Harness for stock seats

[PranK]

Hi Guys,

I'm starting to want to squeeze more out of my car when I go to Wakefield now but while there are a lot of things I want to do to the car still, I am struggling to get a good feel for it while I'm flopping about all over the place. My stock seats are *ok* not great by any means but for the time being its still my daily. I know I can just swap seats in and out but I'd like to just try a harness first to keep my rolling self pinned. 

I think i'll need to use it with the main seatbelt unless it's engineered, so quick clip-in ones are not going to work. I also have two of the new baby seat style clips at the base of my back seat. What I was thinking was clipping in the rear and then adding the front fixtures to the front seats' rear rail mounts. Does that make sense? 

If all this sounds sane(ish) then I'd need to know what to get. It seems like a Sparco harness is the go but there seems to be eleventy billion different types and configurations.

Thanks guys.

C

[The Bogan]

From my limited experience 4 point harnesses are rubbish

I found a CG-Lock much better than a 4 point, pity they no longer make them, but, apparently there is a new version that doesn't chew the seatbelt, and works just as well, apparently 

linky > https://shoft.co.uk/

I've been meaning to try some, more for my posture on long drives as I tend to sink down on the seat (the lounge chair that is the seat in my VX SS Commodore)

With the current exchange rate, 2 delivered to AU with tracking cost $65, but I keep umming and arring read: procrastinating 

The 2 cars I tried a 4 point on were my R33 with R34 GTR seats, and my MX5 with stock and a Sparco Sprint seat

Even after drilling holes in the floor to mount the lower points in a few different spots I found that tightening up the shoulder straps pulled the lap sash up over my abdomen, and the standard seat in the MX5 had the harness falling of my shoulders....which was rubbish

There are other issues with 4 points as well like submarining

Well, that's my 2 cents anyway

Stay safe

[Murray_Calavera]

I use a 4 point harness on the track, I think there are 2 main considerations when doing this. 

1. You need to handle the submarining in a collision. 

2. The angle of the shoulder straps going back to their mounting point. 

To deal with the submarining, I use one of these harnesses (and I hope it actually works, not that I want to test it)

https://competitionmotorsport.com/schroth-profi-ii-asm-4-point-harness-anti-sub#:~:text=The Schroth Profi II ASM,used in Driver Education programs.

I use one of these cages with the eye bolts, the harness is clip in. 

https://www.agi-precision.com.au/product/a-nissan-skyline-r33-2-door-half-cage-4-point-bolt-in/

I would not recommend using the baby seat attachment points as your proposing. They are designed to support the weight of a small child in a collision, they will not hold your weight in a collision. Have a look at this for guidelines on how strong the mounting point for the harness needs to be (reinforced place 75mm x 50mm x 3mm).

https://motorsport.org.au/docs/default-source/manual/general-requirements/schedule-i.pdf?sfvrsn=b143a052_12

Ideally you'd use a cage, next best option would be a very well designed harness bar that ties in to proper anchor points (existing seatbelt mounting points etc). 

You will see some people mounting their harness back to the rear seat seat belt mounting points, while this will hold the weight, it is incredibly dangerous in a collision. In the event of a collision, the belt will put downwards pressure on your shoulders and crush your spine. 

Have a look at the attached picture for the recommended angles for the harness belts. 

 

I will say, using a harness with GTR seats is a huge improvement over the stock seatbelt. It's not the same as using a fixed back seat as the seat has some flex and you'll feel that once the harness is done up tight (I really can't wait to get a fixed back seat).  Still though, once using a harness I'd never go back to using a stock seatbelt. 

[PranK]

Thanks guys, theres a lot of food for thought here.

@Murray_Calaverato your points re. safety, I do plan on putting my seatbelt over the top of the harness (as is required by Wakefield) so the baby seat mounts might still be an option as I don't intend for them to hold my 115kg lump in a crash. Not sure if that changes your mind on them? 

I was also worried about the spine compression when your shoulders go above the seat (which mine do). This issue makes me think that I should get a seat also before using the harness with stock seats.

@mlr I couldn't get the videos to load on that site, but I found the one below. Very interesting. It reminds me of the seatbelt locks that you put on the top of the belt to stop it moving.

 

[Murray_Calavera]

It does sound like you'll need to get a seat. 

With your fix back seat and 4 point harness (with anti-submarining) using the baby seat restraints there is another thing to consider too...

In the event of a rollover, you will be held in a bolt-upright position. There is a strong possibility that the roof will cave in, put pressure on the top of your helmet and crush your spine. 

I really hate to be the safety police as this stuff is a matter for yourself. I just want you to have all of the information available for when you make your decision so you can decide what level of risk you are prepared to take. 

Safety is a long list of things you can do, full cage, 6 point harness, hans device, fire suppression system, battery isolation, sexy (pricy) helmets and race suits.... But at the end of the day we accept the level of risk we want to take. 

I would say fixed back seat, half cage and harness are the starting point and form a system as they all work together.

[The Bogan]

I'll tell you how they work, when, if, they get here

I got tracking so should have an idea soon

[The Bogan]

I found these when I was looking into them

Your is a BMW so basically exactly the same

Tiff Needell runs them in his street car when acting the fool and when doing "driver training"

Very LOL