Thought I’d post up a few pics of a seat rail install I’ve just completed. It’s in a Mk1, but the ideas / process is transferable to other cars. I have to say that this job is easy to underestimate – it looks simple, but get it wrong, and you know about it, every time you sit in the car. Aside from welding in a cage, or fabbing up turbo pipework, downpipes etc, to do this properly is a tricky fabrication job. So I thought it would be worth sharing… Please do not follow this approach if you are preparing a car for the Mk2 Golf GTI Championship - please see the the regulations concerning shell modifications first. Firstly, get rid of bits not needed: Original seat rails have gone before this pic – 6 or so spot welds per side (visible on inspection), plus 4 Mig’d bits, top & bottom, at each end. Takes a while to get these out as it is, and patience is needed to avoid angle grinding through the floor! Front seat support won’t be needed either – buzz off the spot welds (the indentations where can be seen), angle grind and power-file the Mig’d sections against the sill. Power file off the spot weld heads also, and use a heat gun and solvent to remove the factory wax where it sat. Tidy and hammer back the double skin where the support passes through the tunnel (shown afterwards): Then get the seat plus seat brackets into the car on two blocks of wood, the same height as you expect to have the seat…. And sit there a lot. Ponder, ponder, ponder where the seat will be best placed, to keep the seat shoulder wings off a roll cage (if installed), occupant’s heads off the roof etc etc. Time well spent. Mark roughly where you want the seat to go, and note where things could get tricky. Decide at this point where the seat belt eyes will go also. Seat rail end supports need making up next – I used 1.4mm steel plate. Nibbler used to cut it out of the steel plate, and bench grinder to neaten up. Next make up the seat rails. I used 38.1mm CDS tube in 3mm thickness from Merlin Motorsport – though you should be able to use less thickness than that. Use dummy wood, or cardboard tube ideally to mock up a pair, since the ends will need profiling to suit the contours of the inner sill / tunnel. With the end plates sat loosely against the sills, there will be countless trips to and from the bench as you trim the tubes to suit the sill profiles. And I mean countless. My goal was to get this passenger seat pictured as far back and as far down as possible, and profiling the tube ends takes an age, since the sills are all curves. Next up, make the seat fixing tabs. Custom Cages use threaded steel inserts, TIG welded through the seat rails – but you could get away with bolts welded to the underside of the tube – but don’t strip ‘em! MIG tends to be tricky, ruining threads with too much heat if not careful. I went for the seat tag option – happened upon some 2.5mm thick box section which was just the job, and saves using a sheet metal bender or vice hammering: Grab a hole cutter and things start to take shape: Trial fit – yep, job done: Three more to make. I used wide box section, since this allows the fitment of various width seats – just in case etc. The seat needed to be 100% square in the car, so time to cable tie everything up, put the seat in, and shuffle about again for a test fit. Try to decide when the pressure of your shoulders on the seat shoulder wings is equal when looking straight out of the windscreen. The great thing about having the seat, the brackets, and the rails all connected is that it becomes it’s own jig, squaring everything up, so make sure it’s tight, pre seat rail position decision. Time very well spent again. Once decided, tack in back plates, and tack the tags onto the seat rails, but leave the rails unconnected. Haul the seat, brackets and rails out, and seam the backplates in: Then grab the seat again, still connected to the rails and tags, and place in the car. Check that the end plates haven’t warped with the heat and still allow the seat to sit where you had it before. Tack the tubes in, seat out, brackets off, and seam the tubes in. Where the tags are close to the tunnel, I had to remove them again to weld in the rail – the benefits of just a couple of tacks meaning they can easily be removed, but with the important trace of where they need to be put back on. Finally seam the tags on. All in: Then clean up with a wire brush.... Painted (Upol etch primer on the welds, from Halfrauds, plus top coat): Sorted Final job was to etch primer and underseal the underside of the car where the paint had burnt off from the back plate install. Seat rails can be a lot easier to install if you don’t remove the original rails, use square section rail tube and just drill them straight through…. It’s all a case of what finish you’re after though.