The Jaguar E type had become long in the tooth by 1974 and the time was right for Jaguar to launch a new sports car and as a result came up with one of the most stylish new designs of the 70s. The Jaguar XJ-S together with the Saab 900 and Range Rover epitomised what was good about 1970s design in a sea of automotive mediocrity. However it would take a few years for the distinctive design to be accepted!
The XJS was in many respects too modern for its launch in 1975 and struggled for sales for most of the 1970s. Selling some 15000 cars during the 70s almost led to British Leyland ceasing production permanently and for a short time it did, albeit temporarily. British Leyland was really not the place to build a car such as this and the ensuing quality issues proved a further burden on the car, which was already suffering from excessive fuel consumption and mixed reviews of its styling.
Given the popularity of the Jaguar XJ6/12 it was no great surprise that the Jaguar XJ-S was to be largely based on the XJ range for most of its mechanicals with almost identical drivetrain to the V12 variants of this range and similar fundamentals in terms of platform albeit slightly shorter.
The XJS bodyshell followed on from the XJ saloons in terms of a monocoque structure with a front subframe and rear subframe or “cage” supporting the relevant suspension systems. The vast majority of all of the suspension fixings were designed to bolt to these subframes and these subframes were then fully isolated on rubber mounts from the bodyshell. Even the engine was mounted onto the front subframe with rubber mounts to further isolate vibrations and transmitted noise from the bodyshell.
The XJS bodyshell is a complex structure in itself and there are many places where corrosion can start. Typical places are front radiator cross-member, front shock absorber mounting areas on inner wings, front jacking points, sills, rear jacking point and radius mount area. The jacking points on the bodyshell really should not be used except in an absolute emergency as they are not strong and any use invariably damages the paint protection allowing the rust to get a hold. This further weakens the jacking point leading to more damage if it is used to support the car.
Rear valance, rear wheel arches, bottom of front wings and headlight areas are all (relatively visible) potential rust spots as well. Bottoms of the doors as well as the boot panel can also corrode badly if the drain holes become blocked.
As well as watching out for rust much damage is caused to the cross-member by incorrect jacking. Damage from jacks to the body of the cross-member invariably leads to rusting. The XJ-S is not a light vehicle and if it is being lifted centrally then a suitable pad should be used or the car jacked on each front corner under the wishbone base plate.
Whilst the XJS bodyshell is stronger than a comparable saloon, given it only has 2 doors and a very strong roof structure in the case of the coupes, there is still a propensity to rust especially with the earlier cars. Rust protection/prevention was virtually non existent in the earlier cars and there are many ways for the water to enter the body shell and start the process. The bodyshell is an expensive structure to repair and comprehensive professional rust protection should be considered. Cabriolets and Convertibles clearly let even more water in so again care should be taken.
When you lift the bonnet it appears that the V12 engine and ancillaries have been “poured” into the engine bay. The V12 is a reasonably large unit and there is very little space left under the XJS V12 bonnet. This in itself means that great care has to be taken whilst working on these engines to ensure problems are not created. Even replacing spark plugs can be awkward and it is better to create space to do the job correctly rather than try to achieve the same job in a restricted space. It is extremely easy to miss-align spark plugs or break connectors if care is not taken.
The V12 engine creates a lot of heat and this in itself causes an array of general degradations to wiring, hoses, seals and oils so diligent servicing is required and service history is relevant when purchasing an XJS.
Loss of coolant and subsequent low concentrations of antifreeze can lead to a cumulation of problems associated with the cooling system due to corrosion and build up of sludges and corrosion by-products.
All the V12 engines can suffer from this type of problem as the engine is designed with wet liners and is therefore very susceptible to problems from corrosion if the coolant was allowed to degrade. The head gaskets and cylinder head studs are almost completely exposed to coolant and if corrosion sets in, the heads can become seized on the studs and the head gaskets can completely fall apart leaving just the fire rings around the cylinders and the outside edge of the gasket. All the debris from the head gaskets breaking up restricts the water jacket in the block, especially at the back of the block where the water pump flow is slowest. Overheating V12s can lead to valve seats falling out of the head and further major mechanical problems as a result.
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.
Straight 6 engined XJS do not suffer as badly in relation to this general coolant/overheating issue but again the preventative approach of correct concentrations of the recommended coolant is by far the cheapest long term measure.
Radiators, whilst they can become blocked and inefficient, are generally ok but problems do arise on later cars and V12s where there are 2-3 radiators mounted one in front of the other. Here road debris can build up between the radiators and lead to large areas of the radiator being simply unavailable for cooling. Again the problems show themselves on hot days with the air conditioning running and this is typically when the car struggles to cool itself sufficiently.
The lower engine oil cooler is a case in point on V12 XJS as this invariably gets a great deal of debris built up between it and the engine coolant radiator. This leads to increased coolant temperatures and this increases the pressures and temperatures of the air conditioning system placing further unnecessary loads on the pipes, seals and compressor of this system.
As always one thing leads to another but with coolant systems and Jaguar V12s this is very much the case and as the saying goes, a stitch in time saves nine.
PLEASE keep all Jaguars running on the correct levels of coolant. This is by far the best way to maintain the cooling systems!!
Gearboxes are all reasonably reliable with the automatics being somewhat basic 3 speed units. The XJ-S started off with the manual gearbox as fitted to the V12 E-Type and the Borg Warner Model 12 but the manual option was soon dropped and the Model 12 was replaced by the GM Turbo Hydromatic 400 in 1979. Later Getrag 5 speed manual boxes are generally reliable as are the much needed 4 speed ZF4 HP22 automatics.
Front Suspension and Brakes
The front suspension cross-member provides the mounting for the upper and lower wishbones and steering rack. The cross member is a robust steel fabrication mounted on 4 Metalastic mounts, 2 circular ones at the front, bolting through the chassis rails, and 2 more typical Jaguar V mounts at the rear. Whilst the cross-member in itself does not generally cause problems, rust can be an issue especially on the outer uprights that take the upper wishbone mounts. The earlier conventionally painted cross-members seem in many ways to last longer than the later powder coated version which traps moisture under the higher specification finish and this rust can go unnoticed until the damage is critical.
Given all the suspension locations and engine are mounted on the cross-member it is clearly critical that the 4 cross-member mounts are maintained in very good condition.
Front suspension is generally extremely robust and requires little in the way of maintenance. However there are a number of obvious upgrades that should be considered. The standard lower wishbone bushes are of very poor design insofar as they are just parallel rubber bushes and can allow the lower wishbones to move fore and aft over time affecting suspension alignment and becoming the source of annoying knocks. Also, with the tendency of the V12 engines, gearboxes and power steering to leak oil the standard wishbone bushes become extremely soft further adding to problems. After market polyurethane “top hat” type bushes provide far better location, better knock prevention and are largely unaffected by years of exposure to oil.
Shimable outer lower balljoints should be replaced for the later style sealed-for-life Lemforder items but beware of the many poor quality copies on the market. Upper wishbone bushes are the Dunlop developed “slipflex” type and are very good but do suffer with age. If they are worn do not replace with after market polyurethane versions but stay with the standard part. They are not easy to check for wear and many XJ-S pass MOT tests despite badly worn lower balljoints and badly worn or seized upper wishbone bushes. Upper balljoints are generally ok but stub axles can become worn, leading to what appears to be excess play in the front wheel bearings which cannot be removed through adjustment of the front wheel bearing endfloat.
The power steering racks are generally good albeit getting ever older so leaks are by no means unknown. The 3 steering rack mounts are again a poor design and suffer from softening over time with exposure to oil. This leads to excess movement of the steering rack giving a floating, wandering feel to the car especially at speed. Aftermarket polyurethane replacements are a must but some compliance is required on these bushes otherwise the steel mounting bracketry can crack under the force of the power steering at parking speeds.
Front brakes are sensible 4 pot calipers and vented discs but are relatively small by today’s standards with the front discs being a mere 284mm diameter. This means spirited driving or track day use can lead to a distinct lack of anchors especially if the brake fluid is a little aged!!!!
The universal joints on the steering column can become seized leading to an odd but distinctive feeling through the steering.
Rear Suspension and Brakes
Rear suspension is again very robust and is based on a fabricated lower wishbone with a large alloy hub carrier. The driveshaft provides the final support with the cars mass effectively being supported by the differential output shaft bearings. The subframe/cage is of a much lighter construction when compared to the front subframe. The 4HA Salisbury differential is solidly mounted into the cage and inboard brakes are directly mounted onto the differential output shaft flanges. The handbrake calipers are mounted directly on top of the main hydraulic calipers and are a real nuisance to get to for maintenance.
The 4HA differential is generally strong and is fitted with a limited slip version, known as Powerlock, in the XJS. Providing that the differentials are maintained and oil levels are checked regularly and filled with the correct oil for Powerlock differentials, then the units are strong and reliable. However oil leaks can develop and if left unresolved can lead to failure.
Rear brakes are more of an issue due to their location and a general failure to understand how the handbrake calipers are meant to work. The main hydraulic calipers are generally reliable and are wholly separate from the handbrake structure. The handbrake calipers are self adjusting and have their own small handbrake pads. However it is not impossible to drive an XJS with the handbrake left on which can lead to overheating, damage to the dust seals on main calipers and failure of the handbrake pads. Changing the discs is not an easy task and lack of care can lead to camber changes on the rear wheels, discs not central in the calipers, wire locking missing and non functioning handbrakes.
Driveshafts are robust and the universal joints strong if regularly greased. Lower wishbone inboard pivots are very reliable providing they are again regularly greased. There are some 12 greasing points on the rear suspension and all need regular attention but please ensure they are cleaned before being greased as otherwise road grit can be forced into the joint, hastening failure.
The outer alloy hub carriers can be a source of problems as setting up both the wheel bearings and trunnions needs care but both are well engineered and capable of giving many years of reliable use. The hub carriers themselves were a cause for concern for a period as some developed cracks just above the trunnion housing and this potential failure should be watched out for.
The rear axle cage is located fore and aft by the radius arms and movement is absorbed by the large bush at the front of the arm. This arm can be severely weakened by rust and the bushes need to be in good condition to absorb the not insignificant loading from the car. This loading is directly transmitted to the bodyshell at this point so a rusty radius arm mount will deteriorate relatively quickly.
Generally if there is a lot of work to do to the rear suspension of a Jaguar XJ-S then removing the cage in its entirety is a very sensible start.
Exhausts, Electrics and Fuel
Exhaust systems are generally relatively straight forward but pattern ones can be almost impossible to fit correctly due to inaccurate manufacture of the over axle pipes.
Fuel systems are relatively straight forward apart from the fact that by definition the XJS pumps a lot of fuel around the engine and back to the tank in the normal course of events. Because of the under bonnet heat the returned fuel to the tank is invariably heated and over time this leads to a potential build up of condensation in the tank and subsequent corrosion. In worst case scenarios this can lead to pinholing of the fuel tank through rust.
Electrics can be problematic depending on year and systems fitted. Air conditioning and heating/cooling is complex and problems can be hard to resolve. Switch gear can be unreliable on earlier cars as mid 70s manufacturing was not quality led. It was not unheard of for front windscreens to leak and this would invariable lead to various electrical issues.
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 woodwork all suffer this continual degradation over time.
Ideally try and keep all classics in a dry environment with windows slightly open to allow the air to circulate and reduce the moisture levels in the car. Dehumidifiers are also very beneficial over the longer term.
Interior is relatively straight forward but water entry, as described above, to the cabin can lead to seat stitching rotting and to headlining descending in a very inelegant manner!
Overall the Jaguar XJS is a fabulous stylish Grand Tourer in the true sense but probably a full restoration is not for the beginner. General maintenance and the availability of parts remain good but some panels are already hard to source. Preventative measures to maintain the bodyshell and prevent rust would be extremely beneficial for longer term ownership.