toe in / out - alignment settings

[preludacris]

ey guys.

im getting another wheel alignment tomorrow. Just wondering what toe in/out settings ppl are running.

I'm thinking maybe .5 mm toe out on the front, and having a lil toe in on the rear for better turn in but not too much oversteer. my car is generally daily driven with frequent trips to the twisties, and planning for going to track every now and then.

experience with tyre wear, and handling characteristics from fellow members would be great.

[dsp26]

anything over 2mm is noticable for highway cruising on your arms... why not consider castor bushes for improved turn in purposes?

lol my fronts were both toe out ~13mm after sussy install lol. chewed 1/4 tread in 3Km... i didn't realise a car could drift while driving straight :p

[iced]

to get better turn in you run rear toe out
2mm may be too much for beginner to catch oversteer.
1mm is more mild

for front, zero toe is best balance.

if you dont want to run toe out at the back then just run zero toe all around.

where'd only talking toe.
start playing with camber and its another game altogether.

[preludacris]

forgot to mention i'm running around -1.5 degree camber all round on coilovers.

from what i have read, toe out on front, is good for turn in, and rear toe out will cause a lil more oversteer, which is desirable for FF track car.

im not after too much oversteer on throttle off.

[iced]

0 front to be safe, toe out on the front can give you more issues and can feel dangerous especially on the streets.
if you really want the gain of having toe out at the front then yeah go ahead but i wouldnt go more than 0.5mm

1mm toe out rear should give you better rotation but not so much as to increase how the tail comes out that much.

for camber you can leave the front at -1.5deg
change the rear to -1.0deg if it is adjustable.

its just finetuning the balance now.

[aaronng]

Front, I run 0.6mm total toe out and 0.5º negative camber. My castor is not adjustable so it's left as is.

Rear, I run 2mm total toe in and 1º negative camber. I'd prefer to reduce the rear toe in to about 0.5 to 1mm to reduce a little understeer but doing so can cause pulling to the side when cruising at highway speeds or even make tramlining worse.

[todaek9]

stay at 0 if you are driving daily...no point of going fast on the road...waste of tyres...

[iced]

0.5deg neg camber front
1deg neg camber rear
could be improved on.
from experience that will give more understeer.

afaik 2mm toe in at the rear will contribute to more understeer.
i reckon set back to 0 zero or experiment with some toe out at the back.
but going from that setting may require you to go easy on the driving style. it does give better turn in but requires you to be abit more delicate on the throttle and braking so you dont upset the balance during corners.

on my car
i have castor kit to increase 1.0deg positive
front -2.0deg camber, 0 toe
rear -1.3deg camber, 1mm toe out
i can no tyre wear issues at all because i make use of these settings.

[aaronng]

0.5deg neg camber front
1deg neg camber rear
could be improved on.
from experience that will give more understeer.

afaik 2mm toe in at the rear will contribute to more understeer.
i reckon set back to 0 zero or experiment with some toe out at the back.
but going from that setting may require you to go easy on the driving style. it does give better turn in but requires you to be abit more delicate on the throttle and braking so you dont upset the balance during corners.

Yup, most of my setup is stock spec except for the front toe. And stock spec is biased towards straight line stability.

[fatboyz39]

Been running toe in at the rear for 1degree on each side, makes the car turn in better, causing it to oversteer and points the car thru the corner.

Run maximum camber and castor for fronts. I've had -6 degree camber i.e -3 on each side and works well. Never got it align just some guess work but my times says it works so yeh.

fronts around 1mm toe out is ok for fronts.

[preludacris]

yeah got my alignment today, feels a lot better than b4

.5 toe out on each front, 1mm toe in on each rear. toe on rear was previously around 3mm, i find the rear comes around a lil nicer now (still have to set my rear sway a lil harder, so didn't want aggressive settings).

the steering is a lil heavier too, feels good. (guy sed steering will be a lil heavier with the toe out settings)

steering flicks back a lil firmer now after a corner into a straight.

from my understanding, my lude toes in a little after it starts moving, so static toe out of total 1mm would probably even out to about 0 when it starts moving do u thinK?

[JohnL]

Yup, most of my setup is stock spec except for the front toe. And stock spec is biased towards straight line stability.

Aaron(ng),
At the risk of stating the obvious:
Straight line stability is always a desirable feature (even for racing cars and karts) so long as it doesn't come at the cost of acceptable responsiveness, the two not neccesarily being always mutually exclusive (though acheiving both may not be easy).

Stock handling is biased toward understeer with 99% of road car set ups because its safe for unskilled drivers (at least it's safer than oversteer!). When the car gets out of shape the instinctive reaction for most drivers is to back off, which is generally the right thing to do most of the time if out of shape means understeer (though with front drivers there are other strategies possible depending on circumstance), but with oversteer its generally the wrong thing, if not always...

Car manufacturers typically use multiple strategies specifically and deliberately intended to achieve copious quantities of understeer (with various geometries, spring rates , damper rates, ARB rates and suspension bush compliances), which we as enthusiast drivers must identify and 'rectify'! Most cars understeer so much (even at low speeds) that very few drivers ever have the pleasure of driving a truly neutral handling car. Even many cars with overt performance pretensions will typically have some understeer designed in, just less so than those with a less focussed intent (market niche).

We know front drivers tend to chew through front tyres and are gentle on rears, being because FD asks the fronts to do a lot of work (steer, put power down, do most of the braking and carry the majority of weight), but an understeering tendency will add to this problem (i.e. excessive front tyre wear). If we can get rid of the understeering bias then we will have less front tyre 'scrub', and should see an increase in front tyre life, so long as we can resist the temptation to fully exploit the now superior handling!

You say you're running 0.5° front and 1° rear neg camber. If you want less understeer then you'd most probably be better off reversing this, i.e. the same or more front neg camber and less rear. This will tend to allow more rear pos camber gain with body roll, less pos camber gain at the front, and bring the handling bias more into balance.

[preludacris]

hrm, well could also be coz my toe in b4 the alignment was 20mm total. 12mm on the left, and 8 mm on the right.

i buggered it up after takn out my upper control arms, and putting them back in.

felt screwed up b4 the alignment.

[JohnL]

And the wheel coming back to center (flicks back) is controlled by the caster settings NOT the toe settings:)

Sort of. Its not really the caster angle per se, but more specifically its the 'trail' created by the caster angle, which is an indirect effect of caster angle rather than a direct one.

The amount of trail is by how much the centre of the contact patch 'trails' behind the point at which the steering axis intersects the ground. This is obviously greater the more caster angle is designed into a given front end all else being equal, but its quite possible to design with more or less caster with more or less trail depending on whether the hub / wheel centre is placed in front of / behind / or on the steering axis (as veiwed from the side of the car), which can move the contact patch longitudinally closer to or further from the steering axis / ground intersection point regardless of the caster angle that may be used.

Assuming zero scrub radius (for convenience of visualisation), when a front wheel is traveling straight the centre of the contact patch is travelling directly behind the steering axis / ground intersection point, and this is where it 'wants' to be (i.e. its the position of greatest stability where all forces are in balance). To move the contact patch away from this 'preffered' position requires a 'destabilising' force, provided by the driver turning the steering wheel.

When this happens the contact patch 'attempts' to move laterally away from being directly behind the steering axis / ground intersection point (both contact patches attempting to move toward the outside of steered direction), but because of lateral grip the contact patch(es) resists this force and will 'push' against the chassis, literally pushing the front of the car sideways toward the corner entry. This action creates a faster change of direction (i.e. improves steering response), and the affect is stronger the greater the trail is.

Its also why greater trail creates heavier steering, stronger 'spring back' of the steering wheel to the straight ahead and improved on centre feel, i.e. because the greater the trail the more force is required to divert the contact patches from their 'desired' place directly behind the steering axis, even if this is only by a small degree of steering input.

Also, these affects are 'travel direction dependant', meaning that the steered wheels always 'want' to point in the direction in which the car is actually travelling at any moment rather than the direction in which its steered or the angle of the chassis to the actual direction in which its travelling. This creates a rather nice characteristic whereby when you have severe oversteer the front wheels will 'want' to automatically counter-steer (opposite lock) into the slide, and the greater the trail the more the car will tend to do this.

These effects of trail are seperate really to the direct affects of caster, which is mostly desirable for its affect on steered camber gains at both front wheels, i.e. increased steered neg camber at the outside front and increased pos camber at the inside front, which assists in countering adverse camber gains caused by body roll. And, when significant scrub radius exists then caster also contributes to the steered front wheels attempting to change height (relative to the hub), which they can't do due to the road surface being in the way, so a weight 'jacking' effect is created that can be helpful or unhelpful depending on the car specifics.

[JohnL]

Whew.... all that to say changing the caster setting will change the speed and force of come back to center. All nice theory but it is still controlled by the caster setting on the vehicle or changing parts.

Guilty, I'm long winded, so shoot me!

Its nice to know whats actually going on, to say something like "is still controlled by the caster setting on the vehicle or changing parts" isn't the whole truth and in reality somewhat misleading.

Better re-read my post, I've added a bit more, suffer!

[m0nty ITR]

Iced, haven't seen you on msn lately but it'd be great if we go down to WP sometime soon so I can get some setting advice from you. I'm heading down on the 29th for SOTS, but next time there's a CC meet down there give us a heads up.

[iced]

im on appear as offline dude
just message me anyway and i will reply :)

[JHMDA9]

Guilty, I'm long winded, so shoot me!

Its nice to know whats actually going on, to say something like "is still controlled by the caster setting on the vehicle or changing parts" isn't the whole truth and in reality somewhat misleading.

Better re-read my post, I've added a bit more, suffer!

I always enjoy reading your posts :) even if it takes me a while!!!

[JohnL]

"to say something like "is still controlled by the caster setting on the vehicle or changing parts" isn't the whole truth and in reality somewhat misleading."

What's misleading and untrue about it? Yours is nice theory but has nothing to do with what I said. On a real car there is still only two ways to change the speed of come back to center. One is changing the caster settings using the parts that came with the car, or changing the control arms (which in reality IS changing the caster settings). Your explaining WHY the changes in caster settings work to control the speed, I'm telling them HOW it's DONE on the car.

I'm not having a go at you. It is nice theory, and it does have everything to do with what you said! What you say isn't untrue in itself, but misleading by ommision, i.e. it doesn't actually explain the dynamic at work. If you say something like; 'increasing caster improves on centre feel, back to centre etc', then no-one can say this is not correct, but all you're doing is describing affect, not explaining it. Its misleading because its not actually the caster change itself that is causing the change in behaviour, rather its the change in trail that occurs as a by-product of changing the caster.

We now understand the dynamic better, and the better we understand the first principles that work for and against us the better we can make decisions with regards to chassis set up. If we were to be say setting up a racing car, then the better our general understanding the more likely we might be to be able to sort any problems we may encounter, or improve on an already good set up. Besides, the detail of the dynamic is interesting on its own account.

[aaronng]

Wow, miss this thread for a few days and there is A LOT of catch up reading to do. I understand what you mean JohnL, but for most people, they want to know what to adjust to get the desired effect and not the details as to why do you get the desired effect when adjusting. Most of the cars here are street cars anyway.

[aaronng]

Aaron(ng),
At the risk of stating the obvious:
Straight line stability is always a desirable feature (even for racing cars and karts) so long as it doesn't come at the cost of acceptable responsiveness, the two not neccesarily being always mutually exclusive (though acheiving both may not be easy).
Yes, and the cheapest way is to alter the front toe (at the sacrifice of tyre life and straight line stability).



Car manufacturers typically use multiple strategies specifically and deliberately intended to achieve copious quantities of understeer (with various geometries, spring rates , damper rates, ARB rates and suspension bush compliances), which we as enthusiast drivers must identify and 'rectify'! Most cars understeer so much (even at low speeds) that very few drivers ever have the pleasure of driving a truly neutral handling car. Even many cars with overt performance pretensions will typically have some understeer designed in, just less so than those with a less focussed intent (market niche).

Not only manufacturer-specified understeer but also the OEM parts even on performance models don't give you the adjustability that you require to return the car to a neutrally-handling one. At the moment, I don't have the ability to adjust the front camber. My car is still a street-driven car, with trackdays being rare, maybe once or twice a year. So there still isn't an urgent need to swap my camber settings front to rear at the moment. That said, when I get my weekend car, I will take the effort (and money) to do so.

[JohnL]

I always enjoy reading your posts :) even if it takes me a while!!!

I've got a fan, makes me feel all gooey on the inside!

[JohnL]

Yes, and the cheapest way is to alter the front toe (at the sacrifice of tyre life and straight line stability).

And can be affected by tyre selection / inflation, trail, caster angle (if this creates a jacking effect with significant scrub radius also present), KPI (creates a jacking effect on both sides of the chassis that lifts the front of the car with steering input, gravity acting on the unsprung mass will pull it back down until it finds its lowest point which is with the wheels pointed straight ahead), and probably a few other things.

A lot of ingredients in the cake! Not all that easy to play with, so mucking about with the toe is the path of least resistance I suppose!



Not only manufacturer-specified understeer but also the OEM parts even on performance models don't give you the adjustability that you require to return the car to a neutrally-handling one. At the moment, I don't have the ability to adjust the front camber. My car is still a street-driven car, with trackdays being rare, maybe once or twice a year. So there still isn't an urgent need to swap my camber settings front to rear at the moment. That said, when I get my weekend car, I will take the effort (and money) to do so.

Its a pain I know, you'd start to think they didn't want us to mess about with all those settings!

If your rear end is similar to mine (quiet up the back...), then thinking about it, it ought to be possible to shim the the upper arm at the chassis mounting point? (where the bracket is attached to the chassis with two bolts). This will bring the arm outward resulting in a decrease in neg camber. I haven't even thought about trying to actually do this (no need, my rear camber is less than the front), but if its possible it should be pretty easy and straightforward (but then Murphy's Law being what it is...!).