Fitting a Moss headlamp relays kit

Twin relays kit from Moss Europe
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Fitting instructions from Moss Europe
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Posted: 200319

Fitting a Moss headlamp relays kit
With MGBs and derivatives like the MGBGTV8 now approaching the 50 year milestone, modifications that help preserve electrical components such as switches are well worth considering as they are not difficult to install or costly. This useful upgrade uses relays to take the load and potential damage off the ageing switches. Here we have a step by step guide from Andy Goves describing how he had a ready wired twin relays kit (see below) supplied by Moss Europe fitted to his 1973 MGBGTV8.

Installation of the pre-wired twin relays kit
Chris Smith had provisionally allocated four hours for this work (knowing my commitment to originality), anticipating the difficulty would be locating the modern looking relays out of sight. In fact it only took Chris one hour to complete the whole installation!

The approach adopted considered these criteria:
> Preserve the original appearance of the engine bay and electrics.
> Accept the need to lengthen wiring, if necessary, to achieve this objective.
> Achieve proximity of new relays to existing headlamp wiring harness.
> Siting of new relays needs to avoid water ingress.
> Relays will operate in a horizontal or vertical position.

A suitable location was found (see photo alongside) adjacent to the headlamp wiring harness that allowed both relays to be fixed horizontally to the metal structure under the dashboard, near to the windscreen wiper motor, providing a good earth connection. This is very convenient for the bullet connectors for the headlamps wiring; in addition the original equipment switch plug could be unpicked to remove the pins and avoid cutting any wiring.

The Moss Europe unit is extremely well produced and offered an opportunity to continue to use the bullet connectors thus maintaining originality. However, I opted for soldered joints to give a higher degree of reliability, noting that there would be no stress or movement imposed on this new wiring.

The red main 12v feed (item 30 in the annotated photo on page 1) already contains an online fuse and is routed through the main wiring loom rubber grommet in the bulkhead into the engine bay and onto the fuse box, taking care not to damage the grommet as it can become brittle with age. An adequate length of wire was provided with the kit, with no extension required.

Before doing so, a black insulating sleeve was placed over the entire red wire and then heat shrunk to fit - the new wire now looked part of the original wiring loom, being secured below the existing black insulated wiring loom in the engine bay (see photo above right). Although done for purely aesthetic purposes, this sleeve provides additional protection against any abrasion which might, in extreme cases, result in a short circuit, acknowledging that the in line 20 amp fuse should provide primary protection here.
  Wiring options for the relays
There were two options in wiring these relays - first the headlights being switched on via the ignition only, or second having them live at all times. The sidelights operate irrespective of the option chosen. I chose the ignition switched option as a further safety related item. Hazard warning lights suffice for any breakdown occurrence; new twin six volt batteries have just been fitted after replacing the eight year old batteries - I had no wish to cause undue drain on these new batteries!

Noting the excellent wiring diagram supplied by Moss Europe and the protection of an in line fuse, nevertheless we decided to take the positive feed from the existing fuse box, again the photo (lower right on page 2) depicts this.

Pre-wired headlamp relays kit from Moss Europe
The Moss Europe kit is extremely neat, well priced and comes with clear instructions. A copy of the instructions is available on the V8 Website. Instructions

I am very pleased with the result as the engine bay retains its original appearance yet enhancements have been achieved with benefits in safety and operational efficiency. The twin relays kit is currently available at £36 including VAT.
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