IY wheel alignment

[phillpot]

Was having a look on ebay to see what the traditional Dunlop alignment "sticks" go for and found this

looks ok to me in the video, and about same price second hand Dunlop ones go for (and a lot more compact to store somewhere), anyone got one, used one ?

There's also a drive over mat thingy by Gunson, doesn't actually measure toe-in or out just indicates any untoward forces it seems, not too convinced for 50 quid?

Don't know where the D from DIY went

[GreenV8S]

That looks pretty darned cheap for a laser alignment gauge but I wonder how much of the alignment job it does. Is it just measuring toe-in? A full alignment check would cover a lot more measurements. If you're doing this on your own time you really don't need any fancy hardware, the traditional 'string box' method is pretty straight forward and just needs a few sticks and some string. Add in a plumb line to measure camber and castor and you can do the whole thing with almost zero capital cost.

[tvrgit]

Hmm dunno - that looks a bit of a faff to me...

For a quick check I use a bit of string tied at the front of the car, then stretch across the front tyre so that it's only just touching the rear of the front tyre, extend to the rear tyre and measure with a rule, how far off the rear tyre it is.

If the front toe-in is meant to be, say, 0.5 degrees, and the wheel is 15 inches, then the toe-in is just over 3mm (bit of trigonometry there!) Over the car's wheelbase (93 inches) the measurement of 0.5 degrees would be just over 6 times that, about 20mm - or about 10mm on each side. Anything from about 6mm to about 14mm is within specification.

If I wanted to adjust it, I have a pair of the old Gunson track gauges - these were superceded by the trakrite many years ago. They are two bits of angle iron, with wee extensions that fit on the rim of the wheel past the tyres - and near the bottom of the wheel so that you can measure between them. You fix them on with a bungee cord around the back of each wheel, and adjust them till they are about level - then use a tape to measure the distance between them at the front, and at the rear. Subtract one from the other and either convert to the wheel diameter, or to degrees - they are surprisingly accurate.

If you park the front wheels on a couple of old shiny magazines, you can adjust the track and the magazines allow the tyres to move like they were on swivel plates...

I also have a camber gauge I made with a bit of wood, two nails and a plumb bob - again surprisingly accurate.

It's not as accurate as getting a proper 4-wheel alignment done by an expert - but it's probably more accurate than getting a 4-wheel alignment done badly by an inexperienced monkey - and there are a lot of them about.

Edited by tvrgit on Sunday 7th August 23:50

[phillpot]

tvrgit said:

Hmm dunno - that looks a bit of a faff to me...

For a quick check I use a bit of string tied at the front of the car, then stretch across the front tyre so that it's only just touching the rear of the front tyre, extend to the rear tyre and measure with a rule, how far off the rear tyre it is.




I also have a camber gauge I made with a bit of wood, two nails and a plumb bob - again surprisingly accurate.

If I've got it right doesn't the string idea depend on front and rear track beind same ? When I fitted the rear discs the centre of the discs is thicker than a brake drum so will have widened the rear track slightly, guess I could just allow for that in my measurements?


Camber I've done with something similar, piece of wood and a spirit level


Toe-in seems to be measured in degrees now a days, in "my day" we used fractions of an inch. So does 1/16" for example mean 1/16 difference from front to rear of wheels or is it 1/16 from centre line therefore 1/8 front to rear ?

thanks for your answers and suggestions

Edited by phillpot on Monday 8th August 06:58

[tvrgit]

phillpot said:

If I've got it right doesn't the string idea depend on front and rear track beind same ?

True, you would have to make a plus/minus adjustment for any difference in the track width. Forgot that bit.

phillpot said:

Toe-in seems to be measured in degrees now a days, in "my day" we used fractions of an inch. So does 1/16" for example mean 1/16 difference from front to rear of wheels or is it 1/16 from centre line therefore 1/8 front to rear ?

I've always understood the measurement to be the difference between front and rear rim edges.

Converting from degrees to a measurement is easy, if you have a scientific calculator. Formula is

toe-in (mm) = tan (toe-in degrees) x rim size (inches) x 25.4

A specification of degrees will give the same toe-in no matter the wheel size. A measurement in mm would apply to one wheel size only, and would have to be converted (slightly) for a different wheel size.