(22-04-2020, 07:27 PM)Andy Cawley Wrote: Nick, I’m inclined to agree. Cranks usually break at the rear. I need to think positive and imagine that I have a pristine crankshaft??.
I've had the gears break at the front of a mag engine.
What usually happens is that the centre of the cam gear breaks. When that gear broke up it jammed the crank gear and that split into three parts. I don't think that this mode of failiure breaks cranks, which, as you say, usually break at the rear
(22-04-2020, 11:26 PM)Andy Cawley Wrote: Chas, if that's the case, why no damage to the timing case?
Once the crank gear spilt the whole timing gear train stopped revolving - and therefore nothing gets flung around by the forces of momentum or via the drivetrain as with a crank or rod breakage
My Nippy engine broke like that when doing 30mph in top gear on a light throttle opening. Broke almost everything apart form the block, Head & flywheel. Including bending the camshaft.
Bad luck with so much damage. I've only had one broken crank - driving out of the Thruxton circuit gates. Apart from the crank, nothing else was touched. Still, the tow back up the M1 at 70 m.p.h. was entertaining...
24-04-2020, 01:20 PM (This post was last modified: 24-04-2020, 01:22 PM by Dave Wortley.)
I took my badly damaged crankcase to our local scrap dealer. It looked ok until you noticed that it was minus nearly all the front bearing housing. The dealer was impressed with the casting and now has it on his filing cabinet in his office.
The damage was caused by crank rear web fracture, as we came off the M1 after doing the Coast to Coast.
