A History of the Triumph TR4A
The TR4A - beginning of a major transition
Apparently there was always the feeling at the factory that the TR4 was an interim model. Financial woes caused the company to introduce the TR4 when it did; otherwise a car to replace the TR3A mith have been even more complex, technically more advanced and in general more exciting. It might have been the TR4A!
The origins of Harry Webster's IRS design stem from around 1962, and the basis for the TR4A stems from that as well; it was expected that the change to IRS would cause a radical change in the behaviour of the car, so it would be necessary to begin a new project and plan a new model. If evolved steadily until the completed project was vastly different from the car it was to replace. According to Robson, "the TR4A was as different, in its own way, from the TR4, as that car had been from the TR3A. It was yet another step along the transitory path which was to convert the rugged little TR2 into the smooth and thoroughly modern TR6.
Webster's team was faced with a major problem - although they had been asked to design an independently-sprung TR, they also had to make provision for the United States, where the cars would still be sold with a solid axle. No matter how much Leyland tried, the North American distributors would not give up the idea that they could still sell TRs with a live axle at the right price, that roadholding at the limit was not yet critical to sales there, and that irs was bound to be more expensive. So it was agreed that the new chassis would be amenable to both layouts, and that both layouts would be available in the US. It was not ever considered reasonable to keep the narrow TR4 chassis for the live axle cars.
The new chassis-frame had a radically different layout from the previous cars. The rear suspension was semi-trailing wishbone plus coil spring, that design having been proven on the Triumph 2000 saloon. Parts were not interchangeable between the two models, but they were philosophically the same. The TR4A kept lever arm shocks for ease of installation. The IRS cars received a massive pressed-steel bridge piece to support the differential casing and provide upper anchor points for the coil springs; the live axle cars didn't have the bridge piece and got long half-elliptic leaf springs. When prototypes were made ready for the road, managing director Stanley Markland pronounced the new chassis "safe for 120 mph"!
Which, of course, brings us to the motivating unit. Markland wanted more power for the next model, but Triumph's six cylinder engines really weren't ready yet. So the decision was made to continue on with the tried-and-true 2138cc Vanguard derivative - aging design, wet liners and all. There was talk of punching this out from 87mm to 93mm bore to give a 2499cc dry liner engine, to provide an adequate jump in power from the TR4 to TR4A, but the prototypes didn't give the hoped-for results. So the 2138cc engine was given its final boost, to 104bhp at 4700 rpm.
The TR4A was phased in smoothly at the beginning of 1965. Body production changes were limited to a new grille, decoration and badging, along with new body-to-chassis mountings. The press was happy to see an all-independent car, and Triumph was pleased to be the first British car manufacturer to have all-independent suspensions under every car in their line.
Unfortunately, the TR4A was not as fast on the road as the critics expected. (Neither was the TR4.) It wasn't much faster than the TR3A with its optional 2.2 liter engine had been in 1959 - the TR4A had put on weight with age. Even by comparison with the TR2s of 1953 there had not been a dramatic improvement. Fuel consumption was worse. Product planners at Triumph were asked to make a quantum leap in performance and economy, not to mention extended high speed running (for the new European highways). This, combined with the new emission control laws in the US, spelled the end of the four-cylinder TR. For the 1968 model year, the TR250/TR5 answered the call with the old styling but a new engine.
A competition hiatus
The Factory had pretty much stopped competition by the time the TR4A came out - the last major TR-based competition cars were the powder blue Shell 4000 Rally Team TR4s of 1964. The Triumph 2000 had taken over competition in the rough-road European rallyes.
In the United States, however, 'Kas' Kastner continued his wizardry, using his 'unfair advantage' to wring 150 bhp and more out of the 2138cc powerplant. The SCCA went to great efforts to try to keep all entrants competitive, adjusting classes year-by-year to keep the racing exciting. Between Kastner's engine work and Bob Tullius's driving for Group 44, the TR4A dominated SCCA D-Production racing. But the TR4As have very little other competition history.
It would be nice to have price history here, but I don't have it available