Series 3 wheel alignment

Simple trigonometry, though you need to know how far from the hinge- point you take the measurement at. Wheel rim, isn't it?

Anyway, let's say that the rim is 400mm across. That's one side of the triangle. I'm assuming that 1.2mm is the difference between front and back, but is it the total for both wheels?

I'll stick to the math.

Hey, 1.2mm at 400mm is 3 milliradians

There are 2pi radians in 360 degrees. So 57.3 degrees to a radian.

0 degrees, 10 minutes, 19 seconds.

For these small angles, double the distance is double the angle, and vice versa. As long as you have both distance and angle measuring the same thing -- one wheel or both wheels -- and aim for the middle of the range, that should be near enough.

If you've heard of stuff like sines and cosines and tangents, don't worry. For this sort of small angle, the differences don't matter. Radians are based on measuring along the arc of a circle, rather than a right-angled triangle, and you'd need a very sharp pencil to see the difference in a drawing.

Button bashing in practice for another round of Daley Thompson's Decathlon, Liam left Shakespeare to the monkeys by typing...

using a variation of Pythagoras' theorem. Or measure distance between inside edges of rims (not on tyres - just inside lip) on centreline in front of and behind axle. For better accuracy, measure distance at front then roll vehicle forward so wheels turn 180deg. (to compensate for bent rims/dings etc). Getting three heavy friends to bounce on the front bumper a few times first is also a good idea (to settle the suspension - except when you're running a Perkins 4203(/6?) with 13-leaf ultra-heavy-duty springs - then you just get slapped by three heavy friends for taking the piss.....

I have one that measures in degrees, and I'm bloody sure it doesn't have minutes on the scale, merely degrees. It certainly doesn't have seconds.....

Alex

Formula to convert degrees to mm is 2x sine(toe in angle in degrees) x rim dia in mm.

Alan C.

Angles in degrees are usually measured in Degrees, Minutes and seconds rather than as a decimal number. Each degree is made up of 60 minutes and each minute is made up of 60 seconds. For example 1.5 degrees is really 1 degree 30 minutes and 0 seconds.

Liam

Thanks, that's been a real help.

Regards

Liam

I am fully aware of that. However a scale that reads 5 - 0 - 5 degrees in about 2" of space is very unlikey to have minutes on it, let alone seconds. It is more likely to be measured in 0.5 (30s) intervals.

Alex