I'm having fun and games with scrub on my front tyres and it got me thinking

How have other people set up their wheel geometry - camber, (castor I'm leaving alone) & toe.

At the moment its setup by eye. Id be interested to hear before I go to a garage with a geometry rig.

I have a Dunlop camber/caster gauge that I picked up years ago cheap

I found that my eyes aren't that accurate.

Yeah mine are starting to fail judging by the ammount of scrub the front tyres are getting

for starters I've just used a spirit level to set camber (set to zero at full droop) - chassis level & wheel flange vertical. I used a laser pointer to track it to zero toe (point at lines drawn on a far wall the right distance apart). Mind you the mx5 front has zero scrub so zero toe is possibly appropriate: cortina uprights have 3/4 mile of scrub so will need a fair amount of toe in - but it's all easy & accurate to do to a baseline as described above.
Once it's going tweak settings to taste....
cheers
Bob
PS note chassis on stands - susp will be at full droop. At ride height this will give a modicum of negative camber

[Edited on 24/1/06 by Bob C]

Think we need to clarify what you mean by scrub --- you mean the tyres are wearing on the edges or the inside wheel is scrubbing side ways on full lock.

Also if you could post a couple of pictures of your car -- one taken "square on" from the front the other from above without the nose cone off.

Castor is easy all you need is a level floor and a spirit level -- ideally a digital one.
Toe-in is more complex without special tools either bough or home made. --- The string method works to a fair degree espeicially with "laser string".

[Edited on 24/1/06 by britishtrident]

[Edited on 24/1/06 by britishtrident]

I wear the centre section of both front tyres down very quickly

I started with pressures at 20psi and have dropped to 18 & 16 but this hasnt rectified it. I would tkae photos but you wont see any more detail than by eye - so no help really.

I dont want to change castor at the moment. Ive set them as the factory reccomends and will leave castor at that. I will check the camber is vertical on full drop but would very much like to know more about the "string method" or "laser strig method"

Yes wearing in the centre generally indicates over inflation ---
What size tyres are you running on the front ? and rim width ?

185 60 13 on 13x6 minilites

Ive got some dodgy brand tyres on the rear and yoko a021's on the front

Don't know the Yokos intimately they are soft but it could be a tyre construction issue --- some tyres have higher crowns than others. You made need a trye in which the tread has a slightly concave shape when deflated.

Yeah I was thinking along those lines too as the dodgy manufacturer ones on the rear seem quite happy at 20psi

To set front tracking we used two long lengths of angle iron (approx 3m long) bolted to the front hubs and projecting forwards. The tracking was then adjusted, until the measurements between the two lengths of angle iron, at the nearest and furthermost points, were the same.

When set up correctly, it transforms the cars handling. Initially, we had set it up 'by eye' (just for SVA - cos we knew we'd have to adjust the toe to get self-centring) and it handled terribly.

Nowt wrong with that Hellfire done it a few times using a couple of ladders -- not super accurate but a whole lot better than doing it by eye.

Trouble with getting tracking done by tyre fitters and the like is it only as good as the guy doing it.

The laser tracking tool I was toying with building is now in prototype stage -- would have finished before Xmas but life got in the way. Good news is it seems to work pretty well even when just cobbld together I should have pdf drawings made of it by the end of next week.

quote:

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Originally posted by Hellfire
To set front tracking we used two long lengths of angle iron (approx 3m long) bolted to the front hubs and projecting forwards. The tracking was then adjusted, until the measurements between the two lengths of angle iron, at the nearest and furthermost points, were the same.

When set up correctly, it transforms the cars handling. Initially, we had set it up 'by eye' (just for SVA - cos we knew we'd have to adjust the toe to get self-centring) and it handled terribly.

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As long as both measurements are equal between the angle irons, the tracking will be square.

Usual method is to start by centring the steering rack and checking each track rod is the same length.
Then just set the toe-of one wheel relative to the other adjusting both track rods by the same ammount each time.

From the tyre wear perspective the over all toe setting across the axle is the most critical.

If you try setting the toe on each wheel individually one of the problems you run into is establishing exactly where the vehicle centre line lies --- on production cars this can be very diificult which is one of the reasons I am very sceptical about so called "4 wheel alignment". On Locost build it is quite easy to make provision for finding the centre line of the chassis at a later date by providing centre line marks front and rear.

One of the simplest alignment checks you can do is simple find a very straight stretch of quiet road (best if it has a kerb) and find the steering wheel position where the car run exactly straight then stop the car with wheel in this position (mark the wheel position with a white marker so you can use it durring alignment checks) get and see if the car look like its sitting exactly parrallel to the kerb.

When you get it back home put the steering wheel back in this position and check if the sterring rack is in its central position and if the track rods are equal length. If they are you can make use of this mark to centre the sterring next time you set the toe-in.



[Edited on 24/1/06 by britishtrident]

Having used various tracking equipment over nearly 40 years my personal favorite is the SuperTracker 4 wheel alignment kit.The steering wheel is centralised, "flags " are placed on rear wheels (scale), laser units are hung on front wheels and turned on . 4 laser beam are used to check alignment taking readings from front mounted scales and rear flags . Adjustments are then made accordingly . Rear wheel alignment is done by putting laser units on rear and flags on front , with adjustable rear alignment this is done first. All measurements automatically align all wheels. Haven't used any more sophisticated systems so cannot comment but suspect variations of this system.

quote:

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Originally posted by Bob C
for starters I've just used a spirit level to set camber (set to zero at full droop) -
PS note chassis on stands - susp will be at full droop. At ride height this will give a modicum of negative camber

[Edited on 24/1/06 by Bob C]

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Jos I have a crude but very effective way of setting toe. My dad invented it. I'll help you do it some time if you want.

For camber just use a set square on the ground...

quote:

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Originally posted by Hellfire
As long as both measurements are equal between the angle irons, the tracking will be square.

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Yes please andy

quote:

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Originally posted by DarrenW
snip snip snip

Sorry for hijack Jos. Ive just checked my camber, set by eye but measures -1deg on one side and -2.25deg on the other!!! Oops!. Dead easy to adjust though.

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Apologies Darren, I'd assumed you'd have found the centre of the rack and equalled your track rod ends before attempting to align the wheels.

Phil

Should I find dead centre of the rack (equal protrusions either end) or steering wheel dead centre (possibly unequal protrusions)

[Edited on 25/1/06 by jos]

Wheel centre

A simple (but very effective) camber guage can be made for peanuts from a spirit level and a couple of adjustable bolts that sit on the wheel rim.

Chances are that you wont get the camber absolutely spot on side-to-side. This is because the top ball joints have to be turned one complete turn to move the wheel in/out.

Steering rack dead centre ideally needs to be found by getting the *inner* rack dead centre in relation to the chassis. Any other method is assuming that the steering rack is centrally mounted in the chassis. It may well be, but at least you can check

HTH Stu.

Simple tracking tool


25x25 RHS
9"x9" Mirror Tile
Some 15mm Plywood
Pocket Laser Level from Woolies


[Edited on 25/1/06 by britishtrident]

I wonder what you'll all think of how Ive set up my toe this evening.

It will only work if you have a matched pair of tyres on the front with grooves which run around their circumference. R888's sorry cant help

Put the steering wheel to the central position.
Hang a length of string with sufficient length to only just be above floor level in one of the grroves on one side and the exact opposite on the other side. (knot in nuts into the string to create tension in the string if required)
Using a straight rule, yard stick or stiff tape measure, measure the distance between the trailing side of the tyres' string and make a note.

Then measure the distance between the front tyres and make a note of this as well.

To set toe to 0 you are looking to get both these figures to be identical. To have toe in you are looking to have the rear measurement bigger than the front, and to get toe out you are looking to have the front reading bigger than the rear.

Using this method you automatically have the proper vehicle weight on the car (minus driver) and you dont need to jack the car up at all as you can manouver the track rod ends to lengthen or shorten each side as required.

I had a difference of 35mm (toe out) at first and after 2 turns each side had made both measurements identical. I'm going to try these settings at some time to see how she drives and can then play with single or half turns to see how she responds.

What do other people think of this method???

To set up camber I used a small spirit level against my wheel rim and checked to see verticality, and adjusted the ball joint length until the bubble was in the middle (ish) of the marks.

This one does take a lot longer as you need to jack up the front and release it to see the effect of your adjustments.

That is unless you measure how high the centre line of your wheel is (like I did) jack up the front remove the wheel and release the jack until your hub centre is at the required height. Using this method also allows you to use the brake disc to line up your spirit level.

not bad. My approach was to hold a length of metal tube against the tyre, hence over 3 metres there is less chance of inaccuracy. However, i assumed that front and rear track were identical (probably not, but i dont care anyway!)

I centered the rack first, then set the steering wheel to be square too, then adjusted toe to have both pointing slightly outside of the rear wheels (about an inch). Hence, technically some toe in.

make sure you jump on the car after jacking it to resettle the springs.

[Edited on 22/2/06 by JoelP]