thump thump thump...wtf is that?!?

[EricT]

Hey all. I'm rather new to the e30 world. I've got an 86 325es with a manual tranny. For the last couple weeks I have noticed while I am leaving a stop sign or traffic signal...if I press the go pedal any harder than granny speed I get this thump thump thump comming from the floor. So long as I baby the go pedal to get up to speed it doesn't do it....its only when taking off from a stop or I suppose when I put alot of strain on the driveline like going up a steep incline in any gear with low rpms...... I recently had tires replaced and happened to peek under the car while it was in the air on a lift. The guibo appears to be fine, no tears or cracks or loose bolts etc...turned the driveshaft by hand to check for play in the u-joints and they seem ok....didn't think to wiggle it at all but I'm thinking its possibly the center support bearing. Was just wondering if there is anything else I should check whislt I am under there this weekend poking around should the center bearing happen to check out fine....

Thanks in advance, Eric

[Farbin Kaiber]

Guibo/CSB, or halfshaft. That would be my guess.

[Fidhle007]

Csb.

[Liam]

Guibo/CSB, or halfshaft. That would be my guess.

Csb.

Check your U joints while you're at it.

[Farbin Kaiber]

Check your U joints while you're at it.

Fancy meeting you here. :)

[atomic]

Dead cat wrapped around a half shaft?

[Liam]

Dead cat wrapped around a half shaft?

Seen rabbit jerky in there before, but no cats.

Fancy meeting you here. :)

Yep.

What better way of spending the precious moments of your life than helping out the DIY with these "once fabulous wonders of engineering" now that they have become decades old rattle traps?

[jlevie]

For the last couple weeks I have noticed while I am leaving a stop sign or traffic signal...if I press the go pedal any harder than granny speed I get this thump thump thump comming from the floor.

That is a classic description of a failed Center Support Bearing (CSB). A failure of the CSB is almost always the result of binding drive shaft u-joints. So replace both.

[EricT]

I did check for critters......actually had that happen before...but that was in my dakota and it was a possum...not a cat.

[Jean]

Like many have said, bad u-joint and/or csb. Bad flex disc on it's own won't cause this, but could be ruined in the process...

driveshaft jobs suck ass.

[EricT]

That they do. The sheer anticipation of taking the heat shields off keeps me awake at night.......anybody ever umm.....just forget to put them back on????? I mean the 1 or 2 lbs would be a gain if you count it as weight reduction right?????

[Jean]

Taking the heat shields isn't the big deal, I would also put them back on to protect the driveshaft from the elements etc...

It's the exhaust you'll have to drop to get to the driveshaft etc. Now would be a perfect time to order new shifter components to get them replaced at the same time, you'll have a nice and firm shifter. If it's all original, it's probably worn the hell out.

[EricT]

The shifter is rather sloppy. Sounds like a plan. Think I'm just gonna go ahead and replace the u-joints, csb, and the guibo. Prolly get the stuff for the shifter too then. Yeah I just put an exhaust system on there and tucked in tight to the heat shields. YIPPEEE!!!!! It shouldn't be that bad. Thanks for all the input everyone.

[Liam]

Yes, don't leave the heat-shields off. One bad effect from this is warming up the fuel tank and it will also bake the drive shaft especially after parking the car hot.

[EricT]

I will be sure to re-install them.