[TR] Lightening TR3 Flywheel

Randall TR3driver at ca.rr.com
Mon Jan 11 06:40:03 MST 2016

> The advantages of a lighter flywheel are pretty clear. Faster 
> acceleration = more fun.
> Once you have a lighter flywheel installed and balanced, 
> etc., are there any long-term disadvantages? 
> E.g. does that extra mass in the flywheel help absorb 
> vibration that is now absorbed by something else in a 
> flywheel-lightened car?

I did not notice any increase in vibration; but I also did not have the engine balanced either before or after.  (Didn't even have
the engine out of the car.)  And my car has plenty of vibration from other sources.  You might well notice an increase if everything
was balanced perfectly.

The biggest downside that I have noticed is the engine seems much less torque-y at very low rpm.  Coordination of the throttle and
clutch becomes much more important when first launching from a stop, especially when the engine is cold.  I don't recall ever
killing the engine with the old cast iron flywheel, but even now, after some 100,000 miles of driving almost every day, I still kill
it every once in awhile with the alloy.

Perhaps because of that, the friction surface of the flywheel seems to be wearing quite a bit quicker than it did with the old
flywheel.  The wear was noticeable after only 50,000 miles or so; which still isn't bad, just different.  I expect the friction
surface (which is a separate replaceable piece) will need to be replaced by the time the clutch plate wears out.

I also get just a bit of clutch chatter when it is cold.  May or may not have anything to do with the flywheel (as I changed to the
later diaphragm clutch at the same time), but I suspect it does.

The biggest concern with the aluminum flywheel is that aluminum has no fatigue limit; meaning the part has some limit on service
life before it breaks (just like airplanes do).  I'm taking a chance on that not happening during my service life, but I'm not aware
of any analysis that shows when it might happen while still observing the factory redline.  If I were racing with it, I would
definitely have a better scatter shield around it.


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