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.
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.
(from Piggot’s Original Triumph TR):
Suffix letters in Commission numbers
L (as 1st suffix letter) — left hand steer
O — overdrive
Total production numbers:
1965 13735 (CTC 50001)
1966 11097 (CTC 64148)
1967 3633 (CTC 75172)
There are clearly some omissions here – I know that CTC 7xxxxx has Stromberg carburetters, for example. Piggot’s numbers and change points are completely oriented towards the home (UK) market, and he neglects a number of details that pertain to export cars.
In addition to the items listed in the general Triumph Buyers Guide , there are a number of specific items of interest on the TR4A.
Assessing a TR4A for possible purchase is very much like assessing any Triumph. Due to the many mechanical similarities, most of the same strengths and weaknesses of TR4 or TR6 apply to the TR4A range.
This is an attempt to help differentiate the TR4A from the TR4 at a glance. It concentrates on US models; according to the photos in Bill Piggott’s Original Triumph TR , the UK model differ in some small details (notably front turn signals).
From the windscreen back, the TR4A looks essentially identical to the TR4. The top doesn’t disappear under the interior trim any more. The Surrey top is a desirable option; as far as I know, the factory never offered a hardtop, though there were aftermarket units available.
The taillight lenses are still all red, and the boot lid on IRS cars has an extra “IRS” badge. The exhaust was either twin silencers or a single large silencer mounted transversely with dual exhaust pipes. Reversing lights were a rare option, consisting of a pair of chromed housings mounted at either end of the bumper by the outboard bumper mounting bolts.
After 25-35 years, it would not be a surprise to come across a TR4A with major components whose numbers do not match the listings above. Gearbox and differential swaps are common; we have even seen one car with TR4A body panels mounted on a TR4 frame. Much of the above information was taken from Bill Piggott’s Original Triumph TR .
Due to the continuing, even increasing, popularity of the wide chassis Triumphs (TR4A/250/5/6), availability of spares is quite good. In fact, the TR4A didn’t have as many oddball items (green or green-striped hoses come to mind) so in some sense they have the best availability. Some body panels are hard to find, but the TR250 or TR6 part will often do.
Sometimes the original part as numbered in the TR4A parts manual is no longer available, but it will have been improved upon and superceded by a TR6 part. The lower inner front A-arm mounting bracket comes to mind; the TR6 part has two mounting studs instead of one. The TR6 radiator shroud will bolt on directly and provides pre-drilled holes to mount an oil cooler, but you’ll have to make your own holes in the lower valence.
The chassis and suspension pieces are shared by all those cars, pretty much up to the end of TR6 production. As an example, the steering column switchgear is essentially identical from the TR4A through the first series of TR6, except that the later models have black trim instead of chrome. This transformation was originally made by covering the chrome with black plastic tubing, and is easily reversed! Gearboxes swap, as do differentials (though you may have to retain your original rear cover).
By all means, spend the money required to get a reprint of the factory parts book; unfortunately much of the documentation for the TR4A is produced as an addendum to its TR4 counterpart, but the parts book is dedicated to the TR4A and very clear. Supplement that with the free TR250 and TR6 catalogs from The Roadster Factory and compare part numbers.
Parts are available through a number of U.S. vendors: The Roadster Factory, Victoria British, Moss Motors, etc. TRF’s TR250 catalog is a great thing to get – most of the suspension pieces and many of the accessories are correct, and it’s more detailed than the factory manual in places.
TriumphTune and Racestorations are good sources of competition parts. Ken Gillanders’ “British Frame & Engine” is a Stateside source for many of the best bits from Racestorations as well as a few things that he’s developed on his own – he’s been racing Triumphs since the 50s and is more than happy to talk about them. British Parts NW and FASPEC have uprated suspension bits. The Fat Chance Garage has experience with solid axle TR4As and lots of parts both used and new.