Jaguar Mark X

Jaguar Mark X & 420G

1968 Jaguar 420G (North America)
Manufacturer	Jaguar Cars
Production	1961–1970 13,382 3.8 Litre 5,137 4.2 Litre 5,763 420G
Assembly	Coventry, England
Predecessor	Jaguar Mark IX
Successor	Jaguar XJ6
Class	Full-size luxury car
Body style(s)	4-door saloon
Layout	FR layout
Engine(s)	3,781 cc (3.8 L) XK I6 to 1964 4,235 cc (4.2 L) XK I6
Transmission(s)	4-speed manual
Wheelbase	120 in (3,000 mm)
Length	202 in (5,100 mm)
Width	76.3 in(1,938 mm)
Height	54.5 in (1,380 mm)
Curb weight	4,200 lb (1,900 kg)

The Jaguar Mark X (pronounced mark ten) was the top-of-the-range saloon car built by the British manufacturer Jaguar, originally aimed at the United States market. The Mark X succeeded the Mark IX as the company's large saloon model.

Body

'63 Jaguar Mark X

The modern Jaguar face, four headlamps set into rounded front fenders with a vaned grill, first appeared on the Mark X. The interior is the last Jaguar with abundant standard woodwork, including the dashboard, escutcheons, window trim, a pair of large bookmatched fold out rear picnic tables, and a front seat pull-out picnic table stowed beneath the instrument cluster. Over time, air conditioning and a sound-proof glass division between the front and rear seats were added as options.

From its introduction until the arrival in 1992 of the low-slung XJ220, the Mark X stood as one of the widest production Jaguars ever built. Asked in 1972 if he thought the Mark X had grown rather too large, Jaguar chairman William Lyons, agreed that it "definitely" had: he opined that the then recently introduced and notably more compact Jaguar XJ6 was, by contrast an "ideal size".

The substantial doors required helical torsion springs inside the door pillars to enable them to be opened from the inside with an acceptably low level of effort.

Running gear and engine

The Mark X was the first Jaguar saloon to feature independent rear suspension. It used a wider-track version of Jaguar's IRS unit first seen on the E Type, which was subsequently used on Jaguar vehicles until XJ-S production ended in 1996. Front suspension used double wishbones with coil springs and telescopic dampers. Initially Jaguar's XK in-line six-cylinder engine was featured, with 3781 cc. A 9:1 compression ratio was standard, but an alternative 8:1 compression ratio was available as an option. For the London Motor Show in October 1964 the enlarged 4,235 cc unit took over, although the 3.8-litre unit could still be specified until October 1965. Triple SU carburettors were fitted, fed from an AC Delco air filter mounted ahead of the right hand front wheel.

Transmission options were manual, manual with overdrive or automatic. The arrival of the 4.2-litre power unit coincided with the introduction of a newly developed all-synchromesh four-speed gear box replacing the venerable box inherited by the 3.8-litre six-cylinder Mark X from the Mark IX which had featured synchromesh only on the top three ratios. Many domestic market cars and almost all cars destined for the important North American markets left the factory with a Borg Warner automatic gearbox. The 4.2-litre engine's introduction was also marked by a transmission upgrade for buyers of the automatic cars, who saw the Borg Warner transmission system switched from a DG to a Typ-8 unit. The power train was completed by a Thornton Powr-Lok limited-slip differential.

Stopping power for this heavy car came from power-assisted disc-brakes on all four wheels.

Power-assisted steering was standard, the later 4.2 cars receiving Adwest Varamatic variable ratio steering boxes.

420G

1968 Jaguar 420G

For the London Motor Show in October 1966 the Mark X was renamed the Jaguar 420G. (This should not be confused with the smaller Jaguar 420.) Visually, the 420G was distinct from the Mark X only in the addition of a vertical central bar splitting the grille in two; side indicator repeaters on the front wings, and a chrome strip along the wing and door panels (Two tone paint schemes were also available, whereupon the chrome strip was omitted). Interior changes included the arrival of perforations in the central sections of the leather seats, padded dashboard sections for safety, the moving of the clock to a more central position, and the introduction of air conditioning as an option.

A "limousine" version was available, on the standard wheelbase, with a dividing glass screen partition and front bench seat replacing the separate seats of standard cars. The wheelbase was extended by 21" with the mechanical underpinnings of the car being subtly re-bodied for the 1968 Daimler DS420. This car was built until 1992 and used by many countries in official capacities, and frequently by funeral homes; either with a saloon body for carrying mourners or a hearse body.

Despite running for the same length of time as the Mark X (5 years) the 420G sold in less than a third of the numbers: this lack of popularity and the increasing production of the XJ6 resulted in the 420G being run out of production in 1970.

See also

• Jaguar 420 – the Jaguar S-Type (available as 3.4 L or 3.8 L) spawned the 4.2 L Jaguar 420 with its restyled nose in 1966; the same year the 4.2 L Mark X became the 420G.

External links

• www.saloondata.com Volunteer register with records and photos of the Mk. X
• www.gbclassiccars.co.uk/jaguar_mkx.html British classic car website page about the Jaguar Mark X and 420G models