Mechanics

VIBRATION IN STEERING WHEEL

2000 BMW 740

Suspension problem
2000 BMW 740 V8 Two Wheel Drive Automatic 93000 miles

Starting around 40 mph on up, when the brakes are applied lightly the steering wheel starts a back and forth oscilation that can be controlled by either letting off the brake or pushing harder on the brake. I suspect maybe the idler arm needs replacing or maybe the Struts. Can you please give me your input.

Thanks
Nathan
Avatar
Necapps
September 8, 2008.




The center track rod, the idler and the thrust rod bushings are all causes of this concern, if the thrust arm bushings show signs of leakage, replace them, if the idler has play, replace it, there is a bulletin for the center track getting hot from the exhaust and making noise and there is an updated part number.

Dr. Hagerty
Sep 8, 2008.
I replaced the center track rod, and both thrust rods with new bushings. The idler arm was not replaced because it had no movement in any direction. The problem was improved but the oscillation still exist when brakes are applied. Could the control arms are the struts be my problem.

Tiny
Necapps
Jan 25, 2009.
Unless the struts are really worn they probably aren't a contributing factor. You state you replaced the thrust arm bushings, did you install them correctly, they are directional. If there are worn rod ends on the thrust arms, they can be a contributing factor. Are the wheels stock, are the tires old and/or worn and are they properly inflated? Try rotating the tires front to back and see if it changes things.

Dr. Hagerty
Jan 25, 2009.
Thank you for your response. The wheels are stock and the tires have been rotated. I replaced both torque arms with new ball joints and installed the new bushings in the very same position as the old ones. The only thing I have not replaced yet is the Control Arms which have a bushing and a ball joint.
AD

Tiny
Necapps
Jan 25, 2009.
The control arms seldom cause this issue, there is something else at the cause of your vibration. What brand of tires are they?

Dr. Hagerty
Jan 26, 2009.
Michelin 235/60R-16 with about 45K on the tires. Maybe its time to change the Tires even with good tread remaining.

Tiny
Necapps
Jan 26, 2009.
I agree, if I may recommend Tire rack. Com for tires and you may wish to try something besides Michelin, I am a huge fan of Yokohama tires as they are on my truck and my Wife's car too. Just my opinion mate.

Dr. Hagerty
Jan 26, 2009.
I had this problem with my 1997 BMW 740 with 92,000 miles, at first I thought it was a lower control arm bushings, they were worn so I went ahead and replaced, but that wasn't the problem it was only amplifying the original problem, the problem you are describing is identical to mine, my problem was warped rotors on the front, as soon as I change the rotors and the brake pads my vibration was gone, people don't realize BMW seven series weighs 6000 pounds, you're not driving a Toyota you can not wait for the very last instant to slam on the brakes, you've got to look ahead of you what color of the lights and do a little bit more cruising, in other words: take your foot off the accelerator and Coast, or you will have more problems, like, struts, idle or arm, ball joints, control or bushings etc.

Dr Loot
Jan 31, 2009.
Good call, I keep forgetting that brakes can be the cause of these issues too.

Dr. Hagerty
Feb 1, 2009.

AD