M915 headlight alignment instructions?

[JH1]

I've looked at the manuals and can't find the specs for aiming the headlights. I see how to change the assemblies and they say there is no follow-on work necessary. Well, there is if you want them to be aimed right. Something like 'park 20' from a building and adjust for so many feet up and so many feet to the side, etc.' Anyone know where to find that info? Thanks.
JH1

 

[Ferroequinologist]

I don't think it exists. I simply put a mark on the ground 75 ft in front of the truck, and aimed the center of the beam there. At some point I was told 75 ft was what truckers do but I don't remember. I could have just dreamed it up. It works well though on mine.

 

[JH1]

Hi,
I could swear that I've seen it somewhere. The two lights are aimed differently, too. At least I recall that. The left one is tilted a little to the right to keep it out of oncoming eyes. Well, maybe someone can dredge up the actual instructions.

 

[JH1]

Gasp! After perusing the internet, I found that there is every story and method imaginable. The most reasonable and seemingly well thought out ones say that you use low beams only for the adjustment, and both headlights are to aim straight forward and a tad low at 25'. By 'tad', they say about 4". They mention that the beam is not round, but has a fairly well defined upper horizontal cutoff line, so designed to keep the light out of oncoming eyes. That is the point to have depressed the 4" or so.

You have to have a flat surface and a wall. Either mark it up or put pieces of tape on it to locate dead straight ahead of each light. Then diddle the adjustments until your light splats 4" down from there.

Ok, so let's see who knows what. My read could be wrong. I just wandered around looking for what looks right. I can't believe there is nothing in the TMs on this.

JH1

 

[Bighurt]

It's not going to be in the vehicle specific TM, if it exists it will be in the vehicle Mx TM if that exists. I don't believe the army has one.

In the AF the procedures if any can be found in TO 36-1-191.

Otherwise the internet yields a bunch of methods. You don't need a flat surface you just need a surface perpendicular to the road 25' in front of the truck and a way of determining the center of head lamp at that point in which to make your measurements.

 

[JH1]

Amazing. I have a plan in mind. I'll use a cheap laser level from Harbor Freight and plop it on the top of the fender aiming forward to establish the level point (+ a few inches that I can measure down to the actual light bulb) of both sides. This presupposes that the top of the fender is level. Sure looks like it, but worth checking. Put tape on the wall to make a horizontal line. Then do the same thing, but this time plop the level onto the sides of the fenders to establish the side to side point (also account for several inches that the light is inboard of the outer edge). Now I have aiming points that are dead straight ahead of the bulbs. Putting down the latte, I grab a screwdriver and tweak the adjusting screws until the spot on the wall is centered left to right and the light illuminates the wall no higher than 4" below the dot. Do the same for the other side. Btw, this is to be done on low beams. Word on the street is that you do it on low and once correct, then the high beams will also be correct. I'll go with that, unless someone can dredge up some actual instructions that don't involve special light bulb tooling.
JH1