[TR] Electric Fans: Something Different

Andrew Uprichard auprichard at uprichard.net
Sun Jul 22 12:49:23 MDT 2018

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

-- Randall

** triumphs at autox.team.net **

Donate: http://www.team.net/donate.html
Archive: http://www.team.net/archive
Forums: http://www.team.net/forums

More information about the Triumphs mailing list