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BMW 3-Series (E90 E92) Forum > E90 / E92 / E93 3-series Technical Forums > Suspension | Brakes | Chassis > e93 M3 Rear Subframe Brace



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      06-17-2023, 10:21 PM   #67
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That was also what I was referring to? I don't have any interest in the e91 brace as it seems to be a simpler mount and possibly arguably less rigid; the e93 mount is what I am referring two

Either of which, no, I have not installed yet but will eventually. If a writeup doesn't exist by then, I'll draft one up
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      06-18-2023, 03:37 PM   #68
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Quote:
Originally Posted by GnomeChild View Post
That was also what I was referring to? I don't have any interest in the e91 brace as it seems to be a simpler mount and possibly arguably less rigid; the e93 mount is what I am referring two

Either of which, no, I have not installed yet but will eventually. If a writeup doesn't exist by then, I'll draft one up
I’m putting new rear arb bushes in soon I’ll take a look and see if there are provisions for the centre drop-down mount. It looks as though the brace that goes to the front of the subframe are different to the e92. They have holes in on e93 so both are joined in the middle. They are joined together in this photo.

This surely must be one of the best bracing options for the rear of bmw put on the e93 it must make an e92 chassis stiffer to.
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      06-18-2023, 03:45 PM   #69
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While doing an image search I’ve realized the e93 rearunserbody brace won’t work.
Non m3 cars have the plastic spare wheel/underfloor storage in the boot which would get in the way of the hanger bracket.
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      06-19-2023, 09:31 AM   #70
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I bet the e91 part would fit the chassis, and probably the bracing too. 51717160377
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      06-20-2023, 05:30 PM   #71
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Originally Posted by Tambohamilton View Post
I bet the e91 part would fit the chassis, and probably the bracing too. 51717160377
Now we’re back on to something. I cannot find the part sale used. £98 from bmw!

I will keep look out for parts.
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      06-22-2023, 06:24 PM   #72
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Quote:
Originally Posted by Simbl View Post
While doing an image search I’ve realized the e93 rearunserbody brace won’t work.
Non m3 cars have the plastic spare wheel/underfloor storage in the boot which would get in the way of the hanger bracket.
I wouldn't be so sure. There are members than have claimed to have done the e93 brace and currently run it in their builds. That and the fact that no matter how deep that tray goes, you still have the heat shielding and exhaust mufflers back there. The main K brace is meant to attach to the bottom of the exhaust provision area and right between the two mufflers on a stock system; almost guaranteed completely away from the plastic bucket and surely in a space where metal is attached close to the frame to make the largest difference in torsion
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      07-02-2023, 05:11 AM   #73
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Originally Posted by GnomeChild View Post
I wouldn't be so sure. There are members than have claimed to have done the e93 brace and currently run it in their builds. That and the fact that no matter how deep that tray goes, you still have the heat shielding and exhaust mufflers back there. The main K brace is meant to attach to the bottom of the exhaust provision area and right between the two mufflers on a stock system; almost guaranteed completely away from the plastic bucket and surely in a space where metal is attached close to the frame to make the largest difference in torsion
That’s a good point I might have to reconsider then. I have a 330 so the plastic trunk storage is a lot bigger than the 335i or m3 as I only have one muffler. But it makes sense that it would mount to the body.

What I have found is that the e91 version has different mount point for the braces to attach to the drop down bracket. I think it would be cheaper to get a e91 brace setup and I suspect will offer almost the same it terms of stiffening.
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      07-02-2023, 05:17 AM   #74
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I have been looking at the non m e93 front bracing which looks promising and have ordered the parts. It comprises on a lower front sub frame v braces which are larger than the e92 standard brace. It also has 2 diagonal braces that go from the top of the wheel well in the engine bay down to a centre point of the lower subframe. This is the same bracing used in e88. I think I will need the e93 undertray but we’ll see. Have order bolts yet.
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      07-02-2023, 06:38 AM   #75
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Suggest you visit Biginboca's build thread for more info on bracing:

https://www.e90post.com/forums/showthread.php?t=1579797
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      07-03-2023, 12:32 PM   #76
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I just can’t see how the drop down bracket from the m3 would fit with underfloor boot storage of anything without dual mufflers. The bracket extenders to behind the the underfloor storage tray. I think the only option for me is e91 bracing. But if you have a 335i on e92 m3 is should work fine. Unless I change the underfloor to something else.

There’s a photo e93 m3 underneath and a paused video clip from my health check video of my 330i.
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      07-03-2023, 01:02 PM   #77
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Quote:
Originally Posted by Phil325i View Post
Suggest you visit Biginboca's build thread for more info on bracing:

https://www.e90post.com/forums/showthread.php?t=1579797
Yeah I have read it, not really sure the point in some of his bracing mods. The rear brace is pointless due to the parcel shelf, there’s not evidence that suggest the behind the seat m3 brackets do anything. Then he chops in half the structural undertray from the m3, the part he chops of is what ties it to the body so it’s only bracing the subframe itself so it’s no longer structural. The front e93 underbracing is far better and also braces from the top of the shock towers down to the lower subframe. It’s braces further down the body than subframe itself.
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      07-03-2023, 02:50 PM   #78
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Then he chops in half the structural undertray from the m3, the part he chops of is what ties it to the body so it’s only bracing the subframe itself so it’s no longer structural.
Never mind...
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      07-11-2023, 08:59 PM   #79
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It is too bad the M3 plate likely loses it's transversal rigidity when modified to fit the non-M subframe. Someone in Russia used to sell a nice transverse brace on ebay that tied into the stock V brace but it's not available anymore because reasons...

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      07-12-2023, 05:12 AM   #80
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When modified to fit a non-M car, the M brace's main function is to stiffen the front subframe itself, not it's connection to the body which is already handled by the stock V brace.
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      07-12-2023, 06:17 PM   #81
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Anyone had experience doing this yet? Have an Xdrive, rear should be the same, seen people do the left/right braces with good results. Curious on the process.
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      07-18-2023, 12:56 PM   #82
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It is too bad the M3 plate likely loses it's transversal rigidity when modified to fit the non-M subframe. Someone in Russia used to sell a nice transverse brace on ebay that tied into the stock V brace but it's not available anymore because reasons...

It’s available on Ali express from China
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      07-18-2023, 01:14 PM   #83
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Quote:
Originally Posted by Tambohamilton View Post
When modified to fit a non-M car, the M brace's main function is to stiffen the front subframe itself, not it's connection to the body which is already handled by the stock V brace.
Doesn’t really make sense though any bracing should strengthen both the subframe and its connection to the body. The more rigid the connection to the body the more the car as a whole will be rigid. People just putting it on because it’s an m3 part when in reality some sheet aluminum with dimples in would do the same job. Lucky for us bmw made a whole set of bracing specifically to stiffen the chassis for the e93 non m and e93 m3 including both sets of bracing are the same. It also ties in the front strut tops into the front of the subframe and extends all the way to the side sills underneath. I really cannot understand the obsession with the belly pan especially when it gets cut in half.

The stock brace only ties the rear of the subframe in and doesn’t extend to the sills.
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      07-18-2023, 05:31 PM   #84
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Yeah, alu sheet would do the job, but the m3 part is pretty cheap, has holes where you need most of them already and doesn't take a huge deal of chopping to fit. It makes perfect sense.
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      07-19-2023, 03:44 PM   #85
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The M3 subframe plate doesn't mount to the body though. However, the M3 subframe is different in that it has "extensions" with additional mounting points to the body.



M3


Non-M


I think one of the benefits of the M3 plate is the transverse bracing between the rear of the subframe, which is lost when modified to fit the non-M subframe.

BMW also calls these "thrust plates" implying that they brace longitudinal movements as well, so there is still something to gain. I slapped two bars on where the M3 plate mounts and they made a significant difference

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      07-20-2023, 10:19 AM   #86
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You noticed a significant difference when driving the car aggressively?

I noticed the bars are hollow. Wouldn't a solid bar resist flex better?

Did you tap the holes or are there already threaded holes you install the bolts into? It's been forever since I was under my car.
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      07-20-2023, 11:00 AM   #87
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Bolts go into M10 nutserts.

Not sure the rigidity increase from tube to solid would help much in this case, except allowing the bolts to be torqued better.
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      07-20-2023, 11:38 AM   #88
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Quote:
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Bolts go into M10 nutserts.

Not sure the rigidity increase from tube to solid would help much in this case, except allowing the bolts to be torqued better.
You can see the tube deformed when you tightened it. I would assume a solid aluminum bar would have greater rigidity than hollow and add minimal weight. Then again I am not a mechanical engineer.

I am honestly surprised you noticed such a difference from the mod. Could you go into any more detail?

Any chance you know the exact length the bars need to be? Length of bolts? I have to crawl under my car and run some fuel lines and I could easily take a trip to the Depot and do this while in there.


If this really makes such a drastic difference someone could have a bunch of bar stock cut, drilled, powder coated, and sell it as a mod. Call it the Hamilton bars

Last edited by Torgus; 07-20-2023 at 12:21 PM..
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