Jaguar XK120

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Jaguar XK120
1950 Jaguar XK120 34.jpg
1950 Jaguar XK120 roadster on later wire wheels; leather strap and bonnet louvres also unoriginal
Overview
ManufacturerJaguar Cars
Production1948–1954
12,055 made [1]
AssemblyHolbrook Lane, Coventry, England, United Kingdom (1948-1951)
Browns Lane, Coventry, England, United Kingdom (1951-54)
Body and chassis
ClassSports car
Body style2-seat roadster (OTS)
2-seat coupé
2-seat Drop Head Coupé
LayoutFR layout
RelatedJaguar C-Type
Powertrain
Engine3.4 L XK I6
Dimensions
Wheelbase102 in (2,591 mm)[2][3]
Length173 in (4,394 mm)[2]
Width61.5 in (1,562 mm)[2]
Height52.5 in (1,334 mm)[2]
Chronology
PredecessorJaguar SS100
SuccessorJaguar XK140
 
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Jaguar XK120
1950 Jaguar XK120 34.jpg
1950 Jaguar XK120 roadster on later wire wheels; leather strap and bonnet louvres also unoriginal
Overview
ManufacturerJaguar Cars
Production1948–1954
12,055 made [1]
AssemblyHolbrook Lane, Coventry, England, United Kingdom (1948-1951)
Browns Lane, Coventry, England, United Kingdom (1951-54)
Body and chassis
ClassSports car
Body style2-seat roadster (OTS)
2-seat coupé
2-seat Drop Head Coupé
LayoutFR layout
RelatedJaguar C-Type
Powertrain
Engine3.4 L XK I6
Dimensions
Wheelbase102 in (2,591 mm)[2][3]
Length173 in (4,394 mm)[2]
Width61.5 in (1,562 mm)[2]
Height52.5 in (1,334 mm)[2]
Chronology
PredecessorJaguar SS100
SuccessorJaguar XK140

The Jaguar XK120 is a sports car which was manufactured by Jaguar between 1948 and 1954. It was Jaguar's first sports car since the SS 100, which ceased production in 1940.

History[edit]

The XK120 was launched in open two-seater or (US) roadster form at the 1948 London Motor Show as a testbed and show car for the new Jaguar XK engine. The display car was the first prototype, chassis number 670001. It looked almost identical to the production cars except that the straight outer pillars of its windscreen would be curved on the production version. The roadster caused a sensation, which persuaded Jaguar founder and design boss William Lyons to put it into production.

Beginning in 1948, the first 242 cars wore wood-framed open 2-seater bodies with aluminium panels.[4] Production switched to the 1cwt or 112 lb (51 kg) heavier[5] all-steel in early 1950. The "120" in the name referred to the aluminium car's 120 mph (193 km/h) top speed (faster with the windscreen removed), which made it the world's fastest production car at the time of its launch.[6] In 1949 the first production roadster, chassis number 670003, was delivered to Clark Gable.

Alternative text
The ex-Clark Gable XK120 at the 2012 Pebble Beach Concours d'Elegance

The XK120 was ultimately available in two open versions, first as an open 2-seater described in the US market as the roadster (and designated OTS, for open two-seater, in America), then also as a drophead coupé (DHC) from 1953; and also as a closed, or fixed head coupé (FHC) from 1951.

A smaller-engined version 2-litres, 4 cylinders, intended for the UK market was cancelled prior to production.

On May 30, 1949, on the empty Ostend-Jabbeke motorway in Belgium, a prototype XK120 timed by the officials of the Royal Automobile Club of Belgium achieved an average of runs in opposing directions of 132.6 mph with the windscreen replaced by just one small aeroscreen and a catalogued alternative top gear ratio,[note 1] and 135 mph with a passenger-side tonneau cover in place.[7] In 1950 and 1951, at a banked oval track in France, XK120 roadsters averaged over 100 mph for 24 hours and over 130 mph for an hour, and in 1952 a fixed-head coupé took numerous world records for speed and distance when it averaged 100 mph for a week.

Roadsters were also successful in racing and rallying.

Construction[edit]

1950 aluminium-bodied roadster, ex-Clemente Biondetti, has competition seats and aftermarket steering wheel; positions of tachometer and speedometer have been reversed

The first roadsters, hand-built with aluminium bodies on ash frames mounted on modified Jaguar Mark V chassis, were constructed between late 1948 and early 1950. To meet demand, and beginning with the 1950 model year, all subsequent XK120s were mass-produced with pressed-steel bodies. They retained aluminium doors, bonnet, and boot lid. The DHC and FHC versions, more luxuriously appointed than the roadsters, had wind-up windows and also wood veneers on the dashboard and interior door caps.

With alloy cylinder head and twin side-draft SU carburetors, the dual overhead-cam 3.4 L straight-6 XK engine was comparatively advanced for a mass-produced unit of the time. With standard 8:1 compression ratio it developed 160 bhp (119 kW),[2] using 80 octane fuel. Most of the early cars were exported; a 7:1 low-compression version, with consequently reduced performance, was reserved for the UK market, where the post-war austerity measures then in force restricted buyers to 70 octane "Pool petrol". The Jaguar factory, with access to 80 octane fuel, provided roadsters with the higher compression ratio to the press. Journalists could then test the model's optimum performance in Belgium, on a long, straight stretch of road between Jabbeke and Ostend.[8] The XK engine's basic design, later modified into 3.8 and 4.2 litre versions, survived into the late 1980s.

All XK120s had independent torsion bar front suspension, semi-elliptic leaf springs at the rear, recirculating ball steering, telescopically adjustable steering column, and all-round 12 inch drum brakes[3] that were prone to fade. Some cars were fitted with Alfin (ALuminium FINned) brake drums to help overcome the fade.

1951 XK120 roadster racing at Silverstone has a single aeroscreen mounted behind the removable full-width windscreen

The roadster's lightweight canvas top and detachable sidescreens stowed out of sight behind the seats, and its barchetta-style doors had no external handles; instead there was an interior pull-cord which was accessible through a flap in the sidescreens when the weather equipment was in place. The windscreen could be removed for aeroscreens to be fitted.

The drophead coupé (DHC) had a padded, lined canvas top, which folded onto the rear deck behind the seats when retracted, and roll-up windows with opening quarter lights. The flat glass two-piece windscreen was set in a steel frame that was integrated with the body and painted the same colour.

Dashboards and door-caps in both the DHC and the closed coupé (FHC) were wood-veneered, whereas the more spartan roadster's were leather-trimmed. All models had removable spats ("fender skirts" in America) covering the rear wheel arches, which enhanced the streamlined look. On cars fitted with optional centre-lock wire wheels (available from 1951), the spats were omitted as they gave insufficient clearance for the chromed, two-eared Rudge-Whitworth knockoff hubs. Chromium plated wire wheels were optional from 1953. When leaving the factory it originally fitted 6.00 × 16 inch cross ply tyres on 16 × 5K solid wheels (Pre–1951). Later cars could also specify 185VR16 Pirelli Cinturato tyres as a radial option.[9]

In addition to wire wheels, upgrades on the Special Equipment, or SE, version (called the M version in the United States) included increased power, stiffer suspension and dual exhaust system.

Engine specifications[edit]

XK 120 ENGINES[10][11]
ModelYearsDisplacementConfigurationBore/StrokeCarburettorPower
XK 120 3.41948–1954
3442 cc
DOHC Straight-6
83 mm/106 mm
Double SU H6160 bhp (119 kW; 162 PS) @ 5000 rpm
XK 120 3.4 SE ("M" in USA)1951–1954
3442 cc
DOHC Straight-6
83 mm/106 mm
Double SU H6180 bhp (134 kW; 182 PS) @ 5300 rpm
XK 120 3.4 SE (C-Type Head) ("MC" in USA)1951–1954
3442 cc
DOHC Straight-6
83 mm/106 mm
Double SU H8210 bhp (157 kW; 213 PS) @ 5750 rpm

Performance[edit]

The Motor magazine road-tested an XK120 roadster in November 1949. This pre-production car, chassis number 670001, road-registered as HKV 455, was the first prototype built. It was also the 1948 London Motor Show display model, and had been driven by Prince Bira in the 1949 Silverstone Production Car Race. When tested, it had the 8:1 compression ratio, was fitted with an undertray, and ran with hood and sidescreens in place. The magazine reported a top speed of 124.6 mph (200.5 km/h), acceleration from 0–60 mph (97 km/h) in 10.0 seconds and fuel consumption of 19.8 miles per imperial gallon (14.3 L/100 km; 16.5 mpg-US). The car as tested cost £1263 including taxes.[2]

Racing and rallying[edit]

XK120s were active in racing and rallying:

1949[edit]

1950[edit]

In 1950 Jaguar allocated six alloy-bodied XK120s to drivers Johnson, Walker, Nick Haines, Clemente Biondetti, Ian Appleyard and Tommy Wisdom.

This 1950 XK120 roadster won a Coupe des Alpes and a Coupe d'Or

1951[edit]

1952[edit]

1954[edit]

High-speed runs and records[edit]

1949[edit]

1950[edit]

1951[edit]

This 1952 XK120 fixed-head coupė averaged 100 mph for a week

1952[edit]

Jaguar XK100[edit]

A 2-litre four-cylinder version of the twin cam XK engine was to have powered an XK100 variant of the XK120 for the UK market.[17] Details of the model were included in an “Advance Particulars” brochure for the XK [18] but Jaguar's managers were dissatisfied with the engine and the project was cancelled prior to production.[17]

Note[edit]

  1. ^ The Times, May 31, 1949
    Ostend May 30: British Car's Speed Record
    (extracts)
    A Jaguar 3½-litre sports car . . . travelled at a timed speed of 132 mph on the Ostend-Jabbeke motorway today . . . The runs were timed by officials of the Royal Automobile Club of Belgium . . . moreover it was running on normal Belgian pump petrol and at the end of its high speed runs it demonstrated its ability to throttle down to 15 mph in top gear and to accelerate speedily without pinking. Running with the hood up, the car averaged 126.4 mph for a mile in two runs in opposite directions. The fastest mean speed of 132.5 mph was reached with a racing windscreen in place, the best run being made at 133.2 mph. The car also covered a kilometre from a standing start at a speed of 74.1 mph and a mile at 86.4 mph.

References[edit]

Notes[edit]

  1. ^ Robson, G (2006). A-Z of British Cars 1945–1980. Devon, UK: Herridge. ISBN 0-9541063-9-3. 
  2. ^ a b c d e f "The Jaguar 2-seater Type XK120 Road Test". The Motor. 1949. 
  3. ^ a b http://storm.oldcarmanualproject.com/jaguar/1949/06.jpg
  4. ^ Page 167, Chris Harvey.The Jaguar XK, Oxford Illustrated Press, UK. 1978. ISBN 0-902280-57-0, ISBN 978-0-902280-57-1
  5. ^ Page 8 Roger Hicks, Jaguar: an illustrated history of the world's most elegant sports car Crescent Books, New York 1989 ISBN 0-517-67413-0, ISBN 978-0-517-67413-0
  6. ^ Holloway, Hilton;Buckley, Martin (2002). 20th Century Car Design. Carlton Books. ISBN 1-84222-835-8. 
  7. ^ a b c d e f Porter, Philip (1998). Jaguar Sports Racing Cars, Bay View Books. ISBN 1-901432-21-1
  8. ^ "3½-litre XK120 Jaguar Super Sports (road test)". Autocar. September 2, 1949. 
  9. ^ Paul Skilleter, Jaguar Sports Cars, pp.307 ISBN 0-85429-166-0.
  10. ^ Jaguar XK120 Specifications – Retrieved on 4 November 2008
  11. ^ The Jaguar Database – Retrieved on 4 November 2008
  12. ^ Buckley, Martin: Jaguar: Fifty Years of Speed and Style p.120. Haynes Publishing 2003, ISBN 978-1-85960-875-3
  13. ^ a b c Nevinson, Tim: "Flat out for a week" Thoroughbred and Classic Cars June 2008 p. 84.
  14. ^ Photograph of Biondetti's XK120 prepared for the 1950 Mille Miglia.
  15. ^ Al Keller, Legends of NASCAR website; includes photo of Keller with XK120
  16. ^ Manwaring, Leonard Albert, ed. (1969). The Observer's Book of Automobiles (Fifteenth Edition ed.). F. Warne. p. 137. 
  17. ^ a b Generation X – Jaguar’s XK Heritage Retrieved from www.classicmotor.co.uk on 18 November 2009
  18. ^ Advance Particulars of the new Jaguar Type XK “100” & “120” Super Sports Models Retrieved from www.badgers-british.com on 18 November 2009

Bibliography[edit]

  • Holmes, Mark (2007). Ultimate Convertibles: Roofless Beauty. London: Kandour. pp. 82–83. ISBN 9781905741625. 

External links[edit]