A 3 7/8" "speedy Sleeve" is available that does two things- - - -it gives a super slick stainless steel surface for the seal to ride on, and it also increases the crankshaft hub diameter by a few thousandths to give a tighter fit to the seal- - - -rope or rubber. The lip seal I use can handle up to a .015" oversize shaft diameter because of the garter spring, so I'd highly recommend adding the sleeve to the crankshaft in addition to the lip seal.
Jerry

"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!