Clayton H. Accident

Jeff Furrier said:

- Think about how loose your belts are after the first hit because you compress 3 or 4 inches?

-Seat belt set up is the cause of a large percentage of injuries. Today I bet 80 percent of the off road racecars are set up wrong..if not more. You have no chance of a proper set up in most suspension seats because the belts bind as they go through the seats so they are never tight.

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on these 2 points.

- Is 3 or 4 inches a real number or are you just using it for an example? That seams like a lot. that's enough for the shoulder harnesses to come off.

- I've seen some scary seat belt angles and have not doubt injury's result. I don't know about the binding, but I do know they can be very tight, so, your never tight comment isn't accurate.

Poke said:

I don't know about Dakar But he said 'endurance racing' which is what I have done in 3 different series.

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I should have been clearer and said FIA sanctioned Rallye-Raid type endurance racing.

Where the cars are limited to 10" of suspension travel per wheel and still do 100+mph all day long for 8h/day in a race that lasts 5 days or more.

Here is my issue with all of this.

I really want to learn what will keep me safest but from my experience everyone has an opinion and nobody knows the truth. The owner of ISP is the only guy in the off road industry that I know of who has conducted testing. I was really impressed with him but he wasn't focused on endurance racing. I am not talking about looking at a car/seat/injury after the fact. I am talking about closed environment crash dummy testing.

PRP does not do testing like this. I called and asked to speak with them about it. They don't crash test suspension vs hard core.

If you search for real data on it, all you find are forum threads and opinions. I tried to convince my PT to do his masters thesis on it but he didn't want to take it on.


If you want to be safe stay on your couch and only get up with a helmet on. If you want to be safe in a race car, don't start it. If you are going to race, get a comfortable seat with good seat belt angles and go.

Chris has for sure done his homework and knows what he's talking about for sure, but there's been extensive crash testing in any FIA or SFI spec seat. A 10 or 20g off road crash should be the same as a 10 or 20g road car crash, the main difference is in how they feel when you're not crashing. I have tons of data and crash test information, I just usually try to keep the conversations to a common sense level as that's what most people respond to. Building a seat that's safe but comfortable usually means compromising. I'm sure most of you guys are using your rigs for recreation when they are not being raced, so you need to be as comfort is obviously a concern. Even though I'm a lifetime off roader, our business service all types of racecars. We were building custom inserts for road and oval track cars with an SFI spec'd foam before we started doing the same for off road. Our seat pad is a softer version of the same foam we use for other types of racing.

The only ones that think a suspension seat is more comfortable than a hard shell seat that's set up properly are the ones that haven't used hard shell seat. I've been restoring and racing vintage off road cars for since 2010, they all have Sparco seats covered to look like suspension seats. I've got 1000's of miles in Baja in racecars with less than 10" of travel in hard seats with a proper set up, I assure you I wouldn't be doing it just to sell a few seats.

Jeff Furrier said:

Chris has for sure done his homework and knows what he's talking about for sure, but there's been extensive crash testing in any FIA or SFI spec seat. A 10 or 20g off road crash should be the same as a 10 or 20g road car crash, the main difference is in how they feel when you're not crashing. I have tons of data and crash test information, I just usually try to keep the conversations to a common sense level as that's what most people respond to. Building a seat that's safe but comfortable usually means compromising. I'm sure most of you guys are using your rigs for recreation when they are not being raced, so you need to be as comfort is obviously a concern. Even though I'm a lifetime off roader, our business service all types of racecars. We were building custom inserts for road and oval track cars with an SFI spec'd foam before we started doing the same for off road. Our seat pad is a softer version of the same foam we use for other types of racing.

The only ones that think a suspension seat is more comfortable than a hard shell seat that's set up properly are the ones that haven't used hard shell seat. I've been restoring and racing vintage off road cars for since 2010, they all have Sparco seats covered to look like suspension seats. I've got 1000's of miles in Baja in racecars with less than 10" of travel in hard seats with a proper set up, I assure you I wouldn't be doing it just to sell a few seats.

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Cool. You have my attention. I hope you keep sharing.

Any slow motion of a suspension seat rebounding into the belts vs a hard shell?

Any slow motion of a suspension seat in action... like woops at 80mps?

I'd like to see why I should toss mine and how they react.

I never really thought to put the time into collecting any data on a suspension seat, the basic principles of the design don't really require that much thought. If you move up and down in your seat, you're belts are loose 1/2 the time in every movement. The chances of you taking your first hit when your belts happen to be tight are slim because of the obvious forces that disrupted your vehicle to start with.

When you're forced down in your seat while hitting a bump, your shoulders most likely slump forward and curve your spine making you extremely vulnerable to injury. Its like lifting weights or anything else, you want your back straight. Your spine can take up to about a 12g vertical load hit according to an old SAE study when straight and restrained..which is huge. Think about how many times you've hurt your back loading your trailer picking up something relatively light..? 12g's is 12x times your body weight, way more than you could ever lift. We recently had sensors on a UTV racer at a Lucas Oil Short Course race, he was hitting 6Gs measured on his chest when landing off the jumps. This is in a car that was very well set up and not bottoming out.

I've got piles of data from FIA tests, but you guys don't need a lab report to understand this stuff...its not that complicated. Sometimes the reason you do what you do is becasue its always been done that way, but that doesn't make it right.

Here's a couple pictures of a seat in an independent testing lab to show you what kind of rig is used. Everything is measured until the seat fails, a properly engineered seat will go beyond the spec before any damage.

So would you feel comfortable putting a sparco sprint in a buggy that may get the occasional trail beating?

kmcminn said:

So would you feel comfortable putting a sparco sprint in a buggy that may get the occasional trail beating?

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Please sit in one before buying.
I know these seats as they are everywhere in Europe.
They are not meant to be slanted like most bouncers I see. On top of that the bottom cushion is terrible in my experience, most guys end up modifying them.

I watched the clip BustedKnuckle posted. Chris stated the shoulder harness should be at an approximate 10* angle from the shoulder to the harness bar. That being said, is that accounting for the seat at a 90* angle ? If the seat is kicked back at a 15* angle, would that make the shoulder harness number 25* to the seat or stay at 10* ? Any clarification would be beneficial as I will be starting on my cage / seat mounts soon and want to get it setup correctly. Thanks.

kmcminn said:

So would you feel comfortable putting a sparco sprint in a buggy that may get the occasional trail beating?

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It depends on if you fit the seat or not, if you fit it would probably be ok but the seat doesnt offer much side support. From what I see, you guys are bounced from side to side as much as you are up and down, so Id get a seat with some shoulder support.

As far as t

Bebop said:

Please sit in one before buying.
I know these seats as they are everywhere in Europe.
They are not meant to be slanted like most bouncers I see. On top of that the bottom cushion is terrible in my experience, most guys end up modifying them.

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Why would they mounted at an extreme angle? Headroom? The padding is actually adequate from the factory for most applications, but its not ideal. You have to realize that if you're not bouncing up and down in the seat you can deal with less padding. I'm not a fan of suspension seats, but if its what you have to work with setting up the belts properly will make it way safer and more comfortable. My points are as much about harness set up as they are about seats, don't hesitate to correct your harnesses if you cant change the seats.

rugger99 said:

I watched the clip BustedKnuckle posted. Chris stated the shoulder harness should be at an approximate 10* angle from the shoulder to the harness bar. That being said, is that accounting for the seat at a 90* angle ? If the seat is kicked back at a 15* angle, would that make the shoulder harness number 25* to the seat or stay at 10* ? Any clarification would be beneficial as I will be starting on my cage / seat mounts soon and want to get it setup correctly. Thanks.

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0 to 10 degrees is the best, there are several variables..one is you may end up at 0 degrees if you sink in the seat at all after driving, different head and neck restraints can be a factor as well. Once the angle of your seat is fixed, run a level from your shoulders to the mounting point to figure out the belt angle. 10 degrees is 10 degrees on the belt angle, the seat position shouldn't matter unless I don't understand your question.

We have a part we're about to release that will weld onto the crossbar behind the seat and give you 3 inches of vertical adjustment.

Jeff Furrier said:

0 to 10 degrees is the best, there are several variables..one is you may end up at 0 degrees if you sink in the seat at all after driving, different head and neck restraints can be a factor as well. Once the angle of your seat is fixed, run a level from your shoulders to the mounting point to figure out the belt angle. 10 degrees is 10 degrees on the belt angle, the seat position shouldn't matter unless I don't understand your question.

We have a part we're about to release that will weld onto the crossbar behind the seat and give you 3 inches of vertical adjustment.

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Okay, that answers my question. I am interested in the part you will be offering that offers 3" of vertical adjustment. My wife will be driving the Jeep as well, she is 5' 2" and I am 6' 2" and I want both of us to be safely restrained...especially if she is driving ;D

I believe he's asking about a seat being in a reclined position. It is common for room/ comfort to have the front of the seat mounted higher/taller than the rear of the seat. So the harness would be countering different forces if mounted in the same position as when the seat was mounted flat.

The way I read it no matter the seat angle the harnesses need to pull back not down. As far as one dudes opinion in a seat I say let a few people try the seats before a blanket comment is made. Hell if we just listened to one guy no telling where we'd be. Unless it was Timmy that's Bible....lol

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Yeah seats in some bouncers laid back at a 45 degree angle...

Like this one, look at :12 seconds in, good side shot.

WES KEAN NEW BUGGY! - Rock Bouncer for sale

or showtime

:46 seconds

SHOWTIME TIM CAMERONS NEW BUGGY

Seat angle isn't the problem once your in the seat the harness needs to pull back not down it what I gathered. Look at a fighter jets. They get more g's without hitting anything, the harness pulls back on the shoulders not down.

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But which way is "back" if your spine is at a 45 degree angle ? Perpendicular to your back? Or parallel to direction of travel?

If the seat fits you properly (seat belt slots at correct height above your shoulders) and the belts are mounted up close to the seat then you probably can't get them too far out of spec

I would think having the harness slots in the seat at the right height would be an important part. You especially wouldn't want them lower than your shoulders. It might not make a huge difference for vertical containment but I imagine if forward progress was abruptly halted, there would be some pretty significant compression forces at work.

Open wheel road race cars have the seats laid back 40 degrees-ish, the belts mount to the tub directly behind the shoulder.

The problem with most suspension seats s that the harness holes are rarely high enough and are usually just slots with no adjust-ability.

Instead of thinking about a straight spine, think of it as an aligned spine.,,your spine is never really straight.

The closest thing Ive worked with to a rock buggy would be Ultra 4's and other KOH vehicles, they are usually built in the the seat in the traditional upright position. I'm not sure I have understanding for the need to have the seat laid back in a buggy, but I know most seem to be set up like that...whats the advantage?

I'm not trying to jam the hard shell seat deal down anyone's throat and I don't really consider it an opinion, its more science than anything and they are being used all over the world. Desert and short course racers were apprehensive at first as well, now the majority have switched over. If you want to use a suspension seat, use it but set the belts up properly.

Jeff Furrier said:

I'm not sure I have understanding for the need to have the seat laid back in a buggy, but I know most seem to be set up like that...whats the advantage?

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I can't speak for everyone but in my case it came down to packaging. Granted, I'm not anywhere close to a 45° angle but the front end of the base is about 3.5" higher than the back. Otherwise, I would have needed to raise the entire seat 3.5" or move the whole thing back about 6". Neither were realistic options so laid back it was.

I guess I'm still trying to wrap my head around it all. All the talk of testing body movement seems to refer to high speed crashes during desert racing factoring in front collision and side to side movement in a rollover, and not the hard hit from the bottom like casing on a jump or landing skid-plate-first on a rock from a 20 foot drop.
Makes me think of the science project in school trying to drop an egg from two stories up without it breaking. The only kid who passed that test hollowed out a Nerf football and put the egg inside, thus securing it against any movement that wasn't countered by foam. Reducing that foam layer to 1/2" would have shattered the lightweight egg on impact so I'm trying to understand how a thin layer of high density foam can save a 200 pound man's spine from a drop on a rock. Not saying it wouldn't by the way, just asking the question.