Crank lapping

[Mick]

Hi all question to lap flywheel to crank or not bother how important is it if at all

[ULC Soulagent]

Worth doing I'd guess

[Fast n Furious]

Definitely worth doing. Lapping them in means that the taper lock effect works best with the least amount of stress on the retaining nut. I do it by using a modified flywheel extractor tool so it fits in my reversible drill and lap in with a dose of course & fine valve grinding paste. Clean up with isopropyl alcohol and your on a winner.
Just make sure that your woodruff key doesn't protrude up too high upon assembly, especially if using a new key, cos some of them can sit a tad high. If this happens, then the key will try to take the load and not the taper.
Disaster is then imminent, possibly splitting the keyway of the flywheel down its length and grinding your crank and flywheel tapers to shreds when the key shears.
I use an old 4 thou feeler blade, narrowed down, so it will fit up the key way after the nut has been tightened and removed to test for sufficient clearance.

Similarly I also recommend similar procedure for lapping your rear wheel cone to your hub.

[Mick]

Yes makes sense thanks