Harness install question

[Gabe]

looks like fmvss 301r prescribes a moving barrier of 40mph/64kph for rear end collisions, but many OEMs seem to vouch for the optional 50mph. i am not a crash expert and don't know what constitutes pass/fail criteria.

i did find a YouTube Playlist with 170 tests.

When I say little data I mean the 50 or 60 years of clinical research done in labs, millions of miles driven data with se sensors on a large fleet of cars as we do on frontal collisions.

YouTube videos are not clinical research.

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[i3igpete]

not quite sure what you mean by the last statement. do you mean nhtsa videos posted to youtube are untrustworthy? or that the videos could potentially be a mixture of passed and failed tests (i do notice post analysis they dont list passing threshold, hence my previous disclaimer)? or something else?

 

[razorlab]

not quite sure what you mean by the last statement. do you mean nhtsa videos posted to youtube are untrustworthy? or that the videos could potentially be a mixture of passed and failed tests (i do notice post analysis they dont list passing threshold, hence my previous disclaimer)? or something else?

Let Mr. Rivnut flex his text book knowledge. Youtube university will still be here when he is ready.

 

[i3igpete]

ok, so it looks like fmvss 301r doesn't list dummy pass fall criteria directly, but the reason it prescribes dummy configuration is because it's still subject to fmvss 208. i can't find anything regarding fmvss 208 regarding mounting hardware specifically, but it think we can conclude if the hardware fails, the dummy will whack its head against the roof/door/backseat which is an auto-fail anyway.

fmvss 301r with the faster 50mph crash has been required since 2009.

i don't know why i spent all this time reading. nobody cares.

 

[Rocksandblues]

Totally agree on the fact that there are multiple opinions and everyone does as they see fit with their cars. Opinions are talked about, but facts are demostrable, tested and studied.

The issue with seat mount anchoring for the harness is that many people add seat slider rails. That would put the force entirely on one piece which is the lock on the rail itself.

Even anchored on the seat mounts, the torque created from a collision of the seat would exert an extraordinary amount of force over the mount itself, that force would be transmitted to the screws of the seat mount that are not rated to sustain sheer forces the same way the harness anchors are. Remember that when chasis mounted, a backing plate is needed. I don’t think many people place backing plates in their seat mounts (normally you would not need them, the seat is not exposed to the same tenaion

Finally the issue with the OEM seat mount.

It is safer than a seat mounted harness. There is no question about it: the OEM seatbelts are designed to travel and lock. The inertia of the belt decreases the speed of the driver by applying counter pressure for long (in the sense of collision timeline) period of time over a large surface area. That travel of the seatbelt on impact decreases the G forces on the entire system and allows for the rest of the restraints to work (mainly the airbags).

A harness does not travel; the pressure is static and very short in time over a very very large surface area. That’s why you also need a Hans. You are basically a fixed object moving at the speed of the car over something that is not flexible. On a 35mph collision of a 180Lb individual, you get close to 7000 lbs of force over those screws, you and the seat will exert twice the weight of the car over that seat mount - or the Cusco bar. If you think you can hang two Supras on those two pieces of hardware, then that solution should be ok.

Finally let me disclose what I do for a living: I am a trauma surgeon. Amongst other things, I work with The William Lehman Injury Research Center that has done motor vehicle restrain safety and efficiency research for among others BMW for about 25 yrs.

People on the internet always think that the person you are talking to knows about something as much - or as less - as they know.

But again, to each of their own. Is their cars, and their skulls traveling at 90 mph on the track. Or worse, on the highway.

Hey doc,
If oem seats and 3-point belts are safer- according to your medical degree- why do ALL race teams use harnesses and race seats?

Something doesn’t add up?

 

[Gabe]

not quite sure what you mean by the last statement. do you mean nhtsa videos posted to youtube are untrustworthy? or that the videos could potentially be a mixture of passed and failed tests (i do notice post analysis they dont list passing scores, hence my previous disclaimer)? or something else?

Just that the amount of research done in rear collisions is not comparable with the data we have on front and lateral collisions.

 

[Gabe]

Hey doc,
If oem seats and 3-point belts are safer- according to your medical degree- why do ALL race teams use harnesses and race seats?

Something doesn’t add up?

You need to add:

“ALL race teams use harnesses and race seats and the harnesses are properly installed and they use Hans”

Perhaps I have not been clear explaining exactly what the situation is. Let me explain:

3 point restraint + airbags (OEM tested system) safer than 4, 5, or 6 point restraint system without Hans.

Properly installed (manufacturer spec) 4 point is interior to 5 or 6 point restraints. (Almost nobody has 4 point nowadays)

Properly installed 5 or 6 point WITH Hans is better than a 3 point OEM system. But it has to be properly installed and you have to have a Hans. Otherwise is not safer.

Any system that is not installed to manufacturers specifications is not as safe as a system that has been validated in a crash testing (the OEM 3 point belt)

So if you want a 5 or 6 point system that should be trusted:

Install per manufacturer’s specifications and use a Hans. Otherwise, you are safer with your car’s OEM system.

Hence why in many jurisdictions it’s illegal to drive a car using any restraint system that is not the OEM one. Don’t kill the messenger. I’m just relating facts.

 

[Rensuhlo]

Hey doc, can you take a look at this mole on my back?

 

[Rocksandblues]

Hey doc, can you take a look at this mole on my back?

Don’t lie, it’s on your butt

He is not a real dr fwiw. He just want to see you naked

Certainly doesn’t know harnesses

 

[Gabe]

Hey doc, can you take a look at this mole on my back?

Hey doc, can you take a look at this mole on my back?

Nothing that can’t be fixed with a shot of penicillin

 

[Vtec13]

thank you Bryan, the only one to actually show me what they did in their car. then it turned into another useless argument that people in the future will have to wade through when they have the same question i did. can't wait to see what my next thread will turn into.

 

[Rensuhlo]

thank you Bryan, the only one to actually show me what they did in their car. then it turned into another useless argument that people in the future will have to wade through when they have the same question i did. can't wait to see what my next thread will turn into.

Have you heard about the hidden dipstick on the b58?

 

[razorlab]

I find it ABSOLUTELY hilarious that the guy that has an RSR rollbar that is attached to the car at thin sheet metal areas with rivnuts and bolts not to spec (too small and too little) is lecturing others about crash safety.

@Vtec13 Glad to be of some help, let me know if you have any other questions about the setup.

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