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Uprating Front Lights


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o.k I have now found some info and need it translated into laymans

Upgrading your wiring harness

If you make any of these upgrades, add relays, and fuses. The stock harness in most of our cars runs all the headlight current through that teeny-tiny headlamp switch, which often comes from the factory with 18 gauge leads! If the contacts don't burn, and the wires don't melt, you'll be getting a lot of voltage drop. Not to mention that the headlamp circuit is typically unfused - a ground fault/short here will cause serious harness damage. (If your switch isn't the weak point, someplace else will be - our Morris Minor has a great harness all the way out to the fenders, but the subharness that goes through the fenders to the lamp is made up of 18 gauge wire...)

At the very least, you want a relay and fuse on the high beam circuit. The best (and easiest!) way to do this is to buy a fused Marchal 514 relay. They're bulletproof, and can easily be spliced into the high beam circuit. Find some source of unswitched 12V (brown wire, you want a heavy one). Find the blue/white wire leaving the dip switch (usually there's a connector that connects the switch, the lead out to the lamps, and the indicator - this is a good spot). Connect the brown wire to the source terminal on the relay. Connect the U/W wire coming from the switch to the coil. Connect the U/W wire going to the headlamps to the load. Make a good coil ground. Voila! You now have brighter high beams, even if you didn't change the lamps. (If you're particularly anal, wire the new harness with appropriate colors - I would use blue/slate for the lead that splices from relay to the headlamp wire). Use heavy wire for the load connections - 14 gauge.

If you think about it for a little while, you can make up a neat two- or three-wire harness and mount the relay where it's out of the way but accessible (so you can change the fuse if it blows). In the GT6+, I mounted it on the firewall with all the other relays; there's a good source of hot at the overdrive relay, and it was easy to pass the two-wire harness through one of the existing grommets.

Now, if you're having fun, you can rig a parallel relay for the low beams. If you're going to do this, then consider not using two Marchal relays, but two unfused relays, sharing a single source, which you fuse. Lucas makes a very nice metal relay with a separable plastic base (it's called a 28RA) - you can snap the bases together to make up a multi-unit block, and there is available a fuse holder that snaps to the end (holds a modern blade-style fuse). These are all available from British Wiring.

Sometimes this isn't good enough, because the harness out to the lamps is not up to the task. One fellow with a TR3 measured more than a volt voltage drop from the switch to the lamps. In this situation, you want to mount the relays out at the lamp end of the harness; there's usually a spot near the grille where one wire becomes two, and this is the place to splice in to minimize that sort of voltage drop.



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That link was o.k But mine fit fine.. the only problem that i have is the ones i got are 100w rating where i am only supposed to use 65w highbeam and 55w main beam.. yes yes i know that they are illegal but to be honest the chances of being stopped are slim as they give out about the same amount of light as the H.I.D used in cars like merc and new beemers.. its just that i dont really want to melt my wires or bugger the switch.. so not sure what i need to do..

if you look in the gs section you will see the difference between my old ones and the new highbeam that i have in.

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if you could mate that would be excellent.. then if you could just pop round and wire it up that would be

seriously if you wouldnt mind mate it would help if you could sling us a few bits.. still got to work out how to do it though..


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