Brown davis roll bar + harness + stock seat????

4sfed5 · Postby **4sfed5** » Thu Jul 07, 2011 9:11 pm

has anyone got any pics or experience using 4 point harnesses attatched to the harness bar using a stock seat?
Do the belts rub is silly places or should i use one shoulder strap on the stock seatbelt tower and one on the harness bar?

any help appreciated.

Postby **NitroDann** » Thu Jul 07, 2011 9:17 pm

Stock seats+harness=NO

With no way of stopping the shoulder straps from falling off and with no anti dive straps possible, its very arguable that the stock belt is much safer than a harness with the stock seat. I very recent thread on M.net talked about this and the seriously knowledgable super respected guys (mostly Sav from TSE) got on and explained it best.

Dann

deviant · Postby **deviant** » Thu Jul 07, 2011 10:29 pm

I have used a harness with the stock seat but as Dann said...No...

At best it is just good for holding you in place during braking and cornering and I would not consider it a safety improvement. It is a risk I knew and accepted but I bought a Sparco Sprint V after a couple of events anyway.

If you do not want to put a bucket seat in the car consider a CG Lock http://www.cg-lock.com.au/
It allows you to pull the lap portion of your stock belt 'harness tight' without it slipping back through but it does not affect the performance of the belt of you have a bump.

I am yet to see an off the shelf harness bar that actually offers a safety improvement.

deviant · Postby **deviant** » Thu Jul 07, 2011 10:33 pm

Sorry I misunderstood the original post..

The BD bar has a puny captive nut on the flat cross piece that sits on the parcel shelf, on my old car I drilled this out and drilled through to the boot space so I could put a proper spreader plate on the other side. The other eye bolt (for the right hand shoulder belt) was put through the hole for one of the mounting bolts on the bar...it was the forward most hole on the flat bar.

Postby **Okibi** » Fri Jul 08, 2011 12:12 am

I use a 4 point harness with a stock NB8B seat, in terms of control it makes a nice difference, means you can use your arms for steering rather than trying to brace your upper body.

I guess i'm more broad shouldered than most so that might work to my advantage.

I don't know about which would be considered "safer", i've got a race seat I still need to stick in the car and that will bring the harness in closer to my neck but it will also mean the harness is pulling downwards (as most race seats are made for shorties) , i'm still not sure if that's safer than the factory mount either. One of the engineers on the forum might have a better idea than us arm chair experts.

deviant · Postby **deviant** » Fri Jul 08, 2011 12:59 am

It is not ideal having your shoulders above the height of the harness holes in your seat, basically your shoulder belts are going to go up your chest and over your shoulders and then down to the mounting points, if you have a bingle it will have the effect of pulling you down and probably do you a serious back injury.

In an ideal world the top of your shoulders will be level with the bottom of the holes in the seat and you would be able to chose the optimal angle for your shoulder belts to be mounted at. Unfortunately an MX5 has a very limited range of safety kit that fits properly especially if you want to retain a folding roof and all of your interior.

Pamex · Postby **Pamex** » Fri Jul 08, 2011 12:29 pm

I'd highly recommend not doing this.

You would be better with the stock seat belt from a safety point of view. I'd highly suggest talking to some of your race shops that will give guidance.

You can find out a little bit of info in the CAMS manual: http://www.camsmanual.com.au/pdf/10_gen ... I_Q311.pdf on strap angles, and I'd suggest giving this a read.

There is too much room for slippage of the straps, which could have disastrous results in the event of an accident.

Also, mounting one on the stock seatbelt tower means that that strap will be angled slightly to the side, instead of straight back.

I'd highly, highly suggest you talk to the boys at Meridian Motorsport, Revolution Racegear or the like. You really need to get a harness set-up correctly as it is more of a danger otherwise. I know there's a heap of other tips I'm missing here, but I'm running on about 3 hours of sleep so the brain isn't working. You need your harness tight and secure, not able to slip around to keep it in place.

I've done a four point harness with a roll bar just to see what it was like and what adjustment I could get, as I had a four point lying around my room at one point. Granted, I'm going to be a different body shape to yours, but I certainly couldn't get the correct adjustment needed. Even if I were broad shouldered and of the exact right height, it still would not have worked.

Proper seats are not expensive. If you want to go a harness route, I'd suggest you don't cheap out and just get one. There's a reason why the 1k racing guidelines specify that you can spend unlimited money on safety equipment, but only 1k total on the car etc. It's not something you want to compromise on.

Sorry to harp on, but this really is quite crucial that you get it right. I wish you all the best with it. :-)

4sfed5 · Postby **4sfed5** » Fri Jul 08, 2011 11:42 pm

cool thanks guys. thats pretty much all i needed to know.
i guess i'll be searching the web for a second hand race seat for club days and keep my stock belt in for the road.
cheers.

4sfed5 · Postby **4sfed5** » Sat Jul 09, 2011 12:18 am

after a bit of looking i found this site...very informative.

http://www.schrothracing.com/sdocs/2009 ... ctions.pdf

Postby **Okibi** » Sat Jul 09, 2011 12:45 am

Great find, thanks for sharing.

manga_blue · Postby **manga_blue** » Tue Jul 12, 2011 4:51 pm

Yes, thanks for that link, 4sfed5. I think it's a MUST READ for all of us in motorsport.

Looks like I need to do a bit of relocation for the anti-sub straps. :oops: