[NZ_M3]

I voluntarily fitted the BMW official epoxy fix into my car - even though mine has no cracks - quite simply because if you've seen the way the rear floor is designed you will realise that having such a large void space in between the sheet metal that forms the rear floor exacerbates torque stress transfer - and overtime it will tear it out.

Personally I am not a fan of welding extra plates into the rear floor (rust proofing is a big issue as there are areas you simply can't get to) - I've seen failures even with the plates in place - this is because it is a band-aid fix versus a load transfer fix.

By filling the void within the floor space transfers the torque load to a much larger area and most importantly above the floor to the secondary sheet metal that forms the ridge carrier - further the epoxy used has a dampening effect as it is not completely solid. It is a proven product used in Formula 3 race car suspension repairs.

I also don't believe in having a larger subframe bushing footprint helps - as this is no different to having a larger washer in between the subrame and the floor.

The problem is more related to the floor having a void thus allowing it to flex more so than the foot print of the mounting.

I can tell you for a fact that having the epoxy in the floor makes a very noticeable difference to the rear floor rigidity - and that's in a car with KW race 2 ways and 14kg/mm springs. I am not the only CSL owner in NZ with this in the floor and all have noted how noticeably different the rear felt post the epoxy install.