Originally Posted By Hamwich
Originally Posted By RedThree
You're right Dan, with the rubbers removed the inner part spins without touching the outer.


I'm about as far from a materials engineer as it's possible to get, but wouldn't this arrangement mean that the Centa drive rubbers are constantly suffering from shear forces? No wonder they break up.

I wonder why they didn't use a simple cush-drive arrangement of interleaving plates separated by rubber blocks, like in the final drive sprocket of motorcycles? Then the blocks would only be exposed to compressive forces and would presumably last a lot longer (I've never heard of a cush drive wearing out in a few thousand miles).

There must be a reason, maybe they couldn't find one of small enough diameter.


Tim,

The design of the pockets in each half allow a tapered squeezing effect on the rubber rods. So they're not really in a shear as we would think. A true shear would be slots in the inner and outer housings with rubber flat pads inserted, kind of like a vane compressor. This would be a true shear.

At some point though, as you've said, the pinch points would begin together at the far end of each windup and fatigue the rubber rods.



I posted this in another thread about drilling the compensator to grease it.

Something like this could be adapted quite easily. The axial mounting could bolt to a splined plate that attaches to the S&S rotor and the radial mounting could bolt to an extension of the flywheel mounting shaft in the adapter plate for the trans.

The LF22 is actually a four bolt, not three. They don't have a picture of the LF22 though. The LF22 would have enough MAX torque to cover even the 128" high output motors and it will allow up to 7.5 degrees of windup at max torque in both directions. At max torque it is rated at 553.3 lb/ft. It's also rated at 6000 rpms. So it has some safety factor built into it I'm sure. It only weighs 1.4 lb.

This type of coupling is always under pressure as it gets a slight preload when being bolted into place. So there would be no loose spots and it would probably offer more dampening than what Phil ended up with his elliptical urethane inserts.

The model I have shown is for studs on the radial mounting, but they make it with counterbores for the bolts as well.

Again, just food for thought.

Dan