Lambretta Flywheel Woodruff key sheared in half

[drunkmunkey6969]

Only 40ft-lb?

[Muppet]

only 50 for a flywheel tas got humungus inertia; for a wee AF jobby lapped in 40 is the new 50 they do have weedy little bosses that can get mangled if over tightened yup thinks Me like 40 many times more than 50,
muppet,

[coaster]

It used to be a fairly common problem back in my youth when nobody owned a socket set let alone a torque wrench All I had was a selection of box spanners and a bent screwdriver
As per adam's list, I'd get a magnifying glass on the flywheel keyway just in case it has cracked.

[warts]

When wiped clean after lapping, you should see a matt grey surface all over where the flywheel goes on the crank, and the same inside the flywheel itself. If you think its right, try it with layout blue/marker pen, there should be no high spots.
A correctly fitted taper should work without excessive torque on the fastener.

[drunkmunkey6969]

only 50 for a flywheel tas got humungus inertia; for a wee AF jobby lapped in 40 is the new 50 they do have weedy little bosses that can get mangled if over tightened yup thinks Me like 40 many times more than 50,
muppet,

I'm a big fan of the AF light flywheel, I use them more than any other type. I always torque to 50 ft-lbs and have NEVER mangled a boss, nor sheared a woodruff key by doing it this way. Seems to work OK for me.

[stokky]

Same flywheel, and now running OK.

However think i will get some grinding paste and do a proper job.

Can I simply do with crank in position ?

[swizz]

when you refit the new key, take some time and lap the crank to the flywheel it makes sense, last time i sheared a key (about 79) i cut the corners off a sixpence with a pair of pliers and a brick as a hammer and wedged two bits in. it got me home to newcastle from bridlington <(i think), ever since then i have lapped and its never happened again in tens of 1000s of miles,,PS make sure everything is spotless when you refit flywheel, no paste anywhere !

[sean brady scooters]

definatly lap crank to flywheel and torque down to 50 f/lbs

[Spanish Fly]

Challenger 240,

What's a Challenger 240?

SF

[Special X]

definatly lap crank to flywheel and torque down to 50 f/lbs

I'd totally agree with a "proper" flywheel, but 40 lb/ft (using the same halfords wrench featured in last months scootering) stretched the boss on that flywheel.

PS the challenger was a project that involved chiselspeed.