I just ordered a set of the Sparco 6 points (by Schroth) to be installed in a Carrera with a full cage and Sparco Pro 2000 seats. I have done some research and there is a lot of conflicting information about the proper way to install them.

Because they are 6 point, not 5, running the sub straps through the small sub strap hole in the seat would push the two straps together and essentially turn them into a single strap - negating the benefit of a 6 point set up (the benefits as I see them are better control of the pelvis in a wreck and more room for my junk).

I could go over the front edge of the seat with the sub straps but that wouldn't be very tight to my body and would allow too much movement.

I have seen installs that are more similar to a formula car, where the side and sub straps attach to the same point and are routed through the side holes in the seats, forming a cradle for the pelvis. This seems like the right way to do it but I haven't seen any instructions from harness manufacturers instructing me to use that method in a sedan.

The Simpson site gives pretty specific details on how to mount, however their method would require me to cut two new holes in the seats for the sub straps, I'll cut the seats if I have to but I'd rather not.

 

I was looking for some pictures to illustrate what I'm talking about and I believe I've answered my own questions. This is from the Scroth website, it is bascally the same as what's said on the Simpson site. It looks like I need to cut two holes in the seats to mount the sub staps far back enough. They specifically say not to set up a cradle through the side holes and not to mount across the front edge of the seat.

http://www.schroth.com/installation-...geometries.htm

 

Cory, if your S2000 seats are like my Evo's and I think they are, the seat is manufactured with an opening in the forward section of the seat bottom so you won't have to drill holes for the 5th & 6th harness.

 

I'll try the factory hole first and see how it fits, I am under the impression that it will be too narrow and too far forward but I don't have the seats in front of me and the belts haven't arrived yet so we'll see.

 

Cory -

Thanks a lot for the graphics. Good post, useful info.

Let me kow how you make out; do you need to have 2 holes, widen the exsisting slot, or is 1 ok?

I'm awaiting dual Evo 2's and 6-pts as well.

Thanks!

Glenn

 

Cory;

You did not say which belt set you ordered? Tell me which set they are as a Schroth product and then I can better advise you. Either "T" or Hybrid sub, right?

You're on the right path with the diagrams from Schroth. Arguably the most effective way to mount a double sub - in terms of retention - is cradle style, run through the lap belt holes in the seat, and terminated at the lap belt bolts. However, the advantage here comes at a price. They will provide immediate hip control, but they must be worn very tight, which is uncomfortable.

To make the best compromise between comfort and retention, you need two splayed holes in the seat base, positioned such that you can get the straps out against the high-inside of your thighs (groin), and also mount them in the 20-40 degree range behind the imaginary extension line of the spine.

 

The belts I ordered are the T-Style (see pic of sub strap below). They are actually Sparco belts but are made by Schroth and appear to be identical. The only hybrid sub strap style belt (sub straps over top of camlock mechanism) with FIA approval I saw at OG racing was the Sparco formula belt, which is specifically designed for a formula car with pretty short belt lengths. I think Simpson makes one with the hybrid style sub belt but it only has SFI approval and must be replaced after just 2 years so I went with the Sparcos and their 5 year FIA approval.

It is interesting that you mention the cradle style of mounting, if you see my pics from the Schroth site they specifically show that as a way NOT to mount their belts when using an upright seating position.

 

I have the Simpson grey plat 6 pt harnesses and the instructions look identical to the schrott ones.

 

John,

I've seen you mention this mounting style before (and it's actually how my current harnesses are mounted), but the Schroth install manual (p. 24-26 of http://www.schrothracing.com/docs/Co...structions.pdf which I'm sure you are famillar with) shows the pic that Cory posted about about not doing that with the Profi and Hybrid models. It is however mentioned as an installation option for the Profi 'F' model of harness. Or am I reading this wrong?. This is of interest to me since I have to mount my Schroth Hybrid II harnesses before all of this snow melts.

 

It looks like the "cradle" style of mounting is only recommended by Schroth for their Profi F models, which have the sub straps attaching though the lap belts. For the Profi H models like mine, and the Hybrid they recommend the method I showed in my second post above.

The Schroth instructions are very detailed (73 pages!) and I recommend anyone installing a harness check them out.

 

Hey;

First, a correction. Schroth makes the only "Hybrid" sub. It is a means of attaching the sub DIRECTLY to the lap belt, in a wide "equipment friendly" manner, but not using any extra hardware like a "T"-bar to do it. It is a patented design. No one else has anything close.

Good points, Stacy, and you're not missing anything. It is just so complicated that a "simple" answer requires a LOT of setup. There ARE no short simple answers!

The cradle style is your only real effective option when using a stock seat. It is also the only option if you can't or won't cut your racing shell to mount the sub underneath.

If you are not afraid of doing this, then the best way is under the seat at the proper 20 degree angle. In an upright position you do not have a dramatic submarine effect by default. In an upright position, the location of the lap belt is critical to hip rentention; the lower the better. Any sub arranged as a cradle ("V", "T" "Formula") does not do this well because it is not pulling directly opposite of the shoulder belts. As such, it relies on pretentioning (wearing them TIGHT) to control the hips.

Incidentally, cradle subs are lousy for roll overs. The lap belt tight against your thighs is what holds in the seat. This is the one place where a properly adjusted single sub is highly effective. Since the cradle is like sitting in a big loop, it does not hold the lap belt down well (the loop simply rises), and so you will rise up (or down if you are upside down!) farther as a result.

So... if you want to mount any double sub for maximum effect, you split the difference at about 20 dgrees back from the spine line, and mount the ends at least as wide as the distance between your leg bones. This will give you relatively straight opposition to the shoulder straps pulling the lap belt up, and relatively good hip cradling to control forward hip projection under the lap belt.

As opposed to doing one thing to a high degree, but others not so well, the proper racing double sub layout performs ALL of the key functions to a very acceptable level. The best of all worlds. "Hybrid" if you will.