Triumph TR6
Nigel makes a new radiator duct from aluminium sheet
Triumph’s engineers clearly recognised the importance of directing plenty of fresh air to the radiator in order to keep the TR6’S engine temperature within reasonable limits. All TR6S, and many other Triumph models, have a duct between the radiator grille and the radiator itself, to ensure as much air as possible passes through the core. Unfortunately someone in the Triumph organisation – let’s assume the guilty party was a cost accountant – spoiled this excellent idea by making the duct from cardboard. Thick black cardboard, heavy duty perhaps, but cardboard nonetheless – and therefore unable to survive under-bonnet conditions for very long.
I last fitted a new cardboard duct to the TR6 about 10 years ago and inevitably it’s started to fray at the edges and droop across the top of the radiator. It looks tatty and probably no longer feeds air to the rad as well as it should; in short the duct needs replacing once more. While I understand the idea that oil and filters need to be changed regularly, I baulk at the thought that a radiator duct should be seen as a service item! A permanent replacement was called for.
Aftermarket suppliers have recognised the problem and replacement ducts are available made from aluminium alloy or even stainless steel. To my mind, simply buying a new duct online and fitting it seemed too easy. I’ve no great experience of sheet metal work, but the challenge of fashioning a neat new duct in my own garage appealed. I figured it should also be possible to save a few of my hard-earned beer tokens by making the duct at home rather than buying ready-made. Think of it as the classic equivalent of cooking a delicious meal from fresh ingredients in your own kitchen, rather than popping down to the supermarket for a microwave TV dinner.
Banishing the board
There are probably plenty more classics that would benefit from custom-made metal replacements for flimsy cardboard ducts and cowls. This nasty thick black cardboard seemed rather too popular in cars from the Sixties and Seventies, before black plastic became the ubiquitous under-bonnet material for such components. The processes I followed to make
the new duct for the TR could certainly be used in other classic applications.
Here’s one I made earlier
Choice of material was easy – aluminium would be much less demanding to cut and fold at home than stainless. Alloy would also still be strong enough for the job if it was sufficiently thick and perhaps included a few reinforcing folds on its longer edges. I chose 1.5mm alloy sheet, simply because it was the maximum thickness my bench-mounted sheet metal folder could handle.
A sheet was ordered online from Aluminium Droitwich, large enough to cut out a new duct in a single piece, which could then be folded up without needing any riveted or bolted joins. The lack of joins makes for a neater and potentially stronger job, though the cutting and folding is a little trickier, necessitating a jigsaw and a bench metal folder.
As a sheet metal novice, the result is pleasing. Taking a couple of afternoons, I spent far longer on this task than a pro would have done, but turning a flat sheet of metal into something useful with my own hands was very satisfying. Bolted into place in the engine bay, the new duct looks smart, fits well and should ensure good air supply directed at the radiator core. The only downside is that the rest of the engine bay now looks a little shabby by comparison! Maybe an underbonnet smarten-up would make a good winter project.