Results 1 to 11 of 11

Thread: Steering wheel shimmy

  1. #1

    Post Steering wheel shimmy

    Here is the initial post about it from roadfly.........

    I informed them that the steering seemed just a tiny bit loose at about 1/2 turn, more so to the left. It is very subtle - feels like the pinion is not quite fully seated in the rack, and the steering wheel transmits just the slightest amount of high frequency "slop" vibrations during parking lot manuvers. They confirmed the problem, verified that everything is properly mounted and tightened, and ordered a new rack & pinion.

    In response a lot of messages appeared reporting the same issue at that time, and it has contined to be an isue on some cars, but now it seems the issue is more related to the original rather loose bushing used in the front and rear suspension, and sometimes tires flat spotting with infrequent use. (see more below)
    Andrew Macpherson

    Expert Z8 Inspections, with full support for both Z8 sale and purchases.

  2. #2
    Z8 Ate My Homework! Norcal's Avatar
    Join Date
    Nov 2002
    Posts
    2,471
    Sounds like what I was feeling, but dealer tech was unable to feel! It has been greatly reduced after switching to S03s (much softer?) plus, the added (neg) camber may keep more stess on the part for less "rattle" ?

  3. #3

    The same problem continues....

    This post was taken from Roadfly several months after the initial posting on the subject by Russell.


    Some of you may remember my many problems with the front suspension looseness and rumble through steering columb.

    My car has now had 2 new wheel bearings and the rumblings has been majorly reduced, however, there is still a quite rumble felt through the steering columb, which feels very wrong.

    So far my car has had in relation to the "rumbling problem"

    2 Front wheel bearings
    2 Lower front control arms
    Discs and pads
    Steering columb, rack & pinion
    2 Font ball joints !

    And aparently BMW have checked rear axle and bearings and alloy wheels.

    What else could be causing the fault ?

    In addition, when braking ocasionally the steering shakes a little, when I originally reported this problem BMW changed the pads/discs and lower front control arms.

    I really do not know what to do next, BMW have had the car 5 times for repairs and 5 times for diagnosis. Im at the point of taking it to an independant spcialist if their is a such a thing.
    Andrew Macpherson

    Expert Z8 Inspections, with full support for both Z8 sale and purchases.

  4. #4

    Post More steering wheel shimmy

    Several cars have had this same problem. Some have had rotors replaced, and other parts replaced, with varying results. Below is a pair of posts from an owner over on Roadfly who changed many parts before finally getting rid of it.

    It took BMW 7 attempts to fix it in over 16,000 miles.
    These are the parts they replaced -

    Steering Column
    Pads & Discs
    Ball joints
    Wheel Bearings
    Roll Bars
    Engine Mounts

    After all this it was still not cured, yet BMW denied anything was wrong. I replaced wheels myself, which removed the last gremlin in the car. After all these things the car now works fine.


    I asked Russell, who suffered this particular set of problems, what the eventual fix was, and this is his response.

    Basically BWM service would fix something, return it to me and the same problem would still be occuring, so I dont think they test drove it after trying to fix it.

    I believe there were several different problem, the pads and discs fixed the shaking left to right when braking, the steering rack fixed the looseness in the wheeel and the wheel bearings fixed the rumbling. It also turned out to have a warped wheel which seemed to be part of one or more or the problems.

    And get this, BMW did not check the wheels for damage or balance, nor did they do a wheel alignment! When I took it to have the alignment done locally one wheel was 2 degress out!



    Thus I would suggest if you have the 'shimmy' go through this list one step at a time...
    1.) Get a full alignment and wheel balance.
    2.) Check the wheel bearings.
    3.) Check the brake discs aren't warped, and the pads are good.
    4.) Replace the bushings (see below)
    4.) If all this hasn't cured the issue then change the steering rack and pinion.

    It is worth noting that the wheel bearings changed about half way thru production, though the part number remained the same. Visually the new bearings are significantly beefier, especially the rears, but it is around a $1k job to swap them out as they live deep inside the hub/drive shaft assembly.

    Here is a well thought out vehicle vibration chart from Tire Rack.
    Andrew Macpherson

    Expert Z8 Inspections, with full support for both Z8 sale and purchases.

  5. #5
    Z8 Novice
    Join Date
    Jan 2006
    Posts
    4

    Shimmy on Braking solved

    I had a shimmy while braking. I thought it was warped rotors (lots of heat here in the Santa Monica Mountains) but instead the dealer replaced the left and right lower control arm bushing under warranty. 2,500 miles later (and a trip up CA 1) and still no problems.

  6. #6
    This morning I took my car for an oil change, and discovered that I had suddenly developed a serious steering wheel shimmy. I had recently put a new set of Pirelli P-Zero tires onto my 20" rims, and a phone call to Ken turned up some useful info.

    Pirelli and Bridgestone SO3 tires are very prone to flat spottong, and the flatspots will translate to steering wheel shimmy for around 25 or so miles until the tires build up enough heat to stretch and reshape themselves round. Here is a product called the Tire Cradle that you can park on, and thus avoid these annoying flatspots.

    Should you have a continued issue then get this Powerflex Urethane bushing kit from Bimmerworld - 877-639-9648
    The kit has 2 inner control arm bushings, 2 outer control arm bushings, and 2 front strut rod bushings. Ken installed these last August, and told me that it has been a vast improvement.
    Andrew Macpherson

    Expert Z8 Inspections, with full support for both Z8 sale and purchases.

  7. #7
    Sport Button On - DSC Off
    Join Date
    Aug 2007
    Posts
    182
    Just a little input on the Powerflex Urethane Bushings: the front suspension control arms on the Z8 are attached to the hubs by a metal ball joint and to the chassis by a metal spherical joint, neither of which is replaceable, so the Powerflex Urethane Bushings listed by Bimmerworld would not offer any improvement, even if there was some way to install them. Their thrust arm bushings are a different story. The thrust arms on the Z8 are attached to the hubs by metal ball joints and to the chassis by replaceable rubber bushings with fluid damping. The Powerflex Urethane Bushings will make a noticeable difference on a Z8 by eliminating the compliance inherit in the OE rubber bushings but be forewarned, installation is not straight forward. The fitment is extremely tight. The extent of the benefits will depend upon the condition of the OE bushings you removed but you can expect quicker turn-in response, a significant reduction in chassis settling as a turn is initiated, and more stability throughout the corner. If your OE bushings were significantly worn and contributing to steering wheel shimmy under braking, the improvement will be dramatic. The price you will pay is a slight increase in road irregularity feedback into the chassis. Also, urethane bushings can squeak during movement although Powerflex claims theirs won't if properly lubed during assembly. For what it's worth, replacing the rubber bushings on the front thrust arms is the only bushing change Steve Dinan approves of for a Z8, although he uses custom fabricated spherical joints. I do have the Powerflex Urethane Bushings on one of my Z8s and I think the improvement is on a par with Dinan's spherical joints, which I have on another of my Z8s. This is a relatively inexpensive upgrade that will improve the handling of a Z8 but not recommended for those who enjoy the suppleness of the OE suspension.

  8. #8
    I have noticed a slight shimmy in my steering wheel over the entire Monterey trip, and was considering doing this upgrade, so your post is both very informative and timely, and I will certainly take my car up to Dinan on my next run north, as I already have several of their bits in my steering set up already.
    Andrew Macpherson

    Expert Z8 Inspections, with full support for both Z8 sale and purchases.

  9. #9
    Sport Button On - DSC Off
    Join Date
    Aug 2007
    Posts
    182
    Please check with Dinan first since the spherical joints they installed in my car were one off custom pieces. Frankly, I think the Powerflex bushings are just as good, readily available, and provide a modicum of vibration absorption which the spherical joints do not. Steering wheel vibration while driving at a steady speed is most likely wheel/tire imbalance. Steering wheel vibration while braking can be due to warped rotors, uneven pad coating on the rotors, or loose suspension joints. If you've eliminated the brakes as the cause, then the Powerflex bushings may very well cure the problem. Just remember that you will feel more feedback into the car on rough roads and the mechanic doing the work is going to curse you a few times during the install!

  10. #10
    The shimmy was pretty constant, more noticeable on some surfaces than others, and very slight, but at a constant 50 or so it was the most evident, giving about a 1 minute on a clock face shimmy if you let go of the wheel. On some corners it was there, but not on turn in, only as you opened the wheel back out. You could well be right about it being in the tires and/or wheels as they are both new to the car. They are the 20" Motorsport rims and the Pirelli tires.
    Andrew Macpherson

    Expert Z8 Inspections, with full support for both Z8 sale and purchases.

  11. #11
    Sport Button On - DSC Off
    Join Date
    Aug 2007
    Posts
    182
    Being relatively constant and more pronounced at certain speeds is a classic description of wheel/tire imbalance. Large diameter rims are notoriously difficult to balance and BMWs are particularly sensitive to imbalance. Besides having yours rechecked on "Hunter" balancing equipment (the best in the industry), you might also ask the technician to try "match mounting" the wheel/tire combination. Tires and wheels are never perfectly round and this results in an inherent imbalance or force variation. This force variation is referred to as a high (heavy) point and a low (light) point. Match mounting involves the mounting of a tire on a wheel such that the high (heavy) point of the tire aligns with the low (light) point of the wheel. This match mounting cancels out most of the imbalances of the tire/wheel assembly. Tires are usually marked with a painted dot to indicate their high point and wheels often have a painted dot or sticker indicating the location of their low point. If wheels are not marked, you should use the valve stem hole as the low point. In my experience, most tire shops do not take advantage of this technique, so it is worth asking for it.