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i consolidated the tech i posted in another thread into this one post

tech about submarining and spine compression

Quote:it is important for the shoulder straps to extend rearward at no more than a 15 degree downward angle from the horizontal. If the shoulder straps are mounted improperly (e.g. looping the strap over the shoulder and down to a floor mount) you greatly increase the risk of severe injury from spinal compression. Submarining is also a concern with a 4-point harness system for 2 reasons. 1) Since the shoulder straps pull up on the lapbelt, it is possible to raise the lap belt above the pelvic crest bones and onto the abdomen. If the lap belt is too high, serious injury can occur to internal organs. That's why 5 and 6-point systems are used in racecar restraint systems. However, it is not possible to use these anti-submarine straps without the installation of an aftermarket seat that allows the straps to pass directly down to the floor. It is not safe to loop the anti-submarine belt over the front of the seatbecause it does not provide the correct downward force and still allows submarining. 2) A 3-point system allows some chest rotation. The right side of the chest moves forward in an accident, decreasing the tendency to slide under the lapbelt. In all but one 4-point systems, this rotation in prevented increasing submarining risk. Schroth makes a 4-point harness with an anti-submarine feature that does allow some chest rotation and decreases submarine risk.

source


sample rule book showing ineligibility of 4pt Y strap harness

here is the rule book from national auto sport association (nasa), a large sanctioning body in the US. that holds HDPE, time trial, club race and other events

http://www.nasaproracing.com/rules/ccr.pdf

section 15.5 (page 71 in the pdf file) discusses the rules for driver restraints that are permissible at nasa events

note that your harness configuration would fail on the following points
15.5.1 : your harness is 4 point, and not 5, 6 or 7 point
15.5.6 : the mounting of the shoulder harness is below a 20 degree line from horizontal from your shoulders
15.5.8 : your are using a Y type strap that does not have individual mounting points for each shoulder strap

recommended alternative to 4pt harnesses: OE belt with CG lock

there is a product called CG LOCK (http://www.cg-lock.com/track.html) that retains the safety advantages of the OE 3 pt belt and closely simulates the 'tight' feeling from being in a 4/5/6pt harness. EDIT: it does not give show points but it works

Are you allowed to keep the 3point harness and do the "tug-n-twist" they teach at Auto-x school (and thus eliminate need for CG lock)?

Quote:Ok so i have a Y Type 3 point Harness. Its not the cheapest set but I didn't have a spot to mount a 4 point at the time and whos going to put a 5+ point harness in there regularly driven car. So bascailly ur saying any Y type or 4 point and 3 point or not safe then why do they sell them I just don't get it

so first off.. i think a 3 point type driver restraint IS "safe".. (the seatbelts that come on pretty much all modern cars is a 3 point type driver restraint)...

with the OE 3 point there is no spine compression risk (no straps going around your shoulder) and no submarine risk

an unmodified car with OE driver restraints would easily pass nasa tech

secondly, yes in my opinion, the 4 point design is inherently unsafe... (at least one sanctioning body appears to agree with me)

due to the strap configuration only the 4 point harness that has a submarine risk.. to my knowledge this schroth rallye harness is the only 4 point that does not have a submarine risk.. this is a key reason why this particular schroth harness is DOT approved for street use, and others are not. (however, that schroth appears to have a Y shoulder design.. and would still not pass nasa tech)

as to why 4 pt harnesses continue to be sold, to be perfectly honest i think it is because there is a group of people out there who prioritize the looks over performance, and a group of people who does not do adequate research before purchasing vehicle modifications.... i put 4 pt harnesses in the same category as strut tower bars, tein s tech springs, incorrect offset wheels and cheapo 'racing seats'.. parts that look and feel good but perform their intended function very poorly

in my opinion, the driver restraints (seat and seatbelt) should remain OE unless the user is prepared to spend the considerable amount of money on an aftermarket seat, harness (and mounting points) and cage

try the CG lock.. i used it when i had an integra but i don't find it necessary in my sube

Quote:Are you allowed to keep the 3point harness and do the "tug-n-twist" they teach at Auto-x school (and thus eliminate need for CG lock)?

DP.. yea you can keep the OE 3point harness.. (they are actually really safe).. for some reason i have never needed the 'twist' but i'm fairly sure it wouldn't be an issue

naz,Mar 25 2008, 01:17 PM Wrote:DP.. yea you can keep the OE 3point harness.. (they are actually really safe).. for some reason i have never needed the 'twist' but i'm fairly sure it wouldn't be an issue
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I like the twist trick.. an unsecured beer keg and I have a lot in common on tight corners.

just a reminder all these rules and regualtions are for road racing which has alot more rules then the NHRA or the streets so for what i use my car for im still happy with my harnesses

the NHRA would need to have a SFI rated 5 or 6 poin belt system .. which is a higher requirement than NASA or your local club

if your using a 4-point harness for the street then you would want to make sure that its of top quality. I wouldn't put my life in the hands of some brand X harness system just because it looks good .. god forbid you should get in an accident on the street, or while your doing 100mph on the strip, and you have a harness system that is of low quality, or isn't fastened securly

Helmets, belts and a seat are the items that you do not want to cheap out on if you have to use/upgrade to them

schade,Mar 27 2008, 11:17 PM Wrote:the NHRA would need to have a SFI rated 5 or 6 poin belt system .. which is a higher requirement than NASA
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actually NASA *does* require SFI rated 5 or 6 point belt system.. its in the rulebook i posted earlier.. 15.5.10 talks about the SFI rating requirement and 15.5.1 talks about 5/6/7 point belt requirement


and.. for the record i want to make the remind everyone that just because something is *allowed* does not mean it is *safe*.. a great example of this is the state of Illinois which allows people to use motorcycles without a helmet. sure the 5-0 won't give you a ticket for riding without a lid, but your head does not magically become immune to head injury because of the absence of the helmet rule

physics is the same whether you are on the street, strip or road course... just because the places you go don't have rules that prevent people from doing dumb sh!t through ignorance doesn't make you exempt from physics

i hope no one finds this out the hard way by getting into a frontal collision on the street and having a loved one in the passenger seat submarine under a 4 pt harness and sustain injuries that could have been prevented by the OE seat belt