OzVMX Forum

Clubroom => Tech Talk => Topic started by: Expat on February 12, 2008, 10:10:33 am

Title: Crankshafts...
Post by: Expat on February 12, 2008, 10:10:33 am
Is it permissable to recut the crankshaft end taper to suit a different flywheel??

Meaning will the machining process damage any hardening or treatment in original crank end  ?

Crank is mid '70's Husqvarna.
Title: Re: Crankshafts...
Post by: vandy010 on February 12, 2008, 11:12:37 am
i guess anythings possible but why not machine the flywheel to suit the crankshaft?
on my old yamaha's, i had a 'dummy' shaft machined up from 30mm round bar with the same taper {11degrees i think} and then have since machined 2 flywheels using the dummy shaft to get the correct fit-up. it's worked a treat and much easier in my books than messing with the crankshaft. don't be too concerned when machining out the key-way from the flywheel as the 'taper' will hold the flywheel in place when the nut is tightened. at least it has for me.
hope this helps.
Title: Re: Crankshafts...
Post by: Lozza on February 12, 2008, 12:15:44 pm
Very close Vandy, crank end tapers are usually 12deg included angle(set compound to 6deg but check with a dial indicator your on centre) but the diameter varies.If you machine the taper down you will need a new TCT tip to get under the case hardening, then the machined taper isn't hardened, but thats no worries if you have a generous radius where it steps down. It's a common misbelief that the woodruff key 'holds' the flywheel/rotor in place, this is just for ease of assembly at the factory.Vandy you are 100% correct that the taper hold them in place,just after machining lapp the shaft and new tapered flywheel with valve paste(at last a good use for 4T stuff).Machine the flywheel if possible.
Title: Re: Crankshafts...
Post by: Freakshow on February 12, 2008, 03:46:40 pm
there are days i wish i was a hands on kinda guy.    Lots of great ideas but know i dea how to complete them :O(
Title: Re: Crankshafts...
Post by: Expat on February 12, 2008, 07:39:27 pm
Actually the Husky crank ends are separate shafts that press into the crank wheels....they are still available new so easy to re cut the taper.

My Husky has large shaft/taper and intended ignition flywheel does not have enough metal to machine flywheel out to suit shaft.

The later Husky "small" shaft option is a bit too small for flywheel  :(

Could the shaft be re case hardened after machining?
Title: Re: Crankshafts...
Post by: Lozza on February 12, 2008, 10:07:43 pm
Yes and No.The freshly machined part would be able to be heat treated but the part that was already treated would go brittle.If you were to machine a new press in taper( ::) Swedish valiants) you start with a bit of new EN36A or B is better and case harden the whole lot. Job jobbed.