There’s been a century of progress in the science of uprating Jaguars. Ray Ingman investigates the upgrade potential of the older classic models
THEKEY to any successfully modified car is a question of balance (or maybe another Pink Floyd album): every alteration must be considered in harmony. Fitting huge racing brakes to a crossply shod car will result in some interesting tests of your driving skill when heavy retardation overcomes grip. Before deciding on a course of action, it is wise to consider exactly the nature of use you intend to put the car, determine its perceived shortcomings, and modify accordingly. A little-used concours car can be left just as Sir William Lyons intended, but trackday or competition use will require a totally different approach.
As an aside, when modifying a car of this era, it’s worth keeping the original components in a box, should a future owner of the car wish to return it to standard. In that regard, with the ‘classic’ models, the question of reversibility should be considered – your children will not thank you for devaluing their inheritance! Period-style modifications are preferable, taking inspiration from factory racers such as the competition XKs, Lightweight E-types and Coombes Mk2s. In the past, the first thought was to adopt later components from the series, for instance an XK120 or MkVII could be upgraded with XK150 or MkIX disc brake system. But now, the supply of original parts, new and used, has all but dried up, so the modern aftermarket is the only option available.
Any course of modification presupposes that the rest of the vehicle is in good order. When overhauling or replacing any component, it is worth considering whether some form of upgrade would confer other benefits –a prime example being Metalastik rubber suspension bushes which are prone to age degradation and hardening. Substitution by a suitable grade of polyurethane, such as Superflex, (01749 673533; www.superflex.co.uk) will not only sharpen handling response but will also offer virtually unlimited service life.
We take so much for granted in even the humblest of ‘daily drivers’, it’s now unusual
to find a car that overheats in traffic, lacks braking power or even doesn’t start! With the notable exception of the 420, most pre ’68 Jaguars can be said to be deficient in braking performance, cooling capacity and lighting efficiency when compared to a more modern vehicle. When appraising the perceived shortcomings in a modern context, engine power is not a limiting factor. Concentrating on safely exploiting the available performance is the way to go.
Disc brake conversions and upgrades are available from a wide range of sources including BCC (01209 202820; www.bcc-parts.com), Coopercraft (01395 514453; www.coopercraft.co.uk) and Zeus Engineering (01297 300010; www.zeus.uk.com) amongst others. We recommend this as the most effect
