thudding noise while accelerating or turning left

[Oolop]

So i'd thought i'd share my story about my csb, just in case someone ran into this same problem as me and they needed help, call it being proactive I guess lol :P

If u didn't know before, it's the Central Support Bearing. The bearing in the middle of the drive shaft (btw my car is a 87 325e 5 sp). Ever since I got my car, months ago, I always had a horrible thudding noise that sounded and felt like it was coming from the very rear end of the car. It only happened when I accelerated hard or turned left. Sometimes it did it when I turned right whilst accelerating harder than normal. I guess it had to do with that left turns are wider so u accelerate quicker..? Idk, but anywho, at first I thought it was an axle, then my diff, then a bearing where the wheel was but not untill recently someone told me it was my csb. So I disconected the exhaust from the mid point to muffler and removed the heat sheilds. Sure enough, the rubber around the bearing was completely shredded. So what happens is that while acc from a dead stop, or even a little fast, the motor created spin torque that literally spun the shaft so much that it couldn't stay straight because of the load from the wheels, thuss hitting agaisnt the chassis untill the spin torque died down as the car acceleratedd.

So to replace it I had to lower the diff to get the shaft out cus I couldn't take my exhaust off due to rusted bolts on the headers. Tried all day to no avail lol.. anyway, removed tha old bearing and slid the new one in. I removed it by using two equally weighted hammers and knocked it out. To install I used the spline nut thingy from the drive shaft as a driver. I got an ebay set and the mounting holes didn't match to the chassis and the bearing sat about a quarter inch to low. So I cut the base off the original bearing housing and cut out the mounting holes off the new one and welded it on top of the original plate (be careful not to melt the rubber, pause a while to let the metal cool) and there ya have it: mounting holes match and bearing is roughly a quarter inch higher like it was. Next, just put everything back together and there ya go.

Sorry for no pics, was in a hurry to finish cuz I have school the next day lol

Hope this helps someone one day, ask questions if u need, i'd be happy to help! I coulda gone into more detail but figured you'd know most of the other details or figured it out.

[jlevie]

In almost all cases a failure of the CSB will be caused by binding drive shaft u-joints. The only long term fix is to replace both parts. So don't be surprised at early failure of the new CSB.

Your problem with the CSB mount was because you had the wrong part for this car.

[Oolop]

yea, the csb was technically the wrong part, but we modified it so it worked lol. i was just saying what we did in case someone bought it off ebay like i did and it didn't exactly match up

could that (u-joints binding due to shredded rub bearing) be the reason my u-joints were really stiff?

[jlevie]

Stiff u-joints are binding u-joints. Replace the drive shaft.

[Oolop]

I know u could rebuild the joints and heard they were a pain but my dad and one of my friends dad knows how and they've done it a lot so do u know of any rebuild kits around?

[lateracer]

Conventional wisdom and BMW say to not rebuild the joints. Some driveline shops laugh at that wisdom and do it anyway with what seems to be mixed results.

Good but used drive shafts can be found for less than $100 if you look around.

[Oolop]

Gotcha, ok thanks for the info! Hopefully this'll all help someone more too as it did for me

[jhowe]

Thudding noise

I think I may have run into the same problem with my 1990 325ix. I was first told it was my rear passenger cv axle. I got it all changed out and the car is still making a thudding noise almost like a grinding in the rear. It hear it and feel it in reverse also getting up to speed and up hills. Once I get up to speed it goes away. Mechanic is now telling me it's my rear drive shaft. I've got a parts car and I've got the rear shaft all unbolted but having problems sliding them out. Any suggestions on what to do?

[Oolop]

My u joints were so stiff I had to drop my diff in order to get it out. It's 5 bolts holding the diff up. U don't have toundo the axles from it either, just make sure to have it balanced on a jack or something when u drop it enought to slide it out

[jlevie]

I think I may have run into the same problem with my 1990 325ix. I was first told it was my rear passenger cv axle. I got it all changed out and the car is still making a thudding noise almost like a grinding in the rear. It hear it and feel it in reverse also getting up to speed and up hills. Once I get up to speed it goes away. Mechanic is now telling me it's my rear drive shaft. I've got a parts car and I've got the rear shaft all unbolted but having problems sliding them out. Any suggestions on what to do?

You will have to use the entire drive shaft from your parts car. The drive shaft is balanced and a complete assembly and you risk vibrations is you mix & match parts.

To get the drive shaft out, disconnect both ends. Then unbolt the CSB, loosen the collar nut, and pull down at the joint. It should come out. If it doesn't, put the CSB back in place and spin the collar nut off the threads. Then liberally apply PBlaster or Kroil to the splines and use a pry bar at the both ends to compress the drive shaft. Oh yeah, before pulling the drive shaft make sure that you can see both paint marks at the spline area. If you can't find them, mark the halves of the drive shaft.

Once you have the drive shaft out you'll want to clean the splines and grease them before installing the drive shaft. You'll probably find that the fiber spline seal needs to be replaced. It is cheap and you can get it from your dealer.