RTAB pocket failure quick video inside and some info on diagnosing

[m3f_fiveightandten]

A friend of mine was having a suspension clunk, so we put the car up in the air to have a look. I noticed one of the welded bungs on the driver's side RTAB pocket has separated. So I took a quick vid.


The car is on its second set of OEM RTABs. The PO replaced his originals around 120K or so...so he doesn't know what they looked like at the time. We don't know how long the car has been like this.


The symptoms were as follows:

-Clunking noise coming from the rear at low speeds when going over bumps or elevation changes.

-Could reproduce the clunk by shaking the car left to right.

-NO clunk heard as a result of going over bumps while driving at speed.


Sorry for the cell phone video...it was all I had on me at the time. You'll have to look close. This is just me prying gently on the RTAB console with a small pry bar. It pulls away from the unibody pretty readily with little force.


Anyways...hopefully this video will be useful to anyone looking to check their RTAB pocket for failure. A little poke with the pry bar makes it pretty visible. Be gentle under there. And when you get your car aligned, tell the place to be mindful for NOT overtorquing these bolts.



YouTube - ‪E36 M3 Rear trailing arm bushing console pocket failure‬‏

[m3f_PurduinaM3]

Damn, that sucks man. Whose car is this, teh hooms?


It happens though, Poly or not...

[m3f_shaeff]

That sucks. Whenever I get my car aligned, I leave a torque spec sheet sitting on the driver's seat when I leave the car and ask politely that they follow it due to reasons just like this.


And edit: agreed on poly or OEM. My car had 98k on it when I got it, bone stock, and I had a torn threaded insert. Pissed me off when I went to replace the RTABs (which I might add, were still in perfect shape)

[m3f_Z3MCOUPE]

Nick - you are the man. Thanks for posting.

[m3f_M3_ATW]

thank you for the info!!


scared to say that i think i might have this going on with my M


all new bushings coming in soon, but i will either need to have the pocket reinforced or fixed for sure

[m3f_Cawhite78]

Nick - thanks for the help here. I was thinking about it on the way home, and it HAS to be the pocket separation causing the clunk. The noise is 100% coming from the passenger rear where we suspected. That said, I just ordered the bimmerworld kit, and will do the ball joints at the same time, because the play that was present was enough to justify it .


Good to see you as always bro

Damn, that sucks man. Whose car is this, teh hooms?


It happens though, Poly or not...

It's mine Bobby. I want to say I was shocked when we discovered it, but i had a strange feeling.. My car's closet is full of skeletons..


Just my two cents, this definitely is not a Track Car/Auto X/Poly RTAB only issue. Under body rust is something that over time (especially if your car has seen winter use) WILL eventually attack the weak points of the under carriage. Aggressive driving or not, the e36 is 11+ years old at it's newest. If you are under the car - it's worth taking a look at.

[m3f_PurduinaM3]

It's more common than you think; don't get too down on the car. Mine were starting to tear out with zero rust at all... just a very weak area there

[m3f_284Shooter]

Seems we are seeing more and more of this as these cars age. A few years ago, this was a very uncommon post. Now, even removing cross posts, it seems we see better than a dozen of these a year.



These are on my winter to-do list.(as well as a new battery tray with hoops for track tie downs) I may have the front subframe re-enforced as well. I needed an excuse to regrease my RTABS and put the camber plates in, so this is as good as any to get it all done and get lined back up before the spring track days start.



I have to wonder if the newer tire and brake compounds are accelerating these failures? Tire and brake pad technology is FAR ahead of where it was back in the mid and late 90's. Not that fat, sticky tires or agressive brake compounds will cause this, but the extra strain on the chassis could certainly help things along....

[m3f_PurduinaM3]

I have to wonder if the newer tire and brake compounds are accelerating these failures? Tire and brake pad technology is FAR ahead of where it was back in the mid and late 90's. Not that fat, sticky tires or agressive brake compounds will cause this, but the extra strain on the chassis could certainly help things along....

The newer stickier tires along with new R compounds are definitely helping to speed up the failure of most of the weak metal used in chassis points around this car. Grip levels like that just weren't around in the 90's...

[m3f_Cawhite78]

It's more common than you think; don't get too down on the car. Mine were starting to tear out with zero rust at all... just a very weak area there

I hear ya bro.. It's just one of those things, ya know? It's a good winter project though.

I have to wonder if the newer tire and brake compounds are accelerating these failures? Tire and brake pad technology is FAR ahead of where it was back in the mid and late 90's. Not that fat, sticky tires or aggressive brake compounds will cause this, but the extra strain on the chassis could certainly help things along....

I hadn't thought of this, and I think it's a great observation. There are certainly variables that are present now within this aging chassis that were not around back when the car was designed.

[m3f_fiveightandten]

Nick - thanks for the help here. I was thinking about it on the way home, and it HAS to be the pocket separation causing the clunk. The noise is 100% coming from the passenger rear where we suspected. That said, I just ordered the bimmerworld kit, and will do the ball joints at the same time, because the play that was present was enough to justify it .



Good to see you as always bro

Good times man.



I hope you don't mind me posting this up. I figured I wouldn't mention any names without you, but it's definitely valuable to help people out in the future. It's been 6 months or so since i've checked my car for problems under there...it's definitely catalyzing me to do it again.



With regard to doing the ball joints...it makes sense. You'll have to get an alignment after pulling the RTA's down, so mind as well knock them out. It saves the cash of another alignment. It's really only that one on the driver's side that has notable freeplay, but in typical enthusiast fashion, overkill is the norm.



Thanks again for that tripod, BTW. It's bad*** and WAY nicer than the one I was using, which is half broken now anyways.

[m3f_das borgen]

do it


http://m3forum.net/m3forum/showthread.php?t=338910

[m3f_Cawhite78]

Good times man.



I hope you don't mind me posting this up. I figured I wouldn't mention any names without you, but it's definitely valuable to help people out in the future. It's been 6 months or so since i've checked my car for problems under there...it's definitely catalyzing me to do it again.



With regard to doing the ball joints...it makes sense. You'll have to get an alignment after pulling the RTA's down, so mind as well knock them out. It saves the cash of another alignment. It's really only that one on the driver's side that has notable freeplay, but in typical enthusiast fashion, overkill is the norm.



Thanks again for that tripod, BTW. It's bad*** and WAY nicer than the one I was using, which is half broken now anyways.

No worries at all man, I'm glad you posted it up.. You have helped me and *countless* others on this board a great deal. If my situation can help anyone else - please feel free to use whatever you need to help get your point across.



The tripod.... You can tell people you went to URI



We'll have to grab some shots before the snow arrives and you retreat to Soobieville..

[m3f_fiveightandten]

No worries at all man, I'm glad you posted it up.. You have helped me and *countless* others on this board a great deal. If my situation can help anyone else - please feel free to use whatever you need to help get your point across.


The tripod.... You can tell people you went to URI


We'll have to grab some shots before the snow arrives and you retreat to Soobieville..

Of course I went to URI.


And i'm already in Soobieville man. I'm loving that car with the suspension now. I'll give those springs a week to settle, then it'll be off to the alignment shop. It should turn in nicely with some camber.


Not for nothing, but if you get the RTAB business taken care of quickly, I think it would make sense to try and take care of the guibo and stuff before you put her down for the winter. It would be nice to start her up in the spring and start driving, instead of wrenching. Let me know if you want to do that stuff up...before the cold kicks in.


Make sure whoever does the welding definitely knows what they're doing. I think that unibody sheet metal is thinner than it looks (thinner than a shop who hasn't done the job would likely expect it to be). Cal did a pretty good writeup about this a while back. You can find it by searching under his username. I'm sure he'd welcome any questions, as he knows more about the process than most of us.

[m3f_Cawhite78]

Of course I went to URI.



And i'm already in Soobieville man. I'm loving that car with the suspension now. I'll give those springs a week to settle, then it'll be off to the alignment shop. It should turn in nicely with some camber.



Not for nothing, but if you get the RTAB business taken care of quickly, I think it would make sense to try and take care of the guibo and stuff before you put her down for the winter. It would be nice to start her up in the spring and start driving, instead of wrenching. Let me know if you want to do that stuff up...before the cold kicks in.



Make sure whoever does the welding definitely knows what they're doing. I think that unibody sheet metal is thinner than it looks (thinner than a shop who hasn't done the job would likely expect it to be). Cal did a pretty good writeup about this a while back. You can find it by searching under his username. I'm sure he'd welcome any questions, as he knows more about the process than most of us.

Absolutely.. I'd love to knock it all out before she goes into hibernation. I spoke to a guy at Fairfield County Motorsport today and they are going to do the reinforcements. They do quite a bit of race car fabrication and metal work. Mostly BMWs and P Cars. It's not the cheapest place, but it's 10 seconds from my house in FFLD, and I know they will do a good job.



My other winter project just showed up today in five huge boxes