As a precaution, we reinforce the mounting areas with extra steel plate and weld. We custom cut, form and weld new sheet metal for the areas where metal is missing (as in the above example). Simple cracks are first prepped and then welded. We next grind away the paint and body filler. After the sub-frame is removed (along with all the suspension, driveline, brakes and gas tank) the mounting areas are inspected. The fix is relatively simple, though it is quite involved. The car from which these photos were taken showed a slight compression on the right side rear which indicated something was wrong- but it could have just as easily been a bad spring as a sub-frame mounting failure. Thanks to road grim that builds up on the chassis and the limited access to the mounting points, it is extremely difficult to spot these types of failures without removing much of the rear suspension or taking out the sub-frame all together. Here is a photo of the left rear mounting point failure: You can see the outside sheet metal has not only cracked, but chunks have broken off: Over time, the forces begin to fatigue the sheet metal of the body.īelow is a photo of the right side front sub-frame mounting point. The sub-frame is also subjected to impact forces from the road surface (though much of the impact force is directed towards the shock and spring mounts, not the sub-frame). When torque is sent through the axle and to the wheels, a moment is applied to the sub-frame. The sub-frame is bolted to the body at four locations, and isolated by rubber bushings. Talking about sub-frame failures is a bit of a misnomer since it is the mounting points on the body that fail, not the sub-frame itself. The complete sub-frame with attachments removed from the car: Below you see the sub-frame assembly on the car: The differential nests within the box like frame and the suspension attaches to it. Lee had his E46 M3 sent to us (Redish Motorsport) due to the rear E46 subframe floor being badly damaged. The above drawing shows the rear sub frame assembly (sometimes referred to as an axle carrier) for an E46 M3. I took a closer look at photo 161 and I think it is just the light acting weird. I haven't seen any pics on this forum of the repair process so I would like to show you them.First a little background. #E46 M3 SUBFRAME CRACK CRACK#The car has just tipped 56500kms now and no signs of a crack reappearing. One of these problems is the rear mounting points for the subframe, which can rip out from. Big end bearings, check on the wear, will make a call, (expected it) 4. Never tracked the car before then and had only done a few launch controls, a lot of S6 changes etc but regardless dunno why it failed, its supposed to be a motorsport car. Then, cut a metal plate and weld it over the crack to reinforce it. You can see in the pics its just started to crack. My car is a 12/03 build, 04/04 delivered and at the time had 41,000 kms on it. They replace the floor and the boot floor and then fill the new cavity with some hardening sealant for extra strength to prevent it from happening again. The repair has the car pretty much stripped of everything electrical, no doors, no boot, no rear bumper, no exhaust, no rear seat, etc. The car was gone for 1 month while they replaced the floor. Well out of warranty but I tell my friend at BMW about it and within a few hours get the call that they are covering the repair. Had a friend of a friend put it on his hoist and they checked it and confirmed the bad news. Wind back 1.5 years, I took my wheels off for a clean and thought I would check out the subframe mounting points due to all the problems that are well documented on the internet and noticed a 10mm hairline crack.
0 Comments
Leave a Reply. |
Details
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |