead thrust arm bushings. i think ill have to tip my tire guy a little hard and get him to straighten things out.

[Robin-535im]

Well, they said that the wheels are fine, and the tires don't have any flat spots in them, so I'm going to take a look at adjusting the steering box as the first point of attack. I messed with it a few weeks before and was able to eleviate the shimmy, at the risk of lack of feedback above 45mph.

I've found that these cars are very sensitive to tire health: balance, inflation, treadwear, etc. You can dis- and re- mount the tires and make sure all the mating surfaces are clean and flat, even check runout with a dial indicator if you have one. Then have a good tire shop do a high-speed balance - I swear I've had more "suspension problems" that turned out to be "tire problems" than anything else.

HTH

- Robin

[AllanS]

It actually got worse after I changed the arms and had it aligned. Before it was just at around 55, but now it's a lot wider range. I think I may end up calling a shop near me that specializes in BMWs and ask where he gets alignment and balancing work done, but in the meantime I'm going to swap on the old 15" rims and give it a spin tonight.

[bjl4776]

I had the same problem, but under medium braking, got new tires put on the front and changed the brake pads and rotors, now there is no shimmy at all