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Does steering rack baulk original cooling fan.


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Hello all,  just dived into TR3a ownership and evaluating winter jobs.  It has a steering rack fitted.  It also has an electric cooling fan.  And the wide belt.  It looks as though I couldn’t return to a mechanical fan running off the crankshaft if I wanted to, because the nose of the crankshaft fittings run very close to the rack, suggesting the re-installation of a cooling fan tower wouldn’t have enough room.  Is that true?  Put another way…if one fits a steering rack, do we have to fit an electric fan?  Many thanks  

Peter Westhead  

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Hello Peter, welcome to the forum,

In most cases fitting a steering rack also means fitting an electric fan as you have discovered, but usually accompanied by a narrow belt conversion too, the reason being that the original fan and extension turned out to be a very good vibration damper for the crankshaft, and the narrow belt conversion includes a 2 part rubber bonded lower pulley harmonic balancer which does the same job.

Having said all that, there are certain rack conversions available ( I think it may be the ones using a Mini rack) which do purport to enable the original fan to be used. Also there are probably others who have run without the harmonic damper for years and had no problems.

No doubt others will be along presently with their opinions.

Ralph

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I am guessing for originality sake, although the rack is not original anyway, and let`s face it, the mechanical fans rarely go wrong.

Ralph

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This isn't answering your question Peter, but I suspect the 'harmonic damper' thing mentioned above, is just a myth.  The lump of iron which is the original fan/extension is little more than that.  Also It is unlikely the damped-pulley supplied with the narrow belt kit is actually tuned to the TR engine, so it could even do more harm than good if it resonates at the wrong frequencies.  (John Davies has investigated crank dampers in depth, but I think mainly for 6-pot engines. )

My mechanical fan went wrong. It lost part of a blade so it was generating vibration. The fan hub has balance-weights with slotted holes for adjustment. I wonder how many mechanical fans on these cars are still correctly adjusted and in-balance as (presumably) they were originally ?

To get back to your question, it sounds as though you don't have the fan extension fitted though you still have the wide belt pulley ? There must then be some type of adaptor in the centre of the pulley to allow a shorter retaining bolt to be fitted.  A couple of people (Marco for one?) have recently posted pictures of purpose-built fan extentions which were much narrower in the centre than the original, made to give more clearance to ease fan-belt replacement. Maybe you need something like those ? (thread link below. Click on it to open )

 

Edited by RobH
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Well thank you very much gentlemen.  Let me absorb all that and reflect.  Just to respond specifically to your comments…

Thanks Ralph, for the context comments.  I remember reading about Henry Royce discovering the harmonic balancer solution, when the two part metal crankshaft damper pieces, separated by wood spacers, upon dismantling, showed the wood was charred, showing that the two parts were moving against each other.  He changed the wood for lamp wick and resolved the issue, largely.

Morgan say that the electric fan should be fitted behind the radiator, to give the radiator the first gulp of cooling air, and the fan then pulling the air through.  So I looked at this fan, in front of the radiator, and was just wondering.

Hello John, yes, I always try to go original, and treat those original designs as the challenge.  And as I mention above, I would have preferred the radiator to have a clear air flow. Just a matter of taste.  I doubt I am so committed to originality to convert back to steering box though.  I see the next model along got the rack, so its almost a Triumph arrangement.  

Hello Rob, yes I’m not quite sure what was adapted on the crankshaft front, when the rack was fitted. Peering down into the pit of the mucky engine and trying to compare to the parts catalogue.  And thanks for the reference to bespoke adaptors.

And Bill, that made me smile.  Something about simple solutions being the best.  And probably subtle enough to keep alignment.  

If this is representative of the club support, I’m going to enjoy this car, the club and the people. Thanks again. 

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