I have spent a lot of time trying to get Recaro seats fitted with 6 point full harness seatbelt from the main motor sports companies without any success, I come to the conclusion I was better off going to Halfords.
Instead I designed a base plate which links up with the chasis hole centres and with Recaro seat centres. This sounds simple, it took 2 days drawing time and a couple of days to manufacture, but they fitted first time with no problems. It took approximately 1.5 hours a seat to fit.
Within the design I wanted standard seatbelts to operate to M.O.T standards and also the 6 point harness to bolt in without cannibalising the car.
As you can see from the photos the crutch strap bolts directly to the base plate and the locating eyelet bolts are behind the drivers position then the chair is bolted onto the frame, this is as near as I could get without bolting into the existing chassis. The waist straps use similar points as the original seat belts and the shoulder straps are attached to the bolting points to the rear seat belt mounts, ( you will have to take out the childs car seat fixing brackets) all fixing bolts were the same or larger size than existing 3 point harness as approved by BMW®
The seat is still adjustable forwards and backwards but does not tilt so is a bit difficult getting into the back, the position is approximately 20mm lower than the standard CSL seat which gives more head room.
The seats are fantastic on the track but not so comfortable on the road but well worth doing.
Thanks TANKSLAPPER for your post. I was considering 4pt harnesses (so no complications and able to also use OEM belts for road as i use daily), Pole seats with thorney rear strut brace and harness bar, so can be folded up and put away.
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