My 1974 Porsche seat mounts are surprisingly weak. As if a 6mm screw is going to do much in side or rear impact collision! The other issue with the factory seat mounts in my car is that they are too high, especially if aftermarket seats and sliders are used. I’m about six feet tall and the problem is there isn’t any room left for my helmet. Plus, there are significant performance improvements to be gained by lowering the center of gravity of the car. FIA seat mounts are not only safer, but better than factory.
Rather than re-invent the wheel, it was suggested to me that I look into the FIA seat mount rule book. Sure enough FIA tells you exactly how to mount racing seats and harness into your car. Now, my car isn’t a full blown race car and there are some dangers of only following some of the rules. For instance it isn’t wise to use racing harnesses without a roll cage. If the roof collapses and your harness prevents you from moving out of the way, that’s a problem.
Out With the OLD and IN With the New
I cut the factory seat mounts of my car using a spot weld cutter and a cutoff wheel. There are a lot of welds, but its not too bad getting the old ones out. Then, I placed my Sparco R100 seats in the car to see how low they would sit in the car and still let me see over the dashboard. In my case, the seat base barely fits between the sills and the tunnel. In fact, the seat base prevents the seats from going all the way down to the floor.
FIA recommends the use of bars spanning the sill and the tunnel and the required bar size (1.5″ x .120″ square tubing) was perfect for the lowest seat position.
Similar to the roll bar base plates, FIA also recommends a large surface area connection to the cars sheet metal structure. Large plates prevent the seat mounts from ripping out during a horrific crash. I opted to take advantage of the stepped sills in my Porsche and make an angled box structure. This prevents me from drilling holes in the sill, but still allow a threaded nut to go on the backside.
Homemade Brackets and Seat Mounts
The FIA seat mount bars are removeable which is nice in case I change my mind on the seat in this car. The pic above also shows a plumb line showing where the steering wheel is in relation to the seat position. I was not able to center the seat directly behind the steering wheel, but then again neither did the factory. FIA also requires that there is a welded in threaded insert to prevent the tube from crushing.
And My Big Head Fits
When it comes to safety, FIA is a great place to begin your planning. Check my products I make page soon as I may offer this as a kit for sale!
Below are the full videos where I show all the details about these FIA seat mounts.
Hello,
I was the one who asked you on Youtube that if you were interested in selling your original factory mounts. My email is:
ianm19@gmail.com
Thanks,
Ian