Curbside Classic: Triumph TR4A IRS – Stereotype Defying Tractor-Engined IRS Daily Driver

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OK; old British cars have a rep, but this one has been defying it for many years. I’ve seen it coming and going on the streets of Eugene since well before I started documenting the old heaps here. But I could never catch it; not so much because it was being driven particularly fast, but either I was on foot, or at a red light, or going the other way. But then one day at the place Stephanie calls my home away from home, there it was. I half expected to see some 2x4s strapped to its hardtop. Well, for a car with an engine that started out in a tractor, why not?

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Well, why not? When it come right down to it, these old British sports cars are built more like trucks than what we might think of in terms of a modern sports car. In fact, the legendary Triumph four cylinder started life as a tractor engine. That’s not necessarily a bad thing, especially when that tractor engine was quite modern for the times.

Ferguson Traktor_12_juli_2005

Here’s the Standard four, in its original home: the Ferguson TE20 tractor. Yes, it looks just like the fabled Ford N tractor, but after the war, Ferguson and Ford went their separate ways, and Ferguson needed a suitable engine. Standard took on the task of building the TE20 at their Banner Lane plant, and developed a modern new OHV engine for it.

Standard engine,_plug_side_of_head,_Ferguson_TE20_tractor

It had 1850 cc, and was still a bit undersquare (longer stroke than bore), and used replaceable wet cylinder liners. In tractor tune, it made some 23.9 hp “at the belt”, @ 2200 rpm.


Ironically – or not – the Standard four was soon put to use in the Vanguard (CC here), and then the TR2 in 1953. That was of course the beginning of the line of TR sports cars, which rather caught MG off guard. They were quickly appreciated for their ability to handily outrun the weak-chested MGs, yet cost only a modest amount more. The Standard four, with two SU carbs, now made 90 hp. That was an impressive amount, at a time when a new American Ford sedan still came with a 110 hp flathead V8. It could belt out a 0-60 run in 12 seconds flat, and hit 107 mph, numbers an MG (and most American cars) could only dream about. Who would have thought a tractor engined Brit car would outrun a big American V8?

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The TR4A is the ultimate evolution of the line still using the gnarly four. Now displacing 2.2 liters, it was rated at 105 hp. But it was very amenable to further hopping-up, and Judson supercharged versions readily exceeded 200 hp.

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The TR4A may have looked essentially identical on the outside to the TR4, which preceded it for the years 1961 – 1965, but the “IRS” badge was the tip-off that things had changed under its Michelotti-styled exterior.

Triumph TR4 chassis

You got to hand it to Triumph: they were consistently more progressive and adventuresome than MG. One of the endless criticisms of the British roadster was its harsh ride, especially at the back end, which relied on relatively stiff leaf springs to locate the solid live axle. Here’s the TR4 chassis, which is very much in the old school.

Triumph TR4A chassis

I had always assumed that the TR4A’s IRS was just somehow cobbled up to fit the existing frame, but it turns out to be an all-new structure. (scans courtesy of stevemckelvie’s blog). Triumph was quite committed to IRS, although the swing axles that they used in the Herald (CC here) and Spitfire had significant shortcomings in terms of tuck-under at the limit. The TR’s rear suspension is a more sophisticated design, with double-jointed axle shafts and what appear to be semi-trailing arms to locate them.

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The result was decidedly improved road-holding and comfort, and it was one of the key improvements that allowed the TR to evolve into its next incarnation, as the six cylinder TR5/TR250, and to the ultimate TR6, which was still able to provide a lot sporting pleasure without the punishing ride old-school Brit sportscars were being shunned for at the time.

The Triumphs were also know for being available with the optional Laycock de Normanville electrically operated overdrive, which could now be engaged on second and third as well as fourth, making seven closely spaced gear ratios to play with. That’s right up my alley.

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The only thing missing from this slightly-battered but proud daily driver is a utility trailer. Then I’d be truly impressed. Or maybe he was just buying some wire to deal with the ever-challenging Lucas electrics?