Trailing arm bracket bolts ripped from body

[m3f_EliteM3]

So 2 of the 3 bolts that hold the trailing arm bracket to the car ripped out. completely separated from the car ripping out the threads. Curious as to if this is typical of these cars? I'm still learning about these cars ever since picking mine up a few months ago and cant seem to find any info on this.



http://i11.photobucket.com/albums/a161/ilustrius9/GetAttachmentaspx.jpghttp://i11.photobucket.com/albums/a161/ilustrius9/photo2-1.jpg

[m3f_fiveightan_7e37700daf]

Sorry to hear that man. It's happened to a handful of guys over the past few months...more often than I would've thought we'd see this sort of thing after learning about it. Your experience may be the thing that catalyzes me to weld reinforcements on my car. That's some scary stuff.


Listed here in the FAQ's:

http://www.m3forum.net/m3forum/showthread.php?t=300562


Cal posted a good thread about it here:

http://www.m3forum.net/m3forum/showthread.php?t=269831


EDIT: cut and paste from the explanation in the FAQ's:


--Rear trailing arm bushing (RTAB) pocket

Problem: The RTAB is mounted in a metal carrier that bolts to the unibody at 3 points, using threaded bungs that are welded to the body of the car. The sheet metal around these bungs (like the sheet metal in the rest of the car) is weak and has been known to develop cracks and even flat out fail. The RTAB carrier (aka RTAB console) separates from the body completely. I don't think I need to explain how dangerous this is. It has been hypothesized that this is either due to hard track use, and/or due to worn RTAB's, which allow excessive movement of the RTA in the console, causing it to slap up against the metal, which sends mechanical shock through the setup and to the welds around the threaded bungs and unibody.


Solution: Some vendors sell RTAB pocket reinforcements. Welding is required to install these. You will have to drop the RTA, clean the unibody so it's free of undercoat, and weld the reinforcements in. Unless you have the means to turn the car upside down, the welding will be done upside down. This is also tight work with tight tolerances. It needs to be left to a professional that has a lot of experience with similar situations. Your cousin Louie across town (who owns a welder he got at a yard sale and will be happy to "weld that b!tch up for a 6 pack of High Life if you put in a good word for him with your sister") does not qualify as a competent professional.


How common are problems with this?

I'd consider RTAB pocket failure a low occurrence, extremely high risk issue.


It happened to this guy as well:

http://www.m3forum.net/m3forum/showthread.php?t=307592

[m3f_EliteM3]

Thanks for posting that. def didn't see it. well time for some fabrication.

[m3f_OahuMPower_17503f01cd]

www.bimmerworld.com


they make the RTAB pocket reinforcements, and what I had welded into my car (that's my thread)


not too bad if u have a welder, or know a friend who has a welder

[m3f_fiveightan_7e37700daf]

Cal, what did you undercoat the area with when you finished?


This has been happening to too many people lately. It's kind of freaking me out. :rofl3:

[m3f_OahuMPower_17503f01cd]

some rust proof spray to "coat" it (it's clear)


then I sprayed 3M undercoating

[m3f_fiveightan_7e37700daf]

some rust proof spray to "coat" it (it's clear)


then I sprayed 3M undercoating

:thumbsup2:


Do you think there would be enough room to work with by just unbolting the RTA and the shock and letting it fall away from the pocket, or is it necessary to unbolt the axle, control arms, and everything to get it pulled off completely?

[m3f_OahuMPower_17503f01cd]

you can leave the gas tank, control arms, and shock there... but you REALLY SHOULD remove the trailing arm/half shaft assembly to get in there and actually be able to weld...



if you check the link in my sig, about the rear overhaul, I have all the pictures of my RTAB reinforcement and you can see that I did exactly that.. remove the TA/halfshaft combo :thumbsup:

[m3f_EliteM3]

www.bimmerworld.com



they make the RTAB pocket reinforcements, and what I had welded into my car (that's my thread)



not too bad if u have a welder, or know a friend who has a welder



found them thanks. might as well change the bushing out as well and they have the powerflex urethane bushings. recommend?

[m3f_OahuMPower_17503f01cd]

found them thanks. might as well change the bushing out as well and they have the powerflex urethane bushings. recommend?



how crazy do you want to get? My most recent thread

http://forums.bimmerforums.com/forum/showthread.php?t=1408487





about the powerflex RTA bushings, I would definitely do them. I love mine :thumbsup: When you install them, make sure to Marine Grease the SHIET out of them if you dont want them to squeak. It comes with the territory of going to a poly bushing though

[m3f_EliteM3]

yea caught that thread. good stuff. my car has fairly new bushings etc... maybe next go around

[m3f_Sirius_880bd69485]

Did this cause any sort of thudding or clunking sounds while subjecting the car to any sort of body roll?

[m3f_EliteM3]

started with light thudding noise from time to time which i couldn't figure out. then a banging noise that gradually got worse. i thought it was the strut or something but it didn't make any sense. i didn't even know about this problem and glad i caught it when i did.


didn't notice any body roll but the bushing is in good shape and it didn't completely fail yet.

[m3f_Oldman MZ3_66db430103]

Hope pictures stay up for you.



Notes



GROUP 41

Body



Bulletin Number

41 02 99



Woodcliff Lake, NJ

September 1999

Product Engineering



SUBJECT:

Threads Strip When Adjusting Toe on Rear Axle



MODEL:

E46



Situation:

When performing a wheel alignment on an early production (prior to 7/98) E46, it is possible to strip the threads for the toe adjustment, if the bolts are tightened with an impact wrench or are over torqued. The mounts in the body of later production cars were strengthened to be able to take an overtightening without failure.



Correction:

If the threads are stripped in an early production car there is insufficient wall thickness to permit a repair with a helicoil type insert. The mounts in the body must be replaced with late style (7/98 and later production) mounts which have more material.



Procedure:

Remove complete rear axle assembly per Repair Instructions 33 31 000. Remove fuel tank per Repair Instructions 16 11 030.















Scribe a line around both control arm mounts on the body to assist in properly locating the new mounts.



Use a spot weld drill to remove all accessible spot welds, taking care not to drill through the body. Two or three welds that are inaccessible can be ground out with a die grinder.



Remove both mounts and clean up area for welding.















Drill out the ten pre-marked welding points on the new mounts to 8 mm, and drill two additional holes as indicated (1).



Plug weld the mounts in position taking care that the welds are continuous and without voids that can cause corrosion.



Apply four bead welds (2) as per illustration.



Prime, paint and apply corrosion protection to the area. Inject cavity sealer through the bolt holes and through the access hole in the wheel well.



Parts Information:

This repair requires two mounts, part numbers 41 11 7 012 047/048.















Warranty Information:

Covered under the terms of the BMW new car limited warranty.

[m3f_///sleeper_f29d08a5a4]

this is starting to concern me as well....OP, you said you recently got the car, I assume you didn't happen to get a look at those mounting points prior to them failing? Do you track your car or do you live in an area w/ bad roads? I'm just curious if they failed on account of your driving or if they were on their way out when you got the car from the previous owner...seems like a fairly catastrophic failure for simple street driving.