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Light lost through headlight covers? 
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Post Light lost through headlight covers?
Now the clocks have changed and there isn't as much daylight around its back to that time of year when a bit of driving at night becomes inevitable (unless you tuck it up for the winter). My headlights are at best pants. My Spyder has the smoked headlight covers so I was wondering how much light gets lost just by having the covers. For now I've taken them off (in preparation for my local kit car club pub meet on Tuesday evening). Looking through the perspex straight the smoke seems very subtle but when I hold them at the angle the light shines through them they appear a lot darker. Also I noticed that the reflections from the angle are quite severe so quite a bit of the light from the headlamps must be reflected downwards as it hits the perspex. I'm guessing the angle could give some refraction too. That set me thinking that even clear covers must reduce the light quite a bit.

What do people think? Quite a few GTMs and other kits have perspex covers. Do people generally take them off for the winter or just put up with the light output?

I'm considering an LED headlight bulb upgrade but if the cover is the main problem it might not even be required. I'll report back after the run on Tuesday as to how much better it looks.


Sun Oct 30, 2016 9:53 pm
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Post Re: Light lost through headlight covers?
I remember mine being terrible too and thought it was the Perspex too, I guess the easiest thing would be to just remove them and try it?

Is yours a daily driver?

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Mon Oct 31, 2016 10:18 am
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Post Re: Light lost through headlight covers?
yazza54 wrote:
Is yours a daily driver?


Far from it. My GTM does about 2000 miles a year, daily driver (company car) does 10 times that+. I do prefer not to sorn it for the winter and get as much use as I can when I do get the chance. Things like going to the the monthly kit club pub meet in the tin-top seem wrong, although I get why people with exo cars and sevens with no windscreens etc come in their daily drivers through the winter as I wouldn't be hard(foolish?) enough for that either. I guess one of the main advantages of GTM, even rag top ones, is that they are a bit more comfortable and practical than some of the more extreme kits.

Seeing where you are going is quite important though!


Mon Oct 31, 2016 2:13 pm
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Post Re: Light lost through headlight covers?
Well, result of last night's experiment - incredible difference. I could actually see where I was going on dip, and main beam was as good as most modern cars. There is actually definition to the dip beam now rather than just a vague glow so I can now see they are set a little low. Nice sharp cut off and clearly visible flick up on the left.

Conclusion - the covers rob a lot of light and definition.


Wed Nov 02, 2016 8:31 am
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Post Re: Light lost through headlight covers?
Interesting.....is it the smoke effect do you think? Would clear be better?


Wed Nov 02, 2016 7:00 pm
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Post Re: Light lost through headlight covers?
Jaykart1227 wrote:
Interesting.....is it the smoke effect do you think? Would clear be better?


I was having a conversation in the pub with someone who seemed to know all about it. He was talking about the need to make the light collimated and ways to achieve that. His theory of headlight covers is that as the cover is usually angled relative to the headlight beam (for aerodynamics) you will always get considerable reflection of the light as it hits the angled surface. He was saying that more than half of the light that hits the inside face of the cover will be reflected so less than half will make it through. The reflection is more important than the tint. The tint may cut the light transmission by 5% but the angle/reflection is more than 50%. If what hits the cover is reflected back against the inside of the headlight again it will bounce back and forth until it eventually makes it out through the front but may well by then be going the wrong way - i.e. upwards to either light up the sky or dazzle oncoming drivers. In our cars what gets reflected back will most likely hit the GRP and not reflect well so not be of any further real use.

So, headlight covers are good for smoothing out the aerodynamics but rubbish at letting light through.

Two choices, make the lights more than twice as bright or take the covers off, or better still make the lights twice as bright AND take the covers off!


Wed Nov 02, 2016 9:39 pm
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Post Re: Light lost through headlight covers?
sanzomat wrote:
yazza54 wrote:
Is yours a daily driver?


Far from it. My GTM does about 2000 miles a year,.........



Light weight! my Coupe is doing daily duties at the minute!

I imagine the tinting is the main reason for the lack of light. Might be worth parking up facing a wall and do a with and without cover to check how the beam pattern is effected. be interesting to see pics of this. I have a wall which I have marked up to check beam pattern/alignment.

Neil

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Wed Nov 02, 2016 9:41 pm
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Post Re: Light lost through headlight covers?
I must admit my cars lighting in the evenings is awful at best and i have the plastic covers on and they aren't tinted.

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Thu Nov 03, 2016 10:32 am
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Post Re: Light lost through headlight covers?
Also a point to note bulbs can have a huge effect on light output,


Thu Nov 03, 2016 11:39 am
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Post Re: Light lost through headlight covers?
WEST wrote:
Also a point to note bulbs can have a huge effect on light output,


Top tip

Having bulbs fitted will also have a large effect

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Thu Nov 03, 2016 12:07 pm
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Post Re: Light lost through headlight covers?
yazza54 wrote:
WEST wrote:
Also a point to note bulbs can have a huge effect on light output,


Top tip

Having bulbs fitted will also have a large effect

As can turning them on. :lol: :wink:

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Thu Nov 03, 2016 2:14 pm
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Post Re: Light lost through headlight covers?
Trust you lot :!:

Oh Hi Tim, you are still alive and kicking!


I have recently had to drop in my halogen bulbs, the only ones I could find were my bog standard H4 ones, and was shocked how bad they were. Then I found some of my upgraded H4 halogen bulbs I got from Ring, some ultra xenon jobbies, a lot better light. Still not as good as my HID from memory but these currently have an issue I need to investigate.


Neil

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IF wile e coyote had a GTM he would have one with Nitrous too! watch out road runner! The First GTM into the 11s then the 10s, PB 10.87 @ 125.5 Mph on A048 tyres, and fully road legal at Santa Pod


Thu Nov 03, 2016 9:06 pm
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Post Re: Light lost through headlight covers?
WEST wrote:
Oh Hi Tim, you are still alive and kicking!


Always here, just often I'm quiet. :wink: :lol:

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Thu Nov 10, 2016 1:30 pm
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Post Re: Light lost through headlight covers?
Hi
Has anyone got led head light bulbs

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Thu Nov 10, 2016 8:45 pm
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