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MT = Doppler Shifting
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Discussion Starter · #1 ·
Was poking around the E46 forums, primarily because of my interest in the E46 M3, and started learning about fatigue cracks/failures of the subframe on these vehicles (here's a pretty extreme example, shown on a web site that sells a reinforcement kit). Now, I don't want to start an unwarranted panic amongst our younger viewers, and haven't seen even a hint of this kind of thing mentioned during my time on the E83 forum, but I naturally began to wonder if the E83 was susceptible to this as well?

My question is predicated on the knowledge that the E83 is largely based on the 3-Series (which would have been the E46 around the development/introduction of the E83, although the E36 also apparently suffered from this problem), but I really don't know how much of the subframe is common between the E83 and E46/E36. I suspect that it's not very common, since the gross weight rating of the E83 is quite a bit higher than the E46/E36, which would almost certainly have required structural improvements for the E83. Plus with a standard powertrain that uses AWD versus a standard RWD system, I also suspect that the distribution of loads is different between the E83 and E46/E36 -- and especially the M3, which I would guess is even more susceptible to this problem than the base E46/E36 due to the much higher torque output.

So, am I wondering about something I probably shouldn't concern myself with for exactly the reasons I've already outlined; or has anyone here in E83 Land seen/heard of this happening on our vehicles...? I guess it really boils down to whether the E83 and E46/E36 are sisters, or just cousins under the skin...
 

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Tar Heel Faithful
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There have been zero subframe issues with the X3. Plus even on the E46, those were confined to the earlier models before the facelift.
 

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Glfbggy
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There have been zero subframe issues with the X3. Plus even on the E46, those were confined to the earlier models before the facelift.
Unfortunately, the e36 and e46 3 series were not alone and perhaps it is the e36 that originated the situation. The Z3 also had some subframe issues and there are similar fixes. Take a walk throug the Z3 forum and you'll see several discussion trains.

Personally, I don't push my Z3M hard and I am not worried about the X3.
 

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MT = Doppler Shifting
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Discussion Starter · #4 ·
There have been zero subframe issues with the X3...
That's certainly good to hear. I suspected as much, but figured it wouldn't hurt to confirm.

... Plus even on the E46, those were confined to the earlier models before the facelift.
Which E46 facelift? 2002 (sedans & wagons) or 2004 (coupes & convertibles)? I really didn't get the impression from the posts I read that subframe cracks were confined to pre-facelift models, but I wasn't cross-checking model years either. However, I did find a post with photos of an E46 M3 that had nearly split itself from one rear wheel to the other, and that was a 2003. And that one had allegedly been fitted with a reinforcement kit (albeit poorly, according to the post; so it's not entirely clear if the poor workmanship in performing the reinforcement actually contributed to the ultimate failure on this vehicle). Did BMW change the rear structure on the E46 with the facelift(s)?

Unfortunately, the e36 and e46 3 series were not alone and perhaps it is the e36 that originated the situation...
My understanding is that this did originate with the E36, and propagated to the E46 (which shares a similar same rear suspension structure) despite efforts by BMW to address the subframe problems of the E36. In fact, some of the fixes applied to the forward subframe as "lessons learned" from the E36 appear to have exacerbated the problem on the rear subframe of the E46...
 

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Tim, I have a 2003 E46 M3, totally stock, driven spiritedly but not abused, and I have zero problems with the car. I'm not worried about it. I'm also not worried about the X3. While I haven't studied the designs of both, I've been under both and the geometry is different. But consider this: The rear diff on the M3 is seeing all of the power in the car and is transferring that power to the two rear wheels. The resistance from the wheels is transferred back into the subframe on that car. On the X3, you have what--a 40/60 or 50/50 static split FR/RR, with a dynamic transfer of not much more, in a much lower torque application. Plus, the way the X3 is programmed to shift up as soon as possible, I don't even think you are in the optimum torque band of the motor in any given gear unless you are in manual mode. So--I'm not worried about the X3 rear subframe. I'm more concerned if the HVAC starts chirping again....
 

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MT = Doppler Shifting
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Discussion Starter · #6 ·
Tim, I have a 2003 E46 M3, totally stock, driven spiritedly but not abused, and I have zero problems with the car. I'm not worried about it. I'm also not worried about the X3. While I haven't studied the designs of both, I've been under both and the geometry is different. But consider this: The rear diff on the M3 is seeing all of the power in the car and is transferring that power to the two rear wheels. The resistance from the wheels is transferred back into the subframe on that car. On the X3, you have what--a 40/60 or 50/50 static split FR/RR, with a dynamic transfer of not much more, in a much lower torque application...
That's a good point about the power transfer in each vehicle that supports the suppositions I made in my original post: the application points of the torsional loads are going to be different in the E83 versus the E46 [M3]. That, coupled with your observations about the structural differences in the two subframes, puts the matter to rest, I think. :thumbup:

At some point I might want to pick your brain a bit about the E46 M3 and what areas to scrutinize if purchasing one. I'll shoot you a PM on the topic sometime, if you don't mind?
 

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Sure, send me any questions you have. I've found that while the forums are helpful, they'll make you paranoid about the car and a potential purchase. As always, a pre purchase inspection and proper maintenance history key. The E46M3s are aging, but if cared for, are aging well. If I were still in Lex I'd be happy to meet up and discuss, but I'm in SC for the time being.
 

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MT = Doppler Shifting
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Discussion Starter · #8 ·
Sure, send me any questions you have...
Thanks!

... I've found that while the forums are helpful, they'll make you paranoid about the car and a potential purchase. As always, a pre purchase inspection and proper maintenance history key. The E46M3s are aging, but if cared for, are aging well...
Yeah; I find that I'm continually reminding myself of that fact... :angel:

But that's always the trick with any aging car model: finding one that's been properly cared for and not abused. And it seems to be even more of a chore with a high-performance vehicle like an M3. Educating yourself as a prospective buyer goes hand-in-hand with other safeguards like a pre-purchase inspection and review of maintenance records: if you don't know what the potential problem areas are, you risk missing something... Thus, perusing these forums for all the horror stories becomes a double-edged sword. But as a wise man once said: "Learn from other people's mistakes; you won't live long enough to make them all yourself..." ;)

... If I were still in Lex I'd be happy to meet up and discuss, but I'm in SC for the time being.
Well, be sure to drop me a PM if you wander up this way!
 
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