Suspension seat failure

michael.gonzalez

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I define it as I drop my fat ass into my seat and there is zero bounce. Friction within the seat and my body/race suit against the seat back and bolsters provide plenty of friction damping. If the test is to bounce an egg in the middle of the seat bottom with the foam cushion removed it would bounce. That means nothing. Who's hauling groceries in their race car? 🤣 🤣 🤣

In practice the load is spread across the seat bottom reducing the deflection and bounce.

Part of a proper fitting race suspension seat is a snug fit, same as a shell seat. This ensures there is friction along with containment and the belts to hold a person in place.
Egg test is a conceptual test. A more appropriate test would be a 200lb dummy falling a distance that would generate the necessary G-loads.

5, 10, 20 G on a 200lb man is 1000lbs, 2000lbs, and 4000lbs of force.

let's see you not bounce then ;)

PS. Dropping your fat ass is like 1.5 G... maybe haha. I would NOT want friction damping to be the method of damping on which I rely. My 2 cents.
 

cjohnson

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Egg test is a conceptual test. A more appropriate test would be a 200lb dummy falling a distance that would generate the necessary G-loads.

5, 10, 20 G on a 200lb man is 1000lbs, 2000lbs, and 4000lbs of force.

let's see you not bounce then ;)

PS. Dropping your fat ass is like 1.5 G... maybe haha. I would NOT want friction damping to be the method of damping on which I rely. My 2 cents.
My point is there is damping in a suspension seat. Friction damping is a tried and true principle. All racers rely on it to some extent. Even moto riders that use friction tape on their frames and grip the bike with their legs. I guess you could lather up in Vaseline the next time you get in a race car if you don't want to rely on it. 🤣 🤣 🤣
 

A-Tech_Racing

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The good and bad of a suspension seat:

Good: it has some suspension

Bad: the suspension is undefined, uncontrolled, and unreliable

So why not build a real suspension seat? 36” wheel travel does you no good when you land on a bump with the frame hitting the ground. Chuck Strange built a buggy back in the 80’s that he used to jump over stuff like Evil Knevil. It had a seat mounted to a frame with a pivot in the front and shocks behind the seat.

Obviously the seat belts must be attached to the frame, so it must be well designed, but much lower loads than the vehicle suspension. You would need clearance for the travel below the seat. Such a system could be a lifesaver and it would be controlled and tunable. I think it could be made and still comply to the rules, or new rules could be written to allow it.
 

michael.gonzalez

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The good and bad of a suspension seat:

Good: it has some suspension

Bad: the suspension is undefined, uncontrolled, and unreliable


Obviously the seat belts must be attached to the frame,

Great way to say it!

Another thought I just had is total allowed displacment:
The foam in a hard shell seat can compress maybe an inch or so.
How much travel is allowed with a suspension seat at 10, 20 G? My guess is far more than an inch. Not good as the harnesses are hard mounted (don't move with the seat bottom)
 
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Zambo

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I mentioned this in Chad's thread way back in the day, but the most important thing for keeping your back from getting hurt isn't preventing impact but rather making sure your spine is straight when and if the impact occurs. The suspension seats let the drivers bounce around too much, even if it seems like its making life more comfortable at the time. You're much more likely to be in a good position to absorb a big impact when strapped into a shell seat, and yes that means shoulder straps tight. Yes I know its easier to see and a lot more comfortable to keep them loose and "ride" the car like its a motorcycle, but that is what's going to screw you big time in a hard crash or bottom-out.

The high density foam seat bottoms that UPR sells are great, even just the square ones that replace the stock shell seat cushion. They will dampen out a big hit and give you plenty of comfort on a long day, but they don't spring around like a couch.
 

E motorsports

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i compressed my L2 and L4 in a 9 car back in the day
9 cars basically need to run suspension seats due to lack of travel roughly 4 inches the front 8 inches the rear
i designed a secondary seat suspension device that i never proved out.
the thought was to use a firefighter air bag that is used to inflate and hold up walls and cars that have fallen over
these bags come in various sizes for different applications.
the one i chose was 24" x 24"
because they could be inflated to variable pressures it was adjustable.
the idea was after the seat bottom sank a couple inches on impact it would the come in contact with the air bag and absorb some of the energy but could not
over spring on the way back up.
also this would not interfere with seat mounts or seat belts R&D not complete PAT.PENDING
 

michael.gonzalez

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i compressed my L2 and L4 in a 9 car back in the day
9 cars basically need to run suspension seats due to lack of travel roughly 4 inches the front 8 inches the rear
i designed a secondary seat suspension device that i never proved out.
the thought was to use a firefighter air bag that is used to inflate and hold up walls and cars that have fallen over
these bags come in various sizes for different applications.
the one i chose was 24" x 24"
because they could be inflated to variable pressures it was adjustable.
the idea was after the seat bottom sank a couple inches on impact it would the come in contact with the air bag and absorb some of the energy but could not
over spring on the way back up.
also this would not interfere with seat mounts or seat belts R&D not complete PAT.PENDING
Air bags STORE energy. They don't do much to ABSORB/DISSIPATE energy.

Air bags are more akin to Springs rather than Dampers.

Again, the key is ENERGY ABSORPTION/DISSIPATION.
 
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E motorsports

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Air bags STORE energy. They don't do much to ABSORB/DISSIPATE energy.

Air bags are more akin to Springs rather than Dampers.

Again, the keep is ENERGY ABSORPTION/DISSIPATION.
what you say is true
except that air bags absorb all of the energy the problem is they give a high 90% return of energy
but my application will stop the impact with the skid plate and not over spring up because the gap between the seat bottom and the bag top
so on the down stroke the travel will be slowed and there will be no abrupt stop and that's what causes the injury right?
its the abrupt stop that hurts
 
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Tube ride

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B6300216-619E-4F93-83B3-315E545D0D41.jpegno I swear it was the whoopee cushion
 

A-Tech_Racing

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I had been floating around a design for an energy absorbing seat for a few years. It would be designed similar to a crash helmet. It would have an inner shell and an outer shell separated by 4-6” of impact foam. It would absorb impacts from the bottom, but even more importantly from side and rear impacts in a collision or roll over. The seat belts would pass through both shells and attach to the chassis just like any other seat. The foam should only compress on impact and not allow the driver to bounce around.
 

jon coleman

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i compressed my L2 and L4 in a 9 car back in the day
9 cars basically need to run suspension seats due to lack of travel roughly 4 inches the front 8 inches the rear
i designed a secondary seat suspension device that i never proved out.
the thought was to use a firefighter air bag that is used to inflate and hold up walls and cars that have fallen over
these bags come in various sizes for different applications.
the one i chose was 24" x 24"
because they could be inflated to variable pressures it was adjustable.
the idea was after the seat bottom sank a couple inches on impact it would the come in contact with the air bag and absorb some of the energy but could not
over spring on the way back up.
also this would not interfere with seat mounts or seat belts R&D not complete PAT.PENDING
sorta like an air bag stunt people use to jump off buildings, just have the air in the bag bleed out at a certain rate, maybe into some kind of dampened accumulator, that after the 'Big hit', the bag fills back quick, but not Too quick to make it a bouncy mess, and it Only ' pops off' in a Big , potentially dangerous hit, not normal off road hits
 

Scorpion Racing

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The good and bad of a suspension seat:

Good: it has some suspension

Bad: the suspension is undefined, uncontrolled, and unreliable

So why not build a real suspension seat? 36” wheel travel does you no good when you land on a bump with the frame hitting the ground. Chuck Strange built a buggy back in the 80’s that he used to jump over stuff like Evil Knevil. It had a seat mounted to a frame with a pivot in the front and shocks behind the seat.

Obviously the seat belts must be attached to the frame, so it must be well designed, but much lower loads than the vehicle suspension. You would need clearance for the travel below the seat. Such a system could be a lifesaver and it would be controlled and tunable. I think it could be made and still comply to the rules, or new rules could be written to allow it.
RACECO Did this Exact thing back in the late 80's the Bob Renz / Dick Clark Class1 Car had this set up
 

Bro_Gill

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Always wondered when folks would talk about making the seat part of the suspension package, but here they are still saying the seat belts have to be attached to the frame. Why not an integral part of the seat? Ever wonder what the seat belts in a plane are attached to? Ever wonder why? How about children's car seats? The belts should be attached to a seat that is designed to be a part of the safety package of the vehicle they are in.
 

isdtbower

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I wish the foam pad I am sitting on would spring me out of it. And it is basically uncomfortable because of heat. I see that the newer impact foams in Moto Sport have large air gaps. We should be thinking that way. I would think the back would be easiest first with a hard back.

After looking at the attached threads. I believe the seat guys who are working with different layered densities before "Hard" Impact Foam might be on the right track. Incorporating ventilation might be the next big plus and why suspension seats may feel more comfortable long term in wheeling.??? The venting, or voids) might adding slow down cushioning before thevoids lock to provide the stopping impact.???? The science would be in the details. Not the basic idea, as been around for decades. New materials might be opening some doors for them.

I think it is important to differentiate between offroad and other motorsports. In many motorports they are thinking of surviving one event. In Offroading we are thinking multiple events.

A Helmet is basically a single event layered lamination. So not comparable.


Personally, Recreationally, I am sticking with the easily purchased suspension seats with the mid soft NASA impact foam under it. Cool, resilient, "affordable"
 
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Argentino

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I tried working with the people at D30, but they wanted rights to my design I was working on. Basically, it's an item that clips in your seat, goes under your arms, so that you tighten your belts to where they need to be and they don't compress your spine throughout the race. It prevents all your weight from compressing your spine as well.

Might be a tad uncomfortable, but could be easy to forget about after a while.

Remembers those curtain hangers from the yesteryear? Very similar but out of carbon fiber with D30 surround.
1626544351392.png


D30 can be put between seat and skid plate, too. Or on the bars above and near your helmet and body.
 

isdtbower

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ON friction and maybe above:

I used to run the longer multi-day races (ISDT and qualifiers). An exceptionally muddy event made me think about how slippery the seat was, and I should sew in lambs wool on the top. The next race my B HOLE hurt so bad, I could almost not walk. We would also tape over our tities to not inflame them from heavy tool jackets.. Not a big fan of friction between the body and clothing....

Maybe I should have conditioned the B-Hole with, then, European course TP. (When we raced over there. we brought our own)
 
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