NOTE:This method does not use the stock adjuster rails. The SCCA GCR's call for the seat to be mounted "solidly" and these are the most restrictive of the safety rules. Most tech inspectors will shake the seat and if it wiggles or feels lose they will fail the mounting method. Another reason for solid mounting is to get the seat as low in the car as possible since this puts the driver's weight as low as possible. I use grade 10 metric bolts, stacked washers and nyloc nuts for mounting and check them for tightness after every race.
1.Remove the driver's seat, rails and clean the area very well with a vacuum.
2.Remove the stock seat belts and clean both holes in the floor of any rust.
3.Use an angle grinder and cut out the rear mounts on both sides.
4.Use an angle grinder and cut out the bracket for the angle adjuster which is welded to the box area under where the seat mounts. My seat hit this angle bracket and it also hit the rear rail mounts so they were all removed.
5.Clean and remove any rust with a wire brush from these areas.
6.Paint the exposed areas with POR-15 and let it dry for 24 hours.
7.I cut a piece of carpet to fit the rear area since my interior is carpeted and trimmed it with vinyl edging.
8.Put the seat in place, sitting on some phone books or anything that will support it and climb in to see how it feels. If you have a cage with door bar like I do, getting in and out is much easier with a removable steering wheel.
9.Once the position feels good, have someone measure the distance from the top and bottom of the seat to the firewall, save these measurements and then remove the seat.
10.I used some 1/8 by 1 inch aluminum to bend some initial brackets to support the seat and set them under the seat to get an idea of their shape.
11.Once the seat looked centered and even I made a final set of brackets of ' x 11/2 steel and ' x 1inch steel. Note the brackets are bent to follow the curvature of the aluminum seat bottom and have to be the same size.
12.Drill the holes to mount the brackets to the floor and bolt them in place with at least 10mm grade 10 bolts.
13.Put the seat back in place, mark the bottom for the location of the holes and then drill the holes inserting a bolt for each hole to keep things lined up.
14.Put some nuts on the bottom of the steel mounts and snug them down.
15.Get in and try the seat for position, back angle, HEIGHT, etc. Make any changes at this time.
16.Make a seat back brace if your organization requires one. I use one that can be lowered when the seat is far back when my daughter is driving since she is taller than I am. When I an in the forward position the seat brace is up and latched and an aluminum wedge fits between the seat and the movable bracket.
17.Unbolt the mounts from the floor and remove the seat and mounts as an assembly.
18.Get out the MIG welder and tack weld each nut to the mount in several places.
19.If the seat will need to be mounted for drivers of different sizes, repeat the mounting steps and drill another set of holes and tack another set of nuts in place.
20.On the mounts I use three bolts on each side with stacked washers to spread out the load to the aluminum bottom.
21.Clean and degrease the mounts, mark the right and left ones then paint them with POR-15 and let dry over night.
22.Mount the seat belts with new eye-bolts through the floor and through the firewall using large washers behind the nuts to spread out the load.
23.Bolt the mounts into the car loose and then put in the seat and bolt it down. Tighten all bolts until all are tight.
24.Put the cover on the seat and then thread the seat belts through the holes.
25.Make sure the belts do not run on any metal and the adjusters (if used) are inside the seat body.
26.Climb in and test the seat position and enjoy the new feeling of safety.