JD Pinion shaft bush

[aumick10]

I am honing out a new pinion shaft case bush. The motor repairer manual says that this bush has a taper in it. I am using OEM flywheels with new shafts. Is this taper still the accepted way of honing out this bush?
Thanks

[Steve Swan]

i didn't put a taper in the bushes for engines i've set up. i went with a clearance of 0.0015". i'd be interested to learn about the rationale for the taper.

[aumick10]

Steve, I think it was to allow the flywheels to flex, without breaking the pinion shaft

[Steve Slocombe]

The VL was the last Harley model to use the big bronze pinion shaft bushing, and it was also finished with a taper. I used to have the special reamer, or maybe it was just a worn seat post bushing reamer. From memory the Harley spec was 1.5 thou clearance outside and 3.5 inside, which I've also assumed to be to allow for flywheel flex. The VL bushing is even huskier than the JD one, and I would parallel finish them to 2 to 2.5 thousandths clearance.

[Steve Swan]

My bad, on the 0.0015" clearance i stated. i meant to say 0.0025" The back story on my saying 0.0015" is that back in the day, my restored '27's engine's pinion pin/bushing clearance was set up by someone else at 0.0015" and the shaft seized in the bushing, so lesson learned, i reamed the bushing i.d. to 0.0025"

in the spirit of learning and in all humility, i have not heard of the pinion bushing being tapered... Always something new to be learned. Where is that information found? the 1918 Repair Man Manual (p. 24) doesn't mention a taper unless i've missed it, does discuss "...adjustment of the reamer until the shaft has .002 inch to .003 inch clearance." The 1923 Repairer Manual (p. 107) states the same information, "...between 0.002 or 0.003 inch play."

[aumick10]

I checked my copy of the 1923 repair manual and couldn't find any reference to the tapered bush. I can't remember where i came across it, it was a few years ago. I will ream to 2-3 thou parallel.. It might have been a shop dope, or something similiar.

[Steve Swan]

I checked my copy of the 1923 repair manual and couldn't find any reference to the tapered bush. I can't remember where i came across it, it was a few years ago. I will ream to 2-3 thou parallel.. It might have been a shop dope, or something similiar.

for my learning experience about flywheel flex, is this caused by directional forces exerted on length of the pin or at the taper or both? At risk for snapping pin, cracking flywheel or both? The idea of the taper is to cushion some of the flex? Would these concerns be a problem with pins such as JIMS and T&O flywheels?