mrciave

I just did my geometry alignment on a WRX01 sedan, here are the settings before/after:

Left Right
Front camber: -0d12min --> -1d06min -0d24min --> -1d06min
Front toe: total +0d15min --> total +0d10min
Rear toe: -0d09min --> -0d09min +0d07min --> -0d09min

Now my question is: as front toe in should help steering response, but remove precision, and after the alignment I feel the steering more precise, is this due to toe reduction or to camber negative increase?

Anyway, awesome change... Whiteline claims ARBs are the best bang for the buck modifications (I have them in the apartment anyway, waiting for installation), but I think that the alignment is THE MODIFICATION... Car changed so much.

Just I wonder... Subaru has done EVERYTHING POSSIBLE to make the Scooby understeer, hasn't it?

Bye

Andrea

Claudius

Ciao Andrea!

Non ho capito un cazzo alle tue valore. Sono pre- e post- assetto, sinistra e destra?

Allora c'è un pò meno di pinza davanti, dunque sarà più preciso. Invece, dietro c'è pinza negativa, attenzione di non lasciare i gaz troppo all'improvisto in curba o la macchina va cagare didietro! Divertiti bene

mrciave

Mmmmmm... Just realized that tabs do not appear properly.

So, here we go again with the settings:

Front camber left (original/modified): -0d12min / -1d06min
Front camber right (original/modified): -0d24min / -1d06min
Front toe total (original/modified): +0d15min / +0d10min
Rear toe left (original/modified): -0d09min / -0d09min
Rear toe right (original/modified): +0d07min / -0d09min

Hope it is more readable now.

Bye

Andrea

Claudius

Non parlo inglese

Mi pare bene, com'è?

mrciave

Sei lo stesso Claudius del forum italiano?

Claudius

si

Nemis

i have ZERO toe front and rear.
-1,3° camber rear, -1,1° front camber.

e la macchina s'intraversa di gusto

mrciave

Ooooops... Are all the guys from the Italian forum over here?

Anybody that tried front toe modifications on its skin, and can describe the difference?

JamieR

I put 1mm toe in on the front this morning, previously 0mm (MY00 standard UK Turbo). I've only driven about 20 miles so far, but turn-in seems marginally improved although at the expense of a little feel and precision. Steering is slightly heavier and wants to straighten up more. You'd probably notice the difference, but none of it is dramatic.

I'd say both. You have decreased toe-out which should improve precision as the wheels are closer to zero toe. But the outside wheel also will have better road contact during mid corner due to the increased negative camber, but may not be so good in a straight line... Or that's my theory anyway. I suppose bumpsteer should also be mentioned at this point, but I won't!

Since I've started this, next time I should set front toe to zero and add negative camber. This should have a more significant affect on reducing understeer (than my current setting).


[Edited by JamieR - 8/8/2003 11:31:14 PM]

mrciave

JamieR - I agree with you about ALK. Actually, on the Whiteline website there are some mathematical calculations that say that pro-lift is decreased, while pro-dive is increased (or was it the other way around???). In any case, there's somebody around the forum that with ALK and APracing 6pot 330 setup is even able to bottom out while braking!!!

Of course, the caster increase is good, you don't need so much static camber to achieve a good dynamic one, and, what is important, with static camber, the inner wheel will see the grip decreased, while with caster, also the inner wheel will be happy.

You are talking about caster plates, but I recall they were built for camber; do you just turn them 90 degrees? And which brand are you using?

Concerning toe in/out, I noticed that front toe in helped a little with self-realignment at high speed, which is not so bad, considering I have gone all the way in the tail-happy direction (rear arb on 24mm setting + rear drop links, front arb 22mm, all from magic whiteline)...

bigsky

I'm using Noltec (from AU) caster and camber plates. These things are the cat's ***. You can get a little over a full degree of positive caster and a little over a degree of neg camber (in addition to what ever you can get out of the oe eccentric bolts- usually ~ -1.3ish). I looked at the ALK's but they would bump me out of the class I'm competing in Solo II. It's intersting to note that the v8 STi's are running a reconfigured rear transverse link very similar to Whiteline's ALK, thus their increase in positive caster over previous models.

I'm in a 02 (US) WRX GDA. My rear settings are zero toe and oe camber -1.3. I like to run ~ .5 degree more camber in front than rear to dial out some understeer.

big sky

JamieR

mrciave, I think the ALK increases dive and lift. I'll go for some castor plates, but need to stiffen the rear ARB first. I agree that a touch of toe in at the front helps straight line stability, zero toe tends to wander and the steering feels a bit too light (for my taste).

bigsky, I wonder if the STi transverse link just increases castor, or if it affects lift / dive characteristics as well? Bet it doesn't!

While I'm at it, can anyone answer a bumpsteer question for me: I know the effect is toe out under compression and toe in under lift, but if I have zero static toe, will the wheels remain parallel during cornering (by cancelling each other out)?


[Edited by JamieR - 8/12/2003 9:59:21 PM]

vulnax999

iTrader: (7)

Doubt it, as it's the dynamic forces that act on the suspension and their planes of operation that determine all these angles, forcs, ...

Each suspension item will still move as it did before , your zero static settings will just add or remove a certain amount from the setting under load.

JamieR

Perhaps I didn't word the question clearly - what I'm really asking is: during cornering, will the outside front wheel compress by the same amount as the inside front wheel lifts?

If so, then theoretically the amount of dynamic toe (due to bumpsteer) won't change...

mrciave

JamieR, it could be nice if left and right bumpsteer effects would compensate, but:

- even if your wheels would remain parallel in a bump, you would still need to correct with the steering in order to keep the desired corner line;

- in principle, a bump is still compressing or extending both wheels in the same way (let's suppose it to keep things simple), so you would get toe in, or out, in the same amount, at both sides... some kind of Donald Duck behavior;

- probably with roll, in which one wheel goes up and one down, you should keep wheels more or less parallel (outer wheel toes out, inner wheel toes in), but in practice even that is not true;

- not to take into account bushing compliance...

For what concerns the new Sti lower arm rear bushing/mount, I guess they just added caster (moving the hard point outside, so moving fore the knuckle ball joint), but they did not change the height of the same mount (which would change anti lift/dive behavior). In any case, the dynamic caster increase on the Sti will be less than the Whiteline ALK, because the Sti mount is still rubber, and thus more flexible.

In any case, those Noltec plates look greate, just I'm a little bit worried about the absence of reference thicks. Also, do they keep the aligment for a long time, or do you need to check them often?

Bye

Andrea

mrciave

In a linear world, maybe... but in turn in, for example, the outer wheel will normally compress more than the inner will extend, because your bump/rebound rates for the dampers are different (1/3, normally).

Bye again

Andrea

JamieR

Hmmm, thanks Andrea. The reason I ask - front end grip seems to be slightly improved with zero toe-in. I can take a constant radius bend a few mph faster, as long as I am smooth and progressive on the way in.

mrciave

Are you making experiments on a skid pan (or the equivalent supermarket parking)?

I would expect that the more toe out in the front, the better grip, up to a certain point in which the inner wheel would start to have a too big slip angle, and loose grip, thus reducing again overall corner speed...

There's probably an optimal toe out, which gives maximum corner speed, at the expense of a terrible inner side tire wear!!!

Bigsky, any experience?

JamieR

Kinda. It's an industrial estate where I work that has lots of twisties.

From observations so far, I can only presume that zero static toe is closer to zero dynamic toe than 1mm static toe-in. But as you've already pointed out, it probably isn't that simple...

bigsky

Most of the Solo II racers run about 1/8" toe up front to help w/ turn in. Agreed that after a certain point toe out would be a hinderous. Also Solo II (auotx) is runa low speeds). I don't think I'd run a track setup w/ toe out, better at 0 toe or even a smidge of toe in (help w/ braking).

Regarding the Noltec plates, they do now come w/ tic marks. I also was concerned how well the settings would hold- these concern was releived after a little off track incident ending up destroying a rim and bending a control arm (we get cheap stamped steel arms, not the aluminum ones- ofcourse I replaced them w/ the aluminum ones as they were the same price). My front wheel was pushed completely back to the rear of the wheel well. After replacing the arms, I got it realigned and all specs were right on- I was suprised, but pleased. Thus far nothing but praise for the Noltecs, a degree of caster and camber increase makes for real world performance increase.

big sky

mrciave

Good! I mean, bad for the accident, but good that even with the accident the Noltec plates did not move at all.

Could you post any pics of them on the car, and some tips/tricks on how to install them (like, do you have in some way to modify the rear strut top, what do you keep of the original mounts, or stuff like this)?

Concerning toe in/out, so some final answer could be:

- low speed, toe out for better turn in/grip, and less stability, which is good for AutoX;
- medium speed, road use, zero toe for tire life and light steering feeling;
- high speed, track use, a bit of toe in for stability and precision.

And now it's time to open some race vehicle dynamics book and see what they say over there (sorry, I'm an engineer, I cannot help it :-))...

bigsky

You've summarized it very well.

Here's a brief tutorial I wrote up a while back w/ pics, these are just front plates for caster/camber. If you want to add additional camber to the rear- you can use camber bolts or camber plates (cusco, others). I think w/ Noltec front plates you don't need to mess w/ rear camber. OE settings for the WRX are -1.3 which when mated w/ -2.0 ish front (accomplished w/ the Noltec's) you won't need to change any camber settings.

Here's the tutorial:

http://www.clubwrx.net/forums/showthread.php?s=&threadid=29083

big sky

Leslie

The understeer is caused by the inbuilt bumpsteer. The only real way to get rid of understeer is to lose the bumpsteer. Toe in or toe out and camber changes may appear to change things but it usually causes other problems such as excess tyre wear etc.

If you get the anti bumpsteer mod. and fit decent solid anti roll bar links instead of the bendy plastic ones your car will be transformed into a neutrally handling pleasure to drive with outstanding grip wet or dry and your front tyres will stop wearing out prematurely.

Les

bigsky

Toe in / \ (front) will help straight line braking and add a little high speed stability. Toe out \ / will help turn in, but at the expense of tire wear and high speed stability.

Zero toe is much easier on tires and you can add significant neg camber w/o excessive tire wear- I'm running -2.0 w/o any tire wear.

Also consider adding positive caster (through ALK or caster/camber plates) as this will improve turn in and effectively increases dynamic camber.

big sky



[Edited by bigsky - 8/10/2003 12:41:52 AM]

JamieR

Yeah, I can't see much advantage from static toe on the front. The natural bumpsteer setup will give toe out stability under braking. Perhaps all this will change when I increase camber on the front.

I'm still a little wary of the ALK despite all the good reports. I'd prefer to go the adjustable plate route personally, as this increases positive castor without (directly) affecting lift and dive rates. No matter how many times I read the various explanations, I still fail to see how decreasing anti-dive (increasing pro-lift) helps reduce understeer.

Bigsky, what model are you driving and what is your setup on the rear?

[Edited by JamieR - 8/10/2003 11:13:03 AM]