View Full Version : Harnesses
tnord
06-09-2002, 09:49 PM
this is mainly for bbp and maybe transient, lances13, mark, and maybe there are a couple other competition guys around. last fri i installed my 5pt harnesses, and of course i don't have a roll cage, and am using a stock seat, so i had to get the 75'' H shoulder belts. i had some issues finding a place to drill holes for the hardware, the location i finally decided on was the deckplate where the rear speakers are mounted. there are two indents right behind the speaker where small holes already exist. my question is, is this a sturdy enough location to mount the belts? i have seen other people do the same, but not on a 240. it seems like a sturdy enough location, but simulating a 80-0mph stop by way of a tree or wall is difficult. does anybody else have harnesses w/no cage?
flipboi13
06-10-2002, 12:05 AM
I'm not part of your so list.. but if you want my opinion... on the s14 (or s13?) I wouldn't mount the harness on the deck lid because it isn't really a piece of reinforced metal.. You might want to try bolts on the rear seat like the bolt holding the rear seat belt spring and the bolt holding the lower lap belt clip. Basically the bolts holding the passenger in the rear seat behind the driver. I was also thinking of putting it in the bolts holding the drivers seat to the floor but i'm not sure if this is reliable.
uiuc240
06-10-2002, 12:20 AM
well, first off, i remember reading something a while back about the angle in which the harness should be mounted. IIRC, it should go back from your shoulders as close to horizontal as possible. the rear seat belt anchors may be too low. it could be dangerous in a crash.
but more importantly, you should NOT be running a harness without a cage. if you don't want to get a full cage right now, just get a basic one like Art has (MI SO FST). that will be enough to keep you safe and give you something to mount to. i know you've already been racing in midwest council, but seriously. you owe it to yourself and your passengers to get a cage if you're going to rock a harness.
Eric
flipboi13
06-10-2002, 04:09 AM
UIUC?? Haha UIC up here man!! (and don't even think about talking down to the ghetto u of i <img src="http://www.zilvia.net/f/iB_html/non-cgi/emoticons/crazy.gif" border="0" valign="absmiddle" alt=':crazy:'>) Anyways, thanks for the input, i didn't know that!!
HippoSleek
06-10-2002, 06:47 AM
Well, you already know how I feel about a harness w/o at least a 4-pt. bar... (which I may be in the market for by fall <img src="http://www.zilvia.net/f/iB_html/non-cgi/emoticons/sad.gif" border="0" valign="absmiddle" alt=':('> )
Nonetheless, if I am understanding right, you just drilled into the rear deck and attached there? (I assume you used large bolts and washers on the bottom of the deck?) My recommendation would be to use a piece of AL or steel bar beneath the deck. Then sink bolts through the harness mount, the deck, and the bar - and then put a nut on there. That way you transfer the load from a smallish area of AL on the deck (all force concentrated on the area of a single washer) to a larger area (the total surface area of the bar from one bolt to the other. That way instead of being up a creek if one side pulls out, you have to have the whole damb thing break through that deck. <img src="http://www.zilvia.net/f/iB_html/non-cgi/emoticons/crazy.gif" border="0" valign="absmiddle" alt=':crazy:'>
This is mere speculation on what SOUNDS like a good idea from my office - note that I haven't seen the exact application or mounting area (although I recall the deck being kinda flimsy). In other words, if it sounds like I don't know what I'm talking about - it just might be true <img src="http://www.zilvia.net/f/iB_html/non-cgi/emoticons/wink.gif" border="0" valign="absmiddle" alt=';)'> <img src="http://www.zilvia.net/f/iB_html/non-cgi/emoticons/blush.gif" border="0" valign="absmiddle" alt=':blush:'>
uuninja
06-10-2002, 07:20 AM
You are absolutely right, there is really no good way to simulate 80 to 0 in to a wall. I wouldn't risk it. The rear deck lid isn't even part of the frame IIRC. Rahter it's welded to the strut towers. Don't quote me but that is what I remember it looking like, when I installed my rear STB. Because of that I would go with some thing that is proven rather than some thing that might work. Not to harp on the whole harness with no cage, but I don't see the harness alone giving a lot of protection over regular seat belts with out a proper seat and cage. No matter how securly mounted it is.
tnord
06-10-2002, 08:04 AM
yes yes........i know of the concern about harnesses with no cage........but don't tell me......tell MCSCC. the stock belts are still in the car and get used for everything besides council events btw. and to whomever asked, harnesses are safer than stock belts in anything but a rollover. the rear seatbelt mounts was my initial idea for mounting points, but the angle from the seatback to the mounting points can be no less than 45 degrees. and seeing that i sit all the way back, this does become an issue. yes, the deckplate is welded to the strut towers iirc. yes there are rather large lockwashers and nuts keeping the eyebolts in place. after the install i yanked on the straps as hard as i could, probably producing a few hundred poinds of force, they held fine. how much more is produced in a crash? i don't know. i like marks idea of reinforcing the deckplate, me and the other guy doing the install actually thought about this, but it was 9pm on a friday and i had beer to drink. i suppose i should be asking the cheif of tech this question.
flipboi......i know you weren't on the list, but the response is welcome.
uuninja
06-10-2002, 09:01 AM
</span><table border="0" align="center" width="95%" cellpadding="3" cellspacing="1"><tr><td>Quote (tnord @ June 09 2002,10:04)</td></tr><tr><td id="QUOTE">after the install i yanked on the straps as hard as i could, probably producing a few hundred poinds of force, they held fine. how much more is produced in a crash? i don't know.</td></tr></table><span id='postcolor'>
I don't know either, but I am sure that a whole friggen lot is a safe guess <img src="http://www.zilvia.net/f/iB_html/non-cgi/emoticons/biggrin.gif" border="0" valign="absmiddle" alt=':D'>. When I was skydiving (I know apples and oranges but hear me out) <img src="http://www.zilvia.net/f/iB_html/non-cgi/emoticons/wink.gif" border="0" valign="absmiddle" alt=';)'>. My jump master said that the opening force was some thing over a thousand pounds on the straps maybe more (don't want to exagerate). Since in a basic skydive you are hitting terminal velocety at ~120mph (belly down) and slowing to only a few MPH on opening with in a second or 2. The function of the the harness in both cases is roughly the same. If anything, I would think that the force on the harness greater in a car going 60 to 0 in less than a second.
Travis,
I'm going to have to look at my car when I get home, but I think you would be fine putting an eyelet in the stock rear seat belt bolt hole. I don't think the angle is going to that severe, but I will have to look at it.
Another option is using the rear deck. If you do this make sure you put a big plate on the back side and double nut it or safety wire the bolt or eyelet in place. Also whatever you use as a backing plate, make sure the edges/corners are rounded so it doesn't act like a can opener and cut thru the sheetmetal.
A third option is have some one fabricate a bar with two tabs welded on the end of it. A muffler shop or anyone with a welder can do it for you. Bolt this bar in between the upper mounts for your stock belts. then you can use shorter wrap around style belts. I did this in my CRX (i know, i know) and it worked great, saw a few of these in 911's over the weekend (theirs were brushed stainless steel, very pretty)
As for the force of an impact is much greater than you can imagine. I am not real crazy about real long shoulder belts because the matrial is designed to stretch a bit under impact. These may stretch more than short ones, possibly causing injury.
A for the comment of 5 point not being as safe as the stock belt. I disagree. If you are in a rollover where the roof is compromised, the impact of the roof collapsing is going to probably going to kill you regardless of the restraint system.
sykikchimp
06-10-2002, 12:51 PM
I read somehwere that the force of a car hitting a wall at only 40mph was somewhere areound 35-40 G's Sooo.. from 60 maybe 50-60 g's?
uiuc240
06-10-2002, 01:11 PM
What's up flipboi! I'd never rip on the Flamers. <img src="http://www.zilvia.net/f/iB_html/non-cgi/emoticons/hehe.gif" border="0" valign="absmiddle" alt=':hehe:'>
This is taken from http://www.uma.org/files/whybelt.txt
*******************
Seat belts, air bags and harnesses in automobiles are designed to accomplish one primary objective: to hold the passenger and the vehicle tightly together so that they react as a single object. That allows the much smaller passenger to take advantage of the much greater weight of the vehicle they're riding in to reduce the G-forces at work on his or her body during impact. Today's NHTSA load rating requirement for automobile seat belts is 20-G's.
********************
If the belts are rated for 20 g's, I assume that crashes can be 20 g's. That means that your body is accelerating into those belts at 20 TIMES the speed of gravity. Suddenly your 200 pound body (or whatever) is exerting one TON of force on each of the two seat belt mounting points. So, before you test it on the track. Hook those rear deck mounts up to your neighbor's SUV, put your car in gear, and see if he can rip them out. OK, so that's a joke. But really, yanking on them a few times is NOT a test of durability in a crash. We just want you to be safe, bro. <img src="http://www.zilvia.net/f/iB_html/non-cgi/emoticons/inlove.gif" border="0" valign="absmiddle" alt=':love:'> <img src="http://www.zilvia.net/f/iB_html/non-cgi/emoticons/tounge.gif" border="0" valign="absmiddle" alt=':p'>
Eric
240 2NR
06-10-2002, 01:36 PM
Well I'm pretty much in the same market here since if I want to compete in the autox in a few weeks, I have to get my ass in gear and get my harness together too.
I have a 93 HB and I was considering drilling through the trunk panel and reinforcing my mounting points. I think that will make for a good low rise setup, since I'm pretty sure the stock rear seatbelt mounting points will be too low (in any case I'll be installing it with the help of a MC steward so whatever I do should be legal). As for the rear deck mount, I have seen others do it in an S14, but I would be skeptical of how strong that really is. The setups have always been street cars and not subject to track rules. I know Tony ran a 3 pt harness at the track school back to the upper seatbelt mount and it was frowned upon. I'd hate to see you hack up the car and find out it won't pass tech.
Honestly, if you can find one, a harness guide bar is probably your best bet. I was shown a couple at a place that speacializes in porsches so the bars were really nice and really expensive. I really have no idea of the availability for a 240, but I imagine they are out there.
tnord
06-10-2002, 01:50 PM
i don't think the bars are out there, but as always, you can have somebody make one for you. i'm not an idiot, i know that yanking on the harnesses isn't a sufficient simulation. but do you have a better way of testing? at least i know they are somewhat secure. in the end, i'm gonna have to call up chief of tech in the next couple days to see what needs to be done. and steve, if you need some harnesses, i can refer you to a good source.
uiuc240
06-10-2002, 02:15 PM
Travis, I don't have a better way to test it. And don't worry, I know you're not an idiot. I'm just trying to get you to see the reality of your decisions. You may not roll. You may not crash. But if you do either, you could be in for serious trouble...that's all I'm saying.
Has anyone considered welding something between the shock towers that would serve dual function as a STB and a harness mount? Naturally, it would have to be very beefy, but this might work well. Then you'd just have to trim out a hole to pass the belts through (and line it with plastic trim or something). It's just a thought.
Eric
240 2NR
06-10-2002, 02:23 PM
Travis, what is this good source? I'm really not finding much by googleing on the internet for some. I'm pretty much planning to get either a Sparco, Simpson, or Schroth. Anything you discovered while looking that may be of help?
tnord
06-10-2002, 04:01 PM
check out donnybrooke motorsports (http://www.donnybrooke.com/site_home.htm) since i work for them at the track, i am partially bias, but Don Bodine is a good man and will do what he can to help you. you can't order through the website, but just give don a call and see what he can do. if he can't get what you want, check out northstar motorsports next.
HippoSleek
06-10-2002, 04:42 PM
</span><table border="0" align="center" width="95%" cellpadding="3" cellspacing="1"><tr><td>Quote (bbp @ June 10 2002,12:49)</td></tr><tr><td id="QUOTE">A for the comment of 5 point not being as safe as the stock belt. I disagree. If you are in a rollover where the roof is compromised, the impact of the roof collapsing is going to probably going to kill you regardless of the restraint system.</td></tr></table><span id='postcolor'>
I dunno about that. I've seen a few cars go over slowly and a few go over fast. Either way, the passanger compartment will collapse most of the way down on a car without rollover protection.
With a 3 pt. belt, you can slide to the side and hope that the car doesn't flatten beyond the door sills. With a 5 pt., you become the fulcrum until the seat back or you neck breaks... and then you have to hope the car doesn't flatten beyond the door sills (provided (a) the seat back has broken free and can go below this area and (b) the seat back broke in a way that didn't leave your body getting twisted in some other unexpected way.
Mark
-who knows people who have walked away from rollovers w/ 3 pt. belts, but has heard some not-fun stories about rollovers w/o cages, but w/ harnesses <img src="http://www.zilvia.net/f/iB_html/non-cgi/emoticons/sad.gif" border="0" valign="absmiddle" alt=':('>
Another source of info for info on belts is FIA (http://www.fia.com/homepage/selection-a.html)
The rear strut tower bar is a good idea. If you put a plate under the rear deck, that would be fine too.
You may want to check a SCCA GCR and see what they require. It will be very specific as to what kind of reinforment you need.
tnord
06-10-2002, 09:48 PM
that would be great if i ran with SCCA. <img src="http://www.zilvia.net/f/iB_html/non-cgi/emoticons/hehe.gif" border="0" valign="absmiddle" alt=':hehe:'> but i don't, i run with MCSCC, and i don't have a GCR from them either for some odd reason, i suppose i should get a hold of one. <img src="http://www.zilvia.net/f/iB_html/non-cgi/emoticons/biggrin.gif" border="0" valign="absmiddle" alt=':D'>
flipboi13
06-11-2002, 04:35 AM
Another dumb question, but this all happens during autocross or drag?? I still practice drifting at 40mph w/ my stock seat belt... and this is all scaring the CRAP outta me...hehehe
tnord
06-11-2002, 09:23 AM
this is purely an "auto-x" discussion. no driver worth his weight in nomex drag races.
uiuc240
06-11-2002, 09:35 AM
Travis, that comment really didn't need to be made. I agree that turning is more fun, yes. But there is DEFINITELY skill involved in drag racing. I guarantee a veteran at the track would school you, in your own car no less. Learning how to stage, how to play the lights, how to launch, how to properly slip the clutch to keep the powerband where it needs to be, when to shift, how to shift, etc. yes, it's pretty easy to do in a 15 second car. but get behind the wheel of a 9-10 second beast, and I'm sure you'd have more respect for a drag racer. and they need NOMEX more than you.
Eric
240 2NR
06-11-2002, 12:18 PM
Hrmm, I have a MC GCR from 2001 and 2002 and I've been a member for about 3 months (but I also live in Madison where they are written and printed I believe). If you want I could mail you the old one, not much has changed if anything (AFAIK for autox), or at least scan the pages important to this discussion.
tnord
06-11-2002, 05:34 PM
bah......maybe the comment was unwarranted. and sure, there is some skill involved in drag racing, but still, are you even going to try and compare john force to even the lowest F1, CART, WRC, etc driver?
drag racing is a challenge for the engine builder, not the driver.
I know I really shouldn't get into this, and there's this loud voice in my head telling me not to, but I must. I will however, make it short:
I agree w/ tnord. <img src="http://www.zilvia.net/f/iB_html/non-cgi/emoticons/smile.gif" border="0" valign="absmiddle" alt=':)'>
<puts on nomex suit>
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