HA BRABHAM VIVA GT
Here is the last in a series of articles on uprated HA saloons for now… Its almost time to get back to real vehicles and engine, saving the best till last, the Brabham GT HA.
The Vauxhall Viva, a popular small car distinguished from the majority of its competitors in the field by its conventional approach, has followed the general trend of fate these days: if it is small, then tweak it! So far a number of firms have tackled the Viva on this score, but equally, some of the others will have to be pretty good to beat the Brabham version, which was announced at the end of last year and, as is reported elsewhere in this issue, will shortly go into production at the rate of some live cars a week.
As it comes out of the factory, the Viva has a comfortably over-square engine of 74-3 mm. x 60 96 mm., with a compression ratio of 8’5 to 1 and a total capacity of 1,057 c.c. A single Solex carburettor, with 22 mm. choke, is filled, and overhead valves are operated by push-rods. Net power output is 44-2 b.h.p. at 5,200 r.p.m. Front suspension is independent, using the transverse leaf spring which is an unusual approach ihese days, while at the rear there are the usual longitudinal semi-elliptic leaf springs. In the braking department, there are 8 in. drums at the rear and at the front a choice of either 8 in. drums or 8-3 in. discs, and if the latter is fitted then so is a vaccum servo.
At Jack Brabham Conversions Ltd., in Woking, the machine is tweaked up in a whole-hearted manner. The cylinder head is modified, and larger valves are fitted: the compression ratio is raised to 10 to I and two Stromberg CD 125 carburettors are added, together with a special four-branch exhaust manifold. Naturally, the power unit is properly balanced, and by the time they have finished with it the power output goes up to 60 b.h.p. at 5,800 r.p.m. The suspension is lowered all round, competition dampers arc fitted and, inside, the car is given a smart wood-rimmed steering wheel and a new instrument panel, incorporating rev-counter, speedometer, oil pressure, water temperature and fuel gauges. As an extra, Interior Silent Travel can be fitted.
Brabham’s chose the Viva because of the robust qualities of its power unit, because it remains a nice, roomy little car and, not least, because it is obviously going to be in production for a long time. The unusual inlet design—the inlet tract going into the top of the cylinder head—proved to be a helpful feature in developing the engine, but the rather unusual rear suspension arrangement, in which the leaf springs are attached to the axle at points well ahead of it on extended arms, had to be gone into pretty thoroughly before they were satisfied. The engine, obviously, is in a pretty mild state of tune, and the Brabham people have concentrated on the handling with considerable success.
Dampers on the test car were Armstrong at the front, and Koni at the back, with Dunlop SP41 tyres. Externally, the car is distinguished mainly by contrasting flashes down the sides and by Brabham badges: if you happen to park it alongside a standard Viva you notice that it really is a hell of a lot lower, but this is achieved merely by attention to the suspension, so that tall drivers are in no greater danger of banging their heads on the roof than they were before.
At present the standard seats are retained, although optional Restall seats will be offered. We were warned, however, that we should have some difficulty in keeping the editorial behind where it ought to be, and this proved to be only too true, although the driver’s seat was more comfortable than that on the passenger’s side if only because it had carried weighty Woking bodies for a good mileage, and was therefore “shaped”! The engine is an easy starter, assisted no doubt by too-rich needles in the Strombergs. This is a freely-admitted fault in the car, caused by the difficulty of obtaining a wider selection for the instrument, but one which has no adverse effects on its performance except in the matter of fuel consumption: more of this anon, as they say. It warms up quickly from cold and there is no undue mechanical noise. Tractability in standard form was a quality we commented on favourably in our original road test of the standard car, and none of this has been lost in the process of tweaking it. In fact, the increased power and torque, developed over a similarly wide range, rather tends to emphasise it, and if you are lazy enough to potter about in top gear in a car which is liberally sprinkled with GT labels, it is nice to know that you can. The only disadvantage on the cold engine is that the revs must be kept down low at first—-and by that we mean very low, below 2,500 being wise—if the oil pressure is not to go off the clock. This was in cold weather, though, and Phil Kerr assured us that it doesn’t happen in the summer.
The engine is very free-revving, and goes up to 7,000 without distress: at the other end of the scale, it idles as well as the standard unit, and ticks over quietly and smoothly at 750 r.p.m. There are no plug troubles lurking in the background in thick traffic, and at the top end the benefits of balancing are seen in turbine-like smoothness.
The standard transmission is retained, and bottom gear proves a bit on the low side. At about 5,500 r.p.m. there is a slight rattle from the gear lever, which is nothing like as bad as it is on, say, a tuned Mini, and there is some sort of transmission vibration at about 4,000 r.p.m. which stops as soon as the revs go up a bit further. The lowered suspension gives a slightly harder ride, with reduced roll on corners, but it isn’t uncomfortable, and there is no increase in road noise. What it does is to give the car superb roadholding. Really hard cornering on dry roads gets the back wheels hopping across fairly gaily, but for this you have to be pretty cruel, and driven with determination the Viva GT is a real Mini-eater. The acceleration is pretty lively, too: in fact, it is rather better than our figures may suggest, since the morning we chose for performance testing turned out to be a little damper than is desirable. The fact remains, however, that even under these circumstances the Viva GT rushed up to 60 m.p.h. in only 16 seconds, which is better than, say, a standard Triumph Spitfire, and only a second or so worse than a Sunbeam Rapier. Maximum speed is a generous 90 m.p.h., which means that you can hustle the thing along at a little over 80 with plenty of revs in hand. It isn’t particularly noisy, either inside or out, and the performance combined with the outstanding roadholding means that if you’re prepared to chuck it about a bit you can really get places. The brakes are well up to the job — the discs were on the test car – although the back axle tramps a bit under heavy braking on dry roads, and accordingly the wheels lock up. Even so, the car stays going where it is pointed, a feature which is emphasised in the roadholding, and you can hustle a Viva GT round the corners at no mean rate.
Lightness of the controls is another feature of the standard Viva which the GT version retains: steering and clutch are quite astonishingly light, and it doesn’t need an expert to drive it. There is no fuss or nonsense about getting off the mark, and the car is very much what you care to make it: as a shopping car it is quiet and docile, with no vices, while at the other end of the scale it is really a very quick way of getting from place to place.
The conversion costs £160, including fitting Brabham’s won ‘t let you bolt it on yourself, wisely enough -and as a complete car, the Viva GT will set you back £748 4s. 2d.