Can anyone tell me if I am safe to run gear drive cams with crank runout at 2 1/2 thousandths ? I had mine checked and that was what I was told it had, I belive that converts to .00025. .0025
KingDog,
I read somewhere that S&S recommended no more than .002" runout of the pinion shaft.
The following is copied from the S&S instruction sheet, relative to drive gear backlash:
"To check backlash in the outer drive gear set, rotate the 62 teeth cam drive gear back and forth while keeping the pinion gear locked in one place with the engine.
The minimal required backlash for the gear sets should be between .0005” and .001”and no more than .002” for cold gears. The both gear sets should roll freely with no radial or axial binding. If when checking backlash the gear mesh shows less than .0005” of backlash then a smaller crankshaft gear size 33-4160X for the outer gears or 33-4272RX for the inner gears should be used. Gear sets with less than .005” of backlash may whine when run and can cause tooth wear excessive heat generation and gear failure resulting in engine damage. Gear backlash greater than .002” can cause excessive gear noise or clicking caused by the reversing of the forces applied by the lifter springs onto the gears, use the oversized crankshaft gear 33-4160Z for the outer gears and 33-4272RZ for the inner gears to
correct this condition."
While they don't specifically mention measuring the pinion shaft runout, they are looking for a backlash between .0005" and .002", and they measure it with the pinion shaft gear locked in one position. If the pinion shaft has excessive runout, you can see where it would be impossible to get a consistent backlash adjustment as you turn the crankshaft.
This is a link to the entire instruction sheet for those interested:
http://www.sscycle.com/modules/instruction/uploads/51-1047.pdfJerry