[TR] Harmonic Balancer for TR-4?

MMoore8425 at aol.com MMoore8425 at aol.com
Fri Apr 10 22:26:14 MDT 2009


In a message dated 4/10/2009 4:21:05 P.M. Pacific Daylight Time,  
tr3driver at ca.rr.com writes:

IMO it  depends on your intended usage.  For street operation at normal  
rpm,
IMO the "balancer" (which is a misnomer, it's really a harmonic  vibration
damper) is not required.  I've run my street TR3A that way  for almost 20
years, and the only problems related to it were because I  didn't use Rick's
kit.

OTOH if you plan to spend much time at all  above 5200 rpm or so, then it's
probably cheap insurance.  There is  supposedly a resonance point up there
somewhere, where the harmonic  vibrations will build up and cause extra
stress in the crank.  Those  vibrations combined with the much higher forces
at high rpm (plus higher  output from a heavily modified motor) can and do
cause crankshafts to  break.

> If I decide to go to a 
> harmonic balancer how do I  find one to fit?  Does anyone on 
> the list know of a direct fit  harmonic balancer for the TR-4? 

Dampers are available from most of the  vintage race suppliers.  One source
is British Frame and Engine  http://www.britishframeandengine.com

It's also possible to use the  dampener from a MGB, but requires a spacer 
and
special seal to do so.   And it's not clear how well the MG dampener meets
the needs of the TRactor  motor.

> What issues should I 
> expect in converting?   

All of the dampers I know of require converting to a narrow fan  belt.  That
means a different water pump pulley (and a water pump  where the pulley is
removable, some aftermarket pumps are not).  Also  a different pulley for 
the
generator or alternator.  Not difficult  issues of course, just more things
to be dealt  with.

Randall
_______________________________________________



Several years ago, the Triumph Register had a series of articles about  
crankshafts  (most famously Ian Evans crankshaft) breaking at low RPM,  and 
totally unexpectedly. I do not remember all the conclusions, but I do  remember 
I was happy I left my factory (crankshaft) fan on when I  installed my 
Kenlowe electric fan.
 
Best, Mike Moore 


More information about the Triumphs mailing list