How not to check the alignment of your headlights for the NCT!

MrThrifty

This is long-winded but slightly amusing tale...

A few days ago, 'a friend' wanted to check the alignment (vertical) of their car headlights the night before the NCT... So they went driving around looking for a wall with some flat ground in front of it - not an easy thing to find! Eventually they drove into an industrial estate and drove right up to one of the older units after checking first that there were no security cameras on the building. Anyway, they pissed around here for a few minutes with a measuring tape and some driving/reversing to/from the wall before realising that there was a dip in the ground a few feet back from the wall which was screwing the whole thing up... So they in frustration drove hastily up to the newest unit in the estate.

They didn't bother getting out of the car this time - just drove right up to the front brick wall of the unit, almost touching it, then reversed away and watched to see how much the beams moved down on the wall. But again it was clear that the ground was uneven and the beams were jumping about the place on the wall. At this point, the ‘other half’ became curious as to what the whole point of this exercise was so 'my friend' explained what should happen and how the uneven ground was screwing things up by driving right up to the wall and reversing back 5 to 10 times. After that they headed away looking for a better place to do the test. Then the eureka moment struck a few mins along a main road – why not use the road as the level surface and get herself to stand in front of the car as the make-shift wall! Perfect...

But just as she was getting out, a Garda car came flying past from in front of them. This was followed by a Garda jeep 30 seconds later... Given that they were in the middle of nowhere, 'my friend' became a bit suspicious that their activities might have had something to do with this unusual Garda activity. So, just in case, they abandoned the headlight check and sneaked back home! At this point, they were kinda thinking that it was probably all just a big coincidence... Then, the next day, they noticed when driving past the industrial estate 2 CCTV cameras on the front wall of the new unit pointed down at the exact area where they had been driving up to the wall and reversing back... Clearly the cameras were being monitored and the guy monitoring them thought they had been trying to ram the wall in with the car!

I can't stop smiling when I think of the guards arriving, looking at the wall and scratching their heads wondering why there wasn’t even a mark on the wall! Oh yeah, the car failed the NCT after!

kippy

MrThrifty wrote: »

This is long-winded but slightly amusing tale...

A few days ago, 'a friend' wanted to check the alignment (vertical) of their car headlights the night before the NCT... So they went driving around looking for a wall with some flat ground in front of it - not an easy thing to find! Eventually they drove into an industrial estate and drove right up to one of the older units after checking first that there were no security cameras on the building. Anyway, they pissed around here for a few minutes with a measuring tape and some driving/reversing to/from the wall before realising that there was a dip in the ground a few feet back from the wall which was screwing the whole thing up... So they in frustration drove hastily up to the newest unit in the estate.

They didn't bother getting out of the car this time - just drove right up to the front brick wall of the unit, almost touching it, then reversed away and watched to see how much the beams moved down on the wall. But again it was clear that the ground was uneven and the beams were jumping about the place on the wall. At this point, the ‘other half’ became curious as to what the whole point of this exercise was so 'my friend' explained what should happen and how the uneven ground was screwing things up by driving right up to the wall and reversing back 5 to 10 times. After that they headed away looking for a better place to do the test. Then the eureka moment struck a few mins along a main road – why not use the road as the level surface and get herself to stand in front of the car as the make-shift wall! Perfect...

But just as she was getting out, a Garda car came flying past from in front of them. This was followed by a Garda jeep 30 seconds later... Given that they were in the middle of nowhere, 'my friend' became a bit suspicious that their activities might have had something to do with this unusual Garda activity. So, just in case, they abandoned the headlight check and sneaked back home! At this point, they were kinda thinking that it was probably all just a big coincidence... Then, the next day, they noticed when driving past the industrial estate 2 CCTV cameras on the front wall of the new unit pointed down at the exact area where they had been driving up to the wall and reversing back... Clearly the cameras were being monitored and the guy monitoring them thought they had been trying to ram the wall in with the car!

I can't stop smiling when I think of the guards arriving, looking at the wall and scratching their heads wondering why there wasn’t even a mark on the wall! Oh yeah, the car failed the NCT after!

Just shows ya that idiots are all around us.

thenightrider

Did they fail for haveing a broken bumper from raming the wall or broken headlights

MrThrifty

Cringe... Is kippy referring to the guy monitoring the security cameras or the Garda?!

I'll take that back in case I offend anyone or receive an unwanted call...!

CiniO

MrThrifty wrote: »

Oh yeah, the car failed the NCT after!

That's obvious.
Because they didn't finish adjusting the lights, because of the garda.

Matt Simis

Surely the only way of doing this is to get a known good car, shine the lights then mark the position of the light spread then adjust the other car (when in the original car position). It wouldnt matter about the surface then as they would have a benchmark.

mickdw

Matt Simis wrote: »

Surely the only way of doing this is to get a known good car, shine the lights then mark the position of the light spread then adjust the other car (when in the original car position). It wouldnt matter about the surface then as they would have a benchmark.

That would be one way but it is possible to set lights perfectly at home. Car sitting level and knowing the % dip as noted on the headlights, you can draw alignment chart on a wall which will show an area within which the light beam must be.
It will require the distance from the wall being taken into account & also ensuring that the car is square on to the wall. You will need to take a level from car to wall also. Done correctly, it is 100% as good as any alignment machine

Anan1

Matt Simis wrote: »

Surely the only way of doing this is to get a known good car, shine the lights then mark the position of the light spread then adjust the other car (when in the original car position). It wouldnt matter about the surface then as they would have a benchmark.

Wouldn't the headlights of the known good car have to be exactly the same height off the ground as those of the other car?

Tea drinker

good story!
Lucky for me I had no such problems passing the NCT after "aligning" like this. Good walls are hard to find though

Matt Simis

Anan1 wrote: »

Wouldn't the headlights of the known good car have to be exactly the same height off the ground as those of the other car?

I was hoping no one would cop that! Yeah, this would be a variable though arent all cars meant to have a similar beam pattern (within reason)?

Anan1

Matt Simis wrote: »

I was hoping no one would cop that! Yeah, this would be a variable though arent all cars meant to have a similar beam pattern (within reason)?

I'd say so, but i'd imagine the angle at which they shine downwards is a function of the height of the lights above the road!

mickdw

Anan1 wrote: »

Wouldn't the headlights of the known good car have to be exactly the same height off the ground as those of the other car?

They would have to be known good car of same make/model anyway & height checked too

JerCotter7

Anan1 wrote: »

I'd say so, but i'd imagine the angle at which they shine downwards is a function of the height of the lights above the road!

You have to measure the height of the lights. Then go a certain distance from the car to the wall and the cut off of the beam has to be so many inches/mm lower than the headlight. The fall is different from country to country IIRC. Don't know how to aim them left and right though. Guessing just more the left a bit.

I may be completely wrong. Some people put tape on the wall and reverse back then aim it to the tape.

mickdw

JerCotter7 wrote: »

You have to measure the height of the lights. Then go a certain distance from the car to the wall and the cut off of the beam has to be so many inches/mm lower than the headlight. The fall is different from country to country IIRC. Don't know how to aim them left and right though. Guessing just more the left a bit.

I may be completely wrong. Some people put tape on the wall and reverse back then aim it to the tape.

There is a diagram for aligning both up/down & left/right.



So you put line on wall level with centre of headlight - the 0% line
If your lights are below 850mm, use red marking, otherwise use blue.
For side to side, locate the kick up point to the left of the centre line as shown.
1% would be 10mm/m drop so if car was 3m from wall, 30mm drop for 1% etc, all measurements can be worked out from that. That diagram is used to test lights but manufactures usually give the exact percentage (sometimes 1% drop), again easily set