Geschiedenis van Triumph TR-4
De Triumph TR4A kom uit 1965. De ontwerper van o.a. de Triumph TR-4 en 4-A is Giovanni Michelotti (Engelse tekst).
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 140bhp 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 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.
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