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Re: VIBRATION @ 55+ MPH ON 94' 740IL (archive)

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Posted by Alex on December 22, 1999 at 16:36:13:

In Reply to: VIBRATION @ 55+ MPH ON 94' 740IL posted by BOB NADELL on December 22, 1999 at 14:26:32:

: I purchased a certified pre-owned 1994 740IL 18 months ago and have been trying to correct a vibration which occurs usually at 55 mph on up. (it is at it's worst at 63mph.)

: I have recently been told by one of the senior technicians at my dealership that the pre 95 7 series and pre 96 5 series have a design "characteristic" (ie. flaw) which allows for a harmonic vibration to occur at the above mentioned speeds. I find it hard to believe that BMW would have allowed such an oversight to occur.....and if it did, not provide a fix for it.

: It should be noted that this car has never been damaged and I don't abuse it. In the time frame in which I have owned the car, it has been taken to the dealership numerous to try and correct the vibration. Here is a not so brief history on what has been done, (in chronological order,) to try to correct, or at least affect, the problem:

: -Balance tires and alignment.
: -Replaced upper control arm bushings due to wear.
: -Rebalaced tires.
: -Replaced all 4 tires.
: -Rebalanced tires again.
: -6 months later, noted excessive outer tread front tire wear, found alignment way off, replaced front tires and performed alignment.
: -Recenter steering wheel.
: -Rebalance tires.
: -Replaced front brake rotors and pads due to normal wear.
: -Checked wheel rims, one found very slightly bent, had it repaired.
: -Replaced, again, upper control arm bushings (the right one was leaking.)
: -Right front wheel bearing wore out, replaced both from wheel bearings.
: -Idler arm checked, no problem found.
: -Some exhaust hooks found missing, replaced.
: -Replaced all 4 tires again due to unrelated sidewall puncture damage.
: -Performed wheel balance and alignment.
: -Rotated and re-balanced tires again.

: The result???????

: All the above mentioned items have had little if any effect on the vibration and none have ever eliminated it, not even temporarily. Most of the items were paid for by the BMW cert. pre-owned program and the dealer's good will.

: I don't even want to begin talking about the other things which have gone wrong with this car aside from the vibration problem......lets just say I got my money's worth from the CPO.

: My old 95 318i 5sp. which I traded in was much better behaved....and much more manueverable! I guess the 7 series is not nearly as reliable.

: Thank you for reading through all this....any thoughts as to how to correct the vibration? I am tempted to dump this car!


Vibrations as you have described are typically caused by the driveshaft. In order of probable cause of the problem, I would check

- center bearing. If the rubber is damaged or torn the driveshaft will vibrate up and down.

- driveshaft u-joints. Grab the driveshaft and wiggle. I think that your driveshaft has two u-joints (one at the transmission end and one in the middle of the driveshaft just in front of the center bearing).

- driveshaft cv joint where the driveshaft attaches to the differential. check that there is no slop.

- driveshaft out of balance. The driveshaft is a two piece type and is dynamically balanced. If one of the counter balance weights has fallen off the driveshaft will be unbalanced causing the symptoms you describe.

Unfortunately, you cannot really check any of these without removing the exhaust to get access to the driveshaft. I find it really hard to believe that the dealer did not check these things or maybe they did and failed to note this on the service sheet. Good luck.

Alex Lynch
92 735i 167,200 miles

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