[TR] Electric Fans: Something Different

[TERRY SMITH]

Okay.  You have me curious.  What does a harmonic balancer look like and how to you "balance" it?

I've run for a dozen years on the extension hub just swapping out for the yellow blade plastic fan.  I don't race, but do sometimes add spirit to the accelerator pedal!

By the way, has anyone seen the beautiful Morgan on Bring a Trailer?  20 hours left and going presently for somewhat over $16k, which seems exceedingly low for it....

Terry Smith, '59 TR3A
New Hampshire
> On July 22, 2018 at 2:49 PM Andrew Uprichard <auprichard at uprichard.net> wrote:
> 
> 
> I have 2 TR3s with electric fans.  In both cases I removed the old fan
> extension and fitted a harmonic balancer for that very reason.
> 
> Andrew Uprichard
> Jackson, Michigan
> 
> -----Original Message-----
> From: Triumphs [mailto:triumphs-bounces at autox.team.net] On Behalf Of Randall
> Sent: Sunday, July 22, 2018 9:36 AM
> To: 'George Haynes'; triumphs at autox.team.net
> Subject: Re: [TR] Electric Fans: Something Different
> 
> 
> > Many years ago, when the machine shop was balancing my TR4A 
> > engine, the tech asked if I really needed the fan extension 
> > hub on the crankshaft.  Seems he would have to remove metal 
> > from the crankshaft to compensate if the extension hub was 
> > retained.
> 
> I'm just curious, George: Why would he want to remove metal from the
> crankshaft because of the fan extension? 
> 
> Surely, if the extension was out of balance, he should have removed metal
> from it to balance it independantly?  Or is there some problem caused just
> by having the weight on the front of the crankshaft?
> 
> FWIW, there has been a lot of talk in the past about harmonic vibration in
> the crankshaft being dampened by the original fan.  I've always felt that
> applied mostly to racing engines, which tend to see a lot of time above the
> factory redline.
> 
> But then last year, the crankshaft in my current TR3 snapped through the
> front web.  That seems very odd to me, as the stress would be lower at that
> point than almost anywhere else along the shaft.  Unless it has been
> vibrating after I removed the stock fan and extension?  I don't know, but
> when it goes back together, I intend to install a harmonic damper, just in
> case.
> 
> -- Randall
> 
> 
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