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Headlight relay installation
  • duncan
    Posts: 402Gold Member
    I would like to install a headlight relay in our 54 Hornet. Would all the good help people please give me step be step
    instructions to do this job. Also the proper wire size and part number of a relay switch. Thanks Hudsonly Ray
  • RonSRonS
    Posts: 610Platinum Member
    Did you already purchase a relay ? If not may I recommend Fifth Ave Auto parts in Kansas( on line) he has a good 6 volt relay( 12v also) for a fair price and a fine instruction sheet.
  • duncan
    Posts: 402Gold Member
    thanks Ron Ray
  • DocHornetDocHornet
    Posts: 146Expert Adviser
    Ray,

    If your car is already 12V, you can buy any standard 4 or 5 pin relay for $4-5 bucks each. Otherwise, there are plenty of sources for 6V relays, such as mentioned above. You will actually need 2 relays, one for the high-beam and one for the low-beam circuit.

    If It were me, I would mount the relays near the driver-side headlight terminal block just off to the side of the radiator. This way you connect the high-amperage feed to the relay(s) right to the starter solenoid (I assume yours is mounted on the Driver-side inner fender liner, near the battery?), and use the existing wires on the terminal block for the trigger voltage for each circuit.

    Just guessing, but for a 6V system I would use 8 gauge wire for the high-current side, 10 gauge should be sufficient for a 12V system (Please install an inline fuse or auto-resetting circuit breaker between the starter solenoid terminal and the relay.. 30 amps or so).

    Most every standard 4-5 pin relay has the same pin markings. You can Google "standard relay wiring" and get lots of guidance on wiring. I've attached one below, with annotations for your application.

    Now, if I can just find the time to install the same circuit on several of my own cars!
    headlightrelaywiring.jpg
    1242 x 450 - 153K
  • duncan
    Posts: 402Gold Member
    Thanks Doc Ray
  • 50C8DAN50C8DAN
    Posts: 867Platinum Member
    If you watch ebay you can get a dual (hi/lo) 6V or 12V Echlin, Niehoff, Blue Streak or similar NOS headlight relay. I have picked up several for about $20 to $25. Here is a Blue Streak that is a bit more, but you can make an offer for less!

    http://www.ebay.com/itm/NOS-BLUESTREAK-DUAL-HEADLIGHT-RELAY-PN-LP533-/190672257989?hash=item2c64f3c3c5&item=190672257989&pt=Vintage_Car_Truck_Parts_Accessories&vxp=mtr#ht_500wt_971
  • duncan
    Posts: 402Gold Member
    Thanks Dan I will check it out Ray
  • RonSRonS
    Posts: 610Platinum Member
    Ray, I placed a relay (from 5th Ave) on my Hornet and 50 Caddy. Both are wired into the dimmer switch, with a power lead (fused) from the battery at the starter switch (on the fender liner, driver side on the stepdowns). You will get consistant brightness from both low and high beams with no other additions except your own # 14 wire ( not included)... One relay with crimp connectors & instructions come in the package. You will need one inline fuse ( not included) and some wire( as needed). Relay mounts on the fender liner along with the fuse for accessability. You will never replace a circuit breaker again on the headlight switch, as little current draw goes through it. Only one relay is required with this system. I can't speak for other styles. There are four teminals used on the 5th Ave brand. Each terminal has a number embosed on the relay marking each terminal. It will take longer to figure the length of wire needed than the actual installation. Ron
  • DocHornetDocHornet
    Posts: 146Expert Adviser
    True, you can add just one relay to the headlight wire going INTO the dimmer switch. This will certainly reduce the load on the headlight switch, but you'll still be attempting to provide more current flow through a 50 year old dimmer switch contacts and funky old wiring, with varying degrees of success, depending on the condition of the other wiring.

    In my mind, a primary reason for using relays is to provide high-current-capacity power right to the headlight, or close, otherwise there may be little gain in headlight efficiency.
  • RonSRonS
    Posts: 610Platinum Member
    Doc, this is true, however I have a new dimmer. The brittle wires can be a extra nuisance on original wiring. Dave, call Randy Rundle at 5th Ave Parts. I can sympathize with your postal issues in lovely NZ.
  • davegnh1
    Posts: 88Expert Adviser
    As I recall, Geoff Clark did an write up on installing a relay in a fairly recent WTN, I don't remember how long ago it was. He gave a clear explanation.