The key is the direction of the load. That beam isn't really a good design for a forward load. The OEM belt attaches close to the side, where it is reinforced.

 

not sure what you mean by using the OEM belt attachment points on the side, as you can see in the picture that the OEM harness is mount directly on top of my harness. the load path for the OEM harness is sideways though, not forward.

i really think that if i add some additional brace from the back plate to the rear roll bar mount, that should give enough support.

 

the first nut is just a spacer. it's drilled out and grind down at an angle to provide a flat surface for the second nut, and the third nut is a locknut. i'm going to weld the spacer nut to the back plate. this was just test fitting.

 

Sure, the removable harness bar Hard Dog isn't in an ideal position, but I'd rather go too high than too low. The way you mounted it looks like a downward angle, which I thought was to be completely avoided.

 

Exactly. The load path from the OEM belt is sideways. It is only redirected forward way out at the edge, where the beam has a lot more support from the side of the car.

 

according to the Schroth harness install manual, the optimal angle for the solder harness is between 0 and 20*. my shoulder harness is at 15* incline and my seat is at around 20* tilt back. the shoulder holes on my seat is also above my shoulders, so the harness would have to break through those hole to compress the spine.

 

Might be a good place to point out that if you use a HANS, the HANS instructions call for the harness to be attached slightly lower than shoulder-height. Not a lot lower, but lower.

 

i think that with stock roll loop in place, it should provide more support for forward load. that cross member is there to support the roll loop from moving forward or backward. unless we actually do load test on that cross member, we don't really know now much forward load it can support. but i think i will address it by adding brace to the roll bar rear mounting point.

 

i use a Safety Solution Hybrid-Pro. it calls for 0-10* below shoulder.

 

i added some additional brace from the back plate to the roll bar leg.
here are some pics.