If the taper is part of a fastening system and the isolators are not free to move on the taper, it seems unlikely that it will generate thrust and load the engines crank shaft. In any case, make sure the freeplay of the engine crank shaft is available to measure with a magnetic base dial indicator. Loosen the belts. Set up the indicator on the adaptor plate, and place the dial shaft in parallel with the crank. You may have to clamp a bit of material the flex plate to get a target for the dial. Gently pry the front pulley forward with a pry bar or big screw driver. Then set the dial to zero. Pry the flywheel (flex plate) in the opposite direction (gently) and look at the indicator. You should have the same measurement as when the engine was assembled. .0015" to .0035".

 

If it requires that you pry a bit harder in one direction over the other to get your reading, or you need only pry in one direction to get the measurement, then the assembly is preloaded as it sits and requires modification to adjust away that preload. Be very careful doing this, as the thrust plate is more flexible than some folks imagine.

 

 Typically one side or the other of the drive system would run on a set of splines that would accommodate the depth of installation and allow the freeplay to center up in operation. A very small amount of antisieze compound will keep the splined section working. The exact same thinking as the splines in the clutch disc center on the car.

 

If the tapered pins just engage holes in the pucks and the pucks are free to move on the pins, then it is likely that a mild thrust load will be imparted to the crankshaft. So, because of the taper, when the engine imparts torque into the isolators they will try to slide off of the pins and generate a small amount of thrust. 

 

If the pins are free to move, inside the isolators, but are not tapered, then it is unlikely there is a problem. The engine crank should be free to move in the above amount. It would not hurt to check the crank freeplay on a regular basis.  Very closely  in the first few hours of operation. Loosen the belts, grab the front pulley and shove it back and forth. You will be able to feel the movement with a bit of practice. Once a record of good performance is established just make it a phase dock check or annual, or 100 hour, whatever you do inspection wise.

 

The thrust preload problem would be a problem with any auto engine installation. The thrust bearings in car engines are very small and cannot share any of the propeller loads or a constant load for any length of time. It would not be just a rotary problem. 

 

Lynn E. Hanover

 

 

 

Lynn, I have a Marcotte Redrive and the drive disc has 5 pins that appear to have a taper similar to a Morse Taper and the driven disc has isolator bushings, which are internally tapered to fit the pins, of some type to absorb the torsional vibrations.  Will this setup cause an undesirable load on the thrust bearings.  I was hoping to get a first start when the snow goes, now this question comes up.  JohnD