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Shake in front end

Discussion in 'E39 (1997-2003)' started by CG540i, Apr 21, 2009.

    CG540i guest

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    I have a 2002 540i I purchased about 6 months ago and recently have experienced a "shimmer" in the front end when going between 65 and 75 mph. The car has 89k on the odometer and I thought the bushings might be issue. Last week I had new tires on the front, had new suspension arms w/ bushings replaced and an alignment done. Thought that might have solved the problem but still feel the shimmer? The rotors look good and don't appear to need replacing at this time. Any thoughts on what might be causing this and what I might want to check next?
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    CSBM5

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    Perhaps they replaced the control arm and not the thrust bushings? At that mileage, the thrust bushings are surely well worn. BMW refers to the main horizontal locator control arm as the "wishbone" (see #12 in link) and the thrust bushing secured arm as the "traction strut" (see #5 in link). The thrust bushings are #6 in the link.

    realoem link to front suspension diagram

    For E39 M5's, people often use a properly installed X5 thrust bushing or for whackos like myself go with the Dinan monoball bushings.

    CG540i guest

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    Thanks

    Chuck-
    Thanks for info and comments. I checked w/ my mechanic and he assures me that the thrust bushings were replaced as well. He felt the issue might be with the balance on the wheels and offered to check the balance if I brought the vehicle to him.

    Thanks again.

    Charles



    ViolinARC guest

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    Typical problem...

    It surely sounds like the infamous thrust arm bushing failure so I'd question your repair ppl. Did they torque everything in the air or on the ground? You must torque all suspension bolts with the full weight of the vehicle on the ground to prevent preloading the bushings or you're gonna experience other problems.

    My repair facility did everything correctly and the exact same issue dissappeared completely. We only replaced the thrust arm bushings with M5 (I've heard of success with X5 as well), which seems to have eliminated the shimmy permanently. I ran my last set of tires into the ground (only 18k miles but bald and no rebalance) but never experienced the shimmy again. Just put new tires on (Potenza RE760's) and she rides like new with 125k on the original sport suspension (everything feels tight and tested fine).

    Since you've just put new tires on the front, they should be fine but did you have the rears rebalanced at the same time? You had an alignment so did they check your camber as well as the toe? Maybe the front end has experienced a major impact of some sort i.e. taking speed bumps at high speed, accident, etc. Some have stated that it could be warped or out-of-round rotors but from my reading, this is not common and is highly unlikely as brake rotors are TOUGH. Have the wheel bearings tested for play as well but otherwise I'm going back to the thrust arm bushings as the culprit because I've researched this shimmy a lot and they are the main cause of shimmy at those speeds. Double check on the PROPER torquing procedure as that may be the cause...keep us posted and GL. :cool:

    CG540i guest

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    ViolinARC-
    Thanks for the post and your comments are greatly appreciated.... You bring up some great questions and points which I'll try and address:

    Not sure if he torqued everything in the ground or in the air, however, I would think you'd need an underground bay in order to torque the bolts with full wight of the vehicle on the ground? His shop has only lifts and no underground bay area so I'm curious as to whether he has the ability to have the weight of the vehicle on the ground?

    I did not have the rear tires rebalanced when the new front were put on.

    For the alignment they checked the camber and the toe. Both needed adjustment and were aligned: Front left camber -0.36 before adjustment -0.33 after; Front right-0.46 before and -0.47 after; Partial toe left 0.09 before and 0.03 after; Right 0.05 before and 0.03 after; Total front toe 0.14 before and 0.07 after. Curve toe right and left 0.79 and 0.70 before and after.

    For the rear:
    Camber Left -2.17 before and -1.42 after; Right -1.78 before and -1.43 after; partial toe left 0.07 before and 0.03 after; right 0.14 before and 0.03 after; Total toe 0.20 before and 0.06 after.

    Yes, there was an impact on the front end. A deer was hit 3 months ago and the car spent some time getting put back together. I was assured that no damage was done to the frame and that the specs were accurate. Before I purchased the car I brought it the BMW mechanic for a thorough inspection. I was told the control arm bushing were about done and that they'd need to be replaced soon. The tech drove the vehicle and said he felt this and further showed me that the play in the bushings when the car was up in the air. I've been back and forth with the body shop and they're sticking to "the deer hit could not have disturbed the frame"... Checked with local BMW dealers service department on this as well and they agreed that an animal hit would not cause a problem w/ the frame. When I explained the "shimmy" to them they drove the vehicle and said it just in need of new front tires.

    You have given me some good advice / information and I'll follow up accordingly until I get this problem corrected. If you have any other comments / suggestions after reading this "War and Peace" type of reply, please let me know.

    Thanks again.






    ViolinARC guest

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    Mucho appreciatamundo...LOL!

    Thanks for the kind comments. I agree that the deer impact probably wouldn't have anything to do with the shimmy but I had to ask. :p

    Your Indy is gonna have to fess up cause without the right type of lift (flatbed with hydraulic jacks built in) or an underground bay, it's highly likely that he torqued everything in the air and that ain't good. It creates a preloaded bushing situation, which will cause problems i.e. your shimmy. From my research, full vehicle weight when torquing the suspension components is a prerequisite for BMW's. Ask if there is any way he can access the correct type of lift or if he has access to an underground bay so you can torque everything with the full weight of the vehicle on the suspension to avoid preloading the bushings. This has been discussed many times on BF.c so I'm positive regarding this procedure...
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    CSBM5

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    Using an alignment rack makes torquing under normal load/ride height easy.

    ViolinARC guest

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    Thanks Chuck...I was totally distracted when I posted this. :eek:

    Rabino guest

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    I had my thrust arms w/ bushings replaced and my shimmy at 50/60 went to a shake/shimmy at 80. I am pretty sure my indy did all the work on the rack. I also had the tires road force balanced and they check out. I am wondering do I need to try to get my indy to re-torque on the ground? I have not done an alignment yet guess that is next, but the car seems to drive right on line for the most part. Any other suggestions? I have like many put tons of cash into my E39 and its so close to perfect, but running of money trying to get it right.


    Thanks,

    P.S. I also have not replaced shocks yet, could this be a factor in the shakeing?

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