MOT Fail on Headlamp Pattern

[HFStuart]

My spider with the single piece headlamps failed the MOT today on a poor beam pattern. Annoying as it's passed before with the same lights.

It's got the correct Carello single piece lamps with the right reflectors in good condition.

They only thing I could think of would be the wrong bulb of the bulb not seated correctly.

Does anyone know what bulbs the single piece lamps are supposed to take?

[rossocorsa]

The only thing I could think is that one or other bulb could have been manufactured incorrectly. Other than that if your reflectors are good and lenses in good order they really should pass as is because they are as it was originally approved, perhaps your garage is not allowing for the car being not to current type approval?

[rossocorsa]

http://www.transportoffice.gov.uk/crt/doitonline/bl/mottestingmanualsandguides/mottestingmanualsandguides.htm

Section 1.8

[HFStuart]

Thanks.

I have a spare set of quad lamp Cibies so I might just pop them in for the re-test.

If he fails them I'll shove an H1 where the sun shineth not!

To be fair to him though he isn't charging for a re-test and he told me to settle up when I take the car back so he's being fair if a bit picky.

[rossocorsa]

The way I read the mot manual it reads that pretty much any pattern is ok so long as it doesn't cause dazzle or stray into an area above a specific line. When I had a delta hpe the lhd lights passed using beam benders although the testers maybe used their discretion 

[smithymc]

I had a 'no pattern' fail note when I first presented my coupe last year. The garage swapped the bulbs for some branded ones and it passed.

I always thought the lens dictated the pattern but perhaps not.

Hope you get it sorted.

Mark

[rossocorsa]

I think the glass does dictate the pattern however if the bulb element is not precisely placed it will cause an issue

[HFStuart]

Interesting.

I pulled the bulb out and then fished out some of my old 'stock'



The bulb on the left is the unbranded one that was in the lamp, the one on the right a Philips one. Though the filaments are roughly in the same place I cannot believe the beam pattern will be the same.

[andybeta]

My 205 GTi failed on beam pattern, the o/s headlight. Cyril took the bulb out and we examined it to find it was not set straight. Put a new one in and Bob's your uncle it passed fine. How it became unstraight in the first place is still a mystery to me. Only cost me a fiver though, the replacement bulb that is and the MOT which was a pass.

[HFStuart]

While others were enjoying themselves at Stanford Hall I was testing bulbs. The difference is marked.

Beam pattern with generic bulb (not damaged or faulty)



Beam pattern with old Philips bulb - note how much sharper the cut off lines are and how much less light there is above the cut off



I tried two other bulbs Osram Nightbreaker and Osram std. The nightbreaker was nearly as good as the Philips, the standard one nearly as bad as the generic. How very odd.

Anyway back to the MOT place tomorrow with the Philips bulbs in and the laptop in tow to set the mixture!