Folks, I need some advice on headlight relay kits for C3s.


I recently got the world's greatest deal on a set of 4 dedicated HID lights from Dapper Lighting (the Dapper 575s)- the dims are 55 watt HIDs with a proper HID projector housing and the physical metal cut-off to keep the beams properly low- and 2nd set of the same housings (glass & metal) without the cut-offs for the high beam lights- these have normal halogen bulbs in them right now.

I was really hoping that they were only the 35 watt HIDs because they pull a good bit of "juice" when they first startup- with the 55 watt hids and the crazy early startup voltage I'd be crazy to not put in a set of relays so I don't burnup my light switch and/ or the stock wiring.


My question is on exactly what relays to use, I'm torn between going with a relay kit from a dedicated Corvette shop- like Ecklers where I know the fit is going to be great and going with the relay kit that Dapper Lighting offers that goes with my lights....



Can anyone who know's what they're talking about take a look at these for me?


Here's the Dapper 575 Chrome lights: https://www.dapperlighting.com/colle...cts/575-chrome

Here's their 575 relay kit and harness, but it says it only includes 2 relays and 2 harnesses for 4 lights?? -I'm of the understanding that the voltage to our headlights is bad enough in the stock configuration and all the voltage goes through the actual switch and has some pretty significant voltage droop and I should be using relays for all 4 lights; no?


https://www.dapperlighting.com/colle...-harnesses-575


https://cdn.shopify.com/s/files/1/01...14109780468134


Their wiring guide also turns on all 4 lights at the same time when the brights are on- I don't think this is how our cars work from the factory; right? -I don't really want all 4 lights on when I use the brights- my poor alternator is going to have enough to do without having to deal with 4 lights running simultaneously.


Adam

 

I just recently placed my order for a set of Dapper 575's. I ended up going with the SpeedDirect NeverNight harness. The harness is spendy, but the quality, materials, and engineering of it is unreal.

 

That's 5-10x the cost of the wiring harnesses and relay kits I've been looking at.


That harness costs more that my 575s! ;-) (CL super special bargain @ $250)
-I'm sure it is incredible quality, though; but when I'm looking at $30-$50 options, I can't quite wrap my head around that one.)

Adam

 

I just installed the Daniel Stern relays over the weekend. Check out my thread:

Headlamp Relay Questions

Daniel Stern Lighting

Good quality stuff with ceramic lamp plugs. The only thing you have to supply is the wire and your time. I went with 12 gauge wire so I have some upgrade options other than Halogens in the future. Right now I'm looking for better low beams. Mine suck even thought they are getting the full 14.5 volts from my alternator now and are halogens.
Any suggestions?

 

Totally understandable. The Speed Direct part looks like it's designed for the Space Shuttle, but you certainly don't need that on an old car.

 

Ron Francis has a kit for this purpose. Also keep in mind your headlight switch might not be able to handle all this power.

 

My new wiring schematic for my headlamps.

 

If relays are installed this takes all the high current out of the factory switch. This is the reason to install relays and to upgrade the wiring from the relays to the lamps.

 

Don't let the 55W and 35W fool you. With all the lights on you should be only drawing 15 amps. (55w+55w+35w+35w=180w 180w/12volts=15amps). Since these cars are old, I am willing to assume there's excessive resistance, therefore amp draw in both the powers and the ground circuits. Another really good reason to protect your headligth switch.
Since I want the best light performance and I don't want to be buying any MORE parts than I already need to. I too will be adding a relay system. I think the Dapper set is adequate but I'll modify mine for all four lights to come on during high beam application.

 

Yep-you beat me to it!

The factory switch simply tells the relay to actually switch the lights on- it's then sees only incredibly small amps for very short periods of time. -I have a homemade electric home brewery control panel that operates on the same general principal: high amp contactor (huge, 240v, 40 amp relay) actually switches the load and teeny tiny, low voltage and amperage switch remotely tells the contactor to turn on/off).


Adam

 

Yes and no; remember that HID lights actually pull a lot more amps until they get warmed up- they might only pull two amps when up and running, but they pull 10 amps during startup.

HIDs and long runs of 18awg wire running through crappy old switches, particularly when wired to simultaneously run 2 HIDs and to Halogens is a recipe to burn up switches and wires pretty quickly, no?


Adam

 

I think I'm slowly understanding the wiring diagram above- because the traditional halogen bulbs essentially have both a low and a high beam filament you can wire the outer housings to light up both the lows and the high beams; I can't do that with my HID bulb low beams for two reasons (right?):

1. The HID Bulbs don't have separate high beam / low beam filaments
2. The HID projector fixtures have a physical metal sheet inside blocking light from emanating through the upper half of the fixture so you don't blind oncoming cars. -Even if I put a traditional High/Low halogen bulb in the housing and wired it like above, it wouldn't act as a "high beam" because the metal piece would block the "high beam" light path.


What I COULD do is leave the HID "low beams" on AND put the high (halogen or LED) beams on simultaneously.... I'm looking forward to playing with this.


Adam

 

I once added HIDs (35W 5,000k) to a '99 Seville. It had projectors designed for HIDs but the lamps weren't yet approved in the USA so only exports got the HID lamps. The fixture has separate high beams used only with halogens--both in export and when the HIDs were available in the USA a few years later. I found zero need for the high beams as the HIDs gave better visibility. While I used inexpensive ballasts for the HIDs I found there is a noticeable delay from the time they first ignite until they have full output. Since the stock wiring in the Seville burned either low or high lamps it was unsettling at best when switching from hi beams back to low.

Something tells me that your 55W low beams will give all the light you need. If so, your existing wiring and switch should be suitable. Don't forget that incandescents and halogens also have a significant inrush current that lasts a few milliseconds until the filament heats.

Your stock headlights have six filaments in total--two each in the "low" beams and one each in the "hi". With the brights on all six filaments are burning. If you find the need for hi beams I call that a good thing because there's no chance of "light lag" when you go from "hi" to "low". In this case you should really only need one relay--used as an alternate power source for the hi beams. If you want alternate power for both low and hi you'll need two relays. Be aware that all four lamps will light. If you want the low and hi to operate separately and all with alternate power you will need three relays--the third relay will be used to turn off the lows when the highs are burning--obviously it will have to be installed after the low beam relay as it will still be trying to power the lamps.

You'll find a three-connector plug for your existing low beams but your HIDs will only use two. The third connector is simply a parallel connection from the hi beam power.

The existing ground wiring for the headlamps is adequately sized for anything I've suggested BUT the harness ground connections themselves are very likely to be corroded. There are three ground connections for the forward lamp harness: one is between the headlamp vacuum relays (easy to access); the other is in the lower-left corner of the radiator support (an absolute pain to access because the vacuum reservoir is in the way); the third is at the alternator (easy to access). All three of those grounds connect at a single factory splice in the harness roughly between the headlights. If you don't clean all of those grounds by disassembly, abrasive cleaning (wire wheel in a drill is easiest) of terminal, connector and grounding point then I highly suggest that you run a completely new ground for your new headlamp system (to include the ground for the relay coils).

Feel free to send me a PM if you want schematics or other suggestions. I recently had two neck vertebrae fused and can't do squat until mid-June at the earliest so I have plenty of time

 

Update: I finished installing my Dapper 575 relay kit 2 weekends ago and it was really dead simple.

They're now $24.99 and I don't think you'll find anything better even close to that price:
https://www.corvetteforum.com/forums...elay-kits.html


Simply run the power-in to the relays via either the starter lug or the alternator (I went the alternator route, screw the relays to the front of the driver's side fender, attach the male head light plugs from the harness to the stock headlight wire female plugs, -then tuck them out of the way with some zip ties and run the new male plugs to each headlight / bucket making sure that they're in a place where they won't get pinched when the headlights go up and down. --Done!


Adam