The Jaguar Mk 1 and 2 saloons were very popular in their time and were an immediate success, outselling the larger more traditional Jaguar Mk VII and VIII saloons. The Jaguar Mk 1 and Mk 2 were the first of Jaguar’s compact saloons and were the first full monocoque structures ie they did not have a separate chassis structure and the load bearing requirement of the car was fully created from the body panels. This was a revolutionary approach to automotive engineering and was yet another technique that was developed in the aviation world and transferred across to the automotive environment, much like the disc brakes later in this article. Traditional automotive techniques, using a separate chassis to underpin the body structure, stopped at Jaguar with the development of the Jaguar Mk 1. This monocoque approach invariably leads to a stronger bodyshell structure with less flex and creak but it is a more complex structure which can mean that rust can be more of a problem later in the vehicles life.
Jaguar may well have been cautious regarding this approach and consequently over-engineered the bodyshell to ensure that no problems arose however that these compact saloons were very robustly manufactured made for a great basis for a racecar. The weight was not that significant insofar as the saloons recorded performance figures not that far behind those of their XK sports car siblings.
The Jaguar Mk VII had been very successful as a racer but with the advent of the Jaguar Mk 1, especially the 3.4 litre, the interest in racing the big Jaguar saloons started to wain and the emphasis moved across to the compacts. Mark 1 3.4 litre saloons competed successfully in many rallies, touring car, and saloon car races, with notable drivers including Stirling Moss, Mike Hawthorn, Tommy Sopwith and Roy Salvadori. The move by Jaguar to a monocoque structure, and the horsepowers available, meant that these saloons were racers out of the box.
The 3.4 litre Jaguar Mk 1 came out in 1957 with the immediate benefits of 210 bhp and disc brakes all round. This was a massive leap in performance terms over the 2.4 with its 112 bhp and drum brakes all round.
The overall manufacturing techniques developed for the Mk 1 would remain largely unchanged until the end of the E-Type but the monocoque approach was to remain to this day.
The Mk 1 bodyshell was fully formed from pressed steel panels with a large element of hand finishing and fettling to create the final required shape. The pressed steel work is not that accurate, certainly when compared to today’s standards, and there are a number of external seams to the bodyshell and bonnet that have to be filled or disguised to create the finished vehicle. Lead loading was the conventional approach to resolving a variety of bodyshell issues on a steel bodied car, but it is not without its own inherent problems. Nowadays there are high specification fillers which are probably the better option, but it is down to the individual’s choice when repairing these cars.
When the bare steel bodyshell was jigged and welded at the Jaguar factory all the relevant external seams were lead loaded which effectively means they were soldered over. This process requires the use of an acidic flux to clean the steel and the relevant area is then “tinned” whereby a layer of solder is attached to the steel surface. This process requires heating the steel to the melting point of the solder or tin and then building up the “tin” to the required thickness to effect the repair. Where the “tinning” process is correctly achieved all is well but elsewhere acidic flux can remain under or within the repair. Once the lead loading was complete the required shape was formed by wiping the hot solder or by filing and sanding the cooled material with obvious health implications.
What this process means in practice is that there are complex, poorly formed steel joints that have been extensively heated and then had acid flux added and not necessarily fully removed. All in all a perfect place for rust to start and get a grip!
There are lead loaded seams to the scuttle panel, front wings, grille aperture, rear wings and sills and anywhere where damage may have occurred at the factory or panel gaps around doors etc were not correct.
Whilst there does not appear to be any rust protection to the Mk 1 bodyshell, if you look inside a Mk 2 bodyshell it appears that the shells were dipped at the factory up to a height of approximately 8” from the floor pan, so the sills and crows feet etc were protected, but above this line the panelwork was not given any level of rust preventative apart from the external painting process so all the internal surfaces really were bare steel just waiting to corrode.
Repairing an Mk 2 is a relatively straight forward process, and most of the panels are readily available with the exception, perhaps, of the bulkhead itself and some roof panels. However rust can be extensive and to do the job correctly will invariably mean many hours of cutting and welding!
Unfortunately when looking at a Mk 2 typical areas for corrosion could cover the entire car, however typical problems are floor pans, sills, door skins, rear wheel arches, boot floor, rear valance, crows feet, jacking points and rear spring hangers but please do not assume this is a comprehensive listing! There are projects available for sale where virtually nothing is left of the body although this is definitely the harder approach!
The Mighty XK Engines
The famed 3.4 litre XK engine had been designed specifically for the new Jaguar Mk VII; however the XK120 had beaten the Mk VII to market and claimed this world class power unit long before it was fitted to the Jaguar Mk 1 in 1957. The Mk 1 was initially fitted with the short stoke, short block variant of the XK engine with a capacity of 2483 cc.
With the design commenced during the war years the 3.4 litre XK engine was to prove to be a great engine and to remain in production with Jaguar until the early 1990s. In the ’50s this was the engine to have in your sports car, let alone a saloon such as the Mk 1, as it had just won at Le Mans, which was about as high an accolade as was attainable. Imagine a similar situation today with a saloon car being offered by a major manufacturer with a Le Mans winning sports car engine under the bonnet!
The XK engine comprised of a cast iron block with alloy cylinder head with twin overhead camshafts operating 2 valves per cylinder in hemispherical combustion chambers. The crankshaft of EN16 steel was fitted with a Metalastic harmonic damper to remove damaging harmonic vibrations from the crankshaft. This design changed remarkably little over the next 40 plus years which really goes to show how good the original design and development process had been.
The Mk 1 was initially offered with the 2.4 short stroke XK engine giving some 112 bhp and this power figure gradually increased until 210 bhp was available from the 3.4 litre XK in the later Mk 1s. The Mk 2, in 3.8 litre format, increased this horsepower to 220 bhp. At this level of power the Mk 2 gained attention from those in the criminal classes as well as the police. The car made a cracking getaway car and subsequently the police felt they needed a similar vehicle to keep up as well as patrol the new motorway system.
These engines are still regularly raced and can be totally reliable if well looked after or rebuilt correctly. Really all that should be needed is regular servicing but careful attention should be taken of the antifreeze or coolant.
Overheating the XK engine can lead to a number of problems; typically blown head gasket or, more seriously, movement of the bucket guides in the head. This can be detected by a knocking noise from the camshaft area and generally on the exhaust side. This will require a cylinder head off rebuild and some machining operations to resolve. Low oil pressures tend to indicate a worn bottom end and will almost certainly lead to a full rebuild of the engine. Parts are all readily available.
Loss of coolant and subsequent low concentrations of antifreeze can lead to an accumulation of problems associated with the cooling system due to corrosion and build up of sludges and corrosion by-products. All XK cylinder heads were cast from RR50, an alloy developed by Rolls Royce during the war specifically for pistons for aircraft. This alloy was developed for high strength at high temperatures so is probably over specified for a cylinder head but one of its downsides is that it can suffer from significant corrosion to the water jacket. This can most easily be spotted at the interface with the cylinder head gasket where the waterways can corrode to the outside world in bad examples.
Internal corrosion to the blocks on Jaguars leads to underlying tendencies to overheat whenever the external temperature rise unduly, this is often put down to radiators, cooling fans etc but can remain as an unsolvable problem due to the fundamental nature of the corrosion.
Radiators, whilst they can become blocked and inefficient, are generally ok but again the problems always show themselves on hot days when the cooling system is pushed to its limits and struggling to keep core temperatures down.
There is no reason for XK engines to run hot providing they have been built correctly and have fully cleaned waterways.
PLEASE keep all Jaguars running on the correct levels of coolant. This is by far the best way to maintain the cooling systems and engines generally!!
The Daimler V8
The Daimler V8 engine was a 2.5 litre V8 engine designed by Edward Turner for the Daimler Motor Company in 1959. The rights to the engine were effectively acquired by Jaguar Cars in 1960 when Jaguar purchased Daimler. The “lightweight” engine, in period terms, was extremely smooth and really put Jaguars 2.4 litre XK engine in the shade. Having a power output of 140 bhp @ 5,800 rpm it was somewhat more powerful than the equivalent Jaguar engine and was to be the only Daimler engine to be used in a Jaguar car.
The Mk 1 was fitted with the Moss gearbox and, given the engine was such a masterpiece for the period, the Moss gearbox harked back to previous times as it was effectively pre-war. Originally manufactured by The Moss Gear Company, one of Jaguar’s many suppliers, manufacture was taken over by Jaguar and Moss seems to have disappeared by the late 1950s. The gearbox is a relatively simple 4-speed with no synchromesh on first or reverse. Reasonably strong in practise if a little agricultural it was to remain the standard equipment on these graceful saloons. The Borg Warner 3 speed automatic had been introduced in 1953 to the Jaguar Mk VII and became available to the Mk 1 in 1957. There was an option for overdrive as well.
Clutches are again reliable, but original coil spring type clutch cover is a definite candidate for replacement to a diaphragm type as fitted to later Jaguars.
Front Suspension and Brakes
The independent front suspension design was to provide the basic approach for many years to come. The design consisted of a robust fabricated subframe totally isolated from the bodyshell on 4 Metalastic rubber and steel mounts to prevent much of the road noise and vibration from reaching the cars structure.
This was an innovative approach as, up until this time, Jaguar had relied on the chassis of the car to be the mounting structure for all the elements of the suspension. This subframe approach was to be the way that Jaguar were to isolate and minimise road noise and maximise the ride quality. This design was to form the basis for Jaguar suspension systems for many years and indeed remains today on the current production saloons.
Upper and lower wishbones were mounted on conventional rubber bushes and steering was via a steering box and idler arms. Coil springs and dampers were fitted and, in many respects, the front suspension was conventional even by today’s standards. The early manual steering box makes for hard work steering at low speeds, but Mk 2s had the power steering as an option which is definitely a worthwhile benefit.
The first Jaguar Mk 1s were endowed with drum brakes all round and these were not up to the task of slowing what was a relatively fast car for the time. Jaguar was accused of manufacturing an unsafe car by more than one journalist. This was particularly evident on the early 3.4 litre Jaguar Mk 1s where they we still using the 2.4 litre drum brakes. Jaguar Cars had developed the modern brake disc in conjunction with Girling-Dunlop on the racing C-types in 1953 so this braking format was absolutely in its infancy as far as road cars were concerned but, nevertheless, by 1957 Jaguar was able to offer front and rear brake discs as an option and then as standard fitment for the Jaguar Mk 1 and then Mk 2.
These Girling-Dunlop caliper/piston assemblies were a revelation, and Jaguar felt it had to give other road users due warning of the reduced stooping distance of these cars by putting a badge on the rear bumper indicating disc brakes! These units feature an internal mechanical system to retract the pad when the brakes are not under pressure and have a very large high pressure seal by today’s standards. Given they represent the very earliest of disc braking design they should be considered a little unreliable and are susceptible to corrosion and subsequent leakage. Replacement calipers are a good option to invest in on these Jaguars. This is especially the case if the car stands around for long periods of time between runs.
Rear Suspension and Brakes
Whilst the front suspension was an innovative fully independent approach that was to last with Jaguar for many years, the rear suspension was a decidedly more period approach based on the larger saloons live axle arrangement.
The rear suspension was definitely more period in its arrangement, being a live axle located on rear-facing half-elliptical leaf springs. These springs were mounted in pressed steel channels located under the rear seat structure. Two trailing arms located the axle vertically in conjunction with a Panhard rod providing lateral location. Fundamentally the Mk 1 and Mk 2 rear axle layouts are extremely similar apart from the rear track on the Mk 1 is narrower by approximately 4.5”.
Mechanically, the rear suspension is strong and reliable, only needing regular maintenance to keep in good condition and fully functioning. However all the location points are known areas for rust to develop so, to ensure good location, the structure of the car needs to be maintained. The entire lateral location of the live axle is provided by the Panhard rod bushes so these need to be kept in good condition.
The Mk 2 rear suspension resolved the issue of the narrow track that had been a criticism of the earlier Mk 1. The Mk 1 was had a reputation for having some handling issues, and these were believed to be due to the narrower rear track. Clearly Jaguar felt that a change was required because, for the Mk 2, the rear axle was widened by 4.5” to match the front track.
The rear brakes are similar to the front brakes and so the earlier description relating to the front brakes applies equally well to the rears.
Exhausts, Electrics and Fuel
Exhausts are relatively simple and should fit reasonably well as they literally run down the centre of the car. The only problem is likely to be in the region of the downpipes and their proximity to the “chassis” rails.
The fuel systems are generally fine as long as the filters are regularly replaced and tanks kept clean. The fuel tank is external to the boot so it is not unknown for the debris of years to mount up and corrode its way into the tank.
Electrics are all relatively straight forward and period but there is no real reason why it cannot be reliable if well maintained.
Unfortunately water always seems to find a way into older cars, especially given the UK climate! Over time this leads to great damage on a number of fronts, and avoiding this degradation is very beneficial to the longevity of any car. Water tends to pool in the lower areas of the car ie footwells and carpets but as the temperature rises on warmer days this moisture evaporates and fills the car with high humidity air. As the day cools in the evening, this moisture condenses on the colder horizontal surfaces of the inside of the vehicle such as the inside of the roof and boot panels etc. This condensate then runs off and into sections of the car where water could not normally access and can cause significant problems over time. Bodyshell, electrics, trim and interior finishes can all suffer with this continual degradation over time.
Ideally, try to keep all classic in a dry environment with windows slightly open to allow the air to circulate to reduce the moisture levels in the car. Dehumidifiers are also very beneficial over the longer term.
Interior is relatively straight forward but water entry to the cabin, as described above, can lead to seat stitching rotting and to headlining and carpets suffering. Recently we received an E-Type coupe which had been unused for a year or so, but moths had taken up residence and had done a surprising amount of damage. All those natural fibres had kept them well sustained!
The Mk1 and 2 were a great step forwards technologically for Jaguar, and their monocoque structure was to provide the basis for much of Jaguars future manufacture. Disc brakes, power steering and 3.8 litre XK engines all came about during the years of these first compact Jaguar saloons and they really were amongst the first of the sporting saloons. The Jaguar Mk 1 fell out of favour for a number of years, and the Mk 2 was the car to have and restore. Consequently a lot of Mk 1s were lost and it was only relatively recently when they suddenly came back into the public’s interest. Good examples are climbing steadily in value and some gloriously restored examples are at very significant prices indeed in the market today. Some minor upgrades to the earlier brakes, ignition systems and starter motors should prove sensible. Add a battery conditioner/charger to ensure easy starting in our brief summers and they are a joy on the road.