E36 Safety and IT

[gsbaker]

Well, to be fair, there are REAL issues. BMW very recently settled a class-action suit with E46 owners because the unibody fails where the rear subframe mounts, and there is now factory guidance on how to reinforce the unibody at those locations (it involves using structural foam.) Exactly the same sort of structural failure happens on both the E36 and Z3 chassis too, although unfortunately they aren't included in the settlement. It's as though BMW engineers just don't know how to build a chassis that can hold a rear subframe without breaking apart. These failures are relatively common on street cars.

Likewise, the front control arm failures are well-documented -- they have embedded ball joints for the inner pivot and these fail regularly. Racing guidance suggests replacing them every season or two. Likewise there are weaknesses that have shown themselves on racing cars again and again with E36 front subframes, E30/Z3 rear trailing arms, etc.

I'm not lobbying for any sort of rule change. We live with these things and lots of manufacturers have these sorts of struggles. I'm just pointing out that it's not as though these are all performance issues masquerading as safety issues. In a lot of ways, many street cars, especially once they get up there in miles, are not up to the task of racing, or in some cases, even driving around on potholed streets.

I wasn't aware of that. Thanks for the education.

[JLawton]

Isn't there a documented service procedure for E36s that instructs technicians to repair the subframe mounting location cracks? If so, I would think it would therefore be an accepted reinforcement,IF the repair procedure were provided at a prtest or inspection

Everytime this discussion comes up (once a year??), the BMW guys say that reinforcing is the proper official BMW repair procedure for this problem.......... but we have yet to actually see any documentation..........


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[Doc Bro]

So the whole thing just rips out and ends up at teh side of the road at once!?

Kinda...

Last year at NHMS Dave hit some Oil Dry in Nascar 1&2 in his e36, and lost traction, then regained traction with a quick slide ocurring. On corner exit he knew something had happened beyond the loss of grip. He immediately pulled the car in. Dan immediately checked the subframe mounts and noticed a crack. Loaded the car and called it a weekend. When Dan put the car on the lift he noticed it had ALL cracked, including breaking the trans mounts and the motor mounts....literally ripped the driveline out of the car. Took him a week to fix......how's that for a failure from Oil Dry?

R

[Greg Amy]

...how's that for a failure from Oil Dry?

I HIGHLY doubt all that damaged was caused in that one moment; the amount of stress needed to rip sheet metal to that magnitude in one instant is absurdly immense, far more than even the vaulted awesomeness of a BMW can generate (even without the SIR ). I'm much more likely to believe that this damage had been propagating for quite some time, with a small crack fatiguing and growing to the point where a minor incident as you describe finally allowed it to break across a critical area.

Sounds more like lack of adequate on-going inspection of a critical safety area, to me.

GA

[Doc Bro]

I HIGHLY doubt all that damaged was caused in that one moment; the amount of stress needed to rip sheet metal to that magnitude in one instant is absurdly immense, far more than even the vaulted awesomeness of a BMW can generate (even without the SIR ). I'm much more likely to believe that this damage had been propagating for quite some time, with a small crack fatiguing and growing to the point where a minor incident as you describe finally allowed it to break across a critical area.

Sounds more like lack of adequate on-going inspection of a critical safety area, to me.

GA

While what your saying makes sense I doubt highly it's true. The e36 we're talking about is METICULOUSLY prepped and maintained. That car has more nut & bolt jobs done to it than the rest of the ITR field combined, and is constantly on the lift or alignment machine.

When the subframe mounts go (and there aren't that many of them) they go quick....BMW motor mounts are made of paper mache- I don't think that grand scale Newtonian force is necessary to cause serious damage.

R

[Greg Amy]

Rob, sheet metal failures like this are due to fatigue, something that happens over many cycles, not catastrophically. Just as it's impossible for you to pull apart a paper clip with your bare hands, you can easily break one apart by bending it several cycles, starting a crack, and then it comes apart.

It's simply not possible that this car's subframe/chassis/sheet metal failed all of a sudden due to driving through oil dry and then catching grip. No way. What this means is, regardless of meticulousness of prep (and I know who you're talking about, and I'm aware of their reputation, ad I agree with you), a chassis crack was missed during inspection and that crack was allowed to propagate to the point of failure...

If we were to consider these kind of items "safety concerns" and thus deserved of special treatment/mods, then we open the Pandora's Box of just about any parts subject to failure being allowed to be improved. Just ain't gonna happen. - GA

[Greg Amy]

Everytime this discussion comes up (once a year??), the BMW guys say that reinforcing is the proper official BMW repair procedure for this problem.......... but we have yet to actually see any documentation..........

One of my all-time favorite threads on this board...

https://improvedtouring.com...ad.php?t=12163

Those original photo links are long gone...but the InterWeb never forgets (as an unrelated aside, keep that in mind next time you shoot off your mouth, er keyboard...I try to...)

http://web.archive.org/web/200612060.../gallery/car11

http://web.archive.org/web/200612060...k_welded_1_006

http://web.archive.org/web/200612060...g.com/cars.php

[quadzjr]

If we allow this can I re-inforce my motor mount so this don't happen on my MK1 MR2? It is a fairly common problem, being toyota they wouldn't admit it back in 86... ahh com'on! haha

[Ron Earp]

One of my all-time favorite threads on this board...

https://improvedtouring.com...ad.php?t=12163

Great thread, before my time.

"What class does he run in? ITButthead?"

Fellow that said this on that thread in 2004 can't be the same fellow we know now.

And who wrote this one:

"1) Why does the natural performance potential of the E-36 bother you so much?"

[Greg Amy]

Great thread, before my time.

Wanna have some fun? As you read that first post, change:

- "jwsbmw325" to "TNord"
- Andy Bettencourt to Greg Amy
- ITS E36 BMW to ITA 1.8L Mazda Miata

...and see if you don't get a shiver or two down your back...

[mr. black]

Great discussion. How often should you check, where/what parts exactly, and what do you look for besides an obvious crack or welt on the E36?

[Doc Bro]

Great discussion. How often should you check, where/what parts exactly, and what do you look for besides an obvious crack or welt on the E36?

Check religiously the ears where the diff bolts to the car. Check where the subframe bolts to the car, check where the rear control arm bolts to the car in that bucket (3 bolts). I already ripped one of those out this year.

R

[benspeed]

I went over the control arms and ball joint pins methodically the other night - pain in the butt but the known issues on the Porsche make it a mandatory deal - that breaks and really bad things happen. I only have two weekends on the car but I'm not waiting around for trouble.