On Sat, 20 Sep 1997 18:27:07 -0700 Mike Lishego <mikesl@tartan.sapc.edu>
writes:
>Well Bob,
> When I had my first MGB engine apart, I took the flywheel into
>the machine
>shop with the same question in mind. Someone recommended getting an
>aluminum wheel
>to me, but I ccould never find one. When I went to the shop, the said
>that maybe
>four or five pounds for my 4-cyl. engine. It would cost me about $80
>or so, but they
>also told me _not_ to do it. They had problems with flywheels
>shattering, or in one
>frightening case, the flywheel tore lose of the engine and ripped out
>the side of the
>tranny and thru the car! No one was hurt, but they told me that
>they'll really only
>recommend that type of modification for a drag racer.
If this machinist has had problems with flywheels coming off cranks
and/or shattering, I would probably avoid him like the plauge.
The basic reason a flywheel shatters is a flaw or stress raiser
introduced into it, either during manufacture (which has no bearing on
whether it is lightened or not) or through the lightening process via
scratches, tool marks, un-radiused corners etc, etc.
As for one which tears loose from the engine, if it wasn't a
manufacturing flaw, then the question I have is "what the HELL was anyone
doing taking material off the bolt circle?!?"
As an old drag racer, I've seen flywheel shatter (not a pretty sight),
but in every case, it was at extreme RPM's - at or beyond redline.
Remember, forces on rotating masses increase expotientally with speed.
A properly lightened flywheel done by a competent machinest who is
familar with the process, and not lightened excessivley (as is common in
drag cars) should not be anymore prone to shattering as a stock flywheel
at the engine speeds we normally operate at (below 6500 RPM).
Get another opinion from a different machinist.
Rick Morrison
72 MGBGT
74 Midget
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