vibration at 55-80 kph only

[Whit]

I am travelling with the 750il and it has a vibration from 55-80 kph. If I go slower or faster, it feels fine. Tried new tires, wheel balancing, and alignment. What's next?
Should I also ask this on the 5 series forum? It seems to have more members, and more answers for similar problems. Or, someone here mentioned another board on the web that I could join for the 7 series where I could post questions at the same time? Thanks!

[ecangian]

www.bimmerforums.com

[shogun]

for this question. Same symptoms for the 5 series and 7 series.
I would change all wear parts on the front at once. These parts are now
that cheap in a package deal. Because if you only change one part, the others still have a bit more wear and then you have to work on it again and again. Change them all now, and you can forget about it for the next 2-3 years.
http://i23.ebayimg.com/02/i/03/73/a4/be_1_b.JPG
$ 288 the complete set. Single parts orders are much more expensive.

click here (http://cgi.ebay.com/ebaymotors/ws/eBayISAPI.dll?ViewItem&rd=1&item=7955665569&category=33583#ebayphotohosting)
and read this (http://www.bmwe34.net/E34main/Maintenance/Suspension/Suspension_main.htm)

[632 Regal]

Whit, feel free to post on the 5 series board, everyone else does! I'll bet you have shitty tires even though they balance out. I have been there with 2 seperate sets of tires, a multitude of visits to the tire joint and had to live with it since I replaced everything left in question. Bought $260 worth of semperit snow tires and my problem is gone. Its not rare or even common to have 2 sets of **** tires but take my word on it...it does happen.

[Whit]

Thanks, guys. I am wondering what the symptoms are for a bad driveshaft?

[shogun]

That is easy. Usually the center bearing. In your case you do not have a flex disk or socalled guibo.
Go to my website and then to E34.net, there is a nice description on how to change it.
I had a similar symptom some years ago, especially low RPM, accelleration and decelleration. Luckily it turned out that only the screws of the center bearing were loose and moved a bit and went out of line. Had a bad vibration and a noise in between front seats.
I would also recommend to change at the same time the emgine mount bearings and that of the transmission. Not that expensive, the parts and labour cost does not matter anyway for you in the Philippines. The engine runs much smoother and has less vibrations. That can also have an effect on the vibrations of the shaft center bearing.
Check the engine and trans mounts for oil leaks outside. They are oil filled.
http://www.nmia.com/~dgnrg/page_10.htm

[Whit]

Thanks. I can't find that center bearing description--the one on how to change it.

[shogun]

O.k., here we go:
from Johan's page something for the driveline as general info
http://shrubbery.student.utwente.nl/sean750/driveshaft/bmw750_R&R&Rdriveshaft.htm
This includes flex disk and center bearing
http://www.bmwe34.net/e34main/Maintenance/Transmission/CenterBearing.htm
(just forget about the flex disk)

PS: as for the springs/LAD questions in the other thread, changing front and rear shocks/springs is also shown on Johan's page.