Harness bar

How should the bar be made and what size tube? It still needs to be removable for non track use.

Stan

It shouldn't. Do not use just a harness bar, especially for track use.

If you're going to wear a harness, you need at least a 4-point rollbar. The reason is, a harness will hold your body, neck, and head upright. If the car rolls over it will crush the roof lower than your head and cause major damage. With a regular 3-point belt, your body will fold sideways. You won't feel good, but your head will still be on your shoulders.

You need real rollover protection to keep from injuring yourself.

And if you're driving hard enough to need a harness, you're driving hard enough to need real rollover protection, anyway.

Schrothe makes a DOT legal harness that gets around the problem Salanis is speaking of. They are the only ones I know of that make one that is DOT legal.

No, he's talking about the problem that a harness is designed to hold you in place in the seat, and the potential for your head to become a supporting structure in the car's new orientation due to this. DOT-approved has nothing to do with it.

ya the harness bar isn't strong enough to support the car in the event of an oops .... whereas a roll bar is....

Sigh, please do some research on the product before you reply next time. The harness is partly DOT approved because it is built to allow you to move around a little in the case of an accident because it stretches like a factory belt.

In reply to fiat22turbo:

You are probably talking about the 4pts that are DOT approved. If they do allow that much movement, not much point in the first place is there?

Last I checked they don't cure the issue of head/spinal compression upon a roof collapse.

I also say no harness without rollbar or fixed back seat to be honest.

fiat22turbo wrote: Sigh, please do some research on the product before you reply next time. The harness is partly DOT approved because it is built to allow you to move around a little in the case of an accident because it stretches like a factory belt.

Where did you get that information?

From what I understand, the purpose of the shoulder belt stretching is to prevent submarining under the lap belts (the shoulder belts give so the torso rotates around the lap belt). Last time I spoke to Schroth, I was told that the stretching was highly elastic and minimal - not enough to get your head and neck anywhere near parallel to the collapsing roof structure. Especially if the roof is collapsing from the front windscreen back, as is often the case when a street car rolls on the track.

You're not going to be ducking out of the way of a collapsing roof with stock 3 point belts...

As I understand, all belts and harnesses stretch. That is not to prevent submarining. It is to absorb the force of an impact. They absorb the force of a deceleration by deforming, rather than acting like a brick wall.

In a 3 point belt, you will not move quickly enough to duck. But if you're rolling, that means there are lateral forces on the car. Those forces will bend your body sideways. Since the shoulder belt does not hold your torso laterally, you will be folded down by the forces of the crash, below the new roof-line.

If you have a 4+ point harness that holds your torso laterally, you will not fold down. Your spine will become a supporting structure for the new roof line.

docwyte wrote: You're not going to be ducking out of the way of a collapsing roof with stock 3 point belts...

No, but the stock seat has the ability to fail and fold backwards. And the 3pt belt allows the body to be pressed in towards the middle of the car. You don't have that with a harness or solid back seat (proper combo + rollbar/cage).

In reply to Salanis:

You're right. All harness belts do stretch. The Schroth ones just have a special weave to stretch a little more on the shoulders because the "DOT legal" 3 and 4 point belts don't have sub belts.

boxedfox wrote: You're right. All harness belts do stretch. The Schroth ones just have a special weave to stretch a little more on the shoulders because the "DOT legal" 3 and 4 point belts don't have sub belts.

That's a different issue. It's not to prevent submarining. It's to transfer more load to your pelvis (which can take a lot more force), rather than your chest/collar bone.

They're still going to hold your body upright.

Once again: If you're driving hard enough to need a harness, you're driving hard enough to need a rollbar.

Salanis wrote: Once again: If you're driving hard enough to need a harness, you're driving hard enough to need a rollbar.

+1, I wouldn't track a car with a harness unless it had a minimum of a roll bar.