Broken engine!!!
Turbo Mini Forums

Even if it was on the flywheel end?
Just realised what you meant. LOL
I was originally thinking that it wouldve fatigued at the damper end if it had no damper on.

Edited by Jordan on 1st Sep, 2007.

Back once again like a renegade master

Not sure what your question is asking?????

That makes sense, I guess there wasn't enought room for two parts of the crank to be side by side in the block hence bending the crank and forcing the front of the block off. Theres a mark near the journal where it could have hit the block.

Edited by Jay#2 on 1st Sep, 2007.

Looks like I've got a new goal to work towards.

crikey!, bit of chemical metal and ud never notice the difference lol!

http://www.slinden.co.uk/

This lot recon they could fix it, it says so in the second paragraph

I reckon they could fix most engine but this one was way past it, but i wouldnt trust it for a high power motor. 1 thing i would want doing is a crack failure test, (like the sonar systems and xrays)

Edited by Jordan on 2nd Sep, 2007.

Back once again like a renegade master

9.85 @ 145mph
202mph standing mile
speed didn't kill me, but taxation probably will

With a whacking great lump of metal bolted to the crank (the flywheel) generating all sorts of micro vibrations, and it its gyroscopic effect, combined with the crank flexing under load of the pistons, trying to change the direction of the flywheel on the x and y axis. No center main strap so assume the center cap is also flexing (rather than breking, Cooper S caps being made of steel already) I put my money on it going there. A damper simply allows the balance weight to oscilate at a rate that reduces the total vibration, reducing fatigue, but not eliminating it. would it matter where it was fitted on the crank? not necissaraly where the crank would break?

1275 engines known to have a problem with harmonic vibration hence why you find dampers on 1275 and not on 998s

Take into consideration that a cooper S crank is now in the region of 40 years old, and thoroughly stressed anyway although tough you will never know its history. Was it crack tested?

How good was the balance of the flywheel?

I dont see the theory being out of the question.

Back once again like a renegade master

Ok then

this picture is a stress analysis on Fastcarls wizzard cranks. It does not take into consideration any of the reciprocating mass or the flywheel. Note where the max stress point is and the likely point of breakage. Taking the two and comparing them you can see the there is little difference between them yet the stress points are different.

A crank damper does nothing other than move the harmonic frequency to a point outside the normal operating range of the engine. If one is not fitted, the harmonic frequency is in the operatimg range of the engine and fatigue fractures will start at the max stress point, where ever that is.

I stand by my theory and is based on a logical, methodical aproach as to was happening at the time of failure. Which part failed first. Where is the rest of the engine? theory takes into consideration some assumptions on the bits we cannot see

Its my theory and mine alone, in my work i have to find the route cause for stuff like this before i can fix it, otherwise once you have fixed it, whats to stop it happening again, it costs the company money and im out of a job

piccies taken from this topic http://www.turbominis.co.uk/forums/index.php?p=vt&tid=134360

Edited by Sprocket on 2nd Sep, 2007.

I agree with your theory, works for me. As you say the crank damper simply moves the resonant frequency out of the range of normal operation. A crank allowed to resonate will eventually fail, where this failure occurs does not really directly relate to the position of the damper, moreso to the point of max stress, in an old crank that may have been modified or reworked, this could well be in a place not to be expected.

Im still after some cooper S main bearing caps :-

Looks like you win sprocket (sig this if you want) and guess what?

Im convinced.

Back once again like a renegade master