fatbillybob

It’s Friday and for those with nothing to do Here’s something for you guys to think about. Obviously, I’m thinking too much again. So here it is...Back braces! Some people are pretty vocal about why they don’t like them. I think Geo was one who did not like metal rods pointing at his spine. I think this is a valid concern. Since for cars without integral back brace as part of the design why don’t manufactuers design Back braces to still join by the harness bar but attach to seats at the armpit shoulder area? IMO this would be the most likely spot to support the most load where the body is most reinforced by ribs, shoulder blades, and a maze of muscle attachments. If the brace gave way the rods poke into more non-vital areas. Also if you had the typical plate of steel supported at two points rather than just one at the spine you could use thinner and lighter stock. Comments?

MJR911

It's friday... i'm going racing. But our seat back brace has a large pad, not just a 'metal rod'... although the early versions seemed more like it.

RedlineMan

Hey FBB;

I cannot argue with G on a phylisophical basis. I don't like the mental pictures I see in his head either, the likelihood of such occurences being minimal notwithstanding.

I have changed my mind on bracing the seats. I used to feel like everyone else that the seat should flex and absorb energy. Recent research has shown the ineffectiveness of this theory. Absorbing energy equates to lengthening the event, which increases energy levels and potential for harm. I like the solid braced seat idea now.

At this point, you must consider what type of seat is being used. It seems to me that there may be more to be gained from solidly bracing a full containment seat than the ubiquitous "wing" seat that most drivers have. Solidly bracing a seat you are not likely to stay in anyway strikes me as being a potential problem, but that is just a theory.

In the Ultrashield Super you are using, you have a very stiff, well braced seat with a lot of containment. I feel there is a lot to be gained from bracing this bad boy solidly. I have always fealt (as you do) that the shoulders are the point at which one would seek to brace the seat to the cage. Most people have at least a reasonable cocentration of mass there, so it is a rather obvious point.

I feel that a horizontal aluminum plate from the seat back and attached to 2-or-more points on the belt bar would be ideal. If you saw fit, or were concerned about leaving the head rest area unsupported, a simple vertical gussett could be added.

I've also got other ways of bracing seats rolling around in my head. Adjustable for multiple driver ways.

fatbillybob

Yes, I did not think about this. The flexy plastic seat like the OMP touted as a shock absorbing seat that can take 20 or is it 50g's may just act to quicken a drivers "spillout" without full containment if rigidly braced. That's where others comments on the importance of sidenets are really important. I'm back bracing at 2 points between armpits and top of shoulders about armpit width.

kurt M

If you have a plastic seat you should use a large plate that has a proper pad between the plate and seat. Using PCA club race rules, metal seats can be attached to the brace structure but plastic seats are not bolted to the structure but only supported by it using a minimum of 30 SQ in plate with proper 1/2 in padding.
The driving idea behind the brace it to maintain the seat’s integrity and keep it and you in place. Within reason the placement location of the horizontal bar or other method of attaching the brace to the car is not what it important. If the attachment or contact point is too high the seat might be able to fold in the middle. This would only be during a very high energy event and I bet you would have other issues as well. Another very good point to a brace is that without it the seat is only held by the floor attachment points and all that is sticking up (you and the seat) from that point is acting as a lever trying to pull the seat away from those points. Point to point on the floor bolts is around 14 inches =/-but floor to shoulder point is 3 feet or so +/-. In a rear ender there is a very high load put on the front attachment points and if they fail the seat and you move out of place, the harnesses become ineffective and you are loose in the car. The seat might be able to absorb 50 Gs but can the mounts and mounting method do so? It looks to me that a race seat bolted down with stock bolts and locations is not up to the task without some help geometrically. You could build something that is stupidly thought out and built that would support the “drill through your back” argument but you can also, with little effort, build something that does not and adds structural integrity to the containment system.

fatbillybob

Kurt,

I basically agree with you. I use to run an OMP carbon shell. It flexed and had wings but not full containment. I get John's point that if you support the seat it may just yield in other direction and spill the driver out of the seat. Forces always seem to be vectors and never just true rear end or front on. So the spill out concern is very valid from my past personal use hence the need for sidenets. But still sidenets are a poor substitute for working harness suported by a fixed seat as you post. Unfortunately, all the aftermarket devices look like the drill through your back units. Homemade/welded structures are the only things that I have seen make sence. It does not seem too hard to manufacture a better mouse trap/back brace. Why do you think PCA mandates 1/2" padding? This seems to fly in the face of the rigid mounting concept to prevent energy build-up. It would seem to me that the padding that comes with the seat is all that is needed. By the way Aluminium seat makers are o.k. with you drilling and mounting their seats where ever you want as long as you use enough attachement points (4 being absolute minimum and back bracing receommended). What is the current thinking of the plastic seat makers? It used to be that they absoultely did not want you to drill their seats.

JackOlsen

I use the Brey-Krause brace with a Recaro SPG Pole Position seat. The brace has a large flat piece where it meets with the seat back. I like this much better than some of the ones I've seen that bolt to the seat itself, and contain a spear-like arm connecting to the cage.

The BK brace comes with mild 3/8-inch rubber padding, but I took it off and substituted a 1-inch-thick sheet of SFI high-density padding. I think this would provide more meaningful energy absorption as the seat moves back.

Saying the seat's flex in an impact would help because it absorbs energy seems to me a little like saying a rock can rely on a slingshot's elastic straps to help keep it safe.

RedlineMan

Points;

Side nets - I dissagree, FBB. They are a superb way to contain spill out. The BEST fail-safe there is. Of course, they do not eliminate the need for good seat mounting, and they are not necessarily feasible for the dual use car, but for a pure race car I think they are an essential part of the safety system. I have strongly considered them for my DE car... some day. I'm sure guys who have biffed like Adam Richman and Colin (38D) would readily agree. I know Vaughan is down with them!

Back Braces - There is not much of any other way to get relatively infinite adjustability in a device than to mount it on one post. Kind of hard to offer a product like this for generic use without it being built that way. This B-K brace that Jack mentions is pretty fool proof I'd say, and is a good addition to a seat system. Not quite the benefit of a mounted seat back, but enough to make it effective in many instances, I'd bet. I too replaced the foam with something thicker and more dense on a client car.



If I were to build one, it would offer some wrap around containment for the seat being used, cupping the back to also provide some lateral support. Not something the manufacturer can do, not knowing what seat is to be used.

Drilling - The advantage of alloy is that it is not liable to fail catastrophically. Therefore, a hole here or there is not going to adversely effect its integrity. Not so with a plastic seat. One hole is more likely to be the origin of a complete and catastrophic failure.

38D

How I managed to walk away from the crash unscathed, I'll never know. Luckily for me, the flip happened slowly, otherwise I would've had arms flying all over the place. I definitely consider a window net a great safety feature and wish I was allowed to run it in the few DEs I do (maybe I could since I never have to give pass signals anyway ).

John H

I had a brace made the meets the back of the seat and bends around the sides sorta like a ( It is flat up against and follows the contours of the seat back. I also bought a piece of the special padding (after much looking) and affixed if between the seat and the brace. PCA scruts thought the design was great and I got the thumbs up. It looks much different than the Brey Krause model.

fatbillybob

John,

Actually I love sidenets. My post is just as you posted " But still sidenets are a poor substitute for working harness suported by a fixed seat". A fixed seat with good mounting is what you want. You really do not want to rely on the sidenet fail safe hence my statement. I think is is a bad idea for racers to not worry about seat mounting because they think sidenets will catch them. Finally, I think the big boys Dr. Melvin etal are absolutely pro-sidenets and they have data to prove their validity.

Back to back braces why the 1" padding vs the 3/8 rubber stock in the krey brace? I think I would eliminate the padding all together for a contact fit at a minimum. It would seem to me that the 1" gives more wiggle room for the seat to deflect and spill the driver, the rigid mount is ment to stop the build-up of energy just like belt stretch is now a thing to avoid. Finally, don't you think fixed mounting of the back brace to the seat is the best way to mount a seat securely so the seat can do its job in a race car. Crashes are so violent the less stuff that moves around the better. I also think that fixed mounting the back brace fortifys the seat even when manufactureres for liability reasons will not condone drilling say a plastic seat. Dual use cars are always a compromise and then I understand the application.

kurt M

IIRC The padding is for plastic seats as they are not to be drilled and bolted through. Metal seats can be hard mounted. The padding that comes with the braces is firm and made to absorb the initial energy spike. If you are racing in PCA you will want to use the materal that comes with the B/K brace. It is the required materal per PCA Club race rules and I think changing to another padding materal voids the brace. If this realy compromises the brace and seat I don't know but it is spelled out in the book.

zaydik0

Same

zaydik0

You are right my friend.