Is there a crisis looming?

QI’d like to change my MGB’S wiring loom, perhaps while swapping the car over from left- to righthand drive. Do you have any advice? Tony Melo, via email

AUnless things have gone terribly wrong in the wiring department, we generally dissuade people from tearing out looms. Changing the driving side would be a good reason to swap, however. It’ll save a lot of unsatisfactory hacking-about of the original wires. Compare both the old and new looms with a diagram before you do anything. A new loom is by no means self-explanatory, especially if it turns out that some of the colours are different or it’s a slightly different specification from the original.

We’d advise taking a long-winded but foolproof approach. Label each wire of the old loom as you remove it. Also take photographs of how the wires are routed. Routing is critical to a tidy job and to all the wires being the right length to reach their destinations. If the loom passes through sills, pillars or the roof, consider how you’ll get the new one into place.

When you’ve removed the old loom, lay it out on the floor in the rough shape of the car and put the new one alongside. Label each wire on the new loom.

Note any wires that are missing or surplus to requirements. Don’t cut these off – just insulate the ends and tape them neatly to the loom.

Replace rubber grommets where the loom passes through body panels and lubricate them with silicone grease. Arrange the loom with care, starting behind the dash and passing it forward to the engine compartment and back to the boot. Double-check all connections against the diagram before fitting the battery.