How to fit a harness (Newbie question)

OzGuvnor · Postby **OzGuvnor** » Thu Nov 07, 2013 4:33 pm

Hi,
I am putting VELO seats into my NA8 (arrived today!). I am also planning on installing a Brown Davis Roll Bar.

The car is principally a weekender for a bit of spirited driving and I intend also to do some track days for fun once I finish doing it up.

I am looking at fitting SCHROTH 4 point ASM (anti sub-marine) harness (with standard push button release) so that I can also use the harnesses on the road. Main reason being safety as I am 6'1" and worry about striking head on windscreen.

QUESTION: How should the harnesses be fitted? There are 2 styles of SCHROTH and I dont know which to purchase/fit?

Instructions http://www.hmsmotorsport.com/docs/Rally ... ctions.pdf
SCHROTH Harness http://www.hmsmotorsport.com/store/schroth-tuning-belts

Any help, advice, photos appreciated.

hks_kansei · Postby **hks_kansei** » Thu Nov 07, 2013 4:56 pm

The Brown Davis bar has captive nuts in the flat section on the parcel shelf, these are ready for you to attach the shoulder belts to. (Either via eye bolts, or normal bolts. Eye bolts might hit the rear window with the top down, if you have a glass top keep that in mind)

The lap belts might take some modification, the outer belt can simply use the bottom bolt of the factory seatbelt (replace the bolt with a longer one, or an eyebolt)
The inner one may need you to drill a hole in the trans tunnel and add a backing plate to screw a bolt into (although, I think the NA8 already has a seatbelt mount there, so just use that)

As for using the harness on the street, I'd suggest against it.

with a big bolstered seat you've already lost some vision, then add the tight harness and you've basically got no way to check blindspots, see past other cars, etc.
And if you adjust the harness to be loose enough to let you lean around you just end up making it a lot more likely to shatter your collarbone etc in a crash.

Normal seatbelts are a pretty good design, that's why they've not changed a whole lot in 30 years.

hks_kansei · Postby **hks_kansei** » Thu Nov 07, 2013 5:00 pm

As for harness type, you want one with the two shoulder straps to work with the BD bar (it has two bolt holes either side, if you use a 1 strap harness it will be off centre)

and you'll want one with the bolt in or clip in ends, depends on your preference for eye bolts or normal bolts (eye bolts make it easier to put the harness in/out of the car, but stick out when the harness isn't used)

Make sure to check the straps have enough length and adjustment first, some migth be way too long to cater for sedans (reaching to the back seat) and might not have enough adjustment to work in an MX5.

edit:
also have a look on the CAMS website for the motorsport guide, it has a section on correct harness mounting and use, with diagrams to show the correct, and safe, ways to mount them

sailaholic · Postby **sailaholic** » Thu Nov 07, 2013 5:09 pm

Which velos? Looking at fitting one myself.

I was just planning to use a standard seatbelt and have a 5 point for track duties.

Best talk to your engineer and check they will approve the push button 4 point before buying one.

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OzGuvnor · Postby **OzGuvnor** » Thu Nov 07, 2013 5:44 pm

Thanks. I will have re-think on using the 4 point on the road. Obviously 5 point is better for track.

I am mulling over the trade off of head-checking difficulties with a 4 point versus the added safety it potentially offers on the road - if fitted correctly

This comes from me having T-boned my 97 ford fairmont back in 99 at 60 km/hr into the side of a Commodore that ran an intersection. Massive damage, though no-one significantly hurt. That collision was a 15 degree frontal offset (I instinctively swerved left) with me as the driver going forward/right. Despite sitting quite a way back in the seat (being 6'1") I still pitched forward enough to get knocked out by the A-pillar in the collision. Which surprised me because you cant reach that when you try to simulate it by just locking the inertia reel and leaning forward. The air-bag didn't deploy either for the record.

I'd rather avoid a repeat of hitting my head on the A-pillar if I am unlucky enough to endure a repeat incident (touch wood)

OzGuvnor · Postby **OzGuvnor** » Thu Nov 07, 2013 5:44 pm

VELO seats are GPT-1

Jeo · Postby **Jeo** » Thu Nov 07, 2013 6:05 pm

Harness on street isn’t going to win you any favours around here.

Harness on stock seats is a bad idea.

Also have a search around for the benefits of 5/6 point vs 4 point.

Basically; if you want a harness, do it properly.

A.Chen89 · Postby **A.Chen89** » Thu Nov 07, 2013 7:30 pm

As above.

You should try getting buckled into a harness in a bucket seat.

It's impossible to do a head check when your strapped in.

sailaholic · Postby **sailaholic** » Thu Nov 07, 2013 7:50 pm

Agree I tried. Sprint v with a harness and if you can't see it in your mirror you won't see it.

You really don't realise how much movement you use until you don't have it.

Great let me know what you think of the gpt-1 it's the same one I'm looking at. I don't suppose you bought the recent pair of this forum?

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de Bounce · Postby **de Bounce** » Fri Nov 08, 2013 7:36 pm

Instead of using a harness on the street, have a look at a CG Lock.
Locks the hips in but allows the upper body to move around.
If you do buy one, be aware there is a specific one for MX5's

Bit more reading here

Mr nanotech · Postby **Mr nanotech** » Sat Nov 09, 2013 2:18 am

Go to your local nut and bolt shop and buy a couple of these:

You can either screw them by hand into the floor carpet directly behind the seat or into the back of the seat itself. The vinyl is pretty tough and should be good enough. Also make sure the harness goes straight vertically down to the floor after your seat too. Stock seats should be fine too, you can staple the harness to the shoulders of your seat if they slide off.

Guran · Postby **Guran** » Sat Nov 09, 2013 7:57 am

Mr nanotech wrote:Go to your local nut and bolt shop and buy a couple of these:

You can either screw them by hand into the floor carpet directly behind the seat or into the back of the seat itself. The vinyl is pretty tough and should be good enough. Also make sure the harness goes straight vertically down to the floor after your seat too. Stock seats should be fine too, you can staple the harness to the shoulders of your seat if they slide off.

Just in case ... the above is NOT serious advice! :shock:

Guran · Postby **Guran** » Sat Nov 09, 2013 8:00 am

Harness on street is NOT advisable. Your upper body is tightly restricted in a frontal impact, but your head is not. The effect is exascerbated when you wear a helmet, making your head heavier. That's why HANS devices are highly recommended if you use a harness. If you really want to be safer on the street in an MX-5, buy yourself an NC.