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I just finished putting in my Kirkey Seats, 5 point harness, and 4 point Autopower "race" rollbar.

everything went in pretty smoothly, The roll bar was surprisingly easy to install. The seats weren't bad and I used some manual seat tracks as a base since the mustang floor is anything but even. All in all I'm happy with the look and the feel of it all.

My question is about seat back braces. I know I would need them for competition, but do I need them for HPDE's to pass tech? I have no intention of competing anytime soon with this car.

I just wasn't sure if they were mandatory, I plan on doing them soon anyways.

You can back into the wall in HPDE, so I would certainly install them. If it were my car, I'd care more about personal safety than what tech might say.

I was just curious, I actually fabbed up and mounted some really nice seat back braces this morning. Was easier than I thought and it's solid as a rock.

Of course I care about my safety more than anything, thats why I'm doing all this. if not I would have left the stock mustang seats which have absolutely no head support! (how they passed federal crash standards I have no clue!)

might want to add same plates under that bolt in bar. Would also suggest welding it on the vertical so it does not end up like this one - http://jalopnik.com/5390934/mustang-cover-boy-tries-to-corner-flips-over-tire-wall - luckily the seats failed as well! Not trying to burst you bubble but, you seem genuinely concerned with safety and having been on track with this car in the past i just thought you might want to he aware.

Saw that event, talk about a bad day.

The bar came with backing plates. I installed them all of course. I was a little taken back by the size of the floor plates though, only about 6 x 4" if that. I thought they would be a bit bigger. It's not just the size of the backing plates but the "feet" of the roll bar as well. The backing plates are only to keep it from pulling out. The "feet" are what keep the bar from "punching" through in the event of a roll over. Unfortunately increasing the size of the feet is alot more difficult than increasing the size of the backing plates.

I don't want to weld anything to the floor pans or sheet steel of the car, there really isn't much of an added benifit. It's not very thick to begin with, and welding would probably only weaken it more so than strengthen it. If I can generate enough force to shear off (12) 3/8" grade 8 bolts, well I have other problems than just my roll bar (the bolts are probably the strongest point of the whole system, shear strength of (1) 3/8" grade 8 bolt is about 15,000lbs). Remember, the loads aren't going to be a side to side direction where shearing the bolts would be an issue, it would be in a up and dont direction where the strength of the floor pan would be the main concern.

Welding the back two bars to the vertical hoop isn't a bad idea as there is plenty of material to get a good safe weld, and currently only one bolt (through both sides) of each bar... If i come across someone with a welder I will certainly look into it, I just don't have one.


Also, that link you posted if I recall correctly, was a far sub-standard roll bar, just a vertical hoop w/ less than adaquete tubing size. I think the autopower I got is a great added safety measure w/out going to a full cage.

Thanks for the help!

A couple of things...

1) You are correct that the bolts will be loaded in tension, not in shear, BUT the S197 that flipped was running a rollbar with the same mounting scheme you have on yours... The crossbraces will do nothing to prevent the pads from punching through the floorpan.

2) I have an S197 with the Autopower 4-point (road-race) bar myself, and I'm in the middle of adding safety support plates for the bar. I'm tying the floor plate into two vertical surfaces; the rocker sill and the rear seat pedestal/crossmember. Since all three plates are tied together, that puts any vertical load into the sill and rear seat box, and not so much onto the floor pan, thus helping to reduce the chance of a punch-through.

3) A brace as I've described can easily be installed (welded) into the car, and the carpet will lay right over it, if that was your concern. With the carpet down, and the trim pieces back in, it should be invisible, but still provide the safety that you're looking for.

Having it invisable isn't a concern, hell I just dremeled the sh*t out of my back plastic interior moldings for the rear bars to go through lol! Be sure to post/PM me the link when you do this, I'm glad I'm not alone thinking the "feet" of the vertical bars aren't big enough. I had to get it installed to see what options there are to improve it. I will probably end up doing 1 or 2 HPDE's as is, but soon I want to come up for a better design for the vertical mounts, Your's sounds pretty good and I'm interested in seeing how it turns out!

Will do... Granted my chassis is a little different than yours, but it's not THAT different. Essentially, the floor plate, "rear" plate (rear seat pedestal) and "side" plate (rocker sill) form three sides of a box, with a total surface area approaching 100 square inches. THAT will dissipate a lot of load, and not onto the stamped sheetmetal floor.

Dave - my cage is tied into the same vertical areas as yours. The floor pans are for shoo-shiddily-diddily which is why tieing it in vertically becomes even more important. I also have large plates that are under the bar and welded to the plates on both vertical surfaces. Then, both of the vertical plates are tied to the bar. Also, I have steel braces running the length of the door sill that are tied into the a pillar bars on the vertical as well. Crazy how many places you need to tie these things in to do their job. Good luck and let us know how it progresses. If you were in TX, you could come borrow the welder anytime.

As promised, here's what my buddy and I came up with...



Total area is JUST under 100 square inches, and we did it out of 1/8" steel plate. The three main panels are all a single piece (scored and folded on a brake), and the difference in the way the bar feels bolting it back in is HUGE. If I was doing a full-on competition car, I would probably go the same route, but out of 3/16" stock.

And here it is with the carpet in: