Hella H4 conversions ?

[rlane]

I have a pair of the Hella H4 conversion units for my 78SC. Looks really simple but as I read more I wonder about the need for the separate heavy duty relay. (I have one))
Do I need this (I have 55/100W bulbs)
How the heck do I install? Does this relay replace the existing headlight relay in the front fusebox or do I need to wire up a whole new system?
Anyone who has installed these ?
(smelling real good and feeling satisfied after bleeding brakes, draining and Swepcoing tranny fluid and changing oil this afternoon...incredible 60 degree February day for KY!!...kind of a wierd petrochemical brew...wonder why my wife gagged and left the room.....)
Richard

[rlane]

anybody got answers for an electrical idiot? (WELL..OK..I won't limit the idiocy to electrical...)
Richard

[Ted Stringer]

You are going to need the relay for the high beem side (100w). There is no relay in the headlight system on the 911, unless it was added by the PO. If you search the board it was discussed how to install the relay. Its not that complex.

[nhromyak]

I purchased a factory round relay and socket from PP for my low beams. Then again I am running 80/100w H4s. WOW what a great setup.

Unless you do quite a bit of high-beam driving. I wouldn't worry about the high beam really. I don't have one. Then again, I am conscious of not running my high-beams. I still flash though!

I believe the factory ran 55w low beams. If you want to take advantage of all that you can, get the relay. If not, I don't think you NEED the relay. It will save your headlight stalk switch from burning out in a couple (or ten) years.

Have fun!

[72_911T]

Relays are an absolute must. Thanks to a thread from Warren Hall I now have one relay per filament. It’s really quite simple and a quick install. The idea is you want to isolate your under-rated factory light switch and turn signal/flasher from the LOAD side of your high wattage lamps. The 100w high beams draw 8.3amps per lamp or 16.7amps for the pair. Even the 55w “low beams” draw over 9amps per pair. (If I remember correctly its Ohms law: Watts (p)/volts (v)=amps (a)
Here is how I did it on my 72.
You need relays. I got (4) ice-cube relays with pre-wired female connectors. Some #12 stranded wire in red, yellow, blue and black. (This matches the pigtails from my pre-wired connectors. (2) Inline fuses, one 10a and one 20a. This will provide power to the lights and is connected directly to the battery via the pre-threaded screw on the positive terminal. Crimp and butt splice connectors to extend the wires from the pre-wired connector. (You can solder and heat shrink if you want)
Determine a good location for the relays. I wanted mine close to the battery and found room between the windshield washer bottle and the drivers side battery box.
Label each relay 1 through 4. This corresponds to the fuse numbers on the lower fuse block. High beam left, high beam right, low beam left, low beam right. (One relay per filament)
Make a loom of 8 wires, 4 blue labeled 1-4 and 4 yellow, labeled 1-4.
Neatly route the loom from the lower fuse block to the intended home for your new relays.
Loosen the setscrew from the fuse block and remove the #1 wire from the fuse block. Splice this wire to the blue #1 wire.
Insert the new yellow #1 wire into the fuse block were you just removed the factory wire. Repeat steps for the other six wires.
Connect the other end of blue #1 to the CONTROL terminal of the female connector for relay #1. Repeat the steps for the other 3 wires.
Connect the other end of yellow #1 wire to the LOAD terminal of the female connector for relay #1. Repeat the steps for the other 3 wires.
Get Power to the high beams, relays #1 & #2: Splice the red (power) wires from the #1 & #2 female connector to one of the inline fuses then connect the fuse to the positive battery terminal.
Get Power to the low beams, relays #3 & #4: Splice the red (power) wires from the #3 & #4 female connector to the other inline fuse then connect the fuse to positive battery terminal.
Splice all the CONTROL ground wires from #1, #2, #3 & #4 and find a suitable ground. I used a bolt that connects the front quarter panel.
You’re done. Now every time you turn on you lights, power travels through your light switch to the CONTOL side of the relay. It takes very little amperage to make this relay change. The real power goes through the LOAD side to illuminate the lamps. Viola, no fried switches.

[RoninLB]

I suggest rewiring w/12ga. low and 10/ga. high w/130/100 bulbs. I suggest at least 2 75amp relays, better is 4 relays. Relays will be triggered by previous wire feed to the lamps. I use 2 marine cir. breakers. Bulb sockets are heavy duty, not stock. The wireing is simple. I use marine grade wires and Radio Shack 4% silver solder. It is simple to have 2 filiments on in high beam in each lamp. I used a diode for this super high beam. I suggest Euro lens and bulbs. I suggest not to use DOT lens, bulbs, or PIAA bulbs. The inspiration for this up-grade that I did came from a Pelican philosopher who explains reality in a way we can all understand. "If they're slow in the left lane I want to burn their retnas"
Bulbs are Navra [German] #48951, I like the large painted trim ring so I use Cibie Euro H-4 convex lens #082440 No one ever flashed me because they are blinded by the low beam. What is interesting is the low beam coverage when on high beam circut . The dispersion to either side is excellent, which I need for the twisties. The side coverage is a function of the bulb filiment windings and lens. The high bulb wattage would be a problem on a SUV. The 911 is low so doable without a problem. The install is time consuming for a perfect install. Lens covers/stone chip protectors are another story. The more I look at a simple project the more complicated it gets, but that's my problem.

[rlane]

Great advice and thanks to all...I will be stopping by the parts shop this week and will get this project underway...for me this is like rocket science....
Richard