Following on from the FOR SALE thread showing the brief description of our Redish-Motorsport-E46-Rear-Subframe-Reinforcement-Plate-Kit, this thread is for the background, development history, technical info, and more pictures. Development History: Redish Motorsport have been repairing and reinforcing BMW floor's for year now. It started with the E36 where we completely rebuilt the OSF rear subframe threaded mount after it was quite literally torn out of the floor pan on a 1992 325i. Since then we've been mainly repairing & reinforcing E46 M3's (although we still get E36 non M3's requiring the E36 OEM plates). One day we were faced with repairing this 2001 M3 manual coupe with 72,000 miles Up until then we were using reinforcement plates from the USA (like everyone else had to). As you can see they didn't cover the damage on this M3: Nor did the NSR plate cover the hairline crack on this car (outlined in red): (Just for the record, we fully support the BMW goodwill offer of a replacement floor panel. We've helped 7 of our customers obtain this good will repair via our relationship with a BMW dealer. If you qualify for a replacement floor from BMW under the good will offer then go for it. It's a great repair. However, if you're unlucky enough to be over the 10-year build date anniversary, or be turned down, then our Repair & Reinforcement service is the next best option). So we set about designing and producing our own reinforcement plate kit for cars like this one with moderate damage/cracking. We purchased a brand new floor panel from BMW (Rear Axle Carrier Panel) and carried out drawings, templates, CAD models, laser cut prototype plates, stress analysis, engineering consultancy, and 3 incarnations spanned several months work to perfect these plates. Product testing started in house with the introduction of our plate kit to our popular Repair & Reinforcement Service - featured in this month's Performance BMW Magazine (May 2013 issue). We then selected 2 close and trusted workshops to test our kit and give us some 'outside' feedback. Needless to say, they were greatly surprised with our accuracy achieved not only in the line up of all holes for stud mounting and plug welding but also the folding process. Since then they've been sold to members of the public in the UK & Ireland and again customer feedback has been 100%. Every kit is precision folded in house by James @ Redish Motorsport using industrial folding equipment and digital protractors. A perfect hole line up and plate fit is achieved every time and James personally checks each and every plate fits our master jig set before they are used in the workshop or sent out to a customer. The kit consists of 8 individual plates, part numbered and tailored to specific locations on the E46’s chassis: RMS-E46-sub-001 – QTY.1 – Located at the NSR Differential carrier mounting location. This is the most problematic location and the area where most cracks and even material separation is found. RMS-E46-sub-002 – QTY.1. – Designed specifically to follow the contours of the OSR subframe Differential carrier location face/area. RMS-E46-sub-003 – QTY.1. – For use at the OSF Differential carrier location face/area. This is the other major problem area on the sub-frame and where cracking is again most common. This plate has been design to dramatically strengthen the OSF location face, spreading the torque loading and unloading over a far greater area, of a stronger material to the original subframe. RMS-E46-sub-004 – QTY.1. – Tailored to fit the NSF Differential Carrier location face/area. RMS-E46-sub-005 – Qty.2 included in the kit but is fitted optionally, they allow the boot floor to be cut from inside the vehicle to gain access to the internal bracing of the subframe to allow rosette welding of the internal features, these plates are used to cap the holes cut in the boot floor. RMS-E46-sub-006 – Qty.2 plates, spacer plates to accommodate the change in the floor thickness, they ensure seamless fitment of the Differential Carrier. Technical info: The plates are manufactured from 2mm thick automotive grade mild steel, or CR4 as it is professionally known, this is a low carbon steel ranging from 0.05% to 0.26% carbon, which is classified by British Standard BS 1449 and has a Tensile Strength of 270/410 N/MM² Min and a Yield Stress of 280 N/MM2, which makes it significantly stronger than the OEM Subframe material. Our kit is significantly larger than any other available kit which helps dissipate the torsional loading and unloading into the subframe over a greater area, eliminating the risk of cracking/failure. This also helps repair the floor either side of a crack and spreads the unloading or pulling force in a downwards motion. Our kits are laser cut to ensure each kit is perfect for its required application. The plates are then folded individually at Redish Motorsport HQ to the correct angles and checked on the template floor before being carefully packaged for dispatch or stored for fitment in our workshop. In 2012 we repaired 13 E46 M3’s suffering from cracked floors, in 2013 we anticipate this number to grow rapidly as increasing numbers of vehicles fall out of the grace period offered by BMW. We believe the only satisfactory method for installation of this kit is welding. Whilst a competent welder should be able to fit this kit, the removal of the rear axle assembly and fuel tank is required and so we would recommend only qualified professionals attempt installation. It has been suggested that it should be possible to attach the plates via the use of adhesive resins but this is not validated by Redish Motorsport and as such is not a service we offer. A structural foam reinforcement service (as per BMW guidelines) is being worked on and tested at the moment. This additional service will be available shortly. Keep an eye out for the announcement. Thanks for reading, Redish Motorsport.