Theory behind mounting seats to rollcage
09-11-2005, 01:36 PM
#1
Theory behind mounting seats to rollcage
Can someone tell me the theory behind mounting seats to the cage v.s mounting seats to the OEM mounts/floor. It seems to me that it makes more sence to have the seat mounted to the cage via an elaborate square of tubing "free floating" but connected to the cage via a combination of the sill tubes or rear crossover tube or even connection to the harness bar. This spider web of small tubes is difficult to layout especially when the best design would be to go from sill tube to sill tube but 99% of cars have that pesky transmission hump to get over. We in general don't have tube frame cars so I just don't see free floating seat bracket systems. 99% of what I see are not bolted to the cage but some variation of OEMish bracket, rectangular bar, and floor welding or bolting. The other 1% that try to mount to the cage do so with connection to the cage and at least one free corner or corners still mounted to the floor in some way . My understanding is the goal of seat mounting to cage mounting is supposed to have the seat move with the cage in a crash so free floating is o.k... However, the additional mounting to the floor/car defeats this design since the extra floor mount will resist movement of the seat with the cage if they separate. Maybe is just does not matter because the cage is supposed to be welded nicely to the car and never separate. That's why we have so many points of attachment. Am I overthinking these things again? It seems that welding to the cage is extraneous. 
09-11-2005, 04:28 PM
#2
Rennlist Member
As I recall, there was a fatality at a practice or qualifying session for a PCA club race several years ago, the guy spun and went backwards into a wall or guard rail and the seat mounting or reclining mechanism failed. Shortly after that, the seatback support requirement for PCA racing was put in place.
09-11-2005, 07:20 PM
#3
Addict
Rennlist Member
Rennlist Member
Overthinking?
Of course! You are good at it, Bob.
Seriously, the things you are thinking about are all good things to burn brain cells on. That is how people learn, or come up with better ideas if they already know a lot. I've GOT those t-shirts!
Obviously a properly fettled tube frame is going to less likely to buckle and fold than a sheetmetal assembly like a floor pan. Many seat mounting areas are not tied into any structural unibody beams, and are rather free floating enterprises at best. For street use at street speeds, this is fine. For track speeds... well...
You sort of got close to it for a moment. I think this is one of the many things that does not quite transfer over from pure race cars as an intact idea. As you got close to saying, a pure tube frame race car HAS no stamped sheetmeal floorpan. Since they are all tubes, a few more to mount a seat is a natural. When you try and incorporate that into a semi tube sedan, things get a bit murky.
Not many sedan people get to the point that they are cutting out their center tunnels and tubing them. As such, there is not a natural place to attach the inside portion of a tube seat sub-structure to. I think worrying about creating such a structure is bordering on overkill unless you are driving some sort of Land Missile like Norm Goldrich or Bill935K3 are driving. Then I might get interested!
I have used the exisiting sills in 944s, 911s, and 928s to build seat frames that offer far more strength than the stock mount systems (AND more headroom to boot!). I feel they are pretty effective. Examples:
930, similar to my 944 mounting.
928
Of course! You are good at it, Bob.
Seriously, the things you are thinking about are all good things to burn brain cells on. That is how people learn, or come up with better ideas if they already know a lot. I've GOT those t-shirts!Obviously a properly fettled tube frame is going to less likely to buckle and fold than a sheetmetal assembly like a floor pan. Many seat mounting areas are not tied into any structural unibody beams, and are rather free floating enterprises at best. For street use at street speeds, this is fine. For track speeds... well...
You sort of got close to it for a moment. I think this is one of the many things that does not quite transfer over from pure race cars as an intact idea. As you got close to saying, a pure tube frame race car HAS no stamped sheetmeal floorpan. Since they are all tubes, a few more to mount a seat is a natural. When you try and incorporate that into a semi tube sedan, things get a bit murky.
Not many sedan people get to the point that they are cutting out their center tunnels and tubing them. As such, there is not a natural place to attach the inside portion of a tube seat sub-structure to. I think worrying about creating such a structure is bordering on overkill unless you are driving some sort of Land Missile like Norm Goldrich or Bill935K3 are driving. Then I might get interested!
I have used the exisiting sills in 944s, 911s, and 928s to build seat frames that offer far more strength than the stock mount systems (AND more headroom to boot!). I feel they are pretty effective. Examples:
930, similar to my 944 mounting. 928
