Stubborn high speed vibration

[Traian]

I have a 1995 BMW 540i, with about 260000km, and it has a real mysterious vibration that starts up at about 80-90km/h (~50-55 mph). As I speed up it gets even stronger and hits a peak at about 140km/h (~85-90 mph), but it's there all the time. It does not seem to be coming up directly through the steering wheel, although this is vibrating too. Rather, the whole car tends to shake, and all the seats, dash, ... vibrate and jiggle around. It's not terribly bad, but pretty uncomfortable for an autobahn car.

Ok, here is the long story: The vibration was there a while ago, I took it to a shop, they checked my wheels, tires, suspension and steering links, bushings and driveshaft mounts. Eventually they said the rear tires were slightly flat spotted (but not enough to cause a big vibration) and rear brake rotors were warped, replaced these, vibration subsided but still started at about 140km/h. I did drive on some fairly bad roads since then and finally it came back altogether and now it starts at 80 again. I live in Toronto and I took the car to Bruno at Racing King to check it out. He checked all the suspension and steering links again, wheel bearings, motor and transmission mounts. He told me the thrust arms bushings are slightly worn, as is one of the steering links, but none serious enough to cause such a big vibration.

So it is all still up in the air. If anyone has experienced anything like this and knows what it might be, please please let me know! it's driving me nuts!

[Paul in NZ]

aftermarket wheels?
replace your thrust arm bushings,
did you replace the rear tires?
these cars are very sensitive to anything that set up a vibration everything must be in top top shape,in the wheel tyre/suspension department.
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[Traian]

Stock 15 in wheels. Nope, I still have the same rear tires and front thrust arms. Both fellows who looked at my car said neither on its own would cause a vibration (at least not nearly as noticeable). I just don't want to start replacing stuff randomly unless I'm fairly certain, you know.

[Paul in NZ]

well thats a tough one...as I said these cars are vibration sensitive......perhaps start with a wheel balance and alignment then you will be able to rule that out and see if any wheels are bent and see how bad the flat spots are.Go to a good tyre place,perhaps Bruna can recomend a place.perhaps the fronts are also flat spotted or out of round and combined with marginal bushes is giving a double whammy
Good luck

[Traian]

Ok that seems reasonable. Could bad wheel balancing/front end alignment be the culprit if other things more or less check out? Thanks for the help/

[SRR2]

You've eliminated the usual suspects, but until you put those tires and wheels on a Hunter 9700, you haven't tested far enough to eliminate problems there.

Problems like you're reporting that I've had with 'cheap' tires are what convinced me that Michelin was the only tire I'd put on my cars. Through maybe 30 sets of tires, I've never had a problem of any kind with a Michelin tire. Never.

[baileydog]

I had a somewhat similar problem with my 540, I had a bad bearing mount on the driveshaft along with a worn out bearing at the transmission output shaft. Not real easy to check, but I had the same symtoms....Good Luck

[632 Regal]

out of round tires cannot be fixed even on the hunter road force balancer...been here dont that, ended up being shitty tires.

The scenereo went like this: new tires=vibration...10 trips back replaced with new different tires=vibration, 15 trips back. I give up, 3 new replacement rims=vibration.

get $60 snows for winter =vibration GONE.

Draw conclusion.

[Qube]

Is your power steering fluid low? Have you tightened the nut behind the wheel? http://www.bimmer.info/forum/showthread.php?t=15145

[632 Regal]

ahhh the old nut behind the wheel culprit!


Is your power steering fluid low? Have you tightened the nut behind the wheel? http://www.bimmer.info/forum/showthread.php?t=15145

[Tiger]

I would say it is your thrust arm and the lower control arm that needs to be replaced. Bushings are worn and so is the ball joints on those items.

[sdlongboarder]

As others have said, I'd get new tires first and go from there. You also may have slightly bent wheels. Which tires are you running? Stay away from those which have a softer sidewall. I've found that tires with a thick, firm sidewall tend not to fall victim to cupping and flat spots on the e34s/e32s/e38s. We were using toyo proxy TPT's for the longest time, then they switched the construction of the tire and we had nothing but problems after.

Good Luck

[632 Regal]

the falken ziex have a soft sidewall but run smooth as silk.


As others have said, I'd get new tires first and go from there. You also may have slightly bent wheels. Which tires are you running? Stay away from those which have a softer sidewall. I've found that tires with a thick, firm sidewall tend not to fall victim to cupping and flat spots on the e34s/e32s/e38s. We were using toyo proxy TPT's for the longest time, then they switched the construction of the tire and we had nothing but problems after.

Good Luck

[Traian]

I know I'm resurrecting this topic, but i figured I'd say a big Thanks to y'all and let you know how the problem was solved. A lot of you folks suggested the tires might be a culprit, and in fact the ones I was running were Toyo Proxes TPTs, so after I scraped up the money for a new set of tires (the reason I hadn't replied earlier) I took the car in for a balancing and was told all 4 had to be replaced.

I ordered 4 BF Goodrich Traction T/A VRs from Tire Rack, and had them installed and balanced on the Hunter here and woooooooaaaaahhhh!! 90+ is a magic carpet ride now, and eeeeverything feels much better now: the ride, the noise, snow traction, steering response, all of it is just wow :)

I still have a rather different shimmy at about 40-60mph, with and odd vibration under braking at about 50-55: I figure those must be the upper control arms as I understand they take the weight of the car under braking.

[Torque]

I know I'm resurrecting this topic, but i figured I'd say a big Thanks to y'all and let you know how the problem was solved. A lot of you folks suggested the tires might be a culprit, and in fact the ones I was running were Toyo Proxes TPTs, so after I scraped up the money for a new set of tires (the reason I hadn't replied earlier) I took the car in for a balancing and was told all 4 had to be replaced.

I ordered 4 BF Goodrich Traction T/A VRs from Tire Rack, and had them installed and balanced on the Hunter here and woooooooaaaaahhhh!! 90+ is a magic carpet ride now, and eeeeverything feels much better now: the ride, the noise, snow traction, steering response, all of it is just wow :)

I still have a rather different shimmy at about 40-60mph, with and odd vibration under braking at about 50-55: I figure those must be the upper control arms as I understand they take the weight of the car under braking.Thrust arm bushings were what gave me the same braking vibrations you have now.

Good choice of tires; I had those for a while.

[632 Regal]

good ride for tires but not good if you do a lot of high speed runs, they simply arent made for it. If you drive semi sencible youll be fine!

Enjoy the new ride!

[mystical_wings]

I had the exact same prob.Got 4 new tires ,now it rides like a dream

[Traian]

Oooookay, new thrust arms with bushings (Hamburger Tekinc or whatever), new steering tie rods (Lemforder) and an alignment later and woooweee, I knew there was a tight, smooth handling car under all that mess! The shocks on the back seem rather on their last legs as they crash over expansion joints, so that will be the next project. Does Boge make performance shocks for the E34, or only OEM replacements?