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  1. #1
    Join Date
    Jun 2007
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    Huntington Beach, CA
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    656

    Default 3 Point Seat Belts -vs- 4 Point Harness

    So I am at a point in my build that I need to decide if I want to go with the 3 point seat belts like the ones from Morris Classic Concepts or a 4 point harness that requires a roll cage to be welded in. My car will see some Auto-X, but 90% of the time it will be street driven. Comfort is an important factor for me with this build and I have been searching to find something that will give me the best of both worlds.

    3 Point Belt from Morris



    My dilemma with a 4 point harness is you are physically locked in. Once you’re buckled up, your upper torso will have very little movement. That’s fine for the track, but I would prefer a little “slack/comfort” in the safety belts when I am cruising around town. If I wanted to lean forward to open the glove box, I would need to unbuckle first.



    But then I came across these 3 point harnesses made by Schroth. Below is a portion of their description of their S.M.A.R.T. restraint system.

    S.M.A.R.T.™ (Sensor Modulated Automatic Restraint Technology) represents the most advanced design in restraint systems today. The system features a unique 'thinking' electro-sensor which constantly monitors abnormal movement and force inside the vehicle while in motion. During normal driving conditions, the Autocontrol's sensor allows the inertia reel to 'relax', enabling occupants to move more comfortably and freely in their harnessbelts. But, if the electro-sensor detects rapid acceleration or deceleration, a high G-force turn, quick side movement or inclines over 25 degrees, it will INSTANTLY lock the inertia reel and secure occupants in their seats - the safest possible position in a collision.

    http://www.hmsmotorsport.com/store/schroth-tuning/autocontrol/autocontrol-II


    They also have a cutoff switch that puts the seat belts into “lock down mode” that would be great at the track.

    The Cutoff switch is designed to be wired into the inertia reel. When switched, the reel will be locked and the harness will be static. When open, the reel functions normally. A functioning motion sensor is imperative for this to be a safe installation.

    The first thing I noticed with the Schroth harness is that the mounting point behind the shoulders would require the “cross bar” roll cage bar to be set back further to accommodate the roll control mechanism. Other than that, I think I like this set up.

    So I wanted to post this up and see if anyone had any experience with them or if any forum members had any comments.
    Rick
    -----------------------------
    " Better to Be Lucky than Good "


  2. #2
    Join Date
    Sep 2006
    Location
    Henderson,NV
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    Default

    While that is a cool idea you will be on the street 90% of the time. Install something you will use everytime. A modern 3 point will be comfy and be safer than lap belts.
    Todd

  3. #3
    Join Date
    Apr 2005
    Location
    Erie, PA
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    356
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    I had a 4 point and went back to a 3 point. The 3 point is faster to put on and allows you to reach for your radio...

    http://www.popularhotrodding.com/hot...nte_carlo.html
    Andreas
    President First Gen Monte Carlo Club
    www.fgmcc.com

  4. #4
    Join Date
    Jul 2005
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    202
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    I have a 3 pt (much cheaper from street rod supply houses) for street driving and just attach my 5 pt for the track.
    70 Mach I, dry sump & lots of mods
    70 1/2 Z28 project car

  5. #5
    Join Date
    Sep 2006
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    Southern Indiana
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    3,822
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    Gee its not hard to adapt a 4 or 5 point to street use, I actually adapted 5 way to a car. It even had a retracting mechanism, which had a lock for racing.

  6. #6
    Join Date
    Jun 2006
    Location
    Halden, Norway, Europe
    Posts
    213

    Default

    Quote Originally Posted by MonzaRacer View Post
    Gee its not hard to adapt a 4 or 5 point to street use, I actually adapted 5 way to a car. It even had a retracting mechanism, which had a lock for racing.
    I'd LOVE to get the details about that...

  7. #7
    Join Date
    Jun 2007
    Location
    Huntington Beach, CA
    Posts
    656

    Default

    Quote Originally Posted by funcars View Post
    I have a 3 pt (much cheaper from street rod supply houses) for street driving and just attach my 5 pt for the track.
    I think that is the route I will take. I will put in a roll cage and run the 3 point 90% of the time and just swap over to the 4 point on track days.
    Rick
    -----------------------------
    " Better to Be Lucky than Good "

  8. #8
    Join Date
    Oct 2002
    Location
    Houston,TX
    Posts
    634

    Default

    Quote Originally Posted by vp23271 View Post
    I think that is the route I will take. I will put in a roll cage and run the 3 point 90% of the time and just swap over to the 4 point on track days.
    Thats what I will be doing as well, I have a cage with the provision for a 5 point, and when I go tto the track just slap it in there.
    James J.

  9. #9
    Join Date
    Feb 2006
    Location
    Columbia Co. NY
    Posts
    87

    Default

    I was under the impression you really shouldnt run a 4 Pt harness, without a roll cage. In a rollover, you are pinned upright, if the roof collapses on you. Thats when bad things happen.

    Randy

  10. #10
    Join Date
    Dec 2006
    Location
    Burbs of Detroit
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    You shouldn't run a 4 point ever, IMO. In the event of a frontal impact, the shoulder straps will pull the lap belt from your hips, which can take to load, to your soft gushy center section, where you do stuff like pop spleens and hemorrage internally.

    A 3 point will fold you over the lap belt, keeping you more or less in place.

    Schroth has a folding 4 point- they double up one of the shoulder straps so the other one gives to keep you correctly positioned- They have a vid on website, if anyone's interested.

    5 point is the best way (or 6 if you have huge recline). The sub strap keeps the shoulder belts from pulling the lap belts out of position
    Greg Fast
    (yes, the last name is spelled correctly)

    1970 Camaro RS Clone
    1984 el Camino
    1973 MGB vintage E/Prod race car
    (Soon to be an SCCA H/Prod limited prep)

  11. #11
    Join Date
    Aug 2006
    Location
    San Francisco, CA
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    810
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    Quote Originally Posted by Twentyover View Post
    You shouldn't run a 4 point ever, IMO. In the event of a frontal impact, the shoulder straps will pull the lap belt from your hips, which can take to load, to your soft gushy center section, where you do stuff like pop spleens and hemorrage internally.

    A 3 point will fold you over the lap belt, keeping you more or less in place.

    Schroth has a folding 4 point- they double up one of the shoulder straps so the other one gives to keep you correctly positioned- They have a vid on website, if anyone's interested.

    5 point is the best way (or 6 if you have huge recline). The sub strap keeps the shoulder belts from pulling the lap belts out of position
    Great Info!
    Steven

    1968 Camaro: Project "TRACKDAY"

    Latest Track Weekend Video

    Build in Progress



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