Bnorth
Active VIP Member
I've been looking and comparing stock clutch setups over the past few years between the 850 and the Etec to try and get a handle on how the Pdrive is coming setup compared to a TRA. I know it's challenging without really knowing the ramp profiles of each, but there are a lot of similarities. What is really jumping out at me in the spreadsheet I've made is the secondary spring. Helixes are the same, primary spring are of similar forces, gearing at 1:1 on a 154 is very similar... leading me to believe the ramps in the TRA and Pdrive are acting fairly similarily. What is quite different is the secondary spring. The spring used in the G4 is a Blue 157/221 whereas the spring used in last years Etec was a Black 157/303 no matter on track length or depth. Based simply on that it would almost appear the secondary is shifting too soon putting the machine into a higher gear quicker than previous years. This could easily explain why the belt is heating. I would be real curious to see what a change to simply the Black secondary spring would do.
Black secondary is a good upgrade to the early XM's over the blue spring so could see it being a step backward going back to the blue