What I learned is that you have to use the encapsulated roller for reverse, as a standard p-85 will allow the belt to suck down. The one I have has a "427" or "447" on it and a helix angle of 56-48-36 er. I setup a standard p- 85 with a silver and 48-36 in it. 62's with 2 grams taken off the tip, tucked the weights to 4100, gearing at 23/40 and the sled loves the setup. But I don't know how to setup that team, the helix angles are huge and also the spring looks like a truck suspension spring, is there a conversion formula?