Technical Tracking settings

[lee89]

Dont know if any1 has any suggestions or settings but as post says after some tracking setting for my lil beast. Any suggestions most welcome.
lee

 

[alexGS]

Dont know if any1 has any suggestions or settings but as post says after some tracking setting for my lil beast. Any suggestions most welcome.
lee

The only angle that's officially adjustable is the front wheel toe-in. I believe for the Uno that it's best to have the front wheels parallel (0 toe). That is within the specs as well. For an especially-powerful Uno Turbo you may elect to run 1.5mm toe-out each side, but I don't think this is necessary myself.

The rear axle is non-adjustable and there should be 2 to 4mm toe-in each side.

If the front camber is between 0 and -2, that should be OK (definitely no positive camber; negative camber is OK but gets a bit excessive at 3 degrees, you start to lose tyre contact and the steering feels funny). For steering self-centering, you need 2-3 degrees caster each side, no more than 4. These angles are only adjustable if you tweak the suspension. For camber, I file the lower holes in the strut bottom bracket. For caster, I replace the control arm because a bent arm is usually the cause of the caster being off.

If the rear camber is outside the range 0 to -2, that would mean an axle replacement.

Ideally both sides should be similar for camber and caster. The alignment shop should point out any major discrepancies.

Cheers,
-Alex

 

[UNO-MK1]

-- it's best to have the front wheels parallel (0 toe). -- you may elect to run 1.5mm toe-out --

The rear axle is non-adjustable and there should be 2 to 4mm toe-in each side.

If the front camber is between 0 and -2, that should be OK (definitely no positive camber; negative camber is OK but gets a bit excessive at 3 degrees,---
For steering self-centering, you need 2-3 degrees caster each side,---

Some information on suspension/steering settings for front wheel drive cars.

FWD cars have different settings to what is commonly found on RWD -Rear wheel drive cars.

When I have had new tires fitted in the past , the shops have done a free alignment too.
Never saying no to something for free I agreed.
But most often they set the toe settings on the front to TOE-IN. (which is a normal setting for a RWD car)

I tried to explain to the tire guys a few times , ''DON'T DO THAT , set it to the factory toe out setting''.

But tire guys , well , there not the sharpest fella's around.

Of course, it comes back with toe in , an then at my shop I'de have to readjust it right again.

Toe out on the front wheels is required to offset the effects of power being applied to the steering wheels.
When applying power , the suspension and steering is pulled in such a way that it creates a positive amount of toe.
If you start off with a little negative toe (or toe out) , then it will pull straight , and it would be sweet as apples.
If you start off with a RWD toe in setting it pulls even more toe in , and not only does it wear the outside of your tires like crazy , but it gives a weird steering feel.

Going to firmer bushes like polyurethane , or even better spherical rose joints limit or prohibit suspension torquing on acceleration , in this case a zero toe setting is perfect.

In a normal FWD car an excessive toe out will lead to wandering under heavy braking.

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Toe in on the rear axle is likewise a setting required because of the use of relatively soft rubber bushings.

Toe IN is used because of this ---

Imagine cornering hard to the right.
There is a lot of weight on your outside tires and relatively little on your inside tires.
Now imagine half way through the corner and you are holding the wheel steady.
Suddenly your rear outside wheel hits a pot hole.
What will happen ?

Well , with standard (soft ) rubber bushings installed , the outside wheel will pull backwards.
Only a little , but its enough deflection to give a negative toe on that wheel.

If you started with zero toe , it will then become a REAL negative toe.

This will give THAT WHEEL a steering effect.
This effect will require the driver to compensate by changing his steering wheel angle just to maintain the same line through the corner.

In other words , steering on the front will appear vague , because the rear wheels are doing some steering -- unintentionally.

This makes the car jittery over bumpy roads , and very insecure feeling. -Not nice at all.

Having a little toe IN will mean that when the wheel hits that same bump , it may go to ZERO toe , , , and thats OK -- we can live with that.

Again , if we were to have rose joints fitted we could set the rear toe to zero.

Having zero toe front and rear (if possible) reduces tire wear and improves MPG.
Sadly , with rubber suspension bushes used , this isn't practical.

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Camber..
Camber is a tricky one.

Ideally , zero is good , too much positive camber or negative camber creates a condition called ''camber thrust''.
An undesirable handling trait.

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Castor.
As alexGS said castor on the front affects the self centering effect of the steering.
Too little and the car will prefer to turn corners when you don't want it to if you reduce your grip on the steering wheel , too much castor and it increases the effort you have to put into it to turn corners.

This is another angle setting that wheel alignment shops don't alway set right , if they are used to only working on RWD cars.

FWD cars are inherently self centering on the steering.
RWD cars are not.

So , RWD cars require a greater castor angle than FWD cars.


gW