Can some recommend a wheel/machine shop in NYC area??
I have the E39 M Pars on my 540i, they are bored out but I think they did a bad job b/c the steering wheel vibrates at 55-60 mph(only at those speeds). The whole suspension is new and the wheels have been balanced 3 three times so it has to be the hub is off. If someone can recommend a reputable shop that can knows how to do this the rignt way I would really appreciate it.
I'd start at the beginning to find the cause of vibration:
- The main causes of vibration while highway driving (0) (1) (2) (3) (4) (5) & while highway braking (1) (2) (3) & why it's not rotor "warp" (1) & severe ABS shuddering while slow speed braking on bumps (1) & how fluid-filled thrust arm bushings crack and tear causing the BMW to vibrate at speed (0) (1) (1) (2) (3) (4) (5) (6) (7) (8) & a comprehensive TireRack vehicle vibration diagnosis chart (1) (jpg) with wheel match mounting hints (1) & how a worn drive shaft, flex disc, center bearing, or "giunti Boschi", aka giubo (it's not spelled guibo although it sounds like it is to some) can cause the vehicle to vibrate (1) (2) (3) (4) & how to repair the rear driveshaft seal by the differential (1) & how to repair the inner constant velocity (CV) half-drive shaft (1).
I can't help with a recommendation, but ...
I assume from your comment about new suspension that you are confident the thrust links bushings are good. However a problem with tire/wheel runout or balancing should become worse as speed increases, not just a narrow speed range of 55-60. Any chance that one or more components has gone bad?
Were all 3 balance jobs done at the same shop? If yes, how confident are you in their expertise? Also, a good tire shop would check runout - axial and radial; especially given the problem you describe.
I take your description of a steering wheel vibration as a rotation back & forth twisting or shimmy; not just shaking felt in the steering wheel. This is usually caused by either a dynamic imbalance, axial runout in the wheel &/or tire or a twisted belt in the tire.
A "regular" bad job of wheel center boring would generate only radial runout, which would create wheel hop. The vibration would be felt in the seat and feet thoughout the car as well as hands on steering wheel; but unlikely steering wheel shimmy. (But, a truly horribly butchered job could also have created axial runout)
BMW specs at the wheel rim are:
1 piece alloy - 0.3 mm both radial & axial
2 piece alloy - 0.5 mm both
steel - 0.8 mm both
Specs at the tire tread are:
1 piece alloy - 1.1 mm radial, 1.3 mm axial
2 piece alloy - 1.3 mm radial, 1.5 mm axial
steel - 1.6 mm radial, 1.8 mm axial
You can easily check runouts yourself with a dial indicator & the wheel on the car.
like I said the vibration is only in the steering and it does not happen when I brake, it happens anytime the vehicle is going 50-60mph. I could be while accelerating or slowing down without breaking or when breaking. The suspension was done by a tech that worked at and trained by BMW, now he has his own shop and did the work for me. He thinks it has something to do with the boring of the hub because he checked the car and had it for a while and couldn't come up with anything else. I am going to put the factory 540i sport wheels back on and see if I get a vibration then I think I might get a better idea..
The concept is that narrow range vibration is a result of inevitable/unavoidable tiny imbalances at a particular frequency matching a resonance in the restraining links, in this case the suspension. When the driving force frequency matches the linkage's resonant frequency the vibration grows large. The resonant frequency is controlled by the ratio of wheel/tire/suspension mass and the spring rate of the bushings. The vibration disappears during braking because braking forces load the suspension and changes the resonant frequency of the links so they no longer match => vibration disappears.
In any case, trying another wheel/tire set is an excellent method to narrow down the root cause ... so long as they are balanced and true. :D
Theory is nice, experiment is proof. To paraphrase the great physicist Richard Feynman: no theory can fool Mother Nature.
Best of luck.
Another option is to swap the rears to the front. Would all four have bad bores? That would make your car shimmy like it was doing the Harlem Shake. I agree with rdl. Sounds like something else could be amiss.
|All times are GMT -7. The time now is 07:04 AM.|
Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2014, vBulletin Solutions, Inc.
© 2001-2011 performanceIX, Inc. All Rights Reserved .: guidelines .:. privacy .:. terms