BMRBOI 8 Report post Posted May 10, 2008 (edited) Every time I changed gear in my car it would make a clunking noise, turns out the sub frame mount at the rear of the diff assembly is torn out of the floor! The UK boys reckon it’s a common fault in the e36’s (mine is a 92 325i), anyone come across this before? Im pretty screwed aren’t I! Edited May 10, 2008 by BMRBOI Quote Share this post Link to post Share on other sites
BM WORLD 1286 Report post Posted May 10, 2008 yes heard of that before , also the rear arms mounts rip from the floor Quote Share this post Link to post Share on other sites
jochen 4 Report post Posted May 10, 2008 the sub frame mount at the rear of the diff assembly is torn out of the floor! Common problem on vehicles that are driven hard. Happens with early (pre 2002 I think) E46s as well. Continuous flexing of subframe due to motor torque causes metal fatigure which then results in total failue of the mounting points. Doesn't happen if old ladies drive slowly and carefully. Happens when young lads drive cars hard and drop the clutch a lot. If you took the car to a warrent station today they would slap a sticker on the car declaring it dangerous and forcing it off the road immediately until repaired. Do everyone on the road a favour - please don't drive your car. It is not considered safe by any stretch of the imagination. You have a critical problem that affects major drivetrain components and makes your vehicle very unsafe. My Australian mate had the same problem on his E46 M3. Was repaired under warranty by BMW Australia as the car was less than 5 years old. He showed me photos of the process. Repair normally involves cutting out and fitting new floor section as follows Remove rear bumper Remove rear subframe and diff and complete drivechain assembly back to gearbox. Remove exhaust system Remove petrol tank Remove EVERY electronic control unit from the car (due to welding) Remove all airbags Remove rear seats, and all boot trim and fittings Cut out old floor section with gas torch etc Fit new floor section (brand new, not old, which may also have metal fatigue) and weld into place (this is why ALL electronic control units are removed) Fit special spray-and-expand space-age foam between sandwhich sections of floor where subframe mounts to increase rigidity and reduce flexing. Prepare, paint underbody and interior, and reassemble everything Wheel alignment also required. You have to question whether this is worth it for a 16 year old car. Maybe you need to consider wrecking the car for parts, and buying a new car. Get a newer BMW And I know what part of any new car you'll be carefully checking with an inspection lamp.... Quote Share this post Link to post Share on other sites
jochen 4 Report post Posted May 10, 2008 PS: an american company makes special strenghener kits, highly trecommended if you drive these cars (or E46s) hard, especially if you want to race them. However the strenghthener kit needs to be fitted BEFORE total failure of the subframe mounting points...!! Quote Share this post Link to post Share on other sites
BMRBOI 8 Report post Posted May 13, 2008 yep its been off the road the moment i found out about it. the four bolts connecting the diff to the drive shaft, are they security torques bolts? The car will most likely be striped now engine gearbox etc will be sold, shell ill keep to start a project with. oh and removing the ecu for welding? is that because it shorts them? how come you cannot just disconnect the battery? Quote Share this post Link to post Share on other sites
Venatus 2 Report post Posted May 13, 2008 (edited) If Im right, Its because welding you attach a negative cable to the metal to be welded, and then when the welding rod or what not contacts the metal, its connected to postive from the mains as well, and theres so much current thats what melts the rod (shorting out) and fuses the metal...Im possibly wrong though, but Im sure nearly everyone else will know whats right.. Edited May 13, 2008 by Ven Quote Share this post Link to post Share on other sites
jochen 4 Report post Posted May 14, 2008 If Im right, Its because welding you attach a negative cable to the metal to be welded, and then when the welding rod or what not contacts the metal, its connected to postive from the mains as well, and theres so much current thats what melts the rod (shorting out) and fuses the metal...Im possibly wrong though, but Im sure nearly everyone else will know whats right.. Thats right. There are so many electrical currents flowing through the car when welding that the risk of damage to electronic components is quite high. To be safe, remove the electronics when welding to the vehicle body. Quote Share this post Link to post Share on other sites
BMRBOI 8 Report post Posted May 17, 2008 ok i see, so does that mean relays, fuses aswell radio etc? about those diff to sharft bolts anyone know what they are? Quote Share this post Link to post Share on other sites
jochen 4 Report post Posted May 17, 2008 ok i see, so does that mean relays, fuses aswell radio etc? No, just control units which containt electronics A fuse does not contrain any electronics The majority of relays do not contain any electronics. Quote Share this post Link to post Share on other sites
