suspension settings

[batman]

does any one know what the tracking angles are for my amimeya every garage ive been to hasnt got a clue .
hit a pot hole and my bloody steerings out
thanks mr brown for that smooth road i pay my taxes for ! git :2Confused

[lockwood77]

Hope this is what you're after dude. :)

http://www.mazdarotaryclub.com/forums/showthread.php?t=1573

[batman]

thats the kiddy:Thumbs-up

thank you

[dryvern]

Good stuff.
You may want to find someone to set your camber/caster while your at it (if not done already).
To explain why here is an intro i did for a general Jap car forum:

It is only obvious when you know.

After some conversations recently about tuning suspension, I decided to attempt some simple clarification (especially for some who did not understand caster). What follows is obvious but not necessarily totally understood.
Especially for those who only lower a car & do not reset the suspension.

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Toe, Camber & caster....a simplified outlay to explain the concept & aplication.


TOE

Toe in/Positive Toe (wheels turned in towards the vehicle centerline) = straight line stability or cornering stability at higher speed, but slower turning response.
Also majorly increases outer edge tyre wear.

Lowering a car creates bump steer changing the toe angle & suspension geometry, this & will need to be adjusted as it increases positive toe.

Toe Out/Negative toe (wheels turned out away from vehicle centerline) = increased steering response making car turn quicker when cornering & decreasing straight line stability (more corrective steering to keep straight).
Also majorly increases inner edge tyre wear.

Raising a car creates bump steer changing the toe angle & suspension geometry, this & will need to be adjusted as it increases negative toe.

In rear wheel drive cars adjusting the front tyres this way is of greater benefit. If the rear wheel drive car has independant rear suspension, toe out can be increased to counter the effect of toe in, which is usually produced under accelleration; in order to straighten the wheels & counter the suspension getting pulled forward. This can produce severe oversteer & it is recommended to uprate suspension links & bushes instead of rear wheel toe out.
Front wheel drive cars & 4 wheel drive cars get more complicated. On front wheel drive cars the rear wheels can have toe out increased to increase rear end instability in order to counter understeer.


CAMBER

Negative Camber (top of wheels tilted in towards car) = more grip on cornering, but less acceleration /flat grip.
Increased inner edge tyre wear (which is also additional to the wear of toe out)
Lowering a car not only results in lowering the center of gravity, it incidentally increases negative camber & this will need to be adjusted; because it will also increase body roll as the suspension's roll center is now lower, making it less stable due to the increased roll angle/suspension movement.

Positive Camber (top of wheels tilted outwards from car) = less grip on cornering & more instability + less flat grip/acceleration (optimum acceleration grip is 0 camber).
Raising a car will decrease negative camber & further change stability on cornering by also raising the center of gravity.

Generally the camber to the front is adjusted to a larger degree than the rear as the front controls more steering.
If the car understeers front negative camber can be increased for more grip in cornering, also the rear can be adjusted with less negative camber (making it more positive) to allow the rear less grip & to slide out more.

Caster also effects the level of camber i.e. using less positive caster will require more negative camber to balance grip in those hard corners. Best to adjust both & save some tyre wear on long straights/motorways.

CASTER

Aplies to front wheels of a car & only in positive caster (rear caster does not apply).

Positive Caster is, where the car wheel is forwards of its steering pivot axis/ wheel is forward of the vertical line from the steering suspension support as viewed from the side - like a motorbike front wheel in front of its yoke.

Increasing positive caster = more high speed stability. Stiffer steering.

The front wheels will center quicker in a turn, due to increased camber gained whilst turning. This increase whilst turning actually raises the front of the car a little & the weight of the car presses down on the wheels to realign & straighten the steering.
The steering will also get stiffer as it fights the turn more; but most cars built nowadays with speed & luxury in mind use power steering to aid the driver & balance out the increased caster used. On such cars you will notice its bonnet rise on a heavier turn then settle again upon straightening.

Increasing positive caster too much & raising the caster too much in a turn will likely cause tyre heat, loss of grip & excessive tyre wear.



NB.

It is important to set both wheels (front pair or rear pair) the same to avoid tracking problems & adverse handling. This goes for toe, camber & caster (unless you are racing only ever one way around an oval track).

Older cars using double wishbone suspension are usually more adjustable all round; newer cars using McPherson strut suspensions can require aftermarket suspension plates to adjust the strut mounting points allowing caster adjustment front & rear. These are more available to commonly modified cars & significant if lowering your car.
Many road cars will require camber plates to adjust camber also.

Off road vehicles such as tractors usually use positive camber to aid steering.

Know what your doing; overdoing it & excessive adjustment can produce adverse handling & excessive tyre wear which can lead to a blow out.
Know your tyre pressures too, as it also plays a major roll.

Variations, some cars have minimal rear steering (other vehicles more, i.e. military). So whoever does the adjustment should know the car & how to set it up.
Some people with say a Prelude with rear steer actually prefer to lock the rear wheel steer (cheaper in most cases after failure) involving replacing the back axel. Other cars (commonly rear wheel drive) use different differentials to lock the wheels in various conditions (depending on the diff). These require different driving styles & prove gains for high speed or drift handling.

For road use follow car manufacture settings & for racing find proven settings for the type of track & car (for fast road too). Any doubt, see a specialist & get it set up.

ZED/Dryvern

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Table from: http://en.wikipedia.org/wiki/Car_handling#..._gravity_height


Component----------------Reduce Under-steer----------------Reduce Over-steer

Weight distribution..........center of gravity towards rear.....center of gravity towards front
Front shock absorber......softer.............................. ..........stiffer
Rear shock absorber......stiffer............................. ...........softer
Front sway bar...............softer.......................... ..............stiffer
Rear sway bar...............stiffer......................... ...............softer
Front tire selection1.......larger contact area²....................smaller contact area
Rear tire selection.........smaller contact area....................larger contact area²
Front wheel rim width
or diameter...................larger²................ ......................smaller
Rear wheel rim width
or diameter...................smaller................ .....................larger²
Front tire pressure.........higher pressure.........................lower pressure
Rear tire pressure.........lower pressure...........................higher pressure
Front wheel camber.......increase negative camber...........reduce negative camber
Rear wheel camber........reduce negative camber.............increase negative camber
Rear spoiler..................smaller.................. ....................larger
Front height (because
these usually affect
camber and roll
resistance)...................lower front end..........................raise front end
Rear height..................raise rear end............................lower rear end
Front toe in..................decrease...................... ..............increase
Rear toe in ..................decrease........................ ............increase

1) tire contact area can be increased by using wider tires, or tires with fewer grooves in the tread pattern. Of course fewer grooves has the opposite effect in wet weather or other poor road conditions.
2) These also improve road holding, under most conditions.



More Info/Links:

http://www.ikeya-f.co.jp/en/product_notice/foot_works.html - suspension setting - cause/effect

http://www.ozebiz.com.au/racetech/theory/align.html - camber, caster, toe - meaning

http://en.wikipedia.org/wiki/Camber_angle - Camber

http://www.240edge.com/performance/tuning-camber.html - camber tuning

http://en.wikipedia.org/wiki/Caster_angle - caster

http://www.240edge.com/performance/tuning-caster.html - caster tuning

http://en.wikipedia.org/wiki/Toe_%28automotive%29 - toe

http://www.240edge.com/performance/tuning-toe.html - toe tuning

http://www.btc-bci.com/~billben/caster.htm - camber, caster, toe - defined

[Mims]

Fantastic post!

Regards

Mims

[dryvern]

Cheers Mims. I do try. Some of those links are interesting too. Correct caster does make a difference. Not many places can do it though (has to be played with & takes time).
Interesting to note, that even cars off an assembly line differ as setting all to standard does not mean caster etc is set to each car. Manufacturers only do/check 1 in several hundred at best as it would take too long to set each car to its own varience.