Headlamp Alignment

Headlamp alignment shouldn't just be performed for the sake of passing an MoT test. If the beams are set too high you're a nuisance, and if they're set low you're seeing hazards later than you might have done. The MoT test pass band ranges from good to barely acceptable - a DIY alignment can achieve a better result than a 'just passed' and it really doesn't take long to do.

1. On a flat surface, park a few metres away from, and facing square on, a plain light coloured wall or garage door etc.

2. Mark a line horizontally on the wall at the same height as the centres of the headlamps. (Or use string and blu-tac.)

3. Take a length of string and tie it to the exact middle of the top of the rollbar. Pull it taught forward just above the middle fastener on the windscreen and mark where it meets the wall. Drop a vertical to the horizontal line and mark there. This is then on the centreline of the car, midway between the headllamps.

4. Measure the distance between centres of the headlamps and transfer the measurement to the wall, with marks equally spaced each side of the centre previously marked. Mark vertical lines through those points. You now have a cross on the wall directly in front of each headlamp.

5. Measure the distance from the headlamps to the wall and divide by 100. This gives the distance for a 1% drop at the wall, which is comfortably clear of the minimum of 0.5% to be safe for an MoT, but still gives good range. (The maximum allowed is a rather extreme 2.75%,...)

- Assuming the lamps are right hand drive, Euro type, with a horizontal cutoff and left hand upward kink:-

6. Adjust dipped headlamps so that the horizontal cutoff is actually horizontal and at the calculated distance below the horizontal line, and rotate so that the corner of the kink is a similar distance to the left of the vertical mark. (Again comfortably clear of the '0%' MoT limit, and well within the maximum of 'anywhere on the left of the screen'!)

If they're the 'flat dip' type, i.e. where the upward kink (that was rightly regarded as an essential safety feature for many decades...) has been abandoned, then side-side adjustment apparently doesn't matter...

All in all, really not difficult and guaranteed to give a result as good as, or possibly better than, a typical garage might achieve.

How to keep the headlamps aligned?

If a headlamp can be moved by hand then it's likely to go out of alignment again soon, either from vibration or simply bumping into it, maybe even when just cleaning the car. The principle source of difficulties is the way the indicator pod is incorporated into the clamping assembly.

The first problem is that the plastic pod is interposed between the support bracket and the lower ring of the ball joint and is relatively slippery. Secondly, it closely surrounds the clamping nut, restricting access and making it difficult to tighten.

To help prevent rotation, a very light smear of coarse valve grinding paste on the top and bottom mating surfaces works wonders to increase the friction. (Obviously keeping it well away from the thread.)

As for access, a socket or ring spanner obviously can't be used because of the wiring, and it's hard to find an open ended spanner to fit - any typical one fouls the indicator pod at some point or the other end hits some other part of the car.

A 21mm offset ring spanner with a gap cut to clear the wires was still very awkward to use, fouling adjacent components even when reduced to a barely usable length. In the end I cut the modified end of the spanner off and welded it to an old 3/8" socket:-

(I wouldn't be at all surprised if something similar were commercially available, but I've not found it.)

Using it with a short extension and a tommy bar to bring the swing of the handle lower down solves the problem, but that ease of tightening reveals that the condition of the threads is critical. Even when it feels as though you've tightened as much as you dare, dry threads can severely limit the resulting clamping force.

A bit of cleaning and lubrication with coppaslip makes an enormous difference, to the point where just nipping up the nut should lock things up very nicely.

If you can move the headlamp by hand without bending something, it's not tight enough!