Rollbar / seats / harness stuff, yet again...

wstar · 02-28-2012, 09:57 AM

Yeah that stock bar is relatively well mounted, and probably does some good in terms of lateral chassis stiffening, but I wouldn't trust it as a harness mount at all. The forces from the belts would be going longitudinally, and in that direction it's a pretty weak item. Not suitable for a harness mount (not to mention it's a bit further back from the seat than you'd like. The closer the better on harness lengths).

RoshDawg · 02-28-2012, 01:00 PM

Quote:

Originally Posted by sig11

There is no stock harness bar. The stock brace bar is not safe for mounting harnesses.

Quote:

Originally Posted by wstar

Yeah that stock bar is relatively well mounted, and probably does some good in terms of lateral chassis stiffening, but I wouldn't trust it as a harness mount at all. The forces from the belts would be going longitudinally, and in that direction it's a pretty weak item. Not suitable for a harness mount (not to mention it's a bit further back from the seat than you'd like. The closer the better on harness lengths).

Oh okay good to know. Wstar have you figured out the final plan for what you're going to do for your harness solution yet?

wstar · 02-28-2012, 01:36 PM

Nothing for now. CG-Lock and stock belts

Long Term, the plan that's coming together in my head goes something like this:

1) Swap my reclinable pseudo-racing seats that are on sliders for fixed FIA buckets on solid mounts (bolts to adjust, like the normal ones you see with vertical stripes of bolt holes), which have proper holes for anti-sub straps.

2) *Then* put in a well-designed 4-point rollbar, with the harness bar set at the right height based on where my shoulders end up in the new seats, pad it with something that makes a little more acceptable street-wise but is still SFI-rated (dual-density or orange-aid or something like that), and install 6-point harnesses at the same time. Leave seatbelts in the car for street usage, and be extra careful.

3) When the car gets to the "rides to the track on a trailer" stage, upgrade to a full cage and rip out the seatbelts and the airbag system (well, and lots of other changes, but those are the ones most relevant to everything here).

RoshDawg · 02-28-2012, 06:03 PM

^
That's a good plan! You should make sure that the 4 point rollbar can be easily welding onto a future full cage.

I'm almost considering still getting the 4 point harness and using the stock bar as a harness bar JUST to be more planted into the seat (more than the CG Lock I would assume), while simultaneously wearing the stock belt in case of an accident. A part of me really just wants to be placed in my seat with a harness system.
Or does that just sound stupid?

martin82 · 02-28-2012, 06:07 PM

any issues with replicating this harness bar? safety etc?

wstar · 02-28-2012, 06:14 PM

That's an interesting way to do it for sure. If you're comfy with the belt routing (belts may need to cross over at that distance, and needs something to lock them from sliding sideways), and the hardware on the sides is of sufficient strength (high grade hardware, check how many lbs it can hold...), I think it could work. Subject to all the usual harness-bar caveats discussed earlier of course about rollovers.

wstar · 02-28-2012, 06:16 PM

Quote:

Originally Posted by RoshDawg

^

I'm almost considering still getting the 4 point harness and using the stock bar as a harness bar JUST to be more planted into the seat (more than the CG Lock I would assume), while simultaneously wearing the stock belt in case of an accident. A part of me really just wants to be placed in my seat with a harness system.
Or does that just sound stupid?

I really couldn't tell you. Might work, might be safe, might be something we're not thinking of in the interaction of the two belt systems. I'm still just not fond of the harness bar concept in general.

RoshDawg · 02-28-2012, 06:29 PM

Quote:

Originally Posted by martin82

any issues with replicating this harness bar? safety etc?

Here's some more info on that car:

******************************************/id/1379/pageid/1641/robispecs-street-class-time-attack-nissan-370z-simple-is-better.aspx

That method is actually my favorite, as it would serve as both a solid harness bar (as it seems pretty sturdy) and a chassis brace. It's almost like attaching a harness onto a sway bar! lol

Also notice how that Z does not have a roll bar.

martin82 · 02-28-2012, 06:42 PM

here is the link you might be trying to show

That company races cars, etc so I am pretty sure they know what they are doing. The harness seems to mount fairly well. I heard that car is now totaled.

wstar · 02-28-2012, 06:50 PM

Quote:

Originally Posted by martin82

here is the link you might be trying to show

That company races cars, etc so I am pretty sure they know what they are doing. The harness seems to mount fairly well. I heard that car is now totaled.

Well, it seems every company races cars. That doesn't mean every product they put out is good

. Best bet would be to call them up and ask them if that harness bar is meant to withstand real harness forces or not, but I don't see why they'd bother with that big bar if it didn't.

That said though, the harnesses they've presumably just laid on there for show may not be installed right. Hard for me to say without actually being there to see all the angles and lengths up close, but I'd think that those belts need to cross.

It also looks like the belts angle upwards from where they're resting in the seat shoulder slots (should be between level and 20 degrees downward), but perhaps it levels out with a sufficiently tall person's shoulder on the other side? And you'd definitely still need something else on the bar to keep the belts in place, e.g. ziptied rollbar padding at least.

I'm not an expert, nor do I play one on TV. Just stuff I'm picking up poring over safety regulations and harness/seat mfg installation guides, etc

cossie1600 · 02-28-2012, 09:13 PM

Doing a few time trial laps is not the same as a real race car

ryan0 · 02-28-2012, 09:19 PM

Quote:

Originally Posted by wstar

Well, it seems every company races cars. That doesn't mean every product they put out is good

.

Robi knows what he's doing.

I don't know the details behind that bar, but it could just be a custom fabbed one off. I'll check with him, as belts would be nice.

Quote:

Originally Posted by wstar

I'd think that those belts need to cross.

It also looks like the belts angle upwards from where they're resting in the seat shoulder slots (should be between level and 20 degrees downward), but perhaps it levels out with a sufficiently tall person's shoulder on the other side? And you'd definitely still need something else on the bar to keep the belts in place, e.g. ziptied rollbar padding at least.

Why would they need to cross?

I agree that the drivers shoulders would probably raise the belts to the level of the bar. you want about a 90 degree angle with your spine.

If you tighten the straps well enough, they shouldn't slide side to side.. keeping them in place wouldn't be 'needed'... and yould only need to keep them about 6" apart if you use a HANS.

The only thing you would HAVE to check is how the belt is looped to the bar, but at first glance that would pass any race tech. (assuming the bar is sturdy)

wstar · 02-28-2012, 10:16 PM

Quote:

Originally Posted by ryan0

Why would they need to cross?
...
If you tighten the straps well enough, they shouldn't slide side to side.. keeping them in place wouldn't be 'needed'... and yould only need to keep them about 6" apart if you use a HANS.

Apparently there's an ideal angle for the belts to be at in the lateral direction. They're not meant to go perfectly straight back, they're supposed to be ~20-25 degrees angled inward. Thus, if the bar is more than a few inches behind the seat, they end up coming towards each other pretty significantly, eventually crossing over each other somewhere around the 18-20 inch mark from the back of the seat. If the bar's further back than that, you actually do cross them over and then strap them down on the "opposite" side from where they originated. Then again while mounting that far back "works", it's more ideal/safe to have the bar much closer to the seat, so that there's less length for stretching/slack.

The idea behind putting something on the bar to limit sideways travel (e.g. ziptied padding) is that you put it on the outside edges to ensure the belts don't move out (closer to straight) while loose between rides. Or in the case that they cross over, you put it between them (since the angle would "come loose" towards the center).

Again, I've never installed one in my life, I'm just getting this from internet research. One of the primary references I keep going back to is Schroth's install guide, which has pretty detailed information on this stuff. See pages 12, 13, 18, and 28 here: http://www.schrothracing.com/sdocs/2...structions.pdf.

ryan0 · 02-28-2012, 10:40 PM

Quote:

Originally Posted by wstar

Apparently there's an ideal angle for the belts to be at in the lateral direction. They're not meant to go perfectly straight back, they're supposed to be ~20-25 degrees angled inward. Thus, if the bar is more than a few inches behind the seat, they end up coming towards each other pretty significantly, eventually crossing over each other somewhere around the 18-20 inch mark from the back of the seat. If the bar's further back than that, you actually do cross them over and then strap them down on the "opposite" side from where they originated. Then again while mounting that far back "works", it's more ideal/safe to have the bar much closer to the seat, so that there's less length for stretching/slack.

The idea behind putting something on the bar to limit sideways travel (e.g. ziptied padding) is that you put it on the outside edges to ensure the belts don't move out (closer to straight) while loose between rides. Or in the case that they cross over, you put it between them (since the angle would "come loose" towards the center).

Again, I've never installed one in my life, I'm just getting this from internet research. One of the primary references I keep going back to is Schroth's install guide, which has pretty detailed information on this stuff. See pages 12, 13, 18, and 28 here: http://www.schrothracing.com/sdocs/2...structions.pdf.

heh... i think you're getting a little picky on the details..

if you get close to this... you should be fine....

belts level to 20 degrees down from shoulder... slightly closer together (so your HANS doesn't slip through)... mounted as close as you can to the driver...

wstar · 02-28-2012, 11:15 PM

Eh, if I'm gonna spend all the money on harnesses and seats and bars and HANS, and spend all the worry about various risk scenarios, the least I can do is spend the tiny bit of extra time to install and use the belts the way they're intended

02-28-2012, 09:57 AM	#46 (permalink)
wstar A True Z Fanatic Join Date: Mar 2009 Location: Houston, TX Posts: 4,024 Drives: too slow Rep Power: 3594	Yeah that stock bar is relatively well mounted, and probably does some good in terms of lateral chassis stiffening, but I wouldn't trust it as a harness mount at all. The forces from the belts would be going longitudinally, and in that direction it's a pretty weak item. Not suitable for a harness mount (not to mention it's a bit further back from the seat than you'd like. The closer the better on harness lengths). __________________ 7AT Track Car! Journal thread / Car setup details

02-28-2012, 01:36 PM	#48 (permalink)
wstar A True Z Fanatic Join Date: Mar 2009 Location: Houston, TX Posts: 4,024 Drives: too slow Rep Power: 3594	Nothing for now. CG-Lock and stock belts Long Term, the plan that's coming together in my head goes something like this: 1) Swap my reclinable pseudo-racing seats that are on sliders for fixed FIA buckets on solid mounts (bolts to adjust, like the normal ones you see with vertical stripes of bolt holes), which have proper holes for anti-sub straps. 2) Then put in a well-designed 4-point rollbar, with the harness bar set at the right height based on where my shoulders end up in the new seats, pad it with something that makes a little more acceptable street-wise but is still SFI-rated (dual-density or orange-aid or something like that), and install 6-point harnesses at the same time. Leave seatbelts in the car for street usage, and be extra careful. 3) When the car gets to the "rides to the track on a trailer" stage, upgrade to a full cage and rip out the seatbelts and the airbag system (well, and lots of other changes, but those are the ones most relevant to everything here). __________________ 7AT Track Car! Journal thread / Car setup details

02-28-2012, 06:03 PM	#49 (permalink)
RoshDawg Track Member Join Date: May 2011 Location: NM / CA Posts: 981 Drives: '13 911 C2S Rep Power: 14	^ That's a good plan! You should make sure that the 4 point rollbar can be easily welding onto a future full cage. I'm almost considering still getting the 4 point harness and using the stock bar as a harness bar JUST to be more planted into the seat (more than the CG Lock I would assume), while simultaneously wearing the stock belt in case of an accident. A part of me really just wants to be placed in my seat with a harness system. Or does that just sound stupid? __________________ \| EVO X MR \| '11 WRX STI \| 370Z SPRT \| 911 (991) C2S \|

02-28-2012, 06:14 PM	#51 (permalink)
wstar A True Z Fanatic Join Date: Mar 2009 Location: Houston, TX Posts: 4,024 Drives: too slow Rep Power: 3594	That's an interesting way to do it for sure. If you're comfy with the belt routing (belts may need to cross over at that distance, and needs something to lock them from sliding sideways), and the hardware on the sides is of sufficient strength (high grade hardware, check how many lbs it can hold...), I think it could work. Subject to all the usual harness-bar caveats discussed earlier of course about rollovers. __________________ 7AT Track Car! Journal thread / Car setup details

02-28-2012, 11:15 PM	#60 (permalink)
wstar A True Z Fanatic Join Date: Mar 2009 Location: Houston, TX Posts: 4,024 Drives: too slow Rep Power: 3594	Eh, if I'm gonna spend all the money on harnesses and seats and bars and HANS, and spend all the worry about various risk scenarios, the least I can do is spend the tiny bit of extra time to install and use the belts the way they're intended __________________ 7AT Track Car! Journal thread / Car setup details

02-28-2012, 09:13 PM	#56 (permalink)
cossie1600 A True Z Fanatic Join Date: Jun 2009 Location: californee way Posts: 5,380 Drives: 370, Leaf Rep Power: 29	Doing a few time trial laps is not the same as a real race car

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