Race seat mounting for tall drivers

[Pete Millikin]

Hi- I'm 6'2" and in order to fit in my 911 with proper clearance I have bolted the seat brackets to the floorpan. To do this I removed the standard L shaped brackets welded to the pan and the raised trans sill (inner bracket) and the door sill (outer bracket). These pieces are shaped like an inverted L in position.

I'm not very comfortable with this arrangement given the thinness of the floor pan even though I'm using large diameter bolts and large washers to secure the brackets to the pan. I'm thinking of welding an L shaped piece to the sill and the pan and drilling through it to provide better support. This piece will be a non inverted L that fits flush agains the sill and pan that provides better support to the mounting area on the pan.

Any better suggestions?

[kary]

Pete, mine seat is bolted to the floor pan as well. If for some reason it comes loose (yikes), and I survive the incident I will weld some other supports in ther e as well; however, I think the seat is fine where it is right now.

[Dan Chambers]

Pete:

What about using a 1" or 1.5" X 1/4" thick steel "Box" rail welded to the sill & floor (or just sill-welded)? You could weld in the box-rail, drill and tap it, and mount your seat hardware to that?

The rail would sit lower than the original inverted "L" wing that you've removed, it would be very strong (probably stronger than the original), and fairly easy to both weld and drill/tap for your hardware. You might even be able to install slider-brackets for the seats, allowing the seat to be moved. (Oh, wait. Scratch that. Only tall guys should be able to drive your car .)

I'd say you could use the angle of the original wing to align your box-rail so the angle of the seat is similar to original specs. Just check the old weld-points line or the cut mark from the old "L" wings.

Another thought is to take the original inverted "L" wings, and weld them in facing like an "L"? Put another way, "un-invert" the "L"? I'm not sure if there's enough "lip" for the hardware to bolt into, or if the width inside the verticle aspects of the "L's" is wide enough for the seats to fit in between. But, it might be worth a look.

That might be what I'd do. There might be a few options with the current hardware.

In Monica's 912, one previous owner, who's 6'3", drilled and tapped seat-mount holes about 1/2" behind the original holes. Since the inverted "L's" have a descending rake heading toward the back in her car, the seat was both lowered and moved back a scrunch to fit her, and me.

Good luck, I hope it works out for you.

Dan'o

[Jad]

I am curious, how important is the strength of this mount??? Isn't the seat belt what really holds the driver? If you hit something, you are thrown forward, out of the seat, so the mounts don't seem to matter. Only if you hit sideways or back first could the seat help. In that case, is the fiberglass in the seat really stronger than the mount you have? I don't think of fiberglass as that strong? Is it in seats?

[kary]

There is a good thread on Rennlist about this. The newer wisdom on this is that it is best for the seat to be mounted in approximately 6 places. Three on each side rather than two on each side. This spreads the load better upon impacts and helps make sure the seat does not come loose.

As a side note, but very important, the issue with the seats coming loose is after an initial hit when you might be thrown backward in the car once the seat has come loose. Though I contend that once the seat has come loose there are bigger problems one must deal with so it might not matter all that much.

[Jad]

Interesting, my factory seats had 6 mounts, 2 next to each other in the back, my Recaros had 6 mounts, 2 next to each other in front, whereas the full race Momo's only have 4 mounts in the seat and say only use the provided mounting points. In addition, both the Recaros and Momos mount to a second adapter mount that only has 4 mounting points both in the floor and to the seat.

Does anyone have a non-factory seat with 6 mounts in all locations?

[kary]

Jad, the thread I mentioned was primarily talking about the mounts to the car not the bracket mounts to sliders or the seats. Thouhg all those are intereting to think about.

I have never seen a seat set up that had six, the only ones I have seen have been custom jobs in race cars.

[Pete Millikin]

Kary is right there is lots of discussion on the whole safety subject on Pelican and Rennlist by very serious racers. What I have gathered is that a backwards or side hit is more likely that a pure front on hit. In those cases the integrity of the seat itself and the mount is very important.

[Gary Burch]

When I installed new seats in my car I had the same problem. In fact I had to autocross for a year with the roof off, just so my helment would clear. With the roof on I was so slid down in the seat it wasn't comfortable or safe.

So I made a new bracket to bolt into the car. It uses the same 8 holes as the original but is made out of 1 1/4" x 1/8" steel angle and 1/4" flat bar. It's welded so the angle faces downward giving you 1" of extra clearence. It doesn't sound like much, but it makes a big difference. I reinstalled the sliding seat bracket. If you bolted directly to the new mount you would get 2"+.

[ttweed]

I did the same thing as Gary in my '73-- with the sunroof stealing another inch of headroom, I couldn't wear a helmet without hitting the roof. When I had my custom bracket made up, I moved the slider mounting crossbars back 2" as well as down 1-1/2" to give me more leg room as well as headroom.

TT

[Pete Millikin]

Gary /Tom I'm a little unclear on the oreintation. I think you welded the angle iron in an inverted position to the pan and the central tunnel or the door sill. Is the flat bar welded 90 degrees across these pieces tying them together?

[ttweed]

Gary /Tom I'm a little unclear on the oreintation. I think you welded the angle iron in an inverted position to the pan...

Pete-
My mount is not welded to the car. It bolts in using the same 8 bolts as the stock rails. It has "ears" made out of the flat bar stock welded to the top edge of the angle iron, which pick up the mounting holes. The angle iron is placed inboard of the sill and tunnel, hanging off these "ears", and then the rest of the flat bar spans the seat area, welded to the lower "L" of the angle iron. A picture will probably help:

This is the driver's side with the front of the seat to the left. The seat is a bottom mount Corbeau Forza, and you can see the rear bolt for the left seat slider in the pic (on the right, just above the middle of the pic.) If you are using a side-mount seat, this arrangement may not work easily. Your idea to just weld some angle iron to the sill and pan to reinforce it sounds reasonable for the side mount brackets. I would not trust the floor pan alone to support the seat brackets. The considerable forces from the driver's weight being slung from side to side are bound to at least bend and wrinkle that thin sheet metal eventually, no matter how big a washer you use. In an accident, I wouldn't doubt that it could tear the bolts thru it, washer and all.

TT

[Pete Millikin]

Got it! The pic is very clear. I think this design will will work for my side mount seats. Thx