Joe,
I would love to have absolute proof there was a '"tropical fan" for TR4s.
(and any proof is welcomed!)
I believe over the TR4 and TR4A production models, Standard-Triumph installed
four different fans.
The first TR4 fan was the same small 'bi-metal' fan as used on TR3s.
The second TR4 fan was the same style, but with enlarged rectangular paddles.
The third fan - introduced with TR4As - had a similar bi-metal construction
but with six-blades. (the so-called 'tropical fan')
The fourth fan was a six-bladed light yellow plastic one for mid TR4As. It's
flimsy blades sometimes scraped the radiator at high revs so factory
recommended retrofitting TR4As not back to the early 6-bladed metal TR4A fan,
but farther back - to the late TR4 fan.
All late TR4As came off the production line equipped with the late TR4 fans.
I have seen many photos of the so called 'tropical fan'. Some on TR4As, and
some on GT6s. I have two of these fans myself.
At this point it is my belief that the 'tropical fan' is really just the stan
dard early six-bladed metal TR4A fan. You can see a portion of this fan in the
TR4/4A Factory Workshop Manual - it's visible in the 'Steering Rack Mount
Tightening Instructions' photo.
There are two versions of the six-bladed metal fan.
The critical difference seems to be different sized rivet 'heads'.
In the TR4/4A Workshop Manual you'll see the 'fat rivet head' version.
In the eBay photo below - you'll see the 'small rivet head' version.
The small rivet head version might have been for the smoother running GT6s or
simply the first edition of this fan (which then would prove
'fracture-prone').
The small rivet version I have, has hairline fractures in all six aluminum
blade 'tips' - starting at the outermost small-headed rivet. This eventually
would lead to flying aluminum shard(s). A nasty surprize while adjusting your
running motor, eh?
In comparison, the 'fat head' rivet fan has no hairline fractures in this
area and looks less prone to vibrational problems.
In general, the bi-metal six-blader is a great looking fan, more air
grabbing, and suits the antique look of a TR4 motor.
Standard-Triumph's second attempt at designing a plastic fan was much more
successful with the darker yellow plastic TR250 fan for its modern six cylinder
motor.
If I had not found an excellent 'fat-rivet' 4A fan (for $25) I would opt for
the yellow plastic TR250 fan. They are time-proven, light and flexible, and
still available brand new. Some folks paint them aluminum color because they
can
look too modern on the old four-banger. Fitting a TR250 fan to a TR4/4A
usually requires moving the radiator forward a bit and/or using a shorter fan
extension and/or reversing the blade.
If I didn't go with one of the above routes I would probably add an electric
fan.
Hopefully you already know about the TR4 radiator 'thermostat and bypass
port' issues and the latest recommendations...
hmm..where's my can opener??
The latest eBay price for a so-called 'tropical fan' was $200.00! And this
was for the small rivet head version.
See...
http://cgi.ebay.com/ebaymotors/ws/eBayISAPI.dll?ViewItem&item=7900132836&category=34201&sspagename=STRK%3AMEBWA%3AIT&rd=1
..for a couple nice pictures.
And somebody .. please .. send me proof verifying there was really such a
thing called a TR4A 'tropical fan'.
Doubting it,
Carl
'63 TR4 since '74
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