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E46 M3 (2001-2006) Engine: S54 - Max Hp: 333 hp at 7,900 rpm / 262 lb/ft at 4,900 rpm
Total Produced: 45,000+ - Years Produced: 2001 to 2006.


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Old Fri, May-15-2015, 05:06:48 PM   #31
M3_#67
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Default Re: Subframe: Front vs. Rear mount brace

Quote:
Originally Posted by VinceSE2 View Post
While I'm in the midst of this project and haven't installed the back seat yet, i see no reason there would be any space issues.
Basically all I have added is "behind" the sheet metal wall I removed.

The idea is to stabilize the threaded insert such that it does not break loose from the top mounting surface when the tilting/bending force is applied to it.
The bolt going thru the threaded sleeve, and the nut and washer on top is one part of the design. The pipe and its floor (which is welded against the top of the threaded sleeve is another. And finally the pipe itself is welded to the inner skin of the body adding more support against the tilting.
The pipe is a 2" exhaust pipe with 2mm thick walls.
The hole saw is 51 mm OD.

Hera are some more pics:




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Seems well thought out. Definitely something to think about.
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Old Fri, May-15-2015, 05:56:35 PM   #32
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Default Re: Subframe: Front vs. Rear mount brace

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Originally Posted by VinceSE2 View Post
Here is what I'm doing with my fronts and rears (in addition to the Redish plates).



Very interesting how you added structural gussets, I like what you've done
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Old Sat, May-16-2015, 10:12:49 PM   #33
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Default Subframe: Front vs. Rear mount brace

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Originally Posted by BearDeXPS View Post
Very interesting how you added structural gussets, I like what you've done

Thanks!
Here are a few more pictures showing progress.
Spent most my time today prepping the underside for the Redish plates though.












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Old Sun, May-17-2015, 03:47:49 PM   #34
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Default Re: Subframe: Front vs. Rear mount brace

Very cool!
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Old Sun, May-17-2015, 04:03:53 PM   #35
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Default Re: Subframe: Front vs. Rear mount brace

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Originally Posted by nrubenstein View Post
While I still don't think that that level of reinforcement is necessary in a car that is even in the vicinity of stock, Vince's reinforcement is very much the way to go if you want massive overkill, IMHO.
Nick- it is well documented (my own car as well) that the most serious form of RACP failure is actually at the rear. The entire panel pulls away from the frame at the wheel arch seam. Redish has shown this numerous times. The later cars have additional spot welds and even a factory sticth weld at the wheel arch seam (mine has this) and yet separation was present. Bone stock street driven 2004.

The only way to permanently solve this is with a bolt through design that transfers all load to the actual frame, thereby virtually eliminating the RACP from the load equation entirely. A cross bar like we see here is identical to the Forbes design from a load stand point - all load is supported by a stiff cross member that ties into main frame rails. It is not necessary to replace the RACP if it no longer supports the load.

No?
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Old Sun, May-17-2015, 06:54:23 PM   #36
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Default Subframe: Front vs. Rear mount brace

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Originally Posted by mgp333 View Post










I agree with OP that this design is enough to keep rear nice and tight.



yeah, ok, you can still build it further and keep reiforncing more and more. But I think this is pretty sufficient. I had similar situation like OP in one of my project M3s and the brace across solved the problem. The rear end feels so much planted. No twisting, just feels solid. Ill be doing similar to my Resurrection M3 as well.





heres a pic

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Old Sun, May-17-2015, 11:17:31 PM   #37
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Default Re: Subframe: Front vs. Rear mount brace

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Originally Posted by eurosonic View Post
I agree with OP that this design is enough to keep rear nice and tight.



yeah, ok, you can still build it further and keep reiforncing more and more. But I think this is pretty sufficient. I had similar situation like OP in one of my project M3s and the brace across solved the problem. The rear end feels so much planted. No twisting, just feels solid. Ill be doing similar to my Resurrection M3 as well.





heres a pic

Hey that looks great! I'll probably weld the brace on both the frame rail and the strut tower, so I won't be able to conceal quite as much as you did. But you have pretty much the same thing I'm going for. Did you by chance do anything special for the front mounting points?
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Old Sun, May-17-2015, 11:23:31 PM   #38
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Default Re: Subframe: Front vs. Rear mount brace

Quote:
Originally Posted by VinceSE2 View Post
While I'm in the midst of this project and haven't installed the back seat yet, i see no reason there would be any space issues.
Basically all I have added is "behind" the sheet metal wall I removed.

The idea is to stabilize the threaded insert such that it does not break loose from the top mounting surface when the tilting/bending force is applied to it.
The bolt going thru the threaded sleeve, and the nut and washer on top is one part of the design. The pipe and its floor (which is welded against the top of the threaded sleeve is another. And finally the pipe itself is welded to the inner skin of the body adding more support against the tilting.
The pipe is a 2" exhaust pipe with 2mm thick walls.
The hole saw is 51 mm OD.

Hera are some more pics:
...
Very interesting what you are doing here. To be honest I don't quite understand all of it, but it does seem like will achieve your goal which is to lock down the effects of torsion and twisting. I wondered myself about how to reinforce against those types of forces - I think that with the bolt through design from the first brace I showed, I will try to make the radial gap between the bolt and cylinders as absolutely minimal as possible to fight against torsion. It won't be as robust as your setup, but I have a good feeling it will do the job.
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Discussing Subframe: Front vs. Rear mount brace in the E46 M3 (2001-2006) Forum - Engine: S54 - Max Hp: 333 hp at 7,900 rpm / 262 lb/ft at 4,900 rpm
Total Produced: 45,000+ - Years Produced: 2001 to 2006. at BMW M3 Forum.com (E30 M3 | E36 M3 | E46 M3 | E92 M3 | F80/X)