Halogen headlight conversion

[GtoGeoff]

I thought I would post my experience. My GTO has four 5" sealed beam headlights [ HL ] ; Aussie cars like 60/70s Fairlanes, Statesmans, etc also had them.
I decided to upgrade to H4 Halogen globes which have 55w low beam & 60w hi beam.

My GTO has the HLs grounded to the rad support panel, pretty common for most cars of that period. Out of curiosity, I measured the resistance between the bat [-] terminal & the RSP. It was 0.12 ohms. Not much, right? [ Incidentally, you cannot measure this with a normal DVM, you need a special low resistance ohmmeter, which I have ].

Well that 0.12 ohms would mean that with all 4 hi beams on, & a nominal 12v, my lamps are only getting 10v! Putting it another way, 16% of the available voltage is not getting to the lamps. This the worst case scenario, as the voltage drop is less with just the low beams on. Still, why not try & get all of the available voltage?

I ran a ground wire direct from the bat [-] terminal to the RSP & that fixed the problem.
The reason for the resistance in the cct was poor connections between panels, bolts gone rusty etc.

Voltage drop would not be an issue with LED lights because of their very low current draw.

[cluxford]

Geoff, I got a kit from a guy in the US. Plug and play. 61 Buick. Originally 4 sealed T3 beams, which you basically can't buy replacements for, so it kept blowing the replacements (which fit but were not T3's). The kit came with 2 relays and all the wiring done. Plug into existing loom, connect to battery. Done. H4 Halogens. I went 55/100w total install time, roughly 20 mins. Massive massive difference. Easily one of the best upgrades I've done on the Buick. Not as cheap as your fix, but glad I did it

[swampy]

Hi
Halogen fitment to Holdens was well after HQ ,most likely was HZ . Anyways I retrofitted all 4 of my headlights ,
Thermal auto reset circuit breaker 1x lh 1x rh . Both sides picked up power from str motor
Power cable from relays 2x LH, 2x RH Relay to lights 4.5mmsq [6mm auto]
Earth cable each headlight were combined 1 x lh and 1x Rh went back to body earth near battery
Battery to body mount 8mmsq cable

[swampy]

Hi
Halogen fitment to Holdens was well after HQ ,most likely was HZ . Anyways I retrofitted all 4 of my headlights ,
Thermal auto reset circuit breaker 1x lh 1x rh . Both sides picked up power from str motor
Power cable from relays 2x LH, 2x RH Relay to lights 4.5mmsq [6mm auto]
Earth cable each headlight were combined 1 x lh and 1x Rh went back to body earth near battery
Battery to body mount 8mmsq cable

.3 volt drop for headlights which is great batt [+] to rear of headlight [+]