Жагуар S Type және Mark 2 тарихы

The Jaguar S Type is a saloon car produced by Jaguar Cars in the United Kingdom from 1963 to 1968. Announced 30 September 1963 it was a technically more sophisticated development of the Mark 2, offering buyers a more luxurious alternative without the size and expense of the Mark X. The S Type sold alongside the Mark 2, as well as the Jaguar 420 following its release in 1966. A retro styled vehicle with the same name was also produced, based on the design of the original S Type vehicles.

The Jaguar Mark 2 was introduced in 1959 and sold throughout most of the 1960s. It has a live rear axle and is powered by the XK six cylinder engine first used in the Jaguar XK120 of 1948. In the Mark 2 the engine was available in 2.4, 3.4 and 3.8 litre capacities. In 1961 Jaguar launched two new models. The full size Jaguar Mark X saloon (pronounced mark ten) used Jaguar's new independent rear suspension and a triple SU carburettor version of the 3.8 litre XK engine. The other new car for 1961 was the Jaguar E Type sports car, which shared the same 3.8 litre engine as the Mark X and a scaled down version of the independent rear suspension. Having released the Mark X with its many technical refinements, Jaguar boss Sir William Lyons expected the Mark 2 would need updating with similar features if it was to retain its place in the market. Accordingly, work began on developing the S Type (codenamed "Utah Mk III", the Mark 2 having been "Utah Mk II") as soon as development work was finished on the Mark X. The S Type was a major redevelopment of the Mark 2. It used a mid scale version of the Mark X independent rear suspension to replace the Mark 2's live rear axle and featured longer rear bodywork, among other styling and interior changes. The S Type was available with either 3.4 or 3.8 litre XK engines but only in twin carburettor form because the triple carburettor setup would not fit into what was essentially still the Mark 2 engine bay. By the time of the S Type's release in 1963, the Mark 2 remained an unexpectedly strong seller despite its age. Although the Mark X was selling less well than hoped, especially in its intended market of the U. S., Sir William decided to retain all three models in the Jaguar range concurrently. The Mark X was renamed "420G" in 1966 and was joined by another new model, the 4.2 litre 420. The 420 was developed to replace the S Type but because some demand remained for the S Type, all four saloon models (Mark 2, S Type, 420 and 420G) remained on sale until the arrival of the Jaguar XJ6 in 1968. The XJ6 replaced all but the 420G in the Jaguar range.

No new engines were developed for the S Type. It was first released with the SU HD 8 twin carburettor variant of the 3.8 litre XK engine, the same as that which powered the 3.8 litre Mark 2. The 3.8 litre was the only engine offered on S Types sold into the US market. The lower powered 3.4 litre S Type used the same 3.4 litre engine as the Mark 2. It was released a few months after the 3.8S and was not made available at any stage on Jaguar's press demonstrator fleet in the UK. Whereas the 3.4 litre version remained the most popular engine option for the Mark 2, the 3.8 litre S Type outsold the 3.4 S in the ratio 3 to 2, this despite the 3.8 S being discontinued in mid 1968, a couple of months before the 3.4S.

Despite the S Type's weight gain of over the Mark 2, no changes were deemed necessary to the Dunlop four wheel disc braking system. Major changes were made to the S Type's steering system. The Burman power steering system in the Mark 2, with its 4.3 turns lock to lock, was regarded as being excessively low geared and lacking in road feel. In the S Type it was replaced by a higher geared Burman unit of 3.5 turns lock to lock, which linked the input shaft and hydraulic valve by a torsion spring to improve its "feel". The heating and ventilating system of the Mark 2 was not considered adequate for the more upmarket S Type and was replaced with an improved system. Separate control of ventilation direction was provided for both driver and front seat passenger. Warm air could also be directed to the rear passengers through an outlet situated on the propeller shaft tunnel cover between the two front seats.

A key element of the Mark X that Jaguar wanted to include in the S Type was its sophisticated, and by then widely acclaimed, Jaguar independent rear suspension. The suspension was a revelation at the time of its introduction, and remained the benchmark against which others were judged until the 1980s. Essentially a double wishbone setup, it uses the driveshaft as the upper wishbone. It carries the drive, braking, suspension and damping units in a single fabricated steel crossbridge, which is isolated from the bodyshell by rubber blocks. Including this suspension in the S Type necessitated the development of a new crossbridge suitable for its track, coming as it did between the track of the Mark X and 50" track of the E Type. The S Type used the same subframe mounted, coil sprung, twin wishbone front suspension as the Mark 2.

Several significant changes were made to the S Type's interior and mechanicals during its six years in production. Of the various performance enhancing mechanical changes, most were applied to both the 3.4S and 3.8S at the same time. These were:
In June 1964 the original Dunlop RS5 cross ply tyres were replaced with Dunlop SP41 radials, removing the former's tendency to squeal under hard cornering and providing higher limits of adhesion with more gradual breakaway at the limit. In October 1964 the brakes were given a bigger servo, requiring lower pedal pressures. Also in October 1964, the Moss four speed manual gearbox with no synchromesh on first gear was replaced with Jaguar's own all synchromesh four speed gearbox. Revised gear ratios improved acceleration and a more compact Laycock A type overdrive unit was fitted (when the overdrive option was specified)
A very few of the last S Types built had the same Marles Varamatic variable ratio power steering that was available on the 420 and 420G. The only production development not shared by both the 3.4S and 3.8S was that the Powr Lok limited slip differential option ceased to be available on the 3.4S when the 1967 cost saving trim revisions were introduced. In 1966 a dashboard switch was provided for the heated rear window, which had previously remained "on" as long as the ignition was on, leading to instances of flat batteries.

Engine Jaguar 6 cylinder in line, iron block, alloy head Capacities 3.4 L (3442 cc) or 3.8 L (3781 cc) Bore/stroke 3.4 L (83 mm x 106 mm) or 3.8 L (87 mm x 106 mm) Valves DOHC 2 valves per cylinder Compression ratio 8:1 (7:1 and 9:1 optional) Max. power 3.4 L @ 5500 rpm or 3.8 L @ 5500 rpm Max. torque 3.4 L @ 3000 rpm or 3.8 L @ 3000 rpm Carburettors Twin SU HD6 (1.75 in) Suspension Front independent, with wishbones, coil springs, telescopic dampers and anti roll bar. Rear independent, with lower wishbone and driveshaft as upper link, radius arms, and twin coil springs with telescopic dampers Steering Recirculating ball, worm and nut; power assistance optional Brakes Servo assisted discs on all four wheels, inboard at rear Body/chassis Unitary bodyshell with bolted front subframe, five seater saloon, front engine rear wheel drive Tyres/wheels 6.40 x 15 crossply or 185 x 15 radial, 5.0in rim, five stud disc wheels with wire spoke optional Track Front= Rear=

Spot On models, No. 276 (production 1964), Jaguar S type, 1:42 scale. Neo Scale Models produced a 1:43 resin moulded model of the 3.4 S Type.