Please help!

DJ1009 · 12-09-2003, 11:07 PM

I have searched all over and cannot find the following: A U-joint for a 1994 318i. I was told by a mechanic that the vibration I have described in this forum in the past is the result of a bad u-joint. Anyone know of a place that sells just the u-joint? All the local places in and around my home town do not carry it.

Wayne 962 · Wayne 962's Garage

What he is referring to could be the rubber insulating disc that joins the transmission to the driveshaft. U-joint is a lousy way to describe it. Also called the flex disc on this page:

http://www.pelicanparts.com/bmw/catalog/shopcart/BE36/POR_BE36_tranny_main.htm

-Wayne

DJ1009 · 12-12-2003, 12:56 PM

Just talked to the mechanic. Whatever it is....its located at the rear of the car and is connected to the drive shaft. He said he could see the rust and he could move the driveshaft around...something he said you should not be able to do. From what I can gather....it has 4 ends all at a 90 degree angle...sounds like a "+" to me. He said its made out of metal....could it be a flex joint?

stupenal · 12-12-2003, 01:02 PM

the flex disc guibo was the culprit in my vibration under acceleration, combined with weak rear axles or something. i forgot but its the thing that connects the wheels to the diff.

Flex disc wears out over time because it is a rubber piece with some sort of string material inside.

DJ1009 · 12-12-2003, 01:10 PM

I just found this: A driveline vibration occurring in a specific speed range can be caused by a worn or broken rear transmission mount and/or a broken or cracked guibo. Check them before suspecting a bad driveshaft, center bearing or rear U-joint. What are they referring to when they say rear U-joint? By the way...once I hit 30+mph...the vibration gets worse as I go faster. So much so, that once I hit 55+...the rear view mirror shakes.

DJ1009 · 12-12-2003, 01:27 PM

This is what I am looking for: The rear of a BMW driveline (again, excepting early 1600's) uses either another universal joint or a constant velocity joint. They both serve the same purpose, to take up small angle changes, and the constant velocity joint furthermore allows for small length changes in the driveshaft.

Drews323i · Drews323i's Garage

There is also a carrier bearing. as these cars have a 2 piece drive shaft. this usually goes bad before anything else in the driveline. the bearing itself is usually good, but its mounted in rubber, this goes bad just before the flex disk up by the trans goes. when the carrier goes bad it starts out as a nasty vibration then turns into a thumping sound under acceleration. easy inspection, remove heat sheilds and look at rubber around carrier bearing. if it is the bearing , i highly recomend buying a rebuilt driveshaft from Driveline specialties. as the rebuilt will be balanced. hope this helps.

1980 323i
1994 325i

stupenal · 12-12-2003, 04:20 PM

here's what I recall when looking under the car-

the guibo/flex disc is the rubber piece located in between the tranny and driveshaft. not too hard to find, clearly visible if its worn out. You'll see its all shrizzled and ugly. The center support is located further back, its just this thing that holds up the driveshaft. No clue what goes from driveshaft to differential.

here's Rogue engineering's thoughts on it

http://www.rogueengineering.com/Merchant2/merchant.mv?Screen=CTGY&Store_Code=RE&Category_Code=GUIBO

hope this helps