E21: Custom Seat-Base vs. Planted Adapter

Had a go at fitting the passenger Recaro seat, this time using the Ford sub-frame and slider instead of the BMW one. The driver's seat I did last year has sunk into the BMW slider and won't adjust anymore, not to mention the seat is too high. OK, I've got used to it and it's holding for now, but bolting things on top of the E21 slider/base plain doesn't work, is ugly and will need improving before the MOT. Using box-section etc. that won't sag down is out too - my head would be pressed against the roof.

For this side I chopped the left side of the Ford subframe so it would fit on the floor against the original outer seat-mount. This mount is an over an inch higher than the inner mount next to the trans. tunnel and this just adds to the problem, as the mounts are too wide apart for most seats anyway, so simply raising one side is no good, you need cross-bars. Cutting the Ford sub-frame and bolting it through the floor-pan on the outer side is the only way I could see keeping this mount, so stock seats could be later refitted, and without it all being set too high. The inner mount is just the right height, so I reused the bolt-holes to mount a piece of angle-steel, which the seat then bolts on to about half an inch further out. To bolt on to the angle-steel, the base-mounts had to be ground and chiselled off to leave just the sliders on the right side, which was a right pain. The placement of the seat was now perfect, but the funny shape of the E21s belly-pan, bespoke Ford mounts and custom-made risers did not make for the strongest design. The seat felt solid to sit in, but once I'd moved it back and forth a few times I felt the left side mounts twist and the sliders jammed. You could now feel it moving around a bit, so without a safety pass this is another fail.

It seems that there is just no way to keep the stock mounts and be seated nicely, unless you have better tools and materials than us and can fabricate a very flat, snug fitting adapter plate, with feet on one side and a seatbelt bracket. Believe it or not, they exist, made by a company called Planted in the US, available from a few sites over there [http://www.stableenergies.com/Planted/products/393/] and eBay [http://www.ebay.co.uk/itm/Passenger-Seat-Bracket-for-MOMO-NRG-SPARCO-RECARO-BRIDE-BMW-E21-Series-1975-1979-/120994172571?pt=Motors_Car_Truck_Parts_Accessories&hash=item1c2bd08e9b], though pricey at £150, each!

They're very nicely finished in 3/16" thick steel, bolt straight into the existing mounts and have a series of oblong holes to drop most types of sport seat onto, Sparco, Bride, MOMO, NRG, Recaro are menioned, though you don't get sliders. I've seen one with sliders made by Corbeau [http://www.harrisonmotorsports.com/corbeau-seat-brackets.html] available through Demon Tweeks, again £150 and will likely need adapting to fit non-Corbeau seats. I've been weighing up buying these for the best part of a year, so to weigh up the pros and cons they're an easy straight fit and let you keep the stock base-mounts, but with sliders on top the seat still sits too high and the crazy £300 cost for the pair is getting into E21 Recaros territory, so really I think it's worth having one last go at a custom adapter.