Technical 4-point seat belts

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Safety equipment in a race car is designed as a package. The belts are stronger than street type with an additional
crotch strap. There is a "Hans" device involved for the head. There are head restraints built in the seat along with kidney and hip supports. There are arm restraints in the belt system. Air bags might be of some use to protect the body from flying debris but not for the same intended use as in a street vehicle.
Roll bars for the street if designed properly add to safety. "Designed properly" is the key here. They add to safer street driving but are no where as good as a legal race cage system.

 

NASCAR actually use 5 point or more seatbelts, those extra belts being crotch straps, used to hold the lap belts in the proper position over the pelvis, and not allowing the driver to submarine under the belts, and not being restrained properly. Passenger car 3 point belts are designed in such a way that the upper body rotates during an impact, the body rotating towards the door on that side of the vehicle. This locks the lap portion of the belt in the proper position over the pelvis, and also keeping the body from submarining. However there is more upper body movement, and this is where the engineers have devised the total system, with airbags, to prevent parts of the body from hitting solid stuff, like the doorframe, during an impact.

Race belts are kept as tight as possible, to minimize movement, however as in many aspects of life there were unintended consequences for the drivers before hans devices. Locking the body so rigidly but not the head resulted in a whipping motion. This led to basal skull fractures and fatalities. The hans device keeps the head from whipping. However nothing is perfect, and now drivers are experiencing concussion symptoms, as the brain is not rigidly fixed in the skull. It can still slam into the inside of the skull during high g deceleration.

Ultimately the goal of safety devices is to lengthen the time for the deceleration, lessening the peak, and lowering the damage to the body. So seat belts are designed to stretch a bit controllably, while restraining the body and minimizing other impacts. This lowers the peak deceleration. Roll cages should be able to deform again controllably, staying intact and not allowing the driver to get outside of the cage.

Some organizations require that the cage s relatively close to the driver, others require plenty of clearance, to keep body parts from impacting the tubing in an accident. And allowing room for the tubing to deform again controllably absorbing energy and extending the time to decelerate.And absorb multiple impacts (think the big one at Daytona).

To your question: can a cage be safe on the street? Yes, but...there's always a but.it needs to be designed for the vehicle (I know, kind of obvious), adequate clearance to all occupants in case of an accident (not so easy for back seat passenger safety), fabricated and installed properly, and materials selected for the intended use.

I have an ot vehicle with a full rollcage, built to SCCA specs, and when assembled it only had 2 seats, both FIA approved at the time it was built. SCCA has a minimum clearance specification for the driver's head wrt the cage, both above and behind the head, there's no written maximum specifications, however the vehicle dimensions will determine that. And it needs to be padded with energy absorbing padding with SFI rating.

Hope this helps you

 

Simply -
1 - That would be NASCAR, not Nascar, to be more accurate.

2 - Yes, somewhat obviously. The big, 3" wide belts do not stretch nearly as much as a more narrow factory (OEM) belt.

3 - Again, somewhat obviously. That double 3" wide running down your chest will hold you much more securely in your seat. BUT as mentioned, they must be tight to work properly.

4 - NO, unfortunately, as can be seen, the belts are...NOT...connected, wrapped around, or in front of your face. SO, the shoulder harness will do nothing, directly for any head protection.
Neither will the OEM three point belt system, either.
See, airbags, or a Hans Device, (also not for the street !).

5 - The main reason that a "roll cage",..."may" be dangerous on the street, is because tubing is in close proximity to your head. So even a light crash, or even a good pot hole could direct your head right into that solidly built roll cage bar, and do...some long lasting damage to your head. The cage bars would sometimes be unpadded, and closer to your head than the OEM door frame. Even light padding might not be enough.
BUT...a well designed cage, and seat placement can alleviate the above problems, along with some proper rubber padding attached to the tubing.

6 - A well designed "roll bar" assembly, has less possibility of damage per the above comments.

Note - I just bought a custom built, drag race / street legal car with a full roll cage. One of the first things I did was to...lower the seat ! See note #5 above.

Mike

 

Most fatal injuries in motorsport, where the car structure is largley in tact, tended to be side impacts. Belts, bars etc do nothing to help, if your C Spine snaps you die instantly.

Modern race cars are safer because of the use of crash helmet restraints and seats that are designed to protect the upper spine.

 

Safety is a compromise. In racing where crashes are relatively common and often occur at very high speed it makes sense to accept some discomfort to be as safe as possible, with a 4+ point harness to keep you in place, a helmet to protect your head, and a roll cage around you to keep the car from being crushed. All these do a good job of keeping you safe, but they all also limit your freedom to move and be comfortable. Acceptable if you drive on the ragged edge and it lets you survive a crash into a concrete barrier or a full grown tree at high speed.

On the other hand, not a lot of us would accept all that hassle just to get in the car and go grocery shopping, dropping of kids at school and so on. So instead of the maximum safety we go for good enough without annoying the users too much. A 3 point seat belt keeping them mostly in the seat, airbags around them preventing them from moving around and hitting hard objects too badly, and a rather rigid car body instead of a dedicated roll cage. It's far from perfect, but a pretty good compromise for safety equipment a manufacturer need people to use every day despite it being unlikely that it ever will be used (most cars are never involved in a crash, they just get driven until old and worn out).

 

I hate it when I do that...

 

See a lot of 3 point belts, and 5 point harnesses, but not many 4 point belts.

Also, the type of racing has a lot to do with how the driver needs to be restrained, and what type of cage is required. When there's more than one car on the track, you have to consider impacts from other cars.

I guess this is a useless reply....

 

Shoulder belts need to be correctly mounted. Too high the driver can forward too low, and they can compress the driver's spine causing spinel injures.

There is no such thing as a "NASCAR" because NASCAR is a sanctioning body.

National Association of Stock Car Auto Racing.

They sanction everything from Cup, X-finitely, Craftsman truck series to the Pitney Series, NASCAR north, NASCAR west, NASCAR Modifieds to weekly short tracks.

Referring to this as a NASCAR-


Would be like referring to him as a National Football League.

 

Not at all...

Schroth make what they call the harnessbelt. I think it's all one word. Anyway some versions are true 4 point belts, and DOT legal. They work by having one of the shoulder straps having a unique fold sort of thing that allows the body to rotate, analogous to the way factory 3 point belts work, to lock the belts to the body preventing submarining. But still minimize forward motion of the upper body reducing the likelihood of hitting stuff inside the car. I seem to remember reading that there's also a version of hans device designed to work with them for cars used in track day events. Don't quote me on that however...

 

These guys have covered a lot of the points between racing safety and general public safety. I'll add 2 more small points. Vastly greater size variations of the meat bag being protected without the car being sized specifically for them and the physical condition of said meat bag.

 

FTR: airbags are SRS devices, as in Supplemental Restraint Systems.

Some of the biggest push for them came from corporate legal departments.

Why? People refused to wear seatbelts, and their estates were suing car manufacturers for max-bank when the driver got killed in a crash.

People still refuse to wear seatbelts, too. Our local news calls out "ejected from the vehicle and pronounced dead at the scene" every few days.

My anecdote: I got hit in the wifemobile. The impact was hard enough to deploy multiple airbags, and fully total the car.

I was wearing my seatbelt, which aggravated my bad shoulder when the explosive restraint retracted it.

Without that, I'd be certainly dead.

I climbed out (of the passenger-side) with three broken fingers, two sprained thumbs, two sprained wrists, one sprained elbow, and first and second degree burns on my hands, wrists and forearms.

All from airbag deployment.

For a street car, get front seats with good side bolsters and headrests, and install inerta-reel 3-point belts (and watch out for idiots in BMW's driving 80+ in hard rain).

 

My airbags in our winter car deployed at around 45mph and all I got was the stink of the explosive. Wonder why you got burns...?

 

SANCTIONING body...

 

Gunpowder from the charges.

The vehicle had a small steering wheel, and a very compact cockpit.

 

Corrected but I am terribly sorry; I was trying to get it written, posted and see what the uninvited and unwelcome person snooping in my yard was doing!

 

In 1967 I walked away from two helicopter crashes that I was wearing a 4 point harness while flying as a scout observer in the birds. First an OH=6 that had the tail rotor drive shaft snap after it had been shot partitally in two earlier in theflight. We spun into 50/60 ft trees and were hanging upside down a few inches off the ground when things stopped and all three of us got out without a scratch. Second time we were in an OH 13 and had an extreme hard landing in a spot that my pilot missed some huge rocks to put the bird down without hitting one. i wouldn't be here except for those harnesses.
One thing with the 4 point is that you gon't tossed around if you are trying to get the helicopter or car back under control as you might with just a seat belt or even a 3 point.
A few years ago I was rear ended by a garbage truck while stopped in traffic while a school bus about 10 rigs ahead negotiated a traffic circle. I had time to turn the wheel and try to get out of his way when I saw him in the mirror but ended up being driven into a Johnson barrier rather than under the box truck in front of me. Seat belt and shoulder harness saved my bacon that time even though it w as one of those crappy 90's shoulder belt that fastens to the door rather than the door post. 92 Geo Prism GSI that was totaled but I drove it 150 yards to a parking lot and towed it home the next day with my one ton. I would have gone through the windshield on the second impact on that one without the belts
Gimpy posted:
People still refuse to wear seatbelts, too. Our local news calls out "ejected from the vehicle and pronounced dead at the scene" every few days.
IN post 14. I've seen way too much of that around here. As often as not a young woman or teen age girl who didn't want to muss up her top. My wife had a coworker thrown out of a Dodge durango and killed that if she had had her belt on would have walked away from the roll over with a few bruises.

Still if you spin out by hydroplaining after hitting a puddle or hitting the brakes while hitting some gravel on the road or locking up the brakes because of of what ever reason, if you are firmly held down in the seat you can put all of your attention to regaining control rather than hanging on and staying in the seat. That can prevent being in a wreck. The belt doesn't just function in the crash, it often functions to help you stay out of a crash because you can concentrate on getting the car under control

 

I beg to differ....

Look at the vintage photos the cages are built straight up and down no crazy offsets and with gussets and the cages held up vs. the modern crazy offset no gusset design which collapse!
Note- All drivers walked away.






There are no true doorbars (the side bars are just in gussets to stiffen the chassis) a modern D.I.R.T modified they are relying on the Nerf bars, body tin and exhaust system to absorb a side impact.
Running fuel line inside the cockpit was outlawed by NASCAR 70 years ago because of the danger of line being cut and filling the drivers compartment with gasoline, now it's common place!


And something no one is talking about is these modern cars are so flexible and have so much give with these full containment seats being so stiff the full impact is being transferred into the driver and people are being hurt.

 

Not sure what you are disagreeing with in my comment. At least two, possibly three of your pics show modern safety seats designed to protect the drivers spine in a side impact.

 

sgtlethargic seat belt tensioners.
https://www.safetyrestore.com/blog/how-seat-belt-tensioner-works/

 

Vehicle safety is a big business. A lot of safety people refer to their business as risk management. Performance safety has extremely different risk factors than does comfort driving safety. Modern safety equipment in race cars are a system of components and a great deal of research has gone into making it all work together. The same thing applies to modern passenger car safety systems. Professional performance drivers don't require the same amount of creature comfort that casual drivers do and thus the discomfort associated with racing harnesses are less of a factor. Mixing and matching safety components that work in one application doesn't mean they will work the same in a different application. And when you add components to a car not designed for them, you can also be creating negative results in other areas of the safety package. Lets face it, none of our H.A.M.B. on topic cars were built with crumple zones, collapsible steering columns, air bags, or even auto locking seat belts. By adding these features and others such as roll cages and restraint systems we are becoming part of the safety engineering community. Some may be playing the role of safety designer, while others maybe taking on riskier roles like crash test dummies. Put time and thought into the what happens if question, before you just throw parts into your car.

 

Hurt like hell.

 

Hello,

Before the full race suits, full cage roll bars and what not for the so called “street legal” cars, when they became available, seat belts were required. We tried several FED shoulder harnesses in some altered cars and they were uncomfortable. The wide straps and the click in belt was not the most enjoyable, even for a short run down the quarter mile.

So, to meet the rules of safety belts, we bought a simple one that clicked together on your lap that was adjustable for any driver or passenger.
Even the top race cars had simple lap belts as per rules.

Jnaki

But, as the development for more safety came, the 5 point harnesses were the thing.
However the set up then, the straps had the slide in version with a lever lock or the quick release units with one hit unlock. So, at least they were adjustable.


When my wife and I got our 327 powered 1940 Ford Sedan Delivery project, we drove it around until we could not drive safely. So, it was out of commission for months of repair, replace and modify to make it safe. My wife noticed that the bucket seating was making her sit closer to the dash and were limited to any more rearward adjustments. My seat was the same. I had not noticed it as I was overjoyed as owning another 40 Ford Sedan Delivery with more power, since my Flathead days in high school.

So, in order to allow both of us to select the type of seat belts we wanted, we tried all kinds. Stock configuration with the click lap belts to sitting in a modified race car with a over the shoulder 5 point harness with a quick release lock unit. She felt most secure with the 5 point harness, but there was little movement, even if we adjusted it to fit a little loose.

I liked the feeling of sitting in the bucket seat with the 5 point harness, but it did not feel like an everyday driving position. A race car for a short time run is good, but a long road trip under the 5 point harness was not the most comfortable feeling we got, trying them out.

Jnaki

So, we decided to be 20 somethings and get a set of adjustable lap belts new, from the local Chevy dealer that had the click in connection and a button release. We noted that with the seat lap belt in place, we had movement, but not to the point of hitting our heads on the hard Ford dash that seemed close to our bodies. No 5 point harness for either one of us and we definitely were not going to race our sedan delivery.

Note:
Many years later, the child safety industry started to have 5 point seat belts for the safety child seats and that was a standard for those hard shell, but comfortable cushion seats. Our toddler son got the first year harnesses that was the standard. Our granddaughter got the most updated model that had gone through many design changes for better child/toddler safety situations.

Her growing stages moved her up to a larger toddler seat with similar 5 point harnesses as the epitome of safety involved. Finally she outgrew those toddler seats and now could use the safe station wagon retractable seat belts with air bags near her.
from the Britax Safety Seats+ belt system

 

I'd expect that the importance of the crotch strap on a 5-point harness would depend on the seat's cushion-to-backrest angle and the structural design approach to the seat. The crotch strap gets more important as the angle increases away from a right angle, provided that the seat is designed to be an effective part of the vehicle structure and you're not relying on the harness to keep the seat in place in a collision. The closer the seat cushion is to perpendicular to the backrest, the more it's doing the job of the crotch strap, unless the cushion goes away.

I can imagine that submarining became a serious issue on the circuit racing cars of the '60s and '70s, which had the drivers close to lying on their backs, even though there was often no seat as such separate from the monocoque structure. I'm sure the subsequent move to more upright and feet-up driving positions had as much to do with safety as anything else.

Four-point harnesses with inertia reels are used in aircraft, and I see no reason in principle why this couldn't work in a car. Interestingly, the shoulder belts on aircraft harnesses tend to mount higher than shoulder level, sometimes even on the roof. This is in contrast to racing rulebooks which usually require a mounting level with or lower than the shoulders. Logic would suggest to me that, as the harness's job is to keep you in the seat, all the straps ought ideally to pull as close as possible to perpendicular to the backrest.

Freed of the necessity for racing certification it should be possible to rig something like the Schroth collapsible loop — basically a Z-fold with several transverse rows of not-quite-adequate stitching. Or, if you're worried about IP, perhaps something on the principle of a balance bar?

None of this should be undertaken without thinking it through thoroughly.

 

I spent 2½ years in crash and safety at a major OEM services company. Learned a lot, even got a trip to a crash test at Ford (anticlimactic even at 45mph). Lots of lawn clippings above, some good understanding of the topic. Race belts on a street car, I don't care about the science.
I think they look cool af on my vintage Ford seat

 

I’m certainly not an expert on this subject but have read a great deal about it. I think a lot of hot rodders install seat belts as an afterthought. Anchor location points for lap belts and shoulder belts are critical as internal injuries and spinal injuries can result. Read the manufacturer instructions fully and follow the instructions. For the types of cars we build (no airbags) I think four point harnesses would be beneficial keeping driver/passenger from contact with the steering wheel, dash and windshield.

As far as roll bars/cages being dangerous in a street car I think anything that adds rigidity to the chassis and protection from impact from any angle is a good thing. Early cars well into the 60’s were not designed with crash protection in mind especially very early cars with wood framed/sheet metal bodies. Seatbelts (lap belts) didn’t become mandatory until the mid 60’s. If we can incorporate safety into our cars my opinion is we should. Two of my three cars have 4 point and 5 point seat belts. Your mileage may vary!

 

It doesn't hurt to try to strengthen the supporting areas of a cars body or to incorporate somewhat better seats and belts into a build. While they may not be up to some testing standards, they should be helpful nevertheless. My plan for my 32 build is to use a rectangular box tube curved to fit the body for additional support and hopefully far enough from my head for safety. I consider it more of a body structure brace than a roll bar, and hopefully concealed beneath the upholstery and padded.. A cross brace or 2 behind the seats for ridgidity and sideways strength.They will also provide attachment points for the 5 point harnesses. An accomodation will be installed that allows the seat belt to be unsnapped and then quickly raised to the roof and snapped there when not in use. I probably won't use the crotch strap for normal driving but it will be in place anyway in case I get fiesty. As for seats, my tush likes bucket seats better than a bench seat which provides no lateral support. I like the feel of the nice cushy side bolsters.........not full race support but enough to keep my wrinkled old butt somewhat in the seat. I figure the "pucker factor" during an emergency will serve me well for providing additional suction to anchor me to the seat as well..........

 

I have 3-point belts in my Ford and they work great. I took my time with the installation. I have made a few hard stops and they kept me in place.

 

My post was in regard to modern chassis roll cage design, not only does the roll cage protect the driver from impact and roll over but is also stiffens the chassis.

The modern school of thought particularity on dirt is to allow the chassis to flex and act as part of the suspension, as a result of this gussets, and diagonal bars that stiffened the chassis and supported the roll cage have be eliminated and bars in the cages or the cages themselves are collapsing during rollovers, and no racing seat is designed to support the weight of an upside down racecar.

However poor design is not limited to modern racecars.

This is from a video on YouTube of a bar being built for a Gentlemanly Race in N.J.

Unless you have a Unibody car the bar should never be attached to the body, always the chassis and even in a Unibody car the cage needs to be attached to a structure point rockers, subframe etc...

If this car had rolled the bar likely would have been push through the floor providing no over head protection.


Modern full containment seats are not designed to protect the driver from a side impact, the are designed (in theory) to keep the diver's upper body from moving during a crash, and a issue that no one want to talk about, is with these cars flexing and the seats being so stiff is the impact is being transferred through the chassis and seat into the driver and causing injuries.

All safety equipment is designed to work together, H.A.N.S. devices, full containment seats do not good if the Five Point Harness isn't buckled-

This is a video from the 2022 World of Outlaws late model race at Bristol the driver was at full speed with an in car camara and his right harness is clearly not buckled.

 

Fellas, seatbelts are better than nothing, but you are still going to smack that steering wheel. Shoulder harnesses are the way to go.