Would a badly worn crankshaft spigot bearing cause clutch failure?

[greenamex2]

Al, given that two of your cylinders probably have more capacity than my entire engine, perhaps that isn't a complete surpise!

[graham bahr]

i have found over the years that as long as an engine has a fair bit of "cam" a 4 cyl will idle /run/drive quite ok with basically no flywheel at all.

[graham bahr]

[QUOTE=Denis Bassom]I have practically a flex plate for a fly wheel on my high comp 1600 4. I also have a light crank, rods, pistons, single plate Helix race clutch and NO front crankshaft damper.

QUOTE]

the less weight in terms of flywheel etc you have bolted to a crank, the less the need for a damper

[dtype38]

Originally Posted by graham bahr

the less weight in terms of flywheel etc you have bolted to a crank, the less the need for a damper

That's interesting Graham. I thought the damper was there to absorb potentially dangerous high freqency resonances of the crank, and the flywheel was there to iron out the low freqency pulses from the cylinder firing. The latter aren't much of a problem on a race car, but I thought the damper was still needed unless you have a fancy high strength crank.

[graham bahr]

[QUOTE=dtype38]That's interesting Graham. I thought the damper was there to absorb potentially dangerous high freqency resonances of the crank, QUOTE]


it is, but without a heavy flywheel attached to the other end of the crank the rpm point at which these resonances occur moves up the rev range, usually to a point at which they can be ignored.

[youngoldy]

The same thing happened to a friends Formula Ford, although the clutch didn't go, the engine did!

What happened was there was a hairline fracture in the bit of the engine (sorry, not the best of engine parts, yet!), but where the bearing sits, it had visibaly grown. This I then think caused the bearing to spin with the carnkshaft.

But when me and my dad were taking the crankshaft of, the was a smell of burning, this was a weekend after the engine went.

Also, somewhere there were bits of metal in one of the cylinders, and we couldn't see where it had come from.

[Al Weyman]

Originally Posted by graham bahr

i have found over the years that as long as an engine has a fair bit of "cam" a 4 cyl will idle /run/drive quite ok with basically no flywheel at all.

This engine has a bit of a mildish camshaft and the last time I ran this clutch/flywheel setup it had a more stout cam so I agree this probably has some bearing on it.

[graham bahr]

Originally Posted by youngoldy

The same thing happened to a friends Formula Ford, although the clutch didn't go, the engine did!

What happened was there was a hairline fracture in the bit of the engine (.

if were talking FF its most likely were talking about an X/flow in which case the crack is probably across the crankshaft rear main/web, something X/f are prone to after a couple of seasons race use, somewhere else on 10/10 is a huge long thread on the debate as to allowing this formula to used steel cranks