Challenge E90 Harness Bar - any interest?

[MikeM5]

Originally Posted by evilspiritM3

Right, I meant for the 335/328 guys. There might be interest there to get the numbers up for the initial run.

the more the merrier! care to spread the word?

[GTM_Challenge]

Originally Posted by evilspiritM3

Right, I meant for the 335/328 guys. There might be interest there to get the numbers up for the initial run.

Correct, it should also work on the non M cars.

[rzm3]

I usually don't chime in on these things, but this is for safety. I personally would not trust a harness bar supported by two long, small-diameter rods -- the rods will buckle very easily under load. Just my humble opinion.

Perhaps someone can show this to Fall Line or Turner to get their opinion.

[VictorH]

Originally Posted by rzm3

I usually don't chime in on these things, but this is for safety. I personally would not trust a harness bar supported by two long, small-diameter rods -- the rods will buckle very easily under load. Just my humble opinion.

Perhaps someone can show this to Fall Line or Turner to get their opinion.

I thought those rods were in tension, but by the install it does look like they'll be in compression. Agree with your concerns.

[MikeM5]

Originally Posted by rzm3

I usually don't chime in on these things, but this is for safety. I personally would not trust a harness bar supported by two long, small-diameter rods -- the rods will buckle very easily under load. Just my humble opinion.

Perhaps someone can show this to Fall Line or Turner to get their opinion.

Definitely understandable! I will try and get some clarification on this both from Greg and someone at Fall Line.

[Radiation Joe]

Originally Posted by rzm3

I usually don't chime in on these things, but this is for safety. I personally would not trust a harness bar supported by two long, small-diameter rods -- the rods will buckle very easily under load. Just my humble opinion.

Perhaps someone can show this to Fall Line or Turner to get their opinion.

The harness bar is not a cage submitted to shock load in an accident. It is submitted to a relatively mild and slow load due to tension on the harnesses. Also, the compression rods are free in two axis and will see only true compression. Assuming they aren't made from recycled curtain rods, they'll be fine.

[GTM_Challenge]

Originally Posted by VictorH

I thought those rods were in tension, but by the install it does look like they'll be in compression. Agree with your concerns.

When the harnesses are under tension or under any sort of yanking force forward the forces are not in compression on the rods downward.

Similar construction has been used by other companies over the years as well. A lot of the competition actually uses seamed steel where we use seamless.

[GTM_Challenge]

Originally Posted by rzm3

I usually don't chime in on these things, but this is for safety. I personally would not trust a harness bar supported by two long, small-diameter rods -- the rods will buckle very easily under load. Just my humble opinion.

Perhaps someone can show this to Fall Line or Turner to get their opinion.

The rods do not see downward force when the harnesses are under load. If you left the rods off and tugged on the harnesses in your seat, the bar would want to rotate forward and up. This is the best way I can help describe it


FYI: my fabricator trained the current fall line cage fabricator. I'm confident in his engineering and design.

Hopefully this info helps!

[dmw16]

Originally Posted by rzm3

I usually don't chime in on these things, but this is for safety. I personally would not trust a harness bar supported by two long, small-diameter rods -- the rods will buckle very easily under load. Just my humble opinion.

Perhaps someone can show this to Fall Line or Turner to get their opinion.

I'd be less worried about that and more concerned about being harnessed into a fixed back seat with no roll bar.

These harness bars are to pose like you race while hanging out at cars n coffee. Safety systems are designed to be used as a system. So a harness and fixed back seats without at least a half cage and ideally a HANS is less safe than your OEM 3-point setup.

[GTM_Challenge]

I of course agree that a full or 4 point cage is safer than a harness bar. Obviously a full cage deletes ever having rear passengers in the car.

[1MOREMOD]

Originally Posted by GTM_Challenge

I of course agree that a full or 4 point cage is safer than a harness bar. Obviously a full cage deletes ever having rear passengers in the car.

we dont have friends. passenger seat should also be optional on new bmws.

[dmw16]

Originally Posted by GTM_Challenge

I of course agree that a full or 4 point cage is safer than a harness bar. Obviously a full cage deletes ever having rear passengers in the car.

My point was more that the OEM 3-point system is safer than a harness bar.

A harness bar, fixed back seats, and a 4, 5, or 6 point harness is not a safe solution. In a frontal impact you aren't going to move forward the way the car expects so the airbags are less effective and really, in a harness you should have a HANS. And in a roll over you run the risk of spinal compression because you can't fall forward the way the car assumed you would when they designed the B-pillars.

A harness bar is a half-ass solution that compromises safety and is really for posers. Sorry if that ruffles feathers, but I think it has to be said.

If you want to run your car at the track for the weekend and still have use of your back seats, roll with the OEM setup or (if they make them for your car) the Schroth Quick-Fits. But skip the half way solution, it doesn't do anything other than make your car look cool to others that don't have much clue.

[GTM_Challenge]

Thank you for your comments and info.

[GTM_Challenge]

Originally Posted by 1MOREMOD

we dont have friends. passenger seat should also be optional on new bmws.

Very sorry to hear this. Lol. I guess I was one of the lucky few to have copilots

[dmw16]

Originally Posted by 1MOREMOD

we dont have friends. passenger seat should also be optional on new bmws.

Passengers just add weight and slow the car down.

[1MOREMOD]

Originally Posted by GTM_Challenge

Very sorry to hear this. Lol. I guess I was one of the lucky few to have copilots

usually just instructors and i have to pay them to be my friends!

[MikeM5]

Originally Posted by 1MOREMOD

usually just instructors and i have to pay them to be my friends!

Greg, is it possible for us to throw in a free friend with purchase of the harness bar? If so, we may be able to attract a few more buyers. Let me know if this is possible through your fabricator.

[1MOREMOD]

my e46 has cage and fixed back seats and 6 pt harness so no room for the complimentary friend anyways.

[klammer]

Originally Posted by MikeM5

Greg, is it possible for us to throw in a free friend with purchase of the harness bar? If so, we may be able to attract a few more buyers. Let me know if this is possible through your fabricator.

Awesome!!!

[rzm3]

Originally Posted by GTM_Challenge

The rods do not see downward force when the harnesses are under load. If you left the rods off and tugged on the harnesses in your seat, the bar would want to rotate forward and up. This is the best way I can help describe it


FYI: my fabricator trained the current fall line cage fabricator. I'm confident in his engineering and design.

Hopefully this info helps!

I am sorry but what you said makes no sense.

When the safety harnesses are pulled towards the front of the car (e.g. during an impact), they create a mechanical moment around the B pillar mounts, which will "pull" the horizontal bar forward (think of turning a wrench towards the front of the car). The downward bars, however, will oppose this forward "pull", hence putting the bars in compression.

(the B pillar mounts will generate an opposing moment as well against the forward pull of the harnesses, but obviously that is not sufficient; because otherwise you would not even need the downward bars)

I'd be happy to draw a free body diagram and do a summation of moments around the B pillar mounts if you'd like.

[GTM_Challenge]

Originally Posted by rzm3

I am sorry but what you said makes no sense.

When the safety harnesses are pulled towards the front of the car (e.g. during an impact), they create a mechanical moment around the B pillar mounts, which will "pull" the horizontal bar forward (think of turning a wrench towards the front of the car). The downward bars, however, will oppose this forward "pull", hence putting the bars in compression.

(the B pillar mounts will generate an opposing moment as well against the forward pull of the harnesses, but obviously that is not sufficient; because otherwise you would not even need the downward bars)

I'd be happy to draw a free body diagram and do a summation of moments around the B pillar mounts if you'd like.

The bar is lower than the harness holes in the seat, as it should be. The harness when being pulled isn't being pulled directly downward because of this. I have seen a good number of harness bars where the harness bar is higher or at the same level as the seat holes which is not ideal.

The main bar is triangulated by the 2 vertical rods ( 5/8") OD steel. While they see a load it is not the only part that bares a load and how much load depends on the angle of the pulling force (harnesses). Either way, under compression or tension, the vertical tubes would need to see massive forces to buckle them beyond what a human body could sustain.

Regardless, I am confident in the design our fabricator has put together and is consistent with other successful designs he has done in the past for years as well as other manufacturers have done in the past.

[askka]

I would be interested in a harness bar. Over the weekend I talked with a guy that had a Sparco in his 4dr AMG 63, I liked the design all you had to do was take out the rear bottom seat and bolt it in to the seat beats and you were done. Took him less than 5 minutes