Harness/roll bar Tech

[matt'sdrag95]

Harness/Roll bar Tech

I’ve seen bits and pieces here and there about people buying harnesses, or roll bars for one reason or another, or for one purpose or another and it made me want to compile a list of what I feel are important information for all interested parties.

If you want to use a harness/racing seat/roll-bar there are things that you should know, and I’d like to cover some of them. I cannot cover everything, but if this thread evokes a discussion then maybe the topics I cannot cover will come up on their own.
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The very first thing is general rules of thumb when using harnesses/roll bars.

1)Harnesses (with the exception of the DOT approved Schroth 4pts, which I’ll get into later) are not approved for street use, so you should never use them as a replacement for your factory belts.

With that in mind…

2)Not all seats are compatible with both the factory belts and harnesses. Deciding to use one or the other, or an aftermarket seat is a compromise you may have to make.
(one way to get around this is to sometimes unbolt the factory belt and run it through the harness holes in the seat, however this does not always work)

3) This is VERY important: You should never install harnesses without the use of roll over protection. I’ll get into detail below on how 3,4,5,and 6pt belts work, but in short look at it this way; if you run a harness and no roll bar/cage and you flip the car
you=broken-neck=dead.
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Now that we got that out of the way let’s get in detail on each.

Harnesses/Belts:

Not all Harnesses are created equal! And right along with that, not all designs (3pt,4pt, etc) are safe.

Believe it or not your factory 3pt belt is safer than some out on the market.

So there are four different types of belts:

3point
http://www.fhp.state.fl.us/PhotoGall...s/PG102703.jpg


4point(the infamous DOT approved Schroth “harness”):
http://m3.madrussian.net/diy/schroth_rally4/21.jpg

5point:
http://www.dougrippie.com/images/racing_seat.JPG

and
6point:
http://www.nurburgring.org.uk/trip_r...-harnesses.jpg

Now in the event of a straight on collision (like contacting the wall) each belt will work differently, and as follows:

3point: Will allow your upper torso to move forward, hit the air bag, and then will send your body down (submarine) under the lap belt (see how this keeps you safe in a roll over?).

4point: Will try to not allow your upper torso to move forward, however since there is no anti-submarine strap (otherwise known as a crotch strap) the lap belt will rise and allow you to slip underneath it. The crappy “DOT approved” Schroth belts are notorious for causing injury because two things happen. First is the shoulder belts stretch and fray, and then the lap belt yanks up your stomach and has ripped some people up)

Here’s a link to an incident where a guy in an STI hit a wall on an open track course. Both he and his instructor were wearing those great Schroth DOT 4pt (insert sarcasm here) the shoulder belts became so stretched that they submarined quite badly, and both ended up in the hospital. I believe both ended up in a coma.

“Both passenger and driver were wearing open face helmets. Driver hit sparco steering wheel, bending it. Passenger was a female who went under her shroth 4pts and was found in the footwell area. People said he was going maybe 80+ into the wall. Really sucks, especially since it’s a very small wall in the big stretch of open land. One of the instructors said they were both in stable condition, but looking at the sti up close made me feel that it was much worse. The driver side area was pretty bloody. Steering wheel, dash and harnesses had blood on them. My friend even saw a bloody sock nearby. Both were airlifted”
http://forums.nasioc.com/forums/showthread.php?t=800056
http://www.jtuned.com/forums/showthread.php?t=786
http://www.corner-carvers.com/forums...oth#post337904


5point: the anti-sub strap will keep the lap belt down and tight so the shoulder straps can be cranked down hard so you do not move forward, side to side, and you will not slide down (if installed correctly).

6point: the 6 point will do everything the 5point does, only a bit better. Since the dual anti-sub belts wrap around your legs they hold you in place better than the one crotch strap.

Belt Mounting:
The best way to mount the belts is to the factory mounting points for the lap belts, and to a horizontal tube attached to a roll bar/cage for the shoulder straps.
A crotch strap (or any strap that must go through the floor) should be backed on either side of the floor by a 6” diameter 1/8” thick plate and a MINIMUM of grade 8 hardware used, however I recommend aircraft grade.

The angle of the shoulder straps to the roll bar should not exceed 45degrees as to avoid compression of the spine.
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Roll Bars/Cages:
Ok so now you’re decided that you want to spend more time on the track and have found that either dictated by class rules, car, or yourself that you need harnesses; which furthermore means that you need some form of roll over protection.

The very first thing you should do is pull out the rule book for the type of racing/events you plan to participate in and build it/have it built according to those rules.

What’s the point in having this bling bling, great cage/bar built if it’s illegal in the place you want to use it right?? RIGHT!

Typical rule of thumb in most classes is that you cannot modify the floorboards to fit tube,
http://homepage.mac.com/thomasmoran1...935F2D11D8.jpg

And every tube that terminates on the body must be welded to a plate and then to the floor.
That is to spread loads so you do not rip up your floor.
Wrong:
http://homepage.mac.com/thomasmoran1...5D5F2D11D8.jpg
Right:
http://www.dariusrudis.com/mustang/r...s/mvc-140f.jpg


The main hoop and rear bars of a roll bar/cage should be welded to the car. A bar will not protect you in a crash or roll over if it rips the bolts out of the floor, weld it!

Diagonal and horizontal harness bars can be removable if desired, and as long as the mount is strong you should be fine.
http://memimage.cardomain.net/member...0_208_full.jpg

http://memimage.cardomain.net/member...0_209_full.jpg


So how’s this for installment #1?
I’ll see what questions are left after reading this and if need be I’ll make another installment.

Matt

Edit: One last request please. I think we will end up sticking this so please try and keep to the topic, thanks.

[Flyboy 06]

You know, I was typing a thread about what all the info was on a harness, and right before I began typing, I hit the search button and found this. Great deal of information. Basically, what it comes down to is there is no safe way to put in racing seats and harnesses and still use my backseats like normal. That is the delimma I am in now, I want the seat/harness set up, but I think I might need my back seats still, so I am not yet willing to do a RSD and put in a roll bar that would interfere with getting into and out of the back seats. ****, but oh well.

Edit: I see that you still have your back seats. If you remove the bar to allow use of the back seats, do you just replace the bar when the passenger is all in? That bar is your harness mounting point, so you cant drive without it right?

[bluetuesday13]

good information.
very interesting in reading what is "right/wrong"

[Flyboy 06]

HAHAHAHAH, nice sig, those cars were the ****.

[matt'sdrag95]

Originally Posted by Flyboy 06

Edit: I see that you still have your back seats. If you remove the bar to allow use of the back seats, do you just replace the bar when the passenger is all in? That bar is your harness mounting point, so you cant drive without it right?

There are two types of bars, the bolted in horizontal "harness bars", and the "rear bars" that go from the top of the main hoop to plates welded to the floor.

My rear bars were a compromise for the time being because i wanted to retain use of the rear seats (when the harness bars are removed, just like you were thinking). Ideally there would be no bend in the rear bars and they would connect to the horizontal bar between the shock towers, but since the angle would not allow it, I welded a piece to connect them.

To answer your question, yes the rear seat can be used when the harness bars are removed. Obviously rear passengers are only present on the street, and like I stated above, you should not be using harnesses on the street(I won't even get into the fact that 99% are deemed Illegal!).


An even better way to promote use of the back seat would be to have the horizontal AND diagonal bars welded together and have that entire "unit" bolt into the main hoop. That way when you remove it you have nothing obstructing the rear seat.
[also notice in these pictures that you can make an even FURTHER compromise and have the rear bars just run back maybe between the seat and the plastic interior and weld it to a plate welded to the shock tower(not as effective, but it'll still work)]
http://motorheads.net/mustang/rollbar/Dcp_4996.jpg
http://motorheads.net/mustang/rollbar/DCP_4997.JPG
http://motorheads.net/mustang/rollbar/Dcp_5004.jpg

Matt

[Flyboy 06]

That helps a little, its nice to know that I can get a cage that will allow me to keep the rear seats, but the car in those pictures has the stock 3-points, I want 5-points. And I know, they are illegal, but they are safer and I am not the type that runs into police often. I couldnt get my ideal set up of seats and harnesses with no cage, so im not gonna do it. Thanks for the info Matt.

[tedness]

Harness Note:

I'd also like to point out that if you are an autocross or road racer, a 5 or 6-point harness can be one of the best mods you can do to make yourself feel planted into the seat.

You may have the world's stiffest suspension setup, but if you're being jostled around in your seat then you're losing a lot of the road-hugging feeling that's being transfered to the car but not the driver.

This can really come into play if your car is a daily driver and don't want to shell out $700+ dollars for a pair of racing seats that provides not only good bracing but more importantly for a daily driver, especially with good passengers, good comfort.

Plus, unlike a racing seat, a racing harness will unlikely change your vehicle class.

[greensteeda]

what is the best way to mount the racing harness if you want to keep your stock seat belt

[matt'sdrag95]

you can attatch the lap belts to the factory bolts on either side, mount the crotch belt as mentioned above, and then the shoulder belts to a roll bar.

the instal will be the same pretty much if you have a stock seat or racing seat.

Matt

Edit: one BIG thing to keep in mind however.. if the "stock seat" does not have a headrest that the shoulder belts can pass under then do NOT run a harness because it will
1) be at a VERY bad angle, and
2) can slip right off the seat.

I think some mustangs might have come like that, but I know my ranger was like that and that was the reason why I bought real racing seats.

[want2twinturbo]

ok i know this thread is old but do you think it would be easy or slightly easy to get this harness in my car? I have an 03 and i hate the way it takes forever for the seatbelts to recoil so i figure i might be able to put one of these in and have it look good along with fuction decently and i wont use the stock seat belts http://www.performancecenter.com/pro...ss&universal=0

Edit; i dont know if anyones computer will have massive popups showing up dont shoot me if it happens, the link works fine on my computer