Headlamp relays

[Not_Anumber]

Is it still a general recommendation to introduce headlamp relays to avoid switching too much current through the lighting stalk switch ?

[Allan T]

Unless you swap to LED headlights which bring other benefits and make relays unnecessary, yes. These LEDs fit inside your existing headlamp bowls, and are the same colour temperature as tungsten bulbs, so as well as the reduced load on your wiring and improved brightness, they come without any of the usual disadvantages: https://www.classiccarleds.co.uk/produc ... am-pattern

[Charles Farran]

If you have a later RB car( with the forward radiator positioning) you do have an issue as to where to place the "transfer box" for each LED BULB behind the grill or behind the radiator supports.. it was suggested to me that you could include this within the headlight bowl but found this too compact so bought extension leads to enable siting behind the radiator supports. I have bought them, but have held off fitting them, although have converted the rest of the external bulbs to LED versions..
Not withstanding that I would still fit separate line fuses for the H/L supplies.
Cheers, Charles

[Not_Anumber]

Thanks for recommendation for those LEDs. They are food for thought and I will probably order a pair in the summer when i get closer to finishing the paintwork.

My current winter task aside from stripping the GT to bare metal is to add an MGF sourced EPAS steering column. I thought it might be a sensible opportunity to introduce a pair of headlamp relays at the same time whilst I am making up the additional wiring for the column and it's ECU but it sounds as though you are saying the relays could be superfluous if i change to LEDs.

[Allan T]

Thanks for recommendation for those LEDs. They are food for thought and I will probably order a pair in the summer when i get closer to finishing the paintwork.

My current winter task aside from stripping the GT to bare metal is to add an MGF sourced EPAS steering column. I thought it might be a sensible opportunity to introduce a pair of headlamp relays at the same time whilst I am making up the additional wiring for the column and it's ECU but it sounds as though you are saying the relays could be superfluous if i change to LEDs.

That's right, relays are indeed superfluous if you swap to LEDs - though if for some reason anyone stays with tungstens, relays plus fatter headlamp wiring are the excellent upgrade they always were.

As Charles Farran mentions, I've fixed my two i/c units on the inside surface of the radiator shroud. As well as my headlamp bowls being too small to fit the i/cs inside as suggested, I was also concerned about abrasion between the units and the wiring, and having them on the shroud makes then readily available for trouble-shooting with no disassembly. You'll need to get two extension leads for each headlamp to mount them there - ie, a total of four extension leads. It's an easy installation, but as ever with any job on the car, you might want to replace some headlamp bits once you've seen inside.

The LED units are beautifully made and presented, and a pleasure to work with - as is Duncan Rickards, their supplier at Classic Car LEDs.

Enjoy!

[Michael Barclay]

Hi
Back to your original question. Power to the lights takes a lengthy route going through the light and dip switch’s before reaching the lights. Standard headlights draw around 11/12 amps so any small resistance in the switch contacts can result in significant volts drop at the lights. Fitting the relay mod bypasses the switches using the relay contacts to switch the headlight load. Fitting the relays is simple, utilize the existing wiring. The only extra wire needed is a live feed from the fuse box to the relay contacts. I didn’t bother with kits, as you only need a couple of relays, spade connectors and a new length of wire.
Mike Barclay

[Bumpa]

I agree with Michael. With tungsten H4 bulbs relays are almost essential to preserve the 50 year old switch gear. Should the switches fail, the new ones are of poor quality generally. I have quite a few relays and extra fuses which came as standard on my Advance Autowire harness.

[Not_Anumber]

With that LED headlamp conversion, do the low beams turn off when the high beams are operated or are both on together for high beam ?

[Allan T]

The Classic Car LED headlights are wired in exactly the same way as the original headlights, using the original switched connections,

So unless there's been rewiring, either high-beams OR low beams are working at any one time, not both together.

Allan

With that LED headlamp conversion, do the low beams turn off when the high beams are operated or are both on together for high beam ?

[Not_Anumber]

Ive emailed the seller to see whether their LED bulbs are capable of running both at once. Though the standard wiring is Either/ Or thats not the case for the MGF stalk switch I'm constrained to use. That one runs Low = dipped beam only and then High = Full plus Dipped. If the LEDs cannot run both at the same time i'll need to incorporate a relay to cut the dipped when high beam is on.