Author Topic: Crankshafts...  (Read 2053 times)

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Expat

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Crankshafts...
« 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.

Offline vandy010

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Re: Crankshafts...
« Reply #1 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.
"flat bickie"

Offline Lozza

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Re: Crankshafts...
« Reply #2 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.
Jesus only loves two strokes

Offline Freakshow

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Re: Crankshafts...
« Reply #3 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(
74 Yamaha YZ's - 75 Yamaha YZ's
74 Yamaha  flattracker's
70  Jawa 2 valve speedway's

For sale -  PRE 75 Yamaha MX stuff, frame, motors and parts also some YAM DT1,2,A and Suzi TS bikes and stuff

Expat

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Re: Crankshafts...
« Reply #4 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?

Offline Lozza

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Re: Crankshafts...
« Reply #5 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.
Jesus only loves two strokes