Ok so I have been promising an update on this for a while. Basically I have been working since as soon as I got the car on a solution to run some proper 6-point harnesses without compromising on rear interior space (i.e no ugly, heavy, space consuming harness bar).
I initially thought I'd be able to cope with the standard seats, however the first trackday, and even some spirited road driving, has proven that they are not supportive enough for me. So along with a great opportunity to save a fair bit of weight I'm changing them out for some fixed buckets too.
I'll take you through step-by-step with pictures and some explanation for my actions.
Step 1 - rear seats removed:
Step 2 - removed and inspected the rear seat base bar. This will form the basis for the shoulder stap mounts. What do we know about this part? Well we know GM have engineered it to take all the rear seat load from 2 adult passengers in an impact. We know the rear lower seatbelt mounts are on it. We know that GM have specifically stated that it contributes significantly to chassis stiffness and the Z/28 was quicker with it than without it. Therefore , ergo, we know it is very strong!
Certainly strong enough to take the shoulder strap loads from a 6-point harness that actually more even distributes the forces around the chassis than the OEM 3-point in a crash.
p.s - I see Camaro5 owners doing rear seat deletes and not replacing this bar with some suitable bracing...?!?!?
As you can see in the image I started mocking up some additional steel bracketry around the seat base bar. These runners form a guide for the shoulder straps to improve the angle they run from the shoulder, and to correctly thread the belts through the gap between upper and lower rear seat bench. They don't prevent the rear seat base from correctly clipping back down into position.
Step 3 - all welded up and painted and bolted back in. I also cut one set of ISOFIX child mounts off for weight saving as I don't intend ever having two babies in the back (even one is unlikely!). Certainly looks a lot neater under there now.
Step 4 - showing the shoulder strap routing. I benchmarked a couple of OEM hatchback front lower seatbelt mount bars and they were all 10mm steel bar. So we made the new guide rail 16mm diameter steel to be extra safe. A bit of added weight, but certainly nowhere near a full harness bar install.
I'll never use the harnesses when I have rear passengers. When not in use the shoulder straps can be pulled back through the front seats and either placed on the rear parcel shelf or move likely just sat on, and tucked away under the front seats.
Step 6 - onto the front. Seats out!
Step 7 - seat mounts. It is important for me to make sure all of these mods are easily reversible and the car can be returned to standard with the minimum of fuss. I'm am keeping all the OE parts that are in mint condition in storage. Therefore any seatmounting that involved drilling any new holes in the floorpan was a no-no for me. Fortunately I've found that the OEM recaro seat runners lend themselves very well to mounting side-mounts on. A welcome surprise having had seat mounting in other trackcars I've owned present something of a headache. The other advantage of using the OEM runners is again safety. You can mount both the seat and anti-sub and lap belts above the seat runners safe in the knowledge that you are not putting any more load into anything above that which GM already designed for. The moment you drill a hole and use a spreader washer or use an aftermarket sliding runner you don't really know what it might do in an impact. Also in my experience aftermarket sliding runners never feel as good as OEM ones.
As you can see, correct nut, bolt and washer selection and plenty of coffee are essential here!!
Step 8 - just a couple of shots of about where I'm upto now. Seat mounts trial fitted.
Step 9 - some spare Cobra Suzukas being used for mocking up purposes. These aren't the seats I'll be using. I have 99% settled on a similar Sparco seat. The Cobra does look good though
