The economic pain probably happens less often if you build the best engine
you can afford, whatever that means (though you tend to flog a better engine
a lot harder). When I look at a stock Triumph rod I think there's just no
way I want that junk in an engine of mine. The cranks don't look that bad,
though they have a lot of stress risers that give me the willies. It's not
easy to turn stuff with that sharp an edge, you've got to wonder why they
did it that way. Moldex cranks are gorgeous. I don't know if a harmonic
balancer would have saved your crank, but I wouldn't build an engine without
one.
BTW, I crack check everything each year when I tear it down. I have my own
Mangaflux and dye penetrant setup (Microsoft spell checker suggests Megaflop
and Penetrate). I found cracks in several Triumph cranks. Usually in the
rear main journal area. Also found lots of cracked Triumph rods. Very small
cracks, but often in the same area near the oil hole. So far I've never
found a cracked Carillo (knock on wood).
-----Original Message-----
From: owner-fot@autox.team.net [mailto:owner-fot@autox.team.net] On Behalf
Of Richard Taylor
Sent: Wednesday, August 25, 2004 1:54 PM
To: 'BOB KRAMER'; 'Jack W. Drews'; FOT@autox.team.net
Subject: RE: Moldex crank
Group,
I too have just uncovered an arresting discontinuity in my
crankshaft....number three journal at the aft connection to the
throw...fairly clean vertical break. The connecting rod was still attached
to the journal. Nothing came apart.
A Moldex crank might be a little over-kill for a motor which is not revved
over 5500 rpm, except something went wrong with this last one. It had 21
races on it including 18 Enduros and another 9500 street miles towing a
motorcycle trailer.
Which leads me to two questions:
1. If one "does" a Moldex crank, is one then obliged to then cough up the
resources for Carrillo rods...and then go for some sort of special pistons?
2. I have a totally unsupportable notion that my crankshaft failed because
of fatigue caused by harmonic flex. Several years ago I installed a radiator
fan and simply unbolted the old iron one. This left that 6" snout wiggling
out to the front of the engine. Was that a mistake? Should I install an MGB
harmonic balancer? If I have the crank, flywheel & clutch balanced before
installation, will this obviate the malevolent harmonic potential?
On the other hand, now that I am down to a raw block, the temptation to
forget economics and put together a bullet proof bottom end is pretty
tempting.
I look forward to your comments.
Richard Taylor
TR-4
Atlanta
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