Major e28 first gear problem

[TheBugman]

I first discoverd the problem shortly after i bought the car, and have been trying to figure out what the source of it is ever since. It is an automatic. The car behaves perfectly untill I put any load on it when its in first gear between 2800 and 3200 rpm (aprox.), as i so commonly do with my lead foot. As soon as it hits 2800 rpm you can here a very loud sound in the cabin, that is best described as the sound of gears ripping eachtothers teeth off. It makes three loud clunking sounds in close succesion and then acts perfectly normal afterwards. The car never stops accelerating thru all this, as a matter of fact the transmission has never once slipped or acted funny in any other way. Im at my wits end with this problem and need some advice. So far Ive checeked and changed the fluid, checked all the seals and given the transmision as thourogh a going over as i could while it is in the car. ANy help is greatly needed and appreciated.

[mbogosia]

It might have to do with your driveshaft. There is a flex disc, drive shaft with u-joints, and a center bearing. All of these can go bad. You can usually tell by looking at them also.

[slocar]

It might have to do with your driveshaft. There is a flex disc, drive shaft with u-joints, and a center bearing. All of these can go bad. You can usually tell by looking at them also.
Well, I don't think that's his problem because he doesn't say it makes the same noise in other gears.

[thejlevie]

Well, I don't think that's his problem because he doesn't say it makes the same noise in other gears.
Initially, a failing driveshaft will only make noise under high torque conditions. The problem description seems to match that fairly well.

[Hypr5]

YES! As stated above - high torque. Mine only made vibrations and noises in 1st gear and reverse, until it got worse and showed up at around that RPM in second. After some driving time with all of that, it was constant. lol

[TheBugman]

I started to notice a drivline shudder under any lheavy load conditions this morning, and im just about to get under the car and see if i find any prolems. Hopefully i can get this fixed before it goes from something small to big. As of right now ive been shifting it manually in 123 mode and holding it in second and third, and other than the shudder it is doing fine.

[slocar]

YES! As stated above - high torque. Mine only made vibrations and noises in 1st gear and reverse, until it got worse and showed up at around that RPM in second. After some driving time with all of that, it was constant. lol
Dude, you drive a m20-powered 5 series. There is no such thing as high torque.

[mbogosia]

The only problem with just getting under the car is that the driveshaft is usually behind the exhaust. To be able to really inspect the flex and cenetr bearing you should lower the exhaust.

[TheBugman]

Well...after dropping the exhuast and going thru practilly all the mechanicals from transsmison output shaft to the rear bumper i have come to a conclussion...Nothing is at all wrong with any driveshaft componets, but i did discover that whoever worked on this car before was a complete moron. Gota love those bmw "specialists". I think half of them are just expensive volstwagon mechanics. Oh well, on to plan b.

[tjn182]

The bearing could still be going bad, a quick look at it really can't tell you much. But from what you're saying it sounds like it is the driveshaft. My car used to do the same thing under first gear acceleration. I would start off, even slowly sometimes, and you would hear this *thunk* *thunk* *thunk* and then it would keep accelerating like normal. A quick driveshaft replacement and the problem was gone.

My friend also had the exact same problem - went and bought everything you need to rebuild the driveshaft - once he put it back together the sound was gone.

[thejlevie]

Well...after dropping the exhuast and going thru practilly all the mechanicals from transsmison output shaft to the rear bumper i have come to a conclussion...Nothing is at all wrong with any driveshaft componets, but i did discover that whoever worked on this car before was a complete moron. Gota love those bmw "specialists". I think half of them are just expensive volstwagon mechanics. Oh well, on to plan b.
For this particular problem you can't inspect the driveshaft with it mounted in the car. If it is really bad it may have caused damage to the rubber mount of the center bearing or guibo, which you can see. To check the driveshaft for stiff universal joints (that's what causes the thump, thump noise) the driveshaft has to be out of the car.