Hi guys. Recently there has been a great discussion about the number of prongs on the back of various headlight bulbs, yellow bulbs etc. There was great info in that discussion, including a headlight bulb chart etc. Now try as I might, I can't find it again. Can someone direct me to it please. I like the idea of changing my '85 TL to yellow bulbs, and to get some for my '72 car in anticipation of it running again. So I need to digest the info. Thanks, Edwin
- Thread starter edwin
- Start date
André4Renaults
Enthusiast
- Messages
- 757
- Location
- Barnet, Hertfordshire.
I wrote a large piece about this some time ago, but also can't find it, so I'll re-state things:
There are 2 things to consider here: 1/ The bulb type, and 2/ Their colour.
You need to check which type of bulb your car has. It will be one of 2 types: if the bulb has 3 distinct prongs on the plate, which locates the bulb so it can only go in the holder ONE way, then you have what is known as a "H4" bulb. If the bulb's base is circular, with a small raised locating "bump", again to locate it in the holder, then you have a "P43T" bulb (sometimes these are called "472" bulbs.) If you have a "H4" fitting the bulb will be a 60/55 watt halogen one and, should you wish to convert these to "selective yellow" (the approved colour of French style headlamps) you can buy glass covers that clip onto a lip at the bottom of the bulb. That's easy!
If you have a bulb with a circular fitting ("P43T") you need to look carefully at the bulb itself. If it's a circular glass bulb then it will have a lower wattage unit, usually 45/40 watts, and is a non-halogen unit. These cannot be converted to "selective yellow", although some bulbs were manufactured with selective yellow glass anyway, which CAN be substituted for the white ones (I've loads of these!) If your bulb has a sausage looking bulb, these ARE halogen ones, and should be able to accept the yellow clip-on covers referred to earlier. These have two wattage levels; 60/55 watts (same as H4 bulbs) and 45/40 watts. In my opinion (others may differ!) the 60/55 watt ones are better, as they're brighter.
If your car originally had 45/40 bulbs and you're planning to fit 60/55 watt ones you might want to consider a relay to control the lights, since you are placing a greater strain on the existing wiring.
.....And finally, these bulbs ARE legal (providing they are "selective yellow") and I consider them to be better in foggy and misty conditions. If you ned to know more-just ask!
There are 2 things to consider here: 1/ The bulb type, and 2/ Their colour.
You need to check which type of bulb your car has. It will be one of 2 types: if the bulb has 3 distinct prongs on the plate, which locates the bulb so it can only go in the holder ONE way, then you have what is known as a "H4" bulb. If the bulb's base is circular, with a small raised locating "bump", again to locate it in the holder, then you have a "P43T" bulb (sometimes these are called "472" bulbs.) If you have a "H4" fitting the bulb will be a 60/55 watt halogen one and, should you wish to convert these to "selective yellow" (the approved colour of French style headlamps) you can buy glass covers that clip onto a lip at the bottom of the bulb. That's easy!
If you have a bulb with a circular fitting ("P43T") you need to look carefully at the bulb itself. If it's a circular glass bulb then it will have a lower wattage unit, usually 45/40 watts, and is a non-halogen unit. These cannot be converted to "selective yellow", although some bulbs were manufactured with selective yellow glass anyway, which CAN be substituted for the white ones (I've loads of these!) If your bulb has a sausage looking bulb, these ARE halogen ones, and should be able to accept the yellow clip-on covers referred to earlier. These have two wattage levels; 60/55 watts (same as H4 bulbs) and 45/40 watts. In my opinion (others may differ!) the 60/55 watt ones are better, as they're brighter.
If your car originally had 45/40 bulbs and you're planning to fit 60/55 watt ones you might want to consider a relay to control the lights, since you are placing a greater strain on the existing wiring.
.....And finally, these bulbs ARE legal (providing they are "selective yellow") and I consider them to be better in foggy and misty conditions. If you ned to know more-just ask!
retrospecparts
Enthusiast
- Messages
- 219
- Location
- West Sussex
Actually Andrew, the P43t base is used on the 3-prong halogen bulbs and it is those that are often known as '472' (or 'P472' or 'H4').
The round base is P45t.
Here's a bit more explanation of why 'selective yellow' lamps are better in bad weather conditions and the reason that the French government legislated that all vehicles must have them:
The intent of selective yellow is to improve vision by removing short, blue to violet wavelengths from the projected light. These wavelengths are difficult for the human visual system to process properly, and they cause perceived dazzle and glare effects in rain, fog and snow. Removing the blue-violet portion of a lamp's output to obtain selective yellow light can entail filter losses of around 15%, though the effect of this reduction is said to be mitigated or countervailed by the increased visual acuity available with yellow rather than white light in bad weather.
I stock all of the following options, with the P45t (round) base:
Some of the cheap glass covers that you can buy are just dipped in a yellow stain which tends to overheat, crack and fall off, leaving the light white. Some are plastic, rather than glass. I have no experience of those.
The round base is P45t.
Here's a bit more explanation of why 'selective yellow' lamps are better in bad weather conditions and the reason that the French government legislated that all vehicles must have them:
The intent of selective yellow is to improve vision by removing short, blue to violet wavelengths from the projected light. These wavelengths are difficult for the human visual system to process properly, and they cause perceived dazzle and glare effects in rain, fog and snow. Removing the blue-violet portion of a lamp's output to obtain selective yellow light can entail filter losses of around 15%, though the effect of this reduction is said to be mitigated or countervailed by the increased visual acuity available with yellow rather than white light in bad weather.
I stock all of the following options, with the P45t (round) base:
- 6v, 40/45w, clear glass,
- 12v, 40/45w, clear glass,
- 12v, 40/45w, selective yellow glass,
- Halogen, 6v, 55/60w, clear glass,
- Halogen, 6v, 55/60w, clear glass with selective yellow glass cover,
- Halogen, 12v, 55/60w, clear glass,
- Halogen, 12v, 55/60w, clear glass with selective yellow glass cover,
- Halogen, 12v, 80/100w, clear glass, (off-road use only).
Some of the cheap glass covers that you can buy are just dipped in a yellow stain which tends to overheat, crack and fall off, leaving the light white. Some are plastic, rather than glass. I have no experience of those.
André4Renaults
Enthusiast
- Messages
- 757
- Location
- Barnet, Hertfordshire.
Yes, sorry, I meant to put that! My brain must be suffering from "lock-down syndrome"! Glad to see you emphasised the "selective yellow" colour definition. I agree, NOT all yellow headlamp colouring systems meet this criterium and they must, to be legal. The French explanation coincides with my own personal driving experiences and I DO find them better.
retrospecparts
Enthusiast
- Messages
- 219
- Location
- West Sussex
Same here. They also look right on a French classic.
Thanks for that.
Sooo.... the bulbs are all clear, but there are some that have an extra piece available, a yellow'globe' which clips over the bulb but inside the headlamp.Is that correct? And then, I saw somewhere, there is also a yellow outer clip on yellow disc, which fits on the front of the outside of the headlamp. Is that correct?
Now can you explain what 'selective' means in this bulb context.
As my older car has lots of switches, I don't see one that says select yellow headlamps. So I anticipate that 'selective' yellow means it is possible, by some fiddling to change from yellow to white etc. But its not a click switch over, its a fiddle. Can you confirm please.
In the end I would like to have yellow bulbs in our '85 in France and our '72 in the UK, to develop the French look. So I will check the fittings and come back with snaps for you learned folk to direct me as to the correct way to achieve what we want, if its easily possible . And it would have to be the legally acceptable arrangement.
I am trying to move forward with limited experience, knowledge and ,apparently, limited intelligence!!! Thanks chaps, Edwin
Sooo.... the bulbs are all clear, but there are some that have an extra piece available, a yellow'globe' which clips over the bulb but inside the headlamp.Is that correct? And then, I saw somewhere, there is also a yellow outer clip on yellow disc, which fits on the front of the outside of the headlamp. Is that correct?
Now can you explain what 'selective' means in this bulb context.
As my older car has lots of switches, I don't see one that says select yellow headlamps. So I anticipate that 'selective' yellow means it is possible, by some fiddling to change from yellow to white etc. But its not a click switch over, its a fiddle. Can you confirm please.
In the end I would like to have yellow bulbs in our '85 in France and our '72 in the UK, to develop the French look. So I will check the fittings and come back with snaps for you learned folk to direct me as to the correct way to achieve what we want, if its easily possible . And it would have to be the legally acceptable arrangement.
I am trying to move forward with limited experience, knowledge and ,apparently, limited intelligence!!! Thanks chaps, Edwin
André4Renaults
Enthusiast
- Messages
- 757
- Location
- Barnet, Hertfordshire.
The term "selective" yellow is the precise definition of the yellow light that is produced by these lights. Any light colour is measured by its wavelength and the actual yellow colour used in French headlights is called "selective" yellow. I hope that helps (a more lengthly explanation is available on Wikipedia.) You are correct in understanding that there are yellow glass covers which clip over bulbs, although some lamps are sold with the yellow covers already fitted. As to switching the lights on, once the yellow covers are in place and the bulbs are fitted in the car, the headlights will be yellow when they're switched on. The word "selective" is simply a definition of the colour, not an option to "select" yellow or white lights and remember it's the bulb INSIDE the unit that is made yellow, not the headlight glass itself. Feel free to ask any more questions you have, and I'm sure that either myself or Retrospecparts will be able to answer them!
Hi Andrew. Thanks for your explanations. So... The term selective yellow has nothing to do with its ability to be selected. Its the name of that particular, French approved, colour tone. Like sunshine yellow or golden yellow. That is a huge start. So , as said, I will extract a bulb and take snaps and we can discuss the particular situation that applies to my car.. As for the French car, that will be dealt with after we are allowed back into France.....
Again, thanks for your explanations. What you have said is not what I expected, but understandable. So a great help. In due course I will return to this. Its great that we have such detailed knowledge available to this forum. Thank you. Edwin
Again, thanks for your explanations. What you have said is not what I expected, but understandable. So a great help. In due course I will return to this. Its great that we have such detailed knowledge available to this forum. Thank you. Edwin
retrospecparts
Enthusiast
- Messages
- 219
- Location
- West Sussex
Andrew has answered all your questions Edwin but I'd just like to clarify the answer to your first sentence:
All the halogen bulbs are clear but some come with a yellow globe, as you say. However, the non-halogen bulbs come with either clear glass or yellow glass.
Hi Retro and thanks. . In view of the complications and all the alternatives available, as said, I will extract a bulb from the '72 4L and photograph it, and I will post that for your observations and recommendations on how to proceed.Thanks everyone. Edwin