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The Maintenance Files |
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See Pelican Tech Article Upgrading to Hella H4 Headlamps Also see numerous posts Headlights - H4 Upgrade |
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To say that the H5 headlights that were stock issue on North American 911s really suck badly, is a gross understatement. I knew that they were poor from the forums & from a little night driving after a run. I don't usually drive at night, I drink. Other night drives were always on well lit highways so really the poor lights were a non-issue. Then one night I drove home for about 2 hours on rural highways with curves & trees & rocks & potential deer & realized that they were verging on dangerous. I just couldn't see the road. Even with the high beams, it was only tolerable. Maybe I just got spoiled with newer cars. I at first thought that I could clean the glass & re-aim them etc as some suggest. But then I knew that I should do the relays anyway & rather than just Band-Aid them, I would go whole hog & replace. Santa brought me a nice new set of Bosch H4s along with 80W/100W lamps & now I had no excuse. I read all of the posts about the relays & decided on overkill: a 4 relay system with 12 AWG wire on the hot side. I bought all of the components & ordered the last little bits: the Hella sockets. They took 6 weeks to arrive & there was a bit of confusion on the cost, but Daniel Stern Lighting came through with flying colors. He seems to be the only source.
It is worth noting that there are numerous different approaches to the relay question. You can get 4 or 5 contact relays & use 2, 4 or 6 relay systems. Each option is discussed at length in the posts linked above. Have fun reading. I chose an overkill 4 relay system using 4 X $5 Wehrle 4 contact 40A relays from Pelican. I also opted to use the 4W so-called "City Light" as a daytime running light to help keep SUVs at bay. This is stupidly illegal in some localities around the world so be aware. I also used 80W/100W lamps which are illegal in some areas. But then, H4s are illegal in some areas so I guess you're on your own & good luck. The wiring diagram:
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I unraveled & un-insulated the main feeds to the headlight buckets & reused the original headlight wires (18 AWG) to feed the relays. These are fused at the panel in Fuse Block #2, fuses 1 - 4 by the Bentley diagrams. This kept the Fuse Panel wiring consistent & saved time & larger wiring bundles to fit in. And it was safe. All 12 AWG wiring was used after the relays. I fed 3 X 12 AWG cables, the existing 3 conductors for turn signal lamps & parking lights (yeah, I fed the small ground back too) AND another 18 AWG wire for the City Light in a bundle to the bucket. I taped them for the pass-thru area & re-used the rubber bell-shaped grommets. Btw hints about the grommets: There is a ridge inside that you can cut to allow a larger wire bundle to pull through. Put the grommets on the wire & THEN put the grommet in the hole. And treat all holes with a rust preventing undercoat before you grommet them. Ditto any nasty or suspicious areas inside the buckets. I went with 2 power feeds to the relay bank from the battery & double ground wires. 180W max = 15A so it was nicely below the threshold of 20A for EACH conductor which is what I fused them at. Overkill again. I used yellow (10-12) insulated crimp terminals with tinned & soldered wires. All wires were routed to the area beside the washer motor under the convenient battery ground point & hidden in 1/2" wire snakes or whatever they're called. I put the relay bank, temporarily fastened with with Velcro against the wall until I fashion some inspired mount (and replace my behemoth Sears battery). For the City Lights, I tapped off of an Always ON circuit - #7 Fuse on Panel #1. Then I fused them at 6A with an inline fuse. My H4 conversion is done. And it works like a charm (except one city light bulb blew instantly – yes, it’s wired right & 12V showing – just a dud bulb). After another run to the auto parts store, the city light's are on with the ignition, as I wanted. The snap of the relays is quite satisfying & the new headlights blaze. Now, I just have to aim them.
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New wires in the bucket. |
The mess of wires before I connected them. |
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And this is the 4W City Lights at night. It looks brighter than the H5s (hahaha - just kidding) |
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