I have been looking in to blocks of polyurethane which can be cut to shape on the bandsaw thus allowing lots of experimentation; it is a shame the engine has to come out every time one wants to change the coupling elements - I guess I'll just have to get good at it!
Phil, I believe that even the Centa is assembled under a sort of preload on the rubber rods. The Harley dual ramp compensator is preloaded very heavily with Bellville washer packs.
If you use blocks cut to shape up front so they are slide in, my personal opinion would be that it will "rattle", not maybe in a sense that you can hear it, but physically and that could be detrimental to the motor as well as the trans.
Again this is just my thinking.
Without person trying, you never know. Nothing ventured nothing gained, so they say...
I know you'll keep moving forward and report back as you go.
I wish you lots of good luck.
