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Dim Dashboard Lights

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Hey Guys,

This month's <span style="font-weight: bold"><span style="font-style: italic">TRAction</span></span> has a question from a TR7/8 owner re. his dim dashboard lights. It was recommended for him to remove the green covering over the white lights and replace the bulbs with green LED bulbs.

I have the same problem on by TR3B. I do not have a rheostat on my lights; the push-pull switch is either on or off. Is there anything I can do to "beef up" my lights? Is it a "location" problem with the bulbs? They are clearly "on," but not bright enough to light up the individual guages. How much of a problem is it to access these lights?

I cannot "fault" anyone on this, as the car had to have a MAJOR rebuild over a 10-year period. A rheostat knob was put on a non-rheostat switch; I bought a "correct" knob.

I look forward to hearing from you. This weekend, I am having the "pros from Dover" take a look at my carburetors and horn ground problem. Better them than Gordon Badwrench.

I look forward to hearing from you, as usual.

George

Hayseed: "Is this a game of chance?"
W. C. Fields: "Not the way EYE play it."
 
Accessing the bulbs is fairly easy, if you are good at doing things you can't see and have seen them once. But the first time could be a definite problem, as the only way to see them is to lay on the back of your neck with your head in a footwell. The bulb holders have a round phenolic piece that feels like a wooden quarter with a wire attached, and they simply pull out of their holes. Two each for the tach and speedo, then the four smaller gauges share two bulbs mounted to the back of the instrument panel.

There are lots of reasons that the lights fade over time; starting with the bulbs themselves. The original bulbs apparently had very thick filaments, to the extent that the evaporating filament metal can turn the bulb fully black without burning out! Just replacing with new bulbs can make a significant difference.

For the small gauges, then there is a plastic 'window' in the gauge that the light is supposed to shine through. I believe these were nearly transparent when new, but they get darker and cloudier with age until they pass almost no light at all. Unfortunately the plastic window is inside the gauge, so replacing them is not trivial.

The larger gauges don't have a plastic window, but the light is supposed to bounce around on some surfaces that were originally painted white, now turned dark and dingy. Again, you have to disassemble the instruments to repaint. Grounding can also sometimes be an issue for the tach & speedo; as the original ground harness is frequently lost or removed.

My limited experiments with LEDs have not been encouraging. Most (all?) LEDs emit light in a relatively narrow beam, which makes it very difficult to have the light going to two different gauges at once. In addition, most of them don't actually emit all that much light, they only seem bright because of the narrow beam. But there have been a lot of new devices on the market since I played with them, so perhaps there are more suitable ones available today.

BTW, I believe your TR3B should have a rheostat. Earlier TRs did have a push/pull switch for the dash lights (which IMO is entirely adequate), but supposedly somewhere around TS42000 the rheostat became standard. You can tell by looking at the relative hole sizes in the instrument panel, the rheostat takes a larger hole (in the 2nd from top location) while the push/pull takes the same hole as the wiper switch. Also, the push/pull dash light switch was installed in the top hole, while the rheostat got the second hole (because there wasn't room for it at the top).

TS13571LInstrumentPanelcropped.jpg
 
You may find some answers here: SuperBrightLEDS

Obviously, you may have to modify the mounting and wiring. In general, you will achieve a much higher level of lumens per watt and very long life.
 
TR3driver said:
Accessing the bulbs is fairly easy, if you are good at doing things you can't see and have seen them once. But the first time could be a definite problem, as the only way to see them is to lay on the back of your neck with your head in a footwell. The bulb holders have a round phenolic piece that feels like a wooden quarter with a wire attached, and they simply pull out of their holes. Two each for the tach and speedo, then the four smaller gauges share two bulbs mounted to the back of the instrument panel...
Click to expand...

Perhaps this view will let you visualize what you're trying to grab hold of. The 2 circles with Red/White wires connected to them are what Randall describes.

EarlyFacia_8.jpg



Limbo time (cue music)...
 
Thanks Guys,

First, Frank, I am not a "modifier of wiring." Ipso fatso (Archie Bunker)

Second, Randy, as usual, you have provided a definitive description of my problem and its myriad of possible causes and solutions.

Lastly, George, thanks for the photo of the inside workings of the Hubbell Telescope.

I think that I will remove the bulbs and take a look at them. If they are cruddy, I will replace them. If not, I will put them back. That is about the extent to which I want to put my electrical skills to work. (Remember, I have already smoked up my engine compartment once, trying to work on my horns, and now one of my fog lights doesn't work.)

Again, thanks teammates.
 
Why is it every time I see the title of this I think of a Meatloaf song?
 
I dunno ... it's a cinch he wasn't singing about a TR3!
 
I am about to try somthing on my TR4 guages that applies here (at least to the internal light gauges). I assume the white paint inside the guage has lost its relflectivity (if that is word) so I bought some self adhesive chrome foil from a hobby shop. This is the stuff model car guys use to make bumpers and such chrome on the models. I indend to line the insideof the guage with this stuffin hopes that more light will find its way to to the instrument face and give me a brighter guage.

When I get around to it I will let you all know how it went. I have two temperature guages so I will be able to doa side by side test of before and after. Not sure if a picture will work to sow the difference.

I must confess I got the inspiration for this from this forum when someon used tis stuff to "rechrome" the turn signal stock ona TR6 (I think it was).
 
TR3BGeorge said:
I think that I will remove the bulbs and take a look at them. If they are cruddy, I will replace them.
Click to expand...
Something to think about: the light output of all incandescent bulbs falls off over the bulb's lifetime. Even if you can't see the darkening of the glass, the bulb may be old enough to be significantly dimmer than a new bulb.

And new bulbs are only about $1 from the usual suspects.
 
Adrio said:
I am about to try somthing on my TR4 guages that applies here (at least to the internal light gauges). I assume the white paint inside the guage has lost its relflectivity (if that is word) so I bought some self adhesive chrome foil from a hobby shop. This is the stuff model car guys use to make bumpers and such chrome on the models. I indend to line the insideof the guage with this stuffin hopes that more light will find its way to to the instrument face and give me a brighter guage.
Click to expand...

I did this about 4 years ago and it definitely makes a difference. Once I lined the gauges with the foil the dimmer control on my 6 actually did something.
I also used the same chrome foil to "re-plate" the brake light reflectors and other enthusiasts ask me what I did to have such bright brake lights.
 
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