Mounting seat from the bottom....
 

In attempt to install my Sparco seat as low as possible in my FD, I was thinking about making custom braces to the stock seat mounting points, and just using the bolt holes in the bottom of my Sparco, without the use of traditional side rails. This would basically put the seat right up against the floor, and I can fit in the car with a helmet on.

I was wondering if not using side rails would affect the stiffness when mounted, has anyone tried this?

You need some bracing underneath the floorboard for that type of mounting (i.e. little washers won't cut it, something like Grade 8 fender washers or some plates), but it has been done before.

EDIT: Sorry, you were suggesting using the stock bolt locations. That would work, but the braces would probably be more trouble than just mounting directly to the floor with support under the floorboard.

Thanks for the reply but I'm not sure what you mean about being more trouble; it's basically just 2, 3" wide flat strips of steel (I have both 3/16 and 1/4) with a 40*ish bend at one end to line up with the front seat bracket holes. I'd bolt the seat bottom directly to those. No need to drill through the floor of car like you would when installing a harness or anything.

Maybe I should also weld a cross brace between them.

I'm suggesting bolting to the floor rather than making/bending steel for custom braces as a more simple approach. If you don't want to drill the floor, then go your route. It's been done before as mentioned.

Will one be safer than the other? Both just depend on the materials and quality of work.

Rich,

This is how the seat is mounted in my FD.

https://lh5.googleusercontent.com/-Y...0/IMG_0333.JPG

https://lh3.googleusercontent.com/-i...0/IMG_0332.JPG

Guy

What I did on my FC was section the floor. Started at the front of where the seat would be, and cut along the sides and back, dropping the back at an angle 1 1/2" in the process. I left the stock reinforcement in place and cut it at an angle to match the dropped floor and welded it in place. I made a skid plate for the fuel lines since they now sit even with the reinforcement. Since I had already replaced the floor with 16ga metal, I had a section cut to fit the cutout and welded everything in place. I used the Sparco seat mounts with the forward mount as high as possible, and the rear mount the lowest. You cannot get your fingers under the back of my seat! I also added 5/8" spacers under the seat mount on the left side to tilt the seat inward. I can now get in the car without hitting my head and I now finally fit the car!!

Thanks guys, I ended up going back to the traditional route, and using side brackets as well. I found a metal guy to bend me 2 brackets of the 3/16th steel, then mount the side rails to that. The rear of the seat is about a inch off the floor, give me just enough headroom with a helmet. I wanted to keep the stock seat holes for the option of swapping in the stock seat when drifting season is over and I just want to take a cruise or something. Thanks for the tips and pics though.

Attachment 640593

You basically now have the AtomicRex setup:

https://www.rx7club.com/3rd-generati...mounts-852437/