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beam deflectors


magical

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I have read about the undesirable practice of damaging plastic headlamp lenses by fixing sticky beam deflectors. Has anyone tried to determine the part to be blocked, say with card, and then using a non water based black pen, or some other marker, to cover the desired part, which could be be cleaned off when required by a solvent.(meths?). Would this stop the heat build up? What is the actual cause of the problem, the heat build up behind the covered part, or the heat melting the adhesive, which then reacts with the lense? Any comments would be appreciated.
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I have left my beam deflectors on for the 4 years (Ford Transit) with no problems. This included two 2 month trips to Norway with the lights on all the time we were in motion.

 

When the 'van was sold and the deflectors were removed, there were no cracks at all where they had been, but there were some around the outside (i.e. where the deflector had NOT been).

 

Below is a photo of said headlight with the crazing clearly visible above where the mask had been, but none in the area underneath it.

DSCF2240.jpg.f2c7184382f5208ebc4429e4c9c31b5f.jpg

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magical:

 

This is the link to the forum thread to which malc-d refers

 

http://www.outandaboutlive.co.uk/forums/forums/thread-view.asp?tid=13809&posts=28

 

(There are other earlier 'beam deflector' discussions that you can access via the forum's Search facility.)

 

My own gut-feeling is that, if you used a 'paint' that would tolerate being blasted by heavy rain from the front and a fair amount of heat from behind, you might find it difficult to remove the stuff subsequently from the headlamp's surface. Besides which it's likely to be a lot harder 'painting' on a mask and then cleaning it off than just sticking on some tape or beam-benders.

 

I used to keep a couple of mask-shaped templates made from silicone paper on to which I stuck overlapping strips of white insulating tape. I'd cut round the outside of the template to produce the mask itself which could then be peeled easily from the silicone-paper template. I made new masks each time I went abroad (took about 5 minutes) and removed them as soon as I came back to the UK. Still had the headlights craze though!

 

Undoubtedly the wisest thing is to obtain headlight protective shields, then fit masks/beam-deflectors to these. That way the headlamps get protected from external damage and there's no chance of the masks/deflectors affecting the headlamps' surfaces.

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Short answer to question is that unless specifically designed for the purpose, and the substrate, painted on masks would be likely to do permanent damage. 

The lenses are polycarbonate, commonly under the trade name of Makrolon, to which UV resistant and scratch resistant coatings are applied.  Polycarbonates have high impact resistance, and are optically clear but, unless coated, are prone to scratching and UV degradation.  They are also liable to chemical attack from a number of commonly used car type cleaning products, including "tar" removers, and also from diesel fuel. 

For paint to adhere, either a mechanical, or a chemical, bond must be created.  To remove the paint that bond must be broken and, in the process, the coatings, if not the polycarbonate itself, are liable to be damaged.

Re the visible crazing around the headlamp patches, since:

a) they were left in place 4 years, and

b) there is no visible damage under the patches,

it seems to me at least arguable that the visible crazing may be no more than the normal effect of UV degradation, while the area beneath the patches was protected from UV, and so did not suffer in the same way.

Clinically clear picture though!  Well done.

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Just for the sake of clarity, I should have mentioned that the slightly 'milky' area to the right of centre was some of the old adhesive which had yet to be cleaned off.

 

Below is the same headlight with the mask in place, just before it was removed.

 

DSCF2239.JPG.1c90e7d686b8acb7f990ade34db3ed56.JPG

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  • 3 weeks later...

hi all

can anyone help with advise on beam deflectors for a 2005 merc sprinter please?

the 'usual' product available (at halfords, ferries etc.) seems very inadequate for the task (the round one, semi clear) and the location/fitting instructions just dont appear to be clear/accurate enough to my liking. i have clear lenses with no marks to identify. the instructions 'seem' to indicate to me that the location for the masks will not block the light going the wrong way abroad........

very confused and hopeful of devine insight!!!

carl and flo

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carlandflo:

 

It's likely that the deflectors you are referring to are "Eurolites".

 

I have a pack of these and the instructions indicate their suitability for 2003-onwards Sprinters with clear lenses and show where on the lens the deflector should be fitted.

 

Admittedly (in the Sprinter's case) the size of deflector used is pretty small - just a 60mm circle - but that's true for many of the alternative vehicle applications. The principle behind the deflector is not to block a portion of the dipped-beam but to bend the beam in the correct direction for 'right-hand traffic'. With modern projector lights, it seems reasonable to assume that a relatively small-area deflector should be able to do this satisfactorily.

 

I'm doubtful that extreme accuracy regarding positioning of the deflector on the lens is really a practical proposition, particularly when headlights are fitted with beam adjustment. If it really concerns you, then you might wish to follow chatterdog's strategy and get the beam pattern professionally checked. Me, I'd do my best to stick the deflectors on the headlamps where the instructions say they should go and believe that the resultant beam pattern won't dazzle our Continental cousins.

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carlandflo - 2009-01-12 11:24 AM

 

hi all

can anyone help with advise on beam deflectors for a 2005 merc sprinter please?

the 'usual' product available (at halfords, ferries etc.) seems very inadequate for the task (the round one, semi clear) and the location/fitting instructions just dont appear to be clear/accurate enough to my liking. i have clear lenses with no marks to identify. the instructions 'seem' to indicate to me that the location for the masks will not block the light going the wrong way abroad........

very confused and hopeful of devine insight!!!

carl and flo

Remember you are trying to block the reflected beam, not direct line of sight from bulb, also the main part which needs blocking/deflecting will be the 'kickup' on left when dipped, so don't be supprised if the instructions tell you to fit on lower part of lens to right. What I've not looked into yet is how more modern lights with multi reflectors are masked, I'll have to have a play with suzi or astra one night.

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I got via my local Merc agents a diagram from Merc showing where the deflectors should be placed. I seem to remember they faxed it to me. Worth checking too on the Merc price for headlight protectors. I was amazed how reasonable they were (for Merc!). And it saves any bother with crazing of the headlight plastic.
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