For owners modifying their cars
Jaguar Mk2 upgrade guides
These are guides for owners intending to modify their own Mk2 — not restoration notes and not a concours reference. Each one takes a single system, explains what the factory did, what the common upgrade paths are, and what each option actually changes about driving the car. The first guides are published below; the rest of the cluster is in preparation.
Anything mechanical here should be planned with a marque specialist and checked against the workshop manual for your car. Where a figure cannot be verified, it is left out rather than guessed.
Five-speed gearbox conversions
The Tremec/T5 and Getrag XJS routes compared: ratios, adaptor plates, propshafts, clutches and what a fifth gear does to a motorway cruise.
Brake upgrades
Alloy four-pot calipers, vented discs, matching rear kits, an uprated servo and a dual-circuit conversion — bolt-on, reversible, transformative.
Suspension & handling
The fast-road 'Coombs' recipe: uprated springs, adjustable dampers, polyurethane bushes, anti-roll bars and the Panhard-rod fix.
Power steering conversions
Electric and speed-sensitive systems compared with the original box, what they cost you in feel at low speed, and the alternator they demand.
Cooling & electric fans
Radiators, header tanks, viscous versus electric fans, thermostats and sensible switching for a car expected to sit in summer traffic.
Ignition & electrical upgrades
Fused rewires, alternator conversions, electronic ignition, earths and LED lighting — the unglamorous work that decides whether the car gets used.
Still to come
Wheels & tyres
Wire versus bolt-on wheels, rim widths, arch clearance on Coombs-style flares, and modern tyre choices that suit a period chassis.
Guide in preparation
Restomod vs original
When to modify and when to leave a car alone: originality, documentation, reversibility, insurance and value — the judgement call before any of the above.
Guide in preparation
Common questions
- Do these upgrades ruin a Jaguar Mk2's value?
- It depends on the car. A rare, original, well-documented Mk2 is usually worth more left alone. A car that has already been resprayed, retrimmed or re-shelled loses little by being improved, and a well-engineered restomod by a known specialist often sells more easily than a tired original because buyers can use it.
- Which upgrade should come first?
- Brakes and cooling, in that order. Extra performance is worthless if the car cannot stop repeatedly or sit in traffic without boiling. A five-speed gearbox is the single change most owners notice most, but it belongs after the car is safe and reliable.
- Can these changes be reversed?
- Mostly, if you plan for it. Keep every original part you remove, avoid cutting or welding the shell where a bracket or bolt-in mount will do, and document the work with photographs. Reversibility is what separates a considered restomod from a modified car.
For a worked example of most of these decisions on one car, read The Build: 873 EUT.