Hello everyone! My first post here on Car Talk! Long time listener and am glad to be here on the forum.
I have a 1994 BMW 325 convertible that I recently purchased. I had a mechanic look at it when doing some other work (this is a new mechanic to me, just moved recently) and when he did that he showed me that the drive shaft bearing/support was put on backwards so that the bolts where it is supposed to be bolted to the undercarriage dont match up and it is welded to the undercarriage. The welds look good and dont appear to be cracking or anything but the mechanic said that it isnt safe and the complete drive shaft needs to be replaced.
This seems extreme to me and I’m not sure if I should do it. As i understand welds can be stronger than bolts. If i do replace it can I just have that bearing/support replaced or do I really need a whole new drive shaft? Any help will be appreciated!
You mean someone put the driveshaft in wrong, the bolts on the center support would not line up so they just welded it in place?? I suspect there is more to this story…This sounds like one of those 'If it won’t fit, make it fit" deals…Does the car have a salvage title?
The car doesn’t have a salvage title but is new to me. The wings that line up with the bolt holes are offset, if it was flipped around it would fit correctly but it is evidently backwards. When taken in to the mechanic his concern was “it is a safety issue having it welded and needs to be replaced”. I am taking it back in this week but want to be as informed as possible. is the whole driveshaft backwards? Thats not what he said but i guess its possible. the holes for the bolts are mis-aligned only by about .25 inch.
Perhaps a driveshaft shop replaced the center bearing but installed it backwards on the shaft. The shop that installed it should have returned it to have the problem corrected, not welded it into position…Have your mechanic check the position of the rear differential, make sure nothing is out of position back there…If your car could talk, I bet it could tell quite a story…
The welds are probably stronger than the bolts . . . but the metal right next to the weld could break. And then the whole center support would drop. And the driveshaft could beat up the underside of your car
What I would do is put the car on the lift, and see if it’s possible to cut through the welds carefully. Then remove the entire driveshaft. Remove and discard the center support. Clean up and paint/primer the area where the center support bolts up. Reassemble the driveshaft, using a new center support, bolts and nuts, facing the correct direction. Also replace the flexible discs on both ends, if they at all look questionable. Then reinstall the driveshaft
Be aware your mechanic will probably need a press to install the new center support on the driveshaft
wow… thanks for all the good info! I will ask him to take a look at the rear differential and if there is anything funny I will have him proceed as db4690 suggested. I’m not worried about the metal around the welds breaking, it is welded to the pieces of metal that the bolts would go into if it were in the correct position (as I said, it’s only .25 inch off…) so the metal was designed to support the weight.
I love the car but I’m quite sure it could tell a story if it could talk! I have a story behind it too… I used to have a 1990 325is that was in excellent condition with only about 135k on it (30k I put on myself). Aside from a small dent in the driver door (damn shopping mall parking lots!) it really was in awesome condition and I loved that car. It was stolen from my carport one sunday night about 5 months ago and “recovered” (if you can call it that!) by the police an hour away completely gutted with what was left of the frame cut straight in half. Broke my heart! Now I’m fixing this one up… I can do small projects with it myself but I don’t have a proper garage do do the bigger jobs. Thanks for all the advice and I will let you know how it goes!