Seat Belts--3 to 4 point

[fnmag58]

I have a question regarding seat belts. I have a 1982 that came from the factory with standard seat belts(lap belt and one diagonal shoulder belt). I have a 4 point harness set-up for the car and was wondering what the proper method is securing these to the frame--mostly for the top of the shoulder harness to the center of the car. Any thoughts?

 

Thanks--Sal

[bsimon]

If the car is a Caterham, there are threaded bosses in the top lateral cross member behind the seats. The holes are about shoulder width at each seat position and will be hidden by the boot cover. Caterham supplies steel shouldered bushings that bolt through holes cut in the boot cover into the bosses. The bushings allow the belt hardware to pivot properly.

 

Look at section 7 page 6 of the built manual HERE.

 

There was a safety harness thread sometime back that you might wish to read here.

[fnmag58]

Hi Bob,

Thanks for the info--my car is a 1982 production Caterham but it does not have the threaded bosses you mentioned. So is there any other way or am i stuck with the original attachment method and use the 3 point system.

 

Thanks!!

[slomove]

Not sure if this is a touchy subject in Caterham circles but I have heard that people call the 4-points "suicide ropes". In fact, if you go to a NASA track day they will let you on the track with regular 3-point lap/shoulder belts or 5-point harnesses but not with 4-points straps.

 

Makes some sense as you will likely slip under the lap belt in an accident and mush your thigh bones into your pelvis.

On the other hand, the surgeons are pretty good nowadays and a cheap belt may be O.K. :blueangel:

 

Gert

[bsimon]

my car is a 1982 production Caterham but it does not have the threaded bosses you mentioned

 

I would loop the shoulder straps over the top lateral tube behind the seat. I imagine you'll have to cut some slots in the rear bulkhead for the straps to pass through. The various harness manufacturers have specifics on shoulder belt placement.

 

Gert makes a valid point re 4 point harnesses. F1 driver Karl Jochen Rindt died horribly as a result of submarining in a 4 point harness. There are some 4 point harnesses that will stop submarining. Take a gander at the previous thread on the subject.

[gjslutz]

I have seen steel cables with eyelets used on some other type cars to secure the belts to a structure. The crotch belt is wise also.

 

Gary

[JBH]

There was a discussion on seat belts a few weeks back in a "Musings" thread in the General Sevens section that discussed many of the safety issues and mounting locations for five and six-point harnesses. I recommend reading the Schroth document (http://www.schrothracing.com/docs/Competition_Instructions.pdf) to get a sense of the issues. It is pretty comprehensive and should give you all you need to know to make a decision and locate the proper mounting points.

 

A few things to remember:

- your mounting locations must be able to withstand the forces of a crash without failure or substantial deformation

- in a crash, all belts stretch so you want the shortest distance between the mounting point and your body

- as someone pointed out above, belts are intended to be in contact with the structural parts of your body: your hips and shoulders.

- combining the three concepts above, in a crash you want your body and belts to remain in a fixed relationship to one another. A six point harness is the way to go. A seven pt. may be even better.

 

 

[fnmag58]

Wow--what an education. Thanks to all who posted the great info. Looks like I need to give up on the 4 point and look at a better system. The car will primarily be driven on the street but the added protection and security is needed. So back to the stock system for now--get rid of the 4 point--and do more research. Thanks again for helping me avoid a mistake.

Sal:iagree:

[Kitcat]

I switched from 3 point to 5 point belts a few months ago and the new belts have made the car much more enjoyable. Instead of feeling precariously attached to the car, I now feel glued to it. So I am much more in tune to what it is doing and can take full advantage of its responsiveness.

 

Sure. it is a bit of a hassle to belt up every time but this is offset by the opportunity for another Walter Mitty experience (Here's the intrepid Le Mans racer now, belting in for what promises to be a historic drive....).