E46 M3 Subframe Reinforcement Kits

Tap right for info.

Staged Solutions.

These kits enable you to plan according to your use.

Top and bottom.

Plates aren't enough. Top side reinforcement is required to prevent long term catastrophic failure.

Front and rear.

A rear bar is not enough and does not address the weakest section of the chassis: the front upper subframe mounts.

Weld-in installation.

It's the ideal time to restore your underbody.

Get your kit

Subframe Reinforcement Kits

Made in Australia

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Specifications:

Made in Australia
Laser cut & sheet metal fabrication

2mm 250MPa yield zinc coated mild steel (zincanneal)
Rear beam has a roll cage tube with 1.5" OD, 1/10" wall 350MPa yield steel - (~1" long)

Professional welded installation
Prevents catastrophic failure of Rear Axle Carrier Panel (RACP)

Stealth Kit:

Bottom Reinforcement Plates
Chassis Rail Plates
Front & Rear RACP Beams

Stealth Plus Kit:

Bottom Reinforcement Plates
Chassis Rail Plates
Front & Rear RACP Beams
Front Bolt-in RACP Brace

Track Kit:

Bottom Reinforcement Plates
Chassis Rail Plates
Front & Rear RACP Beams
Front & Rear Bolt-in RACP Braces

Plate Kit:

Bottom Reinforcement Plates
Chassis Rail Plates

Beam Kits:

Chassis Rail Plates
Front & Rear RACP Beams

Build journal: Special Series

BMW M got sued over this.

Thanks to bright engineering minds, the technical understanding of the E46 M3's rear chassis weaknesses have evolved.

A comprehensive top and bottom, front and rear solution is recommended if you intend to keep your E46 M3 forever.

In this Special Series, I document my experiences on the Phoenix's restoration: the theory, the practice, the comprehensive solutions I reviewed, and the one I chose.

Enjoy,
- Matt / @m3_epoustouflant

Read the Special Series

If you want more [...]

level up to stage 3!

CMP offers bolt-in front and rear braces upgrades to further transfer loads across the chassis.

For street use, the front brace is an interesting "why not!".

It fits with the rear seats, still allows pass through, and does not compromise rear trunk space.

Need help?
Been there, done that.

Slide in my DMs

Cayn @ CMP Engineering

The most efficient solution is often the most simple.

That's Cayn's moto.

The company began in late 2016 to answer the growing problem of E46 BMW RACP/subframe cracks and failures.

After discovering significant cracks in his low mileage E46 M3, he put his engineering abilities to the test and began developing what is now a comprehensive range of CMP reinforcement products for E46 BMW’s, new products for the M3 V8 and other M chassis.