Adjustable seat back brace?

[s4shon]

Hello all, I have an expired Sparco seat in my e36 racecar, and need to install an adjustable seat back brace. I've looked at the I/O Port brace, but was wondering if it would be NASA legal to drill into the back of my composite seat as required by the install. If it's not acceptable, any opinions about the Autopower or Brey-Krause braces? I need a brace that can adjust in length as I will be sharing the car, and my co-driver and I have different seating positions.

 

Thanks!

[TheSonn]

I too had an expired Sparco [composite] seat and was going to have a back brace installed. But a couple of threads addressed that issue of drilling into composite seats and from what was said, it sounded like drilling into them could reduced their strength in an accident. And then, when I did a little research on seats in general (and went on the FIA website), I realized that a back brace was the least of my problems. As I understand it, (others, please join in with your understanding of this) in order for a composite seat to properly work, it needs to flex in an accident. In the case of a rear impact, the composite seat is designed to flex backwards thereby absorbing some of the g-forces. (That creates some other problems, like harnesses becoming loose on the driver's shoulders, etc.) Anyway, in my case, I had another problem in that my seat back was only about 1-inch away from the roll cage cross bar. FIA mandates that composite seats have to be mounted in such a way as to allow, I seem to remember, 150 mm of clearance between the furthest rearward part of the seat and any stationary part of the car or roll cage. That's about 6-inches! And because I didn't have the room to move the seat forward without my knees being in my chest, that seat is now sitting in my rec room in front of the TV! Plus, if I'd been hit from behind, that seat would have flexed into the cross bar, likely broken, and then my back would have been next. So I put a Kirkey Aluminum seat in and had a seat back brace installed. I actually doesn't bolt to the seat, but has a hard rubber pad that the seat back butts up against (I believe 20-square inches is the area of contact that's required). The seat back brace is adjustable for both forward and rear movement in 1-inch increments via holes drilled in the carrier tube for the mount, and the brace can be adjusted with different rubber pads so that if I change the angle of the seat, the brace is still in contact with the back of the seat.

 

That was my solution to my expired composite seat. Comments anyone?

 

Sorry if this confuses the issue, but knowledge is power - and sometimes and dang nuisance!!

[Bruce L.]

don't drill into a composite seat.

 

The SBB can have a large curved plate such that it cradles side to side movement of the seat.

bruce

[jcindric]

I have a custom fabricated steel seat brace, plate is approximately 12x12 with a 1 inch bolt with nuts to adjust. will bolt onto your roll cage $150

[jcindric]

I also have sparco evo seatsin great condition!

[David Fazzino]

OK right on first comment. A composite seat needs to move. Absorbs energy and also the more important consideration. A hard fixed seat (aluminum) will bend in impact and retain the bend. If the car takes another hit It could increase the next severe impact against the body. Why rally cars tumbling into trees all have composite seats. Absolute secure seat mounting is the best effort to take. Your circumstance is important. You do not want the composite seat to be moving and hit a hard bar. Especially near your neck! I watched a Porsche 911 driver die at LRP from that. Racing team engineers should weigh in on this. Are there secure ways to mount aluminum seats in a means that can allow the seat to move instead of transmitting the complete shock into your body?

[cstreit911]

An FIA seat should NOT have a back brace unless it's over 5 years old, then according the NASA rules, it's required.

 

I wouldn't drill. Brey-Krause makes an adjustable one, can send some pics if you need it.

[Trevor57]

I wouldn't put a back brace on an fia seat period. The engineers that designed the seat did not have a big steel plate on the thing during testing.

[911.racer]

Here is the rule in the PCA rulebook. It is what I have prescribed to in my car. I like the idea of the seat back brace and I also like the idea of the high density padding for composite seats.

 

I still remember the actident that made people start thinking seat back brace.

 

All cars will be equipped with a seat back brace except as provided in Safety Rule 27 below. Said device will mount

securely to the roll cage/bar and will rest firmly against the back of the seat. The portion that contacts the seat will

be a minimum of twelve (12) square inches and larger is suggested. The seat construction must be compatible with

the seat back brace and not pose a hazard to the driver. The seat back brace for composite seats must have a minimum

of thirty (30) square inches contacting the seat back, and must have 0.5” to 2” of high density foam padding between

the brace and the seat back. The seat back brace cannot be bolted to a composite seat unless the manufacturer has

designed the seat to bolt to a brace

[cstreit911]

I wouldn't put a back brace on an fia seat period. The engineers that designed the seat did not have a big steel plate on the thing during testing.

 

Trev, NASA rules require a seat back brace on an FIA seat older than 5 years.