When I converted from 6V to 12V I installed a relay between my headlight switch and dimmer switch, then I wired directly to my headlights. I was looking at the LMC HD headlight harness and got to thinking... do I need relays at my headlights too, or am I covered by the one that I already installed?

 

You're probably fine the way you are, but it would be better to have the relay near the headlights, rather than in between the switches. The whole point of using relays is to remove the high-amp load from going through the switches, and instead going directly to the lamps from the power source. This makes better use of the energy, meaning brighter lights, and helps the switches last longer. The headlight circuit uses two switches, one off and on at the dash, and one on the floor for high and low beams. If you moved the relay to after the high/low button, you would have better results.

 

The LMC HD headlight harness has 2 relays wired into it. If I go with that should I keep the other relay between the headlight switch and dimmer switch, or does that become useless?

 

You shouldn't need the relay that you have now if you install the LMC harness. IIRC, the LMC harness has a low beam relay and a high beam relay. You will have to run a power wire from the solenoid or your fuse panel to power the headlights when the relays are closed. The headlight switch and dimmer switch will only close the relays they will not be providing any power to the lights so there would be very little load on the switches.
Mark

 

I have the LMC Headlight harness. I used it when I rewired my 52. I think it works real well, I've had no issues with it in 3 years.