Hi John
Regards to all after a 6-day list server outage,
Well, not to prolong this thread needlessly, but there are a number of
suppliers of commendable "billet parts" that merit consideration, including
fan-elimination devices that don't affect the properties of the
pulley/damper, and, in fact, eliminate a significant mass hanging off the
crank, so I have a bit of a problem
with the generalization by some posting on this subject, implying that all
billet parts associated with the
crank are a dumb idea and sold by idiots.
But, to the point, the root cause of the confusion is the lack of
understanding of the physics, as pointed out by RML. Fortunately, doing a
Google search on "harmonic dampers" AND "crankshafts" yields a number of
excellent links, including these:
http://zhome.com/ZCMnL/tech/harmonics.htm - Scroll down to the end to see a
great explanation on the physics of the damper itself by "ZORO"
http://www.toyotacelicaonline.com/pulleys.htm - Look at the diagram on the
amplitude of torsional distortions away from the flywheel.
http://www.pro-race.com/faq.htm - More info
I plan on buying a refurbed stock pulley/damper from TRF, since the
elastomer on mine is pretty ratty, and I don't want to risk breaking my
crank. According to Kastner's prep handbook, pp. 114 -121, it pays to drill
an 1/8" hole down to the hub through the elastomer after confirming timing
marks. Then periodically slip the drill back down to the hub to ensure there
is no slippage with use between the hub and the outer inertial ring that has
the timing marks . Like many parts on our LBCs, this is another item to pay
attention to, particularly if you run your car hard.
Hope these links help.
Jerry
Date: Wed, 14 Feb 2007 19:38:09 -0500
From: John Mitchell <jmitch@snet.net>
Subject: Aluminum crank pulley
I see someone Ebay is selling a replacement crank dampener made out
of billet aluminum. Of course it would not have the 2 pieces connected
by rubber. I'm wondering what kind of problems this would create? We
take weight off the flywheel, why not the the other end of the crank?
Thanks, John Mitchell 76 TR6
|