Harness attachement points - De-dion chassis

[DaveMorris]

I've got two de-dion cars in the garage at the moment (one too many I know)

 

On the older car ('88 chassis) there is provision for attachment of the crotch straps of the 6 point harness on two steel lugs at the rear of the cockpit. Also the waist straps attach to anchor points about 2 1/2" forward of the rear bulkhead.

 

On the newer (97 ish) chassis the waist strap attachment points are ~5" forward of the rear bulkhead and there are no lugs sticking out from the rear bulkhead on which to attach the crotch-straps.

 

Where should they be fitted?

Is there a prescribed way to do this?

(Only option I can think of at present is to drill thru floor+floor bracing plate and use this - but I'm not too keen).

 

Dave.

 

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[Mick Day]

My crotch straps are attached to the rear seat mountings.

[Pierson]

Mine are 'piggy-backed' on to the lap belt mounting points using longer tensile bolts. I know that this is technically not a 6-point mounting configuration, but still a 4-point installation instead - any load applied would only be met through the 4 usual mountings. However, the crotch straps do allow me to drive without 'submarining'. How they might stand up in a heavy impact I hope to never find out....

 

Pierson

[SLR No.77]

Dave, on my '99 chassis the leg loops are attached to the rear (redundent) seat mounting brackets. There's approximately 20 - 25mm gap between the brackets and the floor - the mounting buckle and an aluminium spacer are used to fill the gap, with a bolt then passing through the bracket, spacer, buckle and floor, secured with a nut to the underside of the car. The harness was fitted by Caterham, therefore the spacers should be readily available.

 

Stu.

 

www.superse7ens.co.uk..........the rebuild 😬

 

 

[Casbar]

I mounted mine to the floor by drilling new holes, and spread the load with two ali strips.

[Irrelevant]

Casbar: That seems a bit dodgy to me . . . In a shunt I had, I was using the proper lugs at the back of the floor with bolts going through the floor, and one of the bolts almost pulled itself out of the lug - I mean it almost tore out horizontally. Using spacer washers will not help much, the ally just pulls out and you are left with an extra bit of ally that used to be in the floor.

As crotch straps are real life savers in a bit frontal, you really do want to make sure they won't fail . . .if they do, you can easily end up a pile of jelly in the footwell with the belt buckle in your throat - just ask Joachim Rindt.

 

Best to use all 6 attachment points.

Next best, double up on the side points.

Worst, bodge some kind of fastening through the ally floor.

[Casbar]

Didn't have the lugs as its a 98 chassis. Spoke to Bruce at Arch he told me how to mount the straps. Drilled the mounting holes through the channels at the rear, then rivited ali bracing strips in the gauge he recommended between holes, then bolted through.

 

Each strap has its own two mounting points.

 

Having spoken to Steve at Tillet, he said that cutch straps should really be bolted just under where they come through the seat, so that in a rear end shunt, they would stop the driver going backwards out of the seat as well. But with the length of straps etc I couldn't see how to engineer that solution, even if they went through a sleeve under the seat hole, you wouldn't be able to adjust them.

 

I will give Bruce another call to check up, if I'm in any doubt I'll re-mount them doubling up on the side mounts

 

Edited by - Casbar on 1 May 2007 11:30:36

[Irrelevant]

Casbar: It looks like you've researched it and taken expert advice. I pictured a sub-optimal solution when I read "spread the load with two ali strips", that's all.

[DaveMorris]

Stu - your arrangement is what I have on the '88 chassis, and indeed that is how I mounted the straps on the red/yellow crossflow. They're not there however on the Vx

 

I don't want to use the side mounts as I think that they're too far forward and the webbing would foul the seat runners (possibly being abraded by the backs of the runners).

 

I went for a temporary fix using "the Casbar solution" (on the basis that any crotch strap is better than none) but without the additional plates.

I'll be fitting additional weight, in the guise of aluminium strengthening plates, when I've had a couple cut to size at work. Infact if I can get brackets welded up so that the plate fastens onto the waist belt mounting points then I will probably do that.

 

Based on past experience I feel more comfortable with the 6 point system in place.

 

Thanks all,

 

Dave.

 

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