Fitting harnesses

[bennyboy]

I think this has been discussed before, but I would like some detail or other ideas if possible. I'll be using a 4-pt harness, so the two shoulder straps can go to the cage and the outer lap belt to the lower seat belt mount. The inner lap belt is my issue. I have just recieved some harness eye bolts and mounting plates from DT, which a Peter and Fen advised me to weld to the transmission tunnel. However, there is not much thread in the plate, so unless I drill a hole for the eye bolt to pass through, it wont be holding onto much. So, has anybody ever drilled into the tunnel? Is there much clearance to the torque tube? Or is there a more simple solution? Thanks, guys.

 

[944 man]

A four point harness is of very limited worth in a big off: Id suggest looking for a six pointer. Of course, the seating position in a 944, which will be exaggerated in a car that has a competition seat fitted, will help to prevent submarining to some degree, but Id avoid four pointers myself.

Id also take the 'anything other than horizintal straps will kill you' advice with a pinch of salt. Its one of the perpetuated internet myths that really piss me off and its constantly repeated here. My blue book confirms that the MSA are perfectly happy with straps that do not exceed an angle of 45 degrees, which if you believe the repeated (but seldom owned) wisdom, will spell certain death if you crash.....

Simon

 

[bennyboy]

Simon, I'm sure a 6 point harness will be of more worth. However, my car will only do the occasional track day, so a 4-pointer was my choice based on a cost-to-requirement ratio. Besides, I'm having enough trouble trying to mount 4 straps as it is!

 

[PJS917]

Ben,

I know this is not what Forums are for, but I have a solution that may work if you give me a call. It is a bit long winded to type and may not be appropriate anyway.

 

[edh]

ORIGINAL: 944 man

A four point harness is of very limited worth in a big off: Id suggest looking for a six pointer. Of course, the seating position in a 944, which will be exaggerated in a car that has a competition seat fitted, will help to prevent submarining to some degree, but Id avoid four pointers myself.

Id also take the 'anything other than horizintal straps will kill you' advice with a pinch of salt. Its one of the perpetuated internet myths that really piss me off and its constantly repeated here. My blue book confirms that the MSA are perfectly happy with straps that do not exceed an angle of 45 degrees, which if you believe the repeated (but seldom owned) wisdom, will spell certain death if you crash.....

Simon

Very limited worth? - surely not? - 6 point should be better, although I've seen some very grisly "de-gloving" pics (were they posted here?) from badly fitted 6-point harnesses...

as to the "internet myth" - here's a source
http://www.schroth.com/installation-instructions/en/index.html

OK - so it doesn't mention "certain death" [] - it says "severe injury or death", which is fairly dire IMHO

Shoulder Belt Routing · Shoulder belts must run from the shoulders horizontally or down, at no more than a 20° angle. · In cases where the shoulder belts must be routed down to the chassis floor, support by a roll cage bar or harness guide at the appropriate height is essential to establish the horizontal shoulder strap routing off the shoulder/HANS®. Most racing seats are not designed and tested to carry shoulder belt crash loads from downward installation. Severe injury or death could result. A 45° downward shoulder belt installation is possible with seats that SCHROTH has positively tested to take a load measured during a 50 kph [31 mph] and 28 G impact with a 75 kg (175 lb) dummy. Refer to the list of SCHROTH approved racing seats in section "About Seats".

The approved seats list is here: http://www.schroth.com/tuning/seatlist.php

 

[944 man]

I thought that Id written 'fairly', but I am rushing today. As I have pointed out though: with a lowered seat in a 944 the risk of submarining is greatly reduced. With regards to the horizontal straps myth: the last time that I viewed Scroths 'information' page it read more like an extended advert..... Im sure that I can find a page on the internet that confirms that the earth is falt and another that clearly states that the house of Windsor are actually all lizards: this doesnt make it true though. Cars have been built with straps at 45 degrees for twenty - thirty years that can remember. I grew up around racing cars, ny grandfather built them and my uncle is a professional racer: and Ive seen a lot of crashes and a lot of crashed cars. If this nonsense was correct then there wouldnt be any racers left!

 

[Tam Lin]

ORIGINAL: edh

as to the "internet myth" - here's a source
http://www.schroth.com/installation-instructions/en/index.html

OK - so it doesn't mention "certain death" [] - it says "severe injury or death", which is fairly dire IMHO

Shoulder Belt Routing · Shoulder belts must run from the shoulders horizontally or down, at no more than a 20° angle. · A 45° downward shoulder belt installation is possible with seats that SCHROTH has positively tested to take a load measured during a 50 kph [31 mph] and 28 G impact with a 75 kg (175 lb) dummy. Refer to the list of SCHROTH approved racing seats in section "About Seats".

The approved seats list is here: http://www.schroth.com/tuning/seatlist.php

Thanks for the link
1) Product liability considerations mean that if I was producing seatbelts, rather than scrutineering them, I'd want to protect the product from claims as much as possible, too
2) How strange that one of the most common seat types, Recaro, are not listed
3) How strange that a manufacturer of such renowned seatbelts offers those horrid pads, which in the event of a serious frontal accident allow the body a nice 1/4" of spongy acceleration before smashing into the belts themselves

 

[edh]

Tam - I think Keiper Recaro is Recaro

The Scroth installation manual lists these FIA approved seats for harness angles of up to 45deg - presumably because they have been tested for strength? (which is what the website says)
The Harness angle "myth" looks like common sense doesn't it? There's a bit of a difference between finding any old website and a manufacturer's one (particularly German IMHO). My reading of that is that you offset the potential for problems by having a seat that is strong enough. (I guess there are people out there fitting these harnesses with an "ebay special" that may be very poor )

Keiper Recaro: 070.80.xxx Profischale, 070.81.xxx Profischale 070.90.032 Profischale SP-A, 070.91.032 Profischale SP-G Pole Position König: RS 1000 , RS 2000, RSL 1000, RSL 2000 Protech Seating Limited (Corbeau): PRO-RACE PR-1 SEAT, PRO-RACE PR-3 SEAT, PRO-RACE PR-4 SEAT, PRO-SPORT PS-1 SEAT, PRO-SPORT PS-3 SEAT, PRO-SPORT PS-4 SEAT Wiechers: 300, 301, 302, 303, 304, 305, 307, 403/413, 404/414
Does anyone know if the FIA testing includes the capability to withstand that downward load? - which would therefore mean that any FIA seat would be OK.

 

[bennyboy]

What about the central rear seatbelt mounts on the tunnel? Too far back?

 

[944 man]

Theyre used in many, many 944 racers. Subject to your seat positioning; theyd be my mounting point of choice. If, however, you want to use a HANS, then youll need to fit weld on mounts on the leading edge of the load deck.

 

[Fen]

I don't know why you would bother fitting a safety system and not go the last mile to make as certain as possible that it will be safe. It seems clear to me that in the event my body weight has become a projectile that I want to be restrained by some straps then I'd prefer it if the straps just stopped the forward momentum sharpish without trying to convert it into downward momentum that can only be accommodated by compressing my spine and/or breaking the seat which is assisting in keeping me away from slower moving objects.

Presumably you're suggesting 45 degrees is safe enough rather than as safe as horizontal, Simon? I don't personally like "enough" when better is so easily achieved, and motorsport regulations are minimum standards at best, and subject to being updated to improve safety with every new edition, a fact which in itself highlights that there is room for improvement in safety.

Anyway, getting back to the original question: What I meant to suggest is that the reinforcing plate is mounted in the tunnel from under the car, which necessitates drilling the tunnel and then passing the eyelet through the hole and into the nut on the reinforcing plate. You absolutely need more threads through it than you could get if it were on the inside of the tunnel and the eyelot only screwed in until it bottoms out against the tunnel metalwork, and you don't want to be depending 100% on the weld holding the nut to the (thin) plate nor the weld holding that thin plate to the car.

I don't actually remember much about when I did it except that it was a big deep breath then make the hole, followed by relief / anti-climax when it was done. I don't recall anything being in the way, though I did a lot of looking to check before I drilled. My personal view is that the plate is better on the opposite side of the tunnel metalwork to the belt as it seems very unlikely it could pull through the metal whereas any sort of attachment inside the car would be less strong. The problem is that it'svery difficult to weld it on under there with the torque tube in place. I actually don't know that welding it on is essential anyway and I used an adhesive mastic to hold the plate to the tunnel simply to keep it located for screwing the eyelet into.

 

[John Sims]

ORIGINAL: 944 man

.......Id also take the 'anything other than horizintal straps will kill you' advice with a pinch of salt. Its one of the perpetuated internet myths that really piss me off and its constantly repeated here. My blue book confirms that the MSA are perfectly happy with straps that do not exceed an angle of 45 degrees, which if you believe the repeated (but seldom owned) wisdom, will spell certain death if you crash.....

Simon

Having had a mate almost die when his five point harness crushed his seat to leave him flopping about in the cockpit during a multiple barrel roll I am one of those who consider harness positioning very important.

 

[Hilux]

Having had a mate almost die when his five point harness crushed his seat to leave him flopping about in the cockpit during a multiple barrel roll I am one of those who consider harness positioning very important.

Absolutely agree.

I don't know why you would bother fitting a safety system and not go the last mile to make as certain as possible that it will be safe. It seems clear to me that in the event my body weight has become a projectile that I want to be restrained by some straps then I'd prefer it if the straps just stopped the forward momentum sharpish without trying to convert it into downward momentum that can only be accommodated by compressing my spine and/or breaking the seat which is assisting in keeping me away from slower moving objects.

Ditto

I`ve been banging on about this in other threads every time it comes up.

I consider the only properly safe options are.................

1) Fix rear straps to a bar designed for the purpose on the roll cage.

2) Fix rear straps to rear floor pan however they must be over a harness GUIDE bar at or just below horizontal.

Show me one professionally prepared car that has the harnesses at 45 degress (without a guide bar) and I`ll only accept it if it is proved the seat is strengthened accordingly.

I have a 968 harness guide bar which I was going to adapt but havent got around to it yet.

Anyway, getting back to the original question: What I meant to suggest is that the reinforcing plate is mounted in the tunnel from under the car, which necessitates drilling the tunnel and then passing the eyelet through the hole and into the nut on the reinforcing plate. You absolutely need more threads through it than you could get if it were on the inside of the tunnel and the eyelot only screwed in until it bottoms out against the tunnel metalwork, and you don't want to be depending 100% on the weld holding the nut to the (thin) plate nor the weld holding that thin plate to the car

Without wishing to sound picky or clever.............why not weld an FIA sized plate to the inside of the car on the tunnel and then weld the harness mount to it? In shear its ok but on a boot floor where its a straight pull out etc I`d weld one under or a much bigger one over.

 

[Tam Lin]

ORIGINAL: Fen

I don't know why you would bother fitting a safety system and not go the last mile to make as certain as possible that it will be safe.

Because there are degrees of safety? Hans would be a lot safer still. As would lightweight carbon helmets.

I used to rally, driving and codriving. With it came some spectacular crashes. All were very different, and probably different aspects of equipment saved me. In Ypres, the driver rolled a BDA powered Gp 4 Mk2 Escort at pretty much 120 Mph. We came away unscathed, somehow, but it was very frightening to notice that my race uniform was covered in battery acid.

When you crash, you hope the car's integrity, the safety equipment you/others have provided, together with the duty guardian angel are enough. But there's no such thing as "safe".

 

[bennyboy]

I think the shoulder strap issue has been debated at length, so let's leave that for now. Just going back to my idea of fixing the inside lapbelt to the rear central seatbelt mount...

Theyre used in many, many 944 racers. Subject to your seat positioning; theyd be my mounting point of choice.

944 man, I just want to make sure you are reffering to this belt, and not the shoulder belts?
I suppose using this mounting the strap would be almost level, perhaps going up toward the rear of the car a little?

and you don't want to be depending 100% on the weld holding the nut to the (thin) plate nor the weld holding that thin plate to the car.

Fen, the plates I got from DT don't have a nut welded to them, the thread is within the depth of the plate.
I appreciate what you are saying about mounting inside the tunnel, but I'm not skilled enough to remove the torque tube and my opinion is that a good weld will suffice.

 

[Fen]

ORIGINAL: Hilux
Without wishing to sound picky or clever.............why not weld an FIA sized plate to the inside of the car on the tunnel and then weld the harness mount to it? In shear its ok but on a boot floor where its a straight pull out etc I`d weld one under or a much bigger one over.

I'm not sure what you mean. Personally unless someone convinces me different I would prefer to have the reinforcing plate on the other side of the tunnel to the harness such that the eyelet would have to pull the reinforcing plate through the hole in the tunnel to come out as I can't see that that can be anything other than at least as strong as having something welded to the inside of the tunnel. I agree that a plate on the inside of the tunnel also would make it stronger still. I suspect that in a sudden stop from speed with my installation the tunnel might deform around the eyelet and a plate on the inside would help reduce that.


My DT plates are squares of steel maybe 4 inches on a side with a hole in the middle and a nut welded to one side.

 

[Hilux]

Understood but if fully welded I would have thought it would be strong enough

 

[Fen]

We're back to "should" again, which is like the 45 degree shoulder straps. I guess it depends on the quality of the weld as it should as you say be possible to do it well enough. The plates are pretty thin on the mounts I have though and I looked at them and didn't even condier they might be designed to go anywhere but behind other sheetmetal. I guess ultimately I just think there is a way to do it that makes it almost certain that the belt won't pull the mount off in a crash and that is how I'd prefer to do it as that makes me more comfortable.