[Fot] Harmonic Damper Question

Robert Lang lang at isis.mit.edu
Thu Apr 9 07:50:13 MDT 2009


Hi,

I installed a crank fan eliminator on my race car last year if for no 
other reason than it looked kool. It also dropped some weight, maybe 1 lb. 
And $30. :-) BTW - the guy that made this part is an awesome Triumph dude 
in Maine - Rick Patton. He's getting 200 HP to the wheels on a 
supercharged / injected TR6 motor with mostly stock internals!

At any rate, I installed the eliminator and after a few events where the 
motor saw fairly big RPMs, the motor developed a rattle that you could 
only hear at idle. Along with FOT 19to1TR6, we determined that the 
harmonic damper had worked loose. I actually expected that to be the 
source of the noise, but I was more expecting the two damper rings to have 
seperated.

The guy that made the parts looked at the part design and my installation 
and we determined that the back cut on the eliminator was not deep enough 
for my installation and this allowed the stock damper to wiggle a bit in 
the radial direction. Eventually, the crank key got worked over a bit and 
the slot in the dampener got egged out a bit.

Here's the question: if a damper works loose, is it a given that the crank 
snout is damaged? I put a mic on the crank and I get uniform dimensions, 
but as of this moment I don't have another crank pulley to install to do 
some measuring. I'm teetering on the edge of picking up a fancy race 
dampener (I know all the advantages, I'm weighing a new dampener vs. being 
able to "afford" the trip to Nationals this year).

So - the second question is - if the crank is knackered, is it a given 
that I'll wreck whatever dampener I install on that crank?

I hope this is clear in description. I sort of think the answer is a no 
brainer (meaning that the crank is probably not optimal any more and that 
installing a new dampener is probably not the best solution), but I'm 
trying not to have to build a new bottom end on the motor at this time.

Guidance, please?
rml
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