Category: Technical

Posts related to Technical

We have written a short article on the importance of fuel cooling and the infamous V12 hot start problem here

When you are driving at slow speed (15mph) on a flat road, if when turning the steering wheel to change direction of the car it takes more than ½ inch movement of the steering wheel rim, then it is likely to be worn. Most worn cars will need over 2 inches at the rim to change direction.

Over the years, Jaguar has maintained its position as a leader in suspension sophistication and the launch of the E-type in 1961 was where it all began.

At the time, most production cars were still using live axles. This, of course, impacted ride quality and made cornering a fickle affair. Designed by Bob Knight, Jaguar’s first generation of independent rear suspension (IRS) took five years to develop and was a game changer in ride comfort.

While its first production application was in the E-Type, the Jaguar IRS assembly was refined and used continuously until production of the XJS ended in 1996. Even then it carried on in modified form into the XK8, XJ300 and XJ308. The smooth ride and excellent roadholding offered by Jaguar’s IRS assembly played a significant role in making the XJs the highly-desirable classics that they are today.

But even the best designs need a little helping hand. Unless professionally restored within

As one of the UK’s leading restorers of luxury classic cars, we come across all sorts of common problems that require the attention of our specialist engineers.

At KWE our aim has always been to ensure our customers receive a ‘better than new’ restoration service for their Jaguar XJS, XJ, XK and Aston Martin DB7 vehicles. So, we believe it’s important to share information that will ensure these vehicles maintain their reliability and roadworthiness.

We’ve noticed an increase in the number of classic cars being delivered to us for restoration with fuel system failures. Here we offer 7 preventative tips that will keep your vehicle in good condition and help avoid expensive remedial repairs.

Rust and sludge

The primary problem is due to the accumulation of rust and sludge in the fuel tank.

Even though high quality fuel filters are used in the fuel system, fuel pump damage and clogging of the injectors can occur.

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 [...]

KWE has developed a way of repairing the Delanaire Mark 2 aircon servo amplifier. Delanaire 2 amplifierSpares are unobtainable and the amplifier has a limited life. The symptoms of failure of this device are a lack of temperature and air direction control, even though the heating and cooling systems are working.

Similarly, KWE can now replace or repair the Delanaire Mark 3 frost thermostat, Delanaire frost thermostat sensor

It is not uncommon to experience total brake failure after a long, hard period of braking – just when you want full brake power. By far the most likely cause is that the high heat generated in the brake callipers has raised the brake fluid above the boiling point of water, i.e. Screen Shot 2016-07-29 at 15.36.29100°C. Normally, this would not be a problem – brake fluid is designed to withstand at least 200°C – but if the fluid contains water above approximately 3%, then this rise in temperature will cause the water in the brake fluid to boil and turn into a vapour. The vapo [...]

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:

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.

Another advantage of the modern engine management is the much-improved reliability. The old Lucas system

In many V12 HE cars (all of which up to 1993 are fitted with the GM400 box) a common issue we’ve encountered, and one that can worry its owners, is for large clouds of white smoke to emanate from the back of the vehicle, particularly on a hot run and after a service.

GM400Rear

This is usually a result of the gearbox being overfilled, with the excess being blown out of the breather, which is invisibly placed on top of the box. The oil drips down, hits the hot exhausts and produces an impressive cloud of smoke. Equally, it is easy to under-fill, as the procedure is not widely understood, and dipstick readings can be misleading when oil accumulates in the bottom of the dip t [...]

Back to top