e36's weak rear ends

[crispy]

i was talking to a guy today at the paint/body shop where i'm getting my 318 painted and he was showing me this m3 up on the lift with a pretty nasty rear end problem..
bear with me because i'm sort of a newb when it comes to part names and what not..
the point where the "rear end suspension" connects to the frame or "unibody" as he put it had been broken.. i said it just looked like a weak weld, but he said thats just how the back ends are built: weak. sorry if my description is vague, but the actual break was a little in front of the rear passenger wheel well and maybe a few inches to the center of the car. has anyone heard of this happening?

i also talked to him a bit about putting aftermarket suspension parts on my 318, and he told me because of the weak rear end, it wasn't the best idea. anyone know anything about this? are our cars really that delicate?

[Dnz]

rear subframe problems. Put it in search and youll find heaps of info. Bmw has plates that can be welded in to fix that problem... But yes, its a problem if you track the car etc..

[94-325i]

M3 already has reinforce.

[Boomer]

haha... my 325is(when i had it) had the differential mounts hanging in the air.... :) i had to get my whole rear end rewelded back to the body.... they put a thick ass plate, after that i could feel the car got stiffer-better response...

[hwl328is]

i had a weak bolt in my rear subframe, luckily i caught it before it did any damage to my rear subframe, all the mechanics had to do was replace the bolt and it was all good.

[Rich V]

rear subframe problems. Put it in search and youll find heaps of info. Bmw has plates that can be welded in to fix that problem... But yes, its a problem if you track the car etc..

It's not only a problem if you track your car. It is ALWAYS a problem for any car. If your subframe mounts are bad (if you have over 60k they probably are) then you are always in danger of the damage. Thanks BMW for the wonderful german engineering.

[JuiceSqueeze]

It's not only a problem if you track your car. It is ALWAYS a problem for any car. If your subframe mounts are bad (if you have over 60k they probably are) then you are always in danger of the damage. Thanks BMW for the wonderful german engineering.

Was that last part sarcastic or serious? Sorry I couldn't catch your tone.

And what about 323iSs? That seems like a pretty severe problem...
I'm planning on looking at a '98 323iS on Monday, it has 64,500 miles on it. Should I stress the BMW mechanic to check for that problem when I have him do a full inspection? How much does a plate welding job cost?

[Rich V]

Was that last part sarcastic or serious? Sorry I couldn't catch your tone.

And what about 323iSs? That seems like a pretty severe problem...
I'm planning on looking at a '98 323iS on Monday, it has 64,500 miles on it. Should I stress the BMW mechanic to check for that problem when I have him do a full inspection? How much does a plate welding job cost?

Sarcastic ofcourse! C'mon, I've owend 4 BMW's already and have no intention of stopping. Guess it doesn't translate over the keyboard and on the monitor so well.

Any E36 that is not an M3 is affected by the problem. If you just need the plates welded in expect to pay somewhere around $700+. TC Design seems to have the best deal and he REALLY knows his stuff.

[euro4life]

i also talked to him a bit about putting aftermarket suspension parts on my 318, and he told me because of the weak rear end, it wasn't the best idea. anyone know anything about this? are our cars really that delicate?

They aren't that weak. The torn mounts can appear on both street and track cars. Neglected RTAB's tend to be the case for street cars. Regular maintenance can almost completely avoid any problems. Aftermarket suspension will be fine. Just replace the bushings regularly like you are supposed to anyway. RTAB's generally last around 20-30k miles. If you are hard on the car check them every 10k and sooner. A lead foot can lead to quick bushing failure.


JB

[zeit00]

226k miles and I have no evidence of any wear. I have had 3 mechanics look at it.

[old skool]

How much to buy an M3 rear subframe?

[Erik@EDGE]

OK, well RTABs are generally a culprit, and the factory ones are crap somewhere between 40 and 60k. Replace with 96+M3 units and they are good for for another 40k+, more if you use GC shims or similar to limit their lateral movement.

DUDE--Over 200k? If your RTABs havent been replaced and your "mechanic" says they are OK, he is on crack and you need a new mechanic.

We have done over 40 sets of RTABs (probably more) and NO e36 with over 50k that we have taken apart has NOT needed RTABs. Several, even some M3's, have had tearing of the mounting tubes, full failure here can be a $1500 job.

Take a peak in the RTAB carrier housing (front of the rear trailing arm, kinda up in the body) Use a flashlight and look at the sides of the carrier. If you see shiny black up in there (instead of normal undercar dirt) then your RTABs are deflecting and torn and stressing the shit out of your mounting points.

[zeit00]

I think you just assumed too much there.. =)

The RTAB appeared to be replaced not too long before I purchased the vehicle. I am going to replace them soon anyways with the M3 bushings, GC shims. And all of the mechanics where looking at the rear subframe problem. Not the RTABs...

I was not posting in response to the RTAB problem. But to the subframe problem. Everytime my car is up on a lift even with an alignment, I check the subframe for cracks, tears, etc..

Trust me.. I have already replaced the front suspension, and I am now working on the rear..

[Bernman]

Bernman's take on "weak" E36 rear suspensions...

http://forums.bimmerforums.com/forum/showthread.php?postid=1042518#post1042518

Good luck :)

[Rusky325I]

Yeah I had this happen to me too. This weekend i am putting my car in the back yard for a week and going to start taking it apart slowly. Get all the new bushings while its apart and just basicaly rebuild my whole rear end. Right now instead of one bolt being torn from the subframe i have two that are torn and driving is imposible now.

[Bimmer Pilot]

Sarcastic ofcourse! C'mon, I've owend 4 BMW's already and have no intention of stopping. Guess it doesn't translate over the keyboard and on the monitor so well.

Any E36 that is not an M3 is affected by the problem. If you just need the plates welded in expect to pay somewhere around $700+. TC Design seems to have the best deal and he REALLY knows his stuff.
use the sarcastic tags nextime ...



:D

[themadhatter]

about $300-500 - I've purchased two complete subframes for various projects.

you do realize that it isn't the subframe that tears, it's the actual chassis of the car that tears.

-Ron

[old skool]

sop there is no need to replace the subframe...simply to stiffen the chassis by welding those plates? I thought the M3 plates were welded to the subframe?

Bottom line is it may be cheaper to buy an M3 subframe rather than buy the reinforcement plates and have them welded on.

[bimmer95]

I thought the M3 plates were welded to the subframe?
Nope.

[old skool]

so M3s came with them welded to the body?

[bimmer95]

so M3s came with them welded to the body?
Of course.

[bmwm3n528]

So what would you recommend doing to a e36, like my 328is, if it's going to be driven hard/autoxed/tracked ?

[bimmer95]

FYI, http://www.tcdesignfab.com/mark%20diff.htm

[old skool]

I wonder how necessary this all is on a mainly street car with stiff sway bars and lowered suspension?

[94-325i]

All you need to do is replacing all subframe bushing every 60k or 70k. You can use powerflex bushing too. Just thing about this that your car has weak bushing, not chassis.

[old skool]

so the rear bushings are the failure point and if they aren't replaced in time then the body is torn?
So would I need to replace the bushings and weld in the reinforcement plates?

[Dnz]

Is that right? Just keep an eye on the bushings??

[Rich V]

As long as your bushings are in good shape, you shouldn't have any problems with the chassis tearing at the subframe mounting points. But like I said, if they have more than 60k on them, they are probably in need of attention right away.

People that do this repair all the time have told me they have seen it happen on cars from a bone stock 325is automatic that was dreiven very little by an elderly woman to cars with hard driving behind them. Bottom line is it can happen to ANY E36 if you don't maintain them.

[DirtOval]

It's not only a problem if you track your car. It is ALWAYS a problem for any car. If your subframe mounts are bad (if you have over 60k they probably are) then you are always in danger of the damage. Thanks BMW for the wonderful german engineering.

And what about 323iSs? That seems like a pretty severe problem...
I have 61K miles on my 99 323is and I had a diagnostics test done at 60K miles. The dianostics test showed that the Guibo join was getting to be worn out and that I had bad soark plugs. Nothing else showed up. Should I Bring my car back in and have them check it over the sub frame mounts??

[euro4life]

Should I Bring my car back in and have them check it over the sub frame mounts??

Grab a flashlight and lie on your back underneath the boot of your car. Check the mounts yourself. Much easier.


so the rear bushings are the failure point and if they aren't replaced in time then the body is torn?

Bad RTAB's are the primary cause. That doesn't mean the sole cause. Just keep your car maintained. Proper care will prevent most failures in any case. If the mounts are going to tear out, they will tear out. Just do your part and have fun with the car. RTAB's are relatively cheap. Just find somebody who has the BMW tools and locate a friendly alignment shop. Replece them when questionable and check up on them regularly. If you're up to the task, pull the subframe yourself and have the plates welded in.

[Bremsen]

Just wanted to add one thing:

Every car is maintained and driven differently which makes all the difference in the longevity of wear items.

I've replaced several items that members on Bfc say MUST be replaced at 60, 70, 80k and mine were perfectly fine when I replaced them at 125k+ (ex: RTABs). Don't just go replacing things b/c you have X number of miles. That gets expensive.....especially if you have to pay for the labor. Just be aware of the items that tend to fail and keep an eye on them. Or have it checked by a pro if you don't know what to look for.

[Bimmer Pilot]

Just wanted to add one thing:

Every car is maintained and driven differently which makes all the difference in the longevity of wear items.

I've replaced several items that members on Bfc say MUST be replaced at 60, 70, 80k and mine were perfectly fine when I replaced them at 125k+ (ex: RTABs). Don't just go replacing things b/c you have X number of miles. That gets expensive.....especially if you have to pay for the labor. Just be aware of the items that tend to fail and keep an eye on them. Or have it checked by a pro if you don't know what to look for.
Common Sense prevails...

[coolcarlski]

Sarcastic ofcourse! C'mon, I've owend 4 BMW's already and have no intention of stopping. Guess it doesn't translate over the keyboard and on the monitor so well.

Any E36 that is not an M3 is affected by the problem. If you just need the plates welded in expect to pay somewhere around $700+. TC Design seems to have the best deal and he REALLY knows his stuff.Thats not tru, He said it was an M3 on the lift with the problem.Unfortunately it seems like a potential problem for all E36's.