RB5_245

I also own a rally car. I would not drive it on stage with a seatbelt instead of a harness. I've smacked my head off the cage a goodun a few times that I'm always aware of it when on road sections.

Ultimately if I had to crash I'd like to be fully harnessed up in a caged car with fixed-back seats and a helmet.

Could do away with the helmet if you can get the seat mounted far enough away from the cage, but the other 3 go together as one part imo.

Dave T-S

Nobody above has accurately described what the problem is and why you shouldn't fit harnesses with standard reclining seats or without a cage yet. It's as simple as this, as it's all about levers, angles and kinetics. If you fit harnesses without a cage then the only realistic place to fit them is the rear seat anchors, which are much lower than your shoulders. In a frontal impact you get thrown forwards with the weight of a ton or so, and naturally the shoulder straps of the belts try and straighten out, and achieve this in a strong impact by collapsing the seat back forwards. You then suddenly have a foot or so of free belt and your face makes a nice impact with the airbag and goes straight through it snapping your neck. Quadraplegic time.

Harnesses are designed to be fitted with the rear facing parts of the shoulder straps out horizontal behind so the above doesn't happen. They way this is achieved is to mount them to the cage cross bar behind the seats at around shoulder height.

As a logical follow on let's also discuss having a cage in a road car without wearing a helmet. Nice and safe you think? Wrong. Imagine you get side swiped at 30mph. Not a problem, you say? Ok, replicate the accident - you sit stationary in a chair, and someone sideswipes your head at 30mph with three feet of scaffold pole. Have I made my point yet?

Dave T-S

As an aside, if you are still stupid enough to go ahead and do this (but hey, it's no skin off my nose, pardon pun, if you do ), you need to advise your insurance company, except the chances are they won't cover you then if they realise what you are doing. Alternatively, if you don't advise them, and you have an accident and end up in a wheelchair (having someone else have to look after you for the rest of your life), no payout..............

Steve vRS

Good point, well made Dave. I remember you posting something similar about 4 years ago when I asked the question about fitting harnesses in my Bugeye

Steve

Dave T-S

Steve
You are bang on, it would have been around 2002, when I had my bugeye WRX

You might also remember I had Sabelt 4 point harnesses in my WRX, but with Cobra race seats, but was never totally happy with this for the reasons in my earlier post.

As an aside again to anyone contemplating this, what I did was got hold of longer eye bolts and fitted the harnesses with the standard inertia belts so I could use the OEM belts on the road and the harnesses on track. I spent a huge amount of time looking into this and you have to fit them properly (full thread length used) or they are dangerous, and it is really not a good idea having the rear mounts fitted low down. And if anyone thinks of raising the rear fixing points by fitting them to the rear parcel shelf strut or the Isofix points on a newer car, don't even think about it. You will think it was a bit of a daft idea when you are flying through the windscreen with four harness belts flapping in the breeze behind you

RB5_245

image doctor

.....all good information, but you're forgetting one important point, it looks well cool innit.

Dave T-S

Indeed it does, and as the old saying goes, you are a long time dead

minty

iTrader: (1)

I hope mine passes ive only got six piont's in mine now (no seatbelts)

Dave T-S

Are they BS or E marked harnesses? If so, they should pass an MOT, but if they are FIA dated and the date has expired the tester can probably fail them if he's sharp enough to spot it.

DazW

iTrader: (1)

Would an inertia type harness (like the ones in the MG SV) attached to say, a rear strut brace be a better solution? ...or maybe fit a half cage & attach to that?

I want to retain my normal seat belts for road use, but have something a bit more secure for the occasional track/rally day

Dave T-S

Daz

A strut brace would not be anywhere near up to the job. In a front end smash the kinetic forces are immense as there is sudden and total dissipation of energy (Newton's third law - for every action there is an equal and opposite reaction). A strut brace would fold like a stick of liquorice and probably rip the ends out of the strut brace. Also an MG SV type inertia belt would be worse than a harness as you can't preload the inertia mechanism and there would be more slack in the belt.

However, a half cage would work well providing it has a harness cross bar to make the rear shoulder webbing attachment point for the harnesses at around horizontal.

minty

iTrader: (1)

Mine are FIA dated valid until 2010 so i have a few years on the belts before .......(do i have to fit new ones ? or can i get them re-tested???)

They are also part of a complete weld in Sparco competition cage and some Cobra Evolution bolted in bucket seats.

Carlos13

I have the harness bar that was designed to go with my cage still bolted into the car. This is bolted across the car using the remaining roll cage mounts at approx shoulder height (cage now removed).

Is it your view that I should still not use this with standard collapsing seats? I only plan to use harnesses on track, not the road.

As an aside, any harm in using the harnesses AND the seatbelt on track? Belt and braces

Dave T-S

Minty
Technically speaking, they have to be destroyed once they are out of date as they are "lifed" and the belt manufacturer would absolve themselves of any product liability issues after they had time expired.

The main reason they are lifed is for competition use - in theory someone could keep moving them from one rally car to another, have loads of massive accidents in the meantime, and the belts could get stressed beyond their design capability and fail, and the belt manufacturer gets sued.

Carlos, I haven't seen your setup so all liability excluded , but in theory providing the rear webbing ends up near horizontal, any inertia forces are taken by your shoulders and transferred to the cage, and the seat collapsing issue goes away. I personally wouldn't use the standard inertia belt on track with harnesses. Apart from the fact the harnesses will work perfectly well on their own if fitted correctly, in the event of an accident or fire (God forbid), it's one more thing stopping you getting out of the car, or someone else getting you out.

Dave T-S

Carlos

I've just reread your post. If you are saying you have taken the rear cage out and just have the harness bar in, be careful as it may not be up to the job - I would have thought it would be designed to work in conjunction with the cage, but not without it. May be an idea to ask the cage manufacturer if this is ok.