Mounting 4 point harness

smiles · Postby **smiles** » Wed Dec 28, 2005 11:30 pm

I've got a 4 point harness that I use in my other car, I've replaced the drivers seatbelt bolts with eye bolts and the same on the rear passengers and can just clip the harness in easily for track days.

Can something similar be done on an mx5 (NA6)?
Is there somewhere to mount an eye bolt on the rear shelf?

What's the easiest way of mounting a harness on the car?

CT · Postby CT » Thu Dec 29, 2005 9:57 am

Get a brown davis half cage with mounting points. It'll protect your head as well as your body. Highly recommended if you intend to use the 4 pt harness for track work.

Matty · Postby **Matty** » Thu Dec 29, 2005 5:03 pm

CT is right - don't use a harness without a roll bar.

The lower seatbelt mounts can be replaced by the eye bolts, like you did previously. On my car, I made up some sleeves that mimic the shoulder on the OEM bolts, allows the seatbelt to stay in and pivot freely.

rain902 · Postby **rain902** » Thu Nov 02, 2006 5:27 pm

Slugoid wrote:Sorry about digging up this old thread.

Just wondering, is there ways to mount a 4-point harness without a roll bar?? Can the NA8 seat belt brace do the trick?? I really can't afford a roll bar or the brown davis half cage at this point in time

if you must, get out your 7/16" drill bit and your 10mm spanner/socket and lift the carpet on your back deck - at the very back of the deck it angles upwards, the panel there is double thickness. Punch two holes as indicated and dont forget to use reinforcing plates like these shown. Make sure you have most of the afternoon free to mess with removal and reinstallation of the carpet, and in hindsight I woulda removed the seat to allow easy access to the back deck.

I looked @ the seat belt brace and decided that it would be too high to be effective or even safe I think.

rain902 · Postby **rain902** » Thu Nov 02, 2006 8:06 pm

erm - yes it is, but that is not a roll bar, its a style bar - roll bars are designed to prevent the occupants from being crushed in the event of a rollover, style bars are designed to look cool, not save the occupant in the event of a rollever :shock:

Matty · Postby **Matty** » Thu Nov 02, 2006 11:06 pm

rain IS a scrutineer... :lol:

Andy Wana · Postby **Andy Wana** » Thu Nov 02, 2006 11:18 pm

Does this count as a roll bar? (Pardon the newbie question)

rain902 · Postby **rain902** » Thu Nov 02, 2006 11:55 pm

Slugoid wrote:Thanks for the info and pics rain I knew the only real option was a few holes in the rear deck, but was unsure if it was safe just to drill holes there.

Btw, have you had any problems with the scrutineers on track? How strict are they on mounting points and how secure it is?

thanks Matty

All scrutineers have differing opinions however I think that due to my own personal hates my idea of harnesses is pretty harsh - if it gets past me then it should get past anyone. If a scrut knocks you back, you can ask to see the chief scrut and point out to them that the material there is above the crease line, fluted and double thickness. (on an NA it is anyways) Suggest that the material further down is single layer and less substantial - upon second examination they may decide that it is pretty good after all.

I am viciously strict on harnesses helmets and roll cages in that order. I would pass my car with the harness installed where it is, but if they were installed 30cm further forward, in the single layer sheetmetal that bolts on over and around the fuel tank then I would not pass it.

The cams manual requires the reinforcing plates to prevent pull through but is strangely silent on the requirements for location of the holes save for schedule I (3)(b) which states that it must be to a substantial part of the vehicles structure, reinforced (like in the pics) or to the rollcage (see pic below)

My rationale for passing a harness mounted as depicted is "if i hit hard enough for me to worry about tearing out the mounts, thats the least of my problems" :shock:

Just for bragging rights, this pic was taken 5 minutes ago in my garage - this is how i really love my harness to be mounted - can't wait to see you all this weekend!

rain902 · Postby **rain902** » Fri Nov 03, 2006 3:21 am

Slugoid wrote:
Matty wrote:rain IS a scrutineer...

Haha, silly me

Well I guess if a scrutineer says it's ok, then I'll go ahead with the harness purchase and installation. AS 2596-1983 standard, so it should be good. Then I have to get a "3mm steel plate of at least 75mm X 50mm" (Schedule I 3a). Better safe than sorry

Hopefully I'll see you in the future rain. Might be going to the PI on Dec 17

i'll be there with bells on :lol:

love to see you there for the istate challenge

revvo sells the backing plates already made - the dimensions arent exactly the same, but the surface area works out i think. they are about $6 each, beats cutting, bashing and welding if you ask me...

rain902 · Postby **rain902** » Fri Nov 03, 2006 12:21 pm

Slugoid wrote:
rain902 wrote:revvo sells the backing plates already made - the dimensions arent exactly the same, but the surface area works out i think. they are about $6 each, beats cutting, bashing and welding if you ask me...

Where abouts is revvo? Or you mean Revolution Racegear

Btw, the "Phillip Island 1hr" is this weekend right? Didn't get info about it from the mx5 club but maybe i wasn't looking the the right place

yah revolution @ mitcham.

dunno whats on @ PI this weekend - most of us are off to winton for the 6 hour event - 2x mx5 teams competing :lol:

Cal · Postby **Cal** » Fri Nov 03, 2006 12:43 pm

Slugoid wrote:Btw, the "Phillip Island 1hr" is this weekend right? Didn't get info about it from the mx5 club but maybe i wasn't looking the the right place

The PI 1hr is on the 26th.

IMO you are off your face using a harness without a rollbar. Infact I consider a rollbar to be almost essencial in any MX5, especially one used on the track. My road car has a rollbar, but not a harness any more. In the event of a roll over, your body is fixed upright and can not move sideways, hence your head falls off. Best case, you break your neck.

Cal.

zoomzoom · Postby **zoomzoom** » Sun Nov 05, 2006 1:20 pm

Just curious, has anyone else tried using a harness with the std seats? I put it in the onther week to try it and it seems alright, but the harnesses do sit on kinda funny angles when they go round the seat. Didnt seem too bad though like cutting into my shoulders or anything(but i dont have very square shoulders

) though I did only try it for a couple minutes.
Tim
(getting ready for qr track day

woo)

Cal · Postby **Cal** » Mon Nov 06, 2006 10:07 am

Slugoid wrote:Well I have a hardtop, but don't know what will happen if my car does roll.

It will do nothing at all and the end result will be the same as if you had no roof at all.

Cal.

rodent · Postby **rodent** » Mon Nov 06, 2006 1:11 pm

From experience, it seems the NA soft top frame can hack a bit of a beating before collapsing. When my car rolled the a-pillar more or less gave in but the frame supported the weight of the car - seats weren't even scratched.

I think the hardtop also has a whole lot more structural strength (esp at the back) than the a-pillar (remember also seeing a pic of DanielB's rolled car with its roof still intact).

Of course at racetrack speeds none of this would really count

jonno.

Cal · Postby **Cal** » Mon Nov 06, 2006 1:39 pm

rodent wrote:I think the hardtop also has a whole lot more structural strength (esp at the back) than the a-pillar (remember also seeing a pic of DanielB's rolled car with its roof still intact).

Umm I cut said support away with an angle grinder on the weekend. It is made of fibreglass and would do dick in the event of a rollover.

Cal.