XJS & XJ from KWE Cars
Classic Spirit Reborn

Powertrain differential – you are the weakest link!

While external crash damage to a vehicle is clearly noticeable, other parts are less so and therefore require thorough checks and repairs before a car is deemed roadworthy and safe to drive.

A car’s powertrain comprises several important components that are prone to serious damage if a vehicle is unfortunate enough to be involved in an accident.

In most modern vehicles the powertrain includes the engine, transmission, drive shaft, differential and the final drive. Together, these components transmit the engine’s power through to the road surface.

Jaguar XJS differential

Our workshop technicians have been kept particularly busy recently with two Jaguars XJSs that were both involved in serious accidents. In each vehicle, part of the powertrain (namely the differential), had suffered serious internal damage.

The differential allows the outside wheels of a vehicle to rotate faster than those on the inside while still transmitting power to both. This is necessary when a vehicle is required to turn, allowing the wheel that is traveling around the outside of the turning curve to roll farther and faster than the inside one.

(This fascinating video from the 1930s explains the principles of the differential gear)

How differential gears work

In one vehicle, part of the gearing teeth on the differential had broken off causing a terrible noise as they were caught up in the mechanism; the other caused the limited slip clutches to fail resulting in one of the rear wheels to skid on every corner – unnerving to say the least!

Differential damage can be caused when a car is struck head-on or from the rear. When this happens, and the gearbox is in Park, the only thing stopping the car from moving away is the ‘tyre-wheel-halfshaft-differential-propshaft-gearbox’ chain. Surprisingly, the differential is the weakest link in this chain.

If the gearbox is not in Park, there’s usually enough inertia in the chain to result in damage caused by a strong collision, even before the wheels begin to roll forwards or backwards.

Our advice to you is that if you are aware that an unavoidable rear end shunt is about to happen, apply as much braking as possible while obviously paying due attention to your own personal safety, and to the safety of any passengers. This will, to a certain extent, protect the differential.

If you know, or suspect that your Jaguar XJS has been involved in a collision then it’s essential to have a thorough safety inspection carried out by expert technicians.

For all used classic Jaguar and Aston Martin cars, we carry out a comprehensive two-hour, on-site condition assessment. For more information, visit our website here.

 

Differing differentials

Unsure of your differential differences? We list the various specifications below, courtesy of jag-lovers.org.

Salisbury 4HU Powr-Lok

From 1976-1985, the differential was a Salisbury 4HU Powr-Lok that came with either 3.07:1, 3.31:1 (1976-1982), or 2.88:1 (1982-1985) ratios.

DANA

From 1985-1987, a 2.88:1 DANA unit was used for the V12. This unit can be distinguished in that the bearings on the output shafts are held in place with three bolts; the differentials both before and after these years have five bolts. It also has no drain plug.

GKN Power Lock

Beginning in 1987, there was a differential referred to as the GKN Power Lock with a 2.88:1 ratio.

Car of the month achieves celebrity status

Car of the month 1

It can be difficult to distinguish between some of our favourite XJS restoration and upgrade projects. Each one gives the KWE team immense satisfaction. However, one recent project does stand out.

At the request of a famous TV and music industry celebrity, this 6-litre, V12 convertible has been fully restored and upgraded with some unique styling features.

Car of the month 3

We’ve stripped the original aubergine paintwork and resprayed it black, with the addition of unique, colour-keyed bumper tops. The V12 was then given the full KWE treatment with a suspension/brakes/steering renewal and upgrade. You’ll definitely see this Jaguar coming with its quad headlamp fittings. The smart exterior is matched by the luxurious cream leather interior with black piping and the addition of perforated centre sections. The internal refurbishment was completed with new European walnut wood veneers.

Car of the month 4This XJS has undergone extensive restoration and upgrade work and we think it looks stunning. However, we’ll let you be the judge of that. Take a look at our restoration images here.

We currently have two further low-mileage, convertible Jaguar XJS cars for sale.

  • XJS V12 Convertible 1990 under 56,000 miles
  • XJ-S V12 Convertible 1988 only 57,853 miles

Why not take a look at these, and all of our cars for sale here.

A real head turner – Low-mileage V12 XJS convertible for sale

Jaguar XJS V12 convertible (1992)

The roof is down, the wind is in your hair and all that lies in front of you is the open road and the perfectly tuned V12 engine of our latest Jaguar XJS offered for sale.

Solent Blue with a cream leather interior and American Walnut veneers. DSCF2849-S

We’re selling this superb example of a 1992 V12 XJS convertible on behalf of one of our clients. It’s been given the full KWE treatment with our full suspension, brakes and steering renewal and upgrade package, providing that familiar smooth and comfortable ride you’d expect from all of our fully-restored classic Jaguar cars.

With only four previous owners, this low-mileage XJS has just over 40,000 genuine miles on the clock. Its exterior is matched by the quality of workmanship and time spent on its interior. Finished in Jaguar Solent Blue with a cream leather interior and American Walnut wood veneers, this superb convertible sports car is guaranteed to turn heads whenever and wherever it’s driven.

For a full suite of pictures please click here.

For pricing and detailed service information, visit our website here.

You can see the full range of our cars for sale here.

Car of the month: Jaguar XJS V12 coupé

Our Jaguar XJS restoration skills were fully utilised during one of our latest projects, which features as our ‘Car of the month’ for March 2016.

Fully restored Jaguar XJS V12 coupé

Fully restored Jaguar XJS V12 coupé

The new owner of this stunning example of a fully restored XJS V12 coupé requested that we first find and purchase the donor car. (more…)

KWE tech note: V12 cooling system and heater problems

A Jaguar V12 cooling system in good condition is capable of dealing with all conditions, contrary to popular belief, and does not need upgrading or fancy coolants and additives. However, it is relatively complex and more difficult to keep in good condition compared to the I6 engines.

A common problem is that the heater will not blow hot even with the engine up to full temperature. As far as the source of heat is concerned, there are two main likely problems: (more…)

Guest blog post vol. 1: What makes the Jaguar XJ-S special?

As part of a new series of blog posts, we will be inviting a number of XJS owners and Jaguar enthusiasts to contribute to our blog, telling us exactly why they love the XJS. This week, we’ve gone across the pond and asked California-based, Rhett Redelings what makes the car so special to him.

About Rhett

Location: San Francisco Bay area, California, U.S.A.
Occupation: IT Manager, City of Sausalito

Screen Shot 2015-11-13 at 09.39.36

Which cars do you currently own?

  • 1988 Jaguar XJ-S coupe in Glacier White with a Mulberry interior, an HE V12 engine with the stock GM Turbo 400 3-speed automatic transmission, and a very early ABS braking system. This was our first Jaguar, and easily the one we’ve invested the most time, money and love in.
  • 1984 Jaguar XJ6 series 3 with the Vanden Plas trim in Maraschino Black with tan interior. The “series 3” is my daily driver.
  • 1995 Jaguar X300 (XJ6), also with the Vanden Plas trim. This magnificent beast of a car is what my wife drives when she doesn’t need the Subaru for errands not befitting a Jag.

What makes the Jaguar XJ-S special to you?

I would argue that the Jaguar XJ-S is a work of modern art. Just standing still, before you know anything about the car, the lines of the bonnet, that subtle hint of a power bulge and those flying buttresses make the XJ-S look like it’s already moving so fast that it’s pulling ahead of itself and stretching out of its own skin. As onlookers, we are about to witness a transformation or climax and, like the car, we are forever suspended, right at the edge of that forever-unresolved moment.

There is a subtle tension in the design that seems also to reflect the times in which the car was created. Everything works, visually, ergonomically and technically, but only just. Depending which angle you view it from, the XJ-S either looks old and elegant or oddly modern and vital. Sharing the XJ platform is wonderful of ride and handling but makes the car, viewed from the profile, seem slightly too long, and yet perfect when viewed from any other angle.

Rhett's 1988 Jaguar XJ-S coupé in Glacier White

Rhett’s 1988 Jaguar XJ-S coupé in Glacier White

Released in the mid 1970’s, but with a design language from the 1960’s, the XJ-S probably looked old fashioned the day it was revealed, but it’s this very quality that makes the car look timeless today.

Everything is held in a delicate balance and, depending who you are, all that tension and unresolvable anticipation makes the car either uncomfortable to behold or infinitely captivating. In my case, I find the XJ-S irresistibly and enduringly desirable in all its forms but never more so than in the original, pre-facelift coupé body style.

Beyond the styling of the car, a well-sorted XJ-S is just an incredibly capable Grand Tourer. The performance, road manners, ride, and comfort are all excellent, even by modern standards.

While the underpinnings are shared with the XJ saloons, and the transmission made by GM, much of the car is bespoke. The door handles, for instance, are somewhat unintuitive but beautiful in their own way and feel very satisfying and sophisticated when, with a slight squeeze, they click the doors open. The headlamp surrounds, the grille, the steering wheel, seats and so forth, are exclusive to the Jaguar XJ-S. The level of trim exceeds that on my ’84 XJ6 Vanden Plas.

Upon opening the car door, a gentle squeezing motion and the sweet, sophisticated aroma of Connolly leather greets me. When I get in the car, I am insulated in what feels like a very exclusive space; the Recaro-style seat firmly cradling me with exactly the right lumbar support and firmness.

Everything about the car inspires confidence, from the feel of the seats to the sound of the ignition, the power of the acceleration and the way the car can take a fast corner without ever breaking traction. When I do sometimes take a corner too fast, the independent rear suspension has a kind of magical way of bearing down, keeping the car on the surface of the road, defying physics.

I have driven faster cars but never a car so smoothly, consistently powerful. For instance, 80 mph in second gear, the engine is at 3500 rpm and feels like it would let me take it over the red line before it would run out of available power. And then there’s 3rd gear…

Driving it is exhilarating but not effortless, not mindless. It absolutely rewards the skilled driver but it is not forgiving. Almost like a living thing, the XJ-S needs me to drive it as much as I need it. In a way, this is part of what I love about it and, in my opinion, part of its ‘Jag-ness’. Driving it demands that I be fully present in the moment, not absently thinking about projects I left unfinished at work or the pressures that lie ahead.

Driving my XJ-S is a kind of meditation. I feel rejuvenated after driving it, never exhausted. I have never ended a day with it without wishing I could get back in the car and just keep going.

The Legacy

The XJ-S is a car crying out to be understood. For the owner of one, it is essential. But it’s impossible to understand the XJ-S without having at least passing awareness of what came before and what came after. To love the XJ-S is to love all Jaguars, to some degree, but mostly it is to know the XJ-S in its context.

In part, I think the Jaguar XJ-S is special to me because it’s a bit of an underdog. Plenty of other cars in its class, Ferraris, Astons, the beloved E-Type etc., require more than average upkeep, suffer reliability issues, inconsistent build quality and so forth, but the XJ-S seems uniquely dogged by these criticisms.

Despite some initially poorly conceived engineering choices, the XJ-S is, at its core, a brilliant example of automotive craftsmanship. Faster than the MBZ 450 SL, more comfortable than a Porsche 911, and considerably more refined than the Ferrari 308 GTB and very nearly as fast, the Jaguar XJ-S, built under better circumstances, would have been the world-beater it was meant to be.

The XJS is a hugely important car. Not only is it magnificent to drive, sumptuously refined and strikingly beautiful, if somewhat unconventionally so, it’s arguable that we wouldn’t still have either Jaguar or Aston Martin without it.

Jaguar XJ-S

V12 1988 XJ-S – Rhett’s very first Jaguar

Both companies, then essentially divisions of the Ford Motor Company, leveraged the XJS as a shortcut to developing both the Aston Martin DB7 and the Jaguar XK8, two Grand Tourers credited with saving their respective companies. In fact, I’d go even further to say that the Aston Martin DB9 and Jaguar F-Type both drive and feel very much like modern interpretations of the XJS.

The technologies and underpinnings have certainly evolved but our fundamental expectation of what a premier Grand Tourer is, how it should handle, how to blend the luxurious character with its sporting nature, is all built on the example of the XJ-S; a Grand Tourer that was so good at being just that, that it lives on, at least in spirit, in two of the most desirable British car marques today.

Not bad for a car initially regarded as a poor follow up to the E-Type.

Optimise performance with digital engine management

We’ve had the pleasure of working on this increasingly customised V12 XJS on a number of occasions. On its latest visit to our workshop, we’ve been asked to install our Digital Engine Management (DEM) system. The system will release more power, and will allow us to optimise the fuelling and ignition for other modifications, such as cold air inlets.

 

Modifying these engines would normally have little or no effect, unless the fuelling and ignition is re-mappable. Without specialist knowledge of the original firmware-based map and ability to re-blow vintage eproms, this is not really possible.

Our modern Omex system, however, allows for full re-mapping. This XJS was dyno-tested at just over 300bhp, prior to any modifications being carried out. Once the installation of the system has been completed, we will be able to check on the gains we’ve made.

V12 XJS engine

V12 XJS engine. View the full gallery, here

Another advantage of the modern engine management is the much-improved reliability. The old Lucas system using the AB14 ignition amplifier is prone to failure when hot, the new system ensures this is no longer an issue.

Speak to the experts

Follow the progress of this V12 XJS, and view the full image gallery, here. Alternatively, if you’d like to know more about digital engine management systems, or our full range of services, get in touch! Give us a call on 01635 30030, follow us on Twitter, and like us on Facebook.

KWE AT NEC CLASSIC MOTOR SHOW NOVEMBER 2017