Something new from CMP Auto Engineering!

[AussieE46M3]

honest question here, what are the benefits of using these supports vs a 6 point brace that ties in the 4 subframe mounting points and rear shock towers? cheers.

In short, mostly practicality and a little bit load path related.

There's lots of brace options of varying magnitude and complexity however, the big difference is you can put the weld in kits in and retain a completely unobstructed boot space and have a comprehensively reinforced chassis. Compared to a brace, if you ever needed to remove the brace then you also removed the reinforcement for the RACP.

The one thing I feel braces lack is a secure link to the chassis rails. They're braced off one another and the strut towers however, there's still a less direct load path to the chassis rails. This is why there's a major design difference as that's resolved with the weld in kits so the braces are mostly for chassis rigidity/tower support while also supporting the subframe mounts in the process.

I suppose you'd also have to potentially do some work underneath and drill out the subframe bolt holes to put longer studs in for the braces. Unsure as I haven't installed one. The kits above require no attention under the car.

That was CMP’s original product. The benefit of the new stuff is less weight and a simpler design, as he wrote in the OP.

Not wrong, that however bolted down onto the previous weld in kits and not solely to the subframe mounts and towers like some on the market do now.

Would the revised product work on a cabrio?

Rear weld in beam only. Front kit wont as there's existing structure present and the rear towers are not accessible ruling out the rear brace.

Thanks for the reply. Ordered!

Thank you for your support and business!

Just to communicate as clearly as possible, the braces available for pre-order are raw and not powder coated. The rear brace is made from zinc coated steel so it doesn't need sand blasting before being coated. Front is aluminium so coating is optional.

[Kevin]

Thank you for continuing to support the E46 community. Cost/form factor aside, how do the new designs compare in terms of strength/protection to the old designs?

For someone who just wants the absolute strongest trunk containing setup (ie not a roll cage), will the older design with the square beam, FME and 6 point brace still be available?

[///m325i]

For someone who hasn't reinforced their subframe yet. What product selection would you recommend from CMP? I'm just a little confused with all the available products and what's needed.

I have reinforcement plates that I will be installing next year and wanted to order the necessary parts.

[AussieE46M3]

Thank you for continuing to support the E46 community. Cost/form factor aside, how do the new designs compare in terms of strength/protection to the old designs?

For someone who just wants the absolute strongest trunk containing setup (ie not a roll cage), will the older design with the square beam, FME and 6 point brace still be available?

It's my pleasure

Strength wise they are less as I mentioned earlier due to no foresight for what would later contribute however, just as well protected IMO as they're suitable for any reasonably built, street driven E46 M3 (turbo/SC etc). The brace that bolted onto the old weld in kits was comparable to some of standalone braces.

If you were wanting to build a competition car with a dramatically more powerful motor I'd be suggesting something more substantial such as a full roll cage that integrates the rear subframe mounts.

I am planning to keep them available. The weld it kits I will get low volume batches made and keep stock at customer request. The brace I am intending to make a freely available CAD file for anyone to have cut locally. Quite a few people purchased the weld in kits with the brace mounts included so I don't want to terminate them completely.

For someone who hasn't reinforced their subframe yet. What product selection would you recommend from CMP? I'm just a little confused with all the available products and what's needed.

I have reinforcement plates that I will be installing next year and wanted to order the necessary parts.

I hope you don't mind but the answer to your question is almost exactly something I wrote in response to an email recently that I've pasted below with some basic edits.

Because you've already purchased underside plates you can ignore that part. I've also made some suspension recommendations in the below.


Reinforcement Needs:

- Underside reinforcement plates - https://cmpautoengineering.com/colle...ment-plate-kit
-Rear mount weld in beam - https://cmpautoengineering.com/colle...r-weld-in-beam
-Front mount weld in beam - https://cmpautoengineering.com/colle...t-weld-in-beam

The underside plates work to reinforce the sheet metal that has been fatigued and likely torn apart.
The rear beam closes the gap between the frame rail and RACP which is to blame for the boot floor separating itself from the frame rails. This will prevent that from ever happening and improve chassis rigidity.
The front weld in beam prevents the sheet metal under the rear seat from cracking & tearing spot welds as well as reinforces the top welds on the female body the studs screw into that are prone to cracking and further support the subframe mounts.
The combination of the above is a comprehensive top to bottom reinforcement on all four rear subframe mounts.

Reinforcement Optional:

-Front Bolt in Brace - https://cmpautoengineering.com/colle...-bolt-in-brace
-Rear Bolt in Brace - https://cmpautoengineering.com/colle...-bolt-in-brace

The front brace does wonders to increase torsional rigidity and further support the front two rear subframe mounts and only weighs 1.6kg. It also sits flush against the rear seats in their upright position so there’s no loss of boot space. It just makes the folding rear seat function less useful as it occupies the bottom half of the gap.
The rear brace links the rear strut towers with the rear subframe mounts to further support the mounts and brace the towers if you drive aggressively or run true coil over rear suspension. This one is less suggested that the front as it comes with a greater weight penalty and does occupy space within the boot although, with a large opening in the centre.

Suspension Needs:
I’d suggest replacing anything in the suspension that is hard to get to.
e.g.
-Subframe bushings
-Diff bushing
-Upper camber arm inner rubber bush

Suspension Optional:
if the car has done 150k+ km (93k miles) you’re likely in need of a full restoration with:
-Adjustable camber arms
-RTA ball joints
-RTA bush
-Rear wheel bearings
-Rear sway bar end links
-Rear sway bar bushings
-Centre support bearing
-Prop donut

The ideal suspension setup for the chassis is essentially our E46 Suspension bundle paired with stock M3 everywhere else.

https://cmpautoengineering.com/colle...pension-bundle

I've spent years comparing all sorts of combinations and this is peak performance with negligible NVH.

[YoitsTmac]

Compared to a certain bar in the same space...this was a no brainer. Instant purchase. I wish I knew about this earlier and I can't wait to do a video on this kit. I can't wait to see your future developments.

[simonnim]

Maybe I'm not understanding the kit. Does the rear and front weld in need to cut some of the floor out to fit these in? Is there a guide on how these should be installed?

[Nate047]

I feel like if you made a nice video showing the installation process, start to finish, it would be well worth your while. I think I personally have a pretty good understanding of what the process is, but a lot of people are visual and kind of need a video instead of reading a wall of text. A project like this is not exactly a small undertaking so people are for sure going to overthink this, again and again, before deciding what route to take.

FWIW I plan on getting a setup from you within the next few months, looks like a great product and you clearly have a ton of knowledge and great reputation. I am building a split duty track and street car and I believe the front and rear weld in beams are for me, and honestly probably both the rear and front bolt in braces would be good for me, in the interest of rigidity, unless you really don't thin it necessary. My car already has underside plates installed by a previous owner, I would love to just leave those alone for now and add additional top side reinforcements. Would love to hear your thoughts on that though. I plan on running KW Clubsports and 200tw or R comp tires.

[AussieE46M3]

Hi Guys,

Little update, stock has arrived and I have spent the last two days prepping everything (pressing in threads, welding brace parts etc) and should be sending out some pre-orders today.

I'm also getting a price on having the small tube in the rear beam laser cut for greater precision rather than band saw cut like I am now.

There has been a small error on behalf of my contracted laser cutter where they've folded the rear brace tower mounts incorrectly and are being re-made. ETA for them is Monday next week (3 business days). As a result, anyone who ordered the rear bolt in brace will have their ordered dispatched likely mid next week.

Compared to a certain bar in the same space...this was a no brainer. Instant purchase. I wish I knew about this earlier and I can't wait to do a video on this kit. I can't wait to see your future developments.

I'm glad to hear it won you over! I'm very excited to see the video. Please share it when you're done!

I've got a few more ideas for the chassis I'll share when they're close!

Maybe I'm not understanding the kit. Does the rear and front weld in need to cut some of the floor out to fit these in? Is there a guide on how these should be installed?

Yes, small access ports on the front mounts and the spare wheel well covering the rear of the RACP needs cutting out. The kits replace the sections of sheet metal that are removed.

Yes, all kits will come with comprehensive instructions.

I feel like if you made a nice video showing the installation process, start to finish, it would be well worth your while. I think I personally have a pretty good understanding of what the process is, but a lot of people are visual and kind of need a video instead of reading a wall of text. A project like this is not exactly a small undertaking so people are for sure going to overthink this, again and again, before deciding what route to take.

FWIW I plan on getting a setup from you within the next few months, looks like a great product and you clearly have a ton of knowledge and great reputation. I am building a split duty track and street car and I believe the front and rear weld in beams are for me, and honestly probably both the rear and front bolt in braces would be good for me, in the interest of rigidity, unless you really don't thin it necessary. My car already has underside plates installed by a previous owner, I would love to just leave those alone for now and add additional top side reinforcements. Would love to hear your thoughts on that though. I plan on running KW Clubsports and 200tw or R comp tires.

I 100% agree. I'm currently in the middle of a big transition relocating my business and living situation and will be turning much of my focus to social media content covering exactly that kind of work in the near future. THe short youtube series I did on the underside was very helpful to a lot of people so I'm certain a similar production on topside reinforcements will be equally as popular.

Thank you. I look forward to doing business with you!

I wouldn't recommend trying to change the underside reinforcement you currently have installed however, I would suggest getting it looked at to confirm it was done correctly and that no secondary failure has happened since they were installed.

If it helps I wrote an article on where to look.

https://cmpautoengineering.com/pages...ubframe-mounts

You're absolutely right. That will give you a very comprehensive reinforcement on all four mounts. If you wanted to keep weight down you could opt for just the front mount brace with both weld in kits however, more than welcome to purchase the rear brace as well.

Sounds like a great choice for tyre & spring/shocks. You should have enough grip to put the car to work.

If you haven't already upgraded the rear suspension I offer a bundle package that replaces everything worth upgrading in the back end. https://cmpautoengineering.com/collections/bmw-e46/products/e46-suspension-bundle

Thanks for your support guys and I'll keep checking in with more information.

[Nate047]

Awesome, thank you. Would you mind giving me a quick run down on why you would recommend the front mount brace, instead of the rear mount (or both?)

[E46ERIC]

It's my pleasure

Strength wise they are less as I mentioned earlier due to no foresight for what would later contribute however, just as well protected IMO as they're suitable for any reasonably built, street driven E46 M3 (turbo/SC etc). The brace that bolted onto the old weld in kits was comparable to some of standalone braces.

If you were wanting to build a competition car with a dramatically more powerful motor I'd be suggesting something more substantial such as a full roll cage that integrates the rear subframe mounts.

I am planning to keep them available. The weld it kits I will get low volume batches made and keep stock at customer request. The brace I am intending to make a freely available CAD file for anyone to have cut locally. Quite a few people purchased the weld in kits with the brace mounts included so I don't want to terminate them completely.




I hope you don't mind but the answer to your question is almost exactly something I wrote in response to an email recently that I've pasted below with some basic edits.

Because you've already purchased underside plates you can ignore that part. I've also made some suspension recommendations in the below.


Reinforcement Needs:

- Underside reinforcement plates - https://cmpautoengineering.com/colle...ment-plate-kit
-Rear mount weld in beam - https://cmpautoengineering.com/colle...r-weld-in-beam
-Front mount weld in beam - https://cmpautoengineering.com/colle...t-weld-in-beam

The underside plates work to reinforce the sheet metal that has been fatigued and likely torn apart.
The rear beam closes the gap between the frame rail and RACP which is to blame for the boot floor separating itself from the frame rails. This will prevent that from ever happening and improve chassis rigidity.
The front weld in beam prevents the sheet metal under the rear seat from cracking & tearing spot welds as well as reinforces the top welds on the female body the studs screw into that are prone to cracking and further support the subframe mounts.
The combination of the above is a comprehensive top to bottom reinforcement on all four rear subframe mounts.

Reinforcement Optional:

-Front Bolt in Brace - https://cmpautoengineering.com/colle...-bolt-in-brace
-Rear Bolt in Brace - https://cmpautoengineering.com/colle...-bolt-in-brace

The front brace does wonders to increase torsional rigidity and further support the front two rear subframe mounts and only weighs 1.6kg. It also sits flush against the rear seats in their upright position so there’s no loss of boot space. It just makes the folding rear seat function less useful as it occupies the bottom half of the gap.
The rear brace links the rear strut towers with the rear subframe mounts to further support the mounts and brace the towers if you drive aggressively or run true coil over rear suspension. This one is less suggested that the front as it comes with a greater weight penalty and does occupy space within the boot although, with a large opening in the centre.

Suspension Needs:
I’d suggest replacing anything in the suspension that is hard to get to.
e.g.
-Subframe bushings
-Diff bushing
-Upper camber arm inner rubber bush

Suspension Optional:
if the car has done 150k+ km (93k miles) you’re likely in need of a full restoration with:
-Adjustable camber arms
-RTA ball joints
-RTA bush
-Rear wheel bearings
-Rear sway bar end links
-Rear sway bar bushings
-Centre support bearing
-Prop donut

The ideal suspension setup for the chassis is essentially our E46 Suspension bundle paired with stock M3 everywhere else.

https://cmpautoengineering.com/colle...pension-bundle

I've spent years comparing all sorts of combinations and this is peak performance with negligible NVH.

Sorry for my own lack of understanding. I end up getting reddish motorsport under side plates which I have not installed yet but base on the updated parts can I just purchase the front and rear weld beams without needing the stage 1.5 plates? I don't track and abuse the car too much or have any crazy power. I also really don't want to add braces since I do use my trunk at times and it can get limited already lol

[AussieE46M3]

Sorry for my own lack of understanding. I end up getting reddish motorsport under side plates which I have not installed yet but base on the updated parts can I just purchase the front and rear weld beams without needing the stage 1.5 plates? I don't track and abuse the car too much or have any crazy power. I also really don't want to add braces since I do use my trunk at times and it can get limited already lol

Hi E46 Eric,

The chassis rail plates are actually included in the rear weld in beam so yes, you can buy just the front and rear weld in beams and pair it with the underside plates you have and will have a comprehensive fix.

That sounds like the perfect combination based on your needs. If you want to upgrade the suspension in anyway while you're in there and have questions about that let me know. Happy to help!

The reason the chassis rail plates are available separately are for those on a tighter budget and don't want to overcapitalise on a Non-M chassis but still close the gap between the chassis rails and RACP.


All the pre-orders were sent out a little while ago so if anyone who ordered a set would like to share their finished install, please do!

I'm excited to see and hear what you think.

[AussieE46M3]

Awesome, thank you. Would you mind giving me a quick run down on why you would recommend the front mount brace, instead of the rear mount (or both?)

Sorry mate, didn't see this comment till now.

Front brace doesn't take up boot space, is lighter & cheaper.

Both braces do a lot to increase torsional rigidity so if you're wanting to maintain the full boot space it's the one I'd suggest to get started. I feel it comes with less compromise and helps make the old chassis feel as tight as something modern.

I recently replaced my prototype rear brace with a production version of the rear brace and was blown away by how much of a difference it made even with the front brace already installed (I'm running true coils with solid bushings throughout as well) so from my personal experience, if you want to go all out it's not a case of one or the other, I'd do both.

For those who opted for the full package, I think it will blow your mind on how tight it feels. I'm really looking forward to feedback!

[mrgizmo04]

AussieE46M3 Hi Cayn, long time no chat, buddy. Great to see new developments.

Could you touch on backward compatibility of the new bolt in front brace and rear brace for those who have the original welded beam and extension kit?

Seems like by drilling a few holes in the original front beam would adapt to make the new front brace work? The contour might be slightly different, but there should be enough bending to make it lie flush?

What about the new rear brace with the original rear beam? that is just a weld job and then bolt it in to shock towers? Or is the thickness/height of the beams too different to make it work?

Sent from my SM-G950U using Tapatalk

[Cronenberged]

I'm not an engineer, nor do I fully understand torsional rigidity, but why does the front mount only use half rear seat from and not extend all the way across i.e., like the Slonik CF one. I know you're products are different, but serving similar purposes. Appreciate all the feedback and answer to responses you've already provided.

[AussieE46M3]

AussieE46M3 Hi Cayn, long time no chat, buddy. Great to see new developments.

Could you touch on backward compatibility of the new bolt in front brace and rear brace for those who have the original welded beam and extension kit?

Seems like by drilling a few holes in the original front beam would adapt to make the new front brace work? The contour might be slightly different, but there should be enough bending to make it lie flush?

What about the new rear brace with the original rear beam? that is just a weld job and then bolt it in to shock towers? Or is the thickness/height of the beams too different to make it work?

Sent from my SM-G950U using Tapatalk

Thanks Gizmo!

The mounting location of the rear brace has been moved down and back 50mm so I can't imagine there's any simple way of making the rear brace work without cutting it up quite significantly.

The front brace may be able to fit with the old stage 2.5 kit in place as they were based on the same contours however, where the front brace bolts to the front subframe mounts would be an opening for a hollow tube and thus, nothing to bolt to nor a flat surface of sheet metal a blind fastener (rivnuts) could be added to mount the brace.

I can't imagine a scenario where the new braces could be added to the old kits without somewhat compromising their function due to the substantial amount of cutting that would occur. It could be done as a one off but, ultra-low volume production is not cheap.

I do not have stock of the old race brace however, was intending to offer all the parts as a virtual file so they could be tube notched locally rather than here & shipped for customers with the previous generation of topside reinforcements.

I'm not an engineer, nor do I fully understand torsional rigidity, but why does the front mount only use half rear seat from and not extend all the way across i.e., like the Slonik CF one. I know you're products are different, but serving similar purposes. Appreciate all the feedback and answer to responses you've already provided.

Hey mate,

totally reasonable question that has two reasons.

The simple one is packaging. If it was made the full height the cubic volume would be greater than most carriers allow and would come at an exorbitant cost to have it shipped making it a far less cost effective solution. The brace as it is fits within the allowable dimensions by 10mm (0.4") before packaging so it's right on the limit.

The other is also function. The reason it doesn't go all the way to the top is because (it's assumed as no simulations were done due to a lack of complete chassis model) going higher would come with diminishing returns and additional weight. Where it does mount is as direct to point loads in the area as possible while there are no loads applied directly to the rear bulkhead.

The front two subframe mounts experience the driveline forces while the sides of the bulk head experience the force of the shock's/spring pushing up on either side as they're mounted to the chassis rails and strut towers.
Due to the movement that occurs during torsional deformation, the brace supports those edges to resist them going up and down and braces them to the opposing side and floor linking the 4 point loads in that area.

All theory however, as a result should be as effective as possible for its size.