Hope this isn't too OT - I did think electroncs and/or auto ng but this has a strong element of diy - so here goes.
History After my not-so-local tyre place fitted and balanced some new tyres (good job, no complaints there) they did a free track aligment check and of course it was out. When I asked by how much they said an amazing (to me) 4mm. Given that the old tyre tread wear pattern was even and steering direction rock steady (no wander or drift), I stupidly agreed to them resetting it (with their wonder laser kit). Of course, now the car wanders nicely to the left and I have to keep the steering wheel right-hand down slighty to go straight ahead. Well, just returned from my 4th visit to them to try and correct this and I'm well and truly ******-off!
Searching the web last night there were a couple of article by folk who'd had exactly the same problem outlined above and made their own Heath-Rob settup with excellent results (so they claim). Setup was some wooden planks, paint-tins to act as pedestals and bits of string! (No kidding). One claimed 1/32" accuracy by some devious way of reversing the planks to cancel the error.
Now to the diy bit. I wonder if it may be possible to diy ones own track kit using a laser! At first that sounds expensive, but as a source, I thought a simple laser pointer device (~£20) may do the job. A photo detector is easy to rig-up in a lightproof can - connected to as a microammeter to detect peak of laser alignement.
As to the mechanics of it all - I'm still trying to learn what it does exactly. Toe-in concept is easy enough - but as to measureing it it accurately - well, that's not so easy of course. I guess two parallel laser lines down the side of the car is a starting point - maybe some sort of collimator to ensure alignment and mirror or prism to turn the right-angles. Measuring from beam to wheel-rim could simply use a steel rule. (And always wear laser-safe goggles of course).
Well that's as far as I'm taken the idea. Any comments, ideas, etc?