Dash gauge cluster dummy light retrofit.

Straight to the point, I've got a '71 Ford F-100. It's gauge cluster is equipped with dummy lights instead of the charge/discharge gauge and the oil pressure gauge. I'm swapping the stock cluster for one from a nicer trim model with gauges. This is mostly for aesthetics. The gauges operate of current generated heat and are very slow to react to change, therefore the dummy light is still useful. What I want to do is illuminate the gauge with red LEDs to act as the dummy light. The gauges have a black steel plate over top. There a small standoff between it and the gauges. I figue I could mount some LEDs on the backside at the edges of the aperture and have them aimed at the gauge to illuminate it. That'll have to be trial and error, what I need to figure out is how stout these LEDs need to be to get your attention. They'll be reflecting off flat black with 40 year old chalky white markings. They'll need to grab you're eye in broad day light.



While I'm at it, I'd also like to replace the turn signal's and bright's tell tales with LEDs. All the bulbs in the instrument cluster are apparently little 2.2 Watt incandescent. What would be suitable LED replacements? I've tried some run of the mill 5mm LEDs that came with a lab kit last semester, but they seem a bit on the dim side. Something that can be made a little too bright would be best I'd assume since the current can then just be lowered to the desired brightness.

The goal with this is to keep it looking as original as possible, otherwise I'd drill a hole in the gauge face and have a 'lil LED pokin' it's head out ready to inform you that your oil pump 'naded its self.

Thanks in advanced!

You can use indicator LEDs from Kingbright, or Everlight, but I don't know how you will be able to mount them as you are likely going to need a custom PCB for this.

As for your idea to change the rest of your vehicle's exterior lighting to LED, don't. Despite the age of your vehicle, I'm pretty sure it still falls in the illegal category to mess with the exterior lighting. 5mm LEDs are not a suitable replacement for the bulbs that are in the housings already. This should be in the automotive section of this forum too.

You can try LED 'bulbs' for the telltales but you probably want to get the brightest ones that will fit. I got some red 194s for my map lights from highperformancebulbs; they seem good (although some of the products sold on that site I wouldn't touch with a pole.)

I'm assuming that you've already thought this through but you will need a tee for the OP sender or else use a sender that has provisions for both a gauge sender and a low pressure switch for the warning light.

For the idiot lights themselves, I would probably drill a hole in the back of the housing right next to the backlight bulb, and use a LED that is as bright and as wide angle as possible. Also if you can disassemble the new panel you will probably find that the hidden areas behind the gauges are painted with a white or slightly blue tinted white paint; this is to help get all the light from the backlight bulbs to the front of the gauge. If this isn't in good condition, repainting it will definitely help.

Good luck and post updates, I really like the idea of gauges w/ idiot lights built into them to draw your eye to the gauge with a problem. I've only seen it implemented on one car that I've owned though (an old Porsche) not sure why.

Optical Inferno said:

As for your idea to change the rest of your vehicle's exterior lighting to LED, don't. Despite the age of your vehicle, I'm pretty sure it still falls in the illegal category to mess with the exterior lighting. 5mm LEDs are not a suitable replacement for the bulbs that are in the housings already. This should be in the automotive section of this forum too.

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Sorry if I mislead anyone, I'm not changing the exterior lighting. The tell tale lights for the blinkers I'm referring to are the green arrows in the gauge cluster. Strictly instrument panel lighting here. Also sorry about the misplacement, I saw "Beyond Flashlights" and thought "yup..." then "LEDs" and figured "sounds about right". Guess I wasn't looking for the word "Transportation".

N8N said:

I'm assuming that you've already thought this through but you will need a tee for the OP sender or else use a sender that has provisions for both a gauge sender and a low pressure switch for the warning light.

Click to expand...

I'll have both the low pressure switch and the gauge sender tee'd into the engine block.

N8N said:

For the idiot lights themselves, I would probably drill a hole in the back of the housing right next to the backlight bulb.

Click to expand...

I'd like to do that but that's where this instrument cluster varies from more modern ones. All the gauge faces are painted stamped steel. They're lit at night by a couple of the 2.2 Watt bulbs above and behind all the gauges. The light just filters over the faces, glows like an old radio.



The gauge in question. I suppose, now that I'm looking at it again, I could tuck some LEDs up in the top left and shine them across the gauge. I just don't want the emitters themselves being visible.

Thanks for the quick replies!

EDIT:

Checked out Kingbright. Came across this little guy. http://www.kingbrightusa.com/product.asp?catalog_name=LED&product_id=APT3216SRCPRV

At first I thought "Oh! 150 Lumens! That'll get the job done!" The I realized the units were in mcd. After figuring out what a milicandela even is (a bit new to this), I then calculated that this thing puts out 0.4712 Lumens with the LED's 120° viewing angle. If I did that right then this thing is really weak. I think I might need a bit of schooling on this topic. I don't think it should be that weak. Glad I know what a steradian is now though! Cool concept.

Yeah you will need brighter LEDs for the color to be noticeable. Also give me a few days and I'll find the brand/color of paint I've used in the past to renew the gauge needles in old cars, those look like the same color orange as the gauges in the 60s Studes I've worked on.

Ha! Yeah, my gauges are a bit sun burned. Not quite as bad as that pic I googled, but I would like to know what paint you used. Guessing it has some sort of high UV resistance?

Don't know about UV resistance... glass should provide most of that. But it was about the right color and more importantly lit up well at night - before someone gave me a recommendation I tried Testers model paint and it looked good in the day but disappeared at night. It was some kind of hobby/craft paint available in both spray and brush. That's important because e.g. Krylon will go on too thick and you'll lose the crisp crease in the needles. Some GITD paint lit by UV would be cool (actually there have been some done like that from the factory) but you'd have to find someone to silkscreen the gauge faces in GITD for you. Personally a little patina doesn't bother me though but the badly faded needles do.