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Wheel alignment for autocross by Fredrik
Started on: 06-17-2003 05:37 AM
Replies: 15
Last post by: shark93726 on 06-17-2003 11:44 PM
Fredrik
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Report this Post06-17-2003 05:37 AM Click Here to See the Profile for FredrikClick Here to visit Fredrik's HomePageSend a Private Message to FredrikDirect Link to This Post
Anyone have any tip on alignment data for a Formula 88 for autocross?

Front.
Camber, Caster, Toe ?

Rear.
Camber, Toe ?

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*GT 87 3800 in progress.*
*Formula 88 Std.*

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Report this Post06-17-2003 08:07 AM Click Here to See the Profile for shark93726Click Here to visit shark93726's HomePageSend a Private Message to shark93726Direct Link to This Post
Front.
Camber, Caster, Toe ?

About negative one degree camber, all the positive caster you can get with the adjustment washers on the top a-arms, about 1/16" to 1/8" toe-out.

Rear.
Camber, Toe ?

About negative 1.5 degrees camber, about 1/16" to 1/8" toe-in.

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Gerald Storvik

http://www.8shark.com

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Formula88
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Report this Post06-17-2003 11:11 AM Click Here to See the Profile for Formula88Send a Private Message to Formula88Direct Link to This Post
Is that a "track-only" spec, or could it be run on the street without chewing up your tires?

I'd like to get as agressive an alignment as I can get for my 88 Formula, but it has to be a streetable setting so I don't chew through tires so fast.

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Mach10
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Report this Post06-17-2003 11:17 AM Click Here to See the Profile for Mach10Send a Private Message to Mach10Direct Link to This Post
I have -1º camber on all four, 1/8" toe-out front, 1/8" toe-in rear. Didn't touch the castor.

Impressions? It REALLY likes to corner. But straight-line stability is reduced quite a lot. The car will wander a little more from road-surfacing, and steering feels REALLT twitchy. Once the car gets into the corner, it feels rock-stable, though.

Streetable? Yep. I just wouldn't try and WOT runs in 5th gear

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The Aura
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Report this Post06-17-2003 12:44 PM Click Here to See the Profile for The AuraSend a Private Message to The AuraDirect Link to This Post
Maxing the Front Castor increases steering effort a lot but helps transfer weight for better cornering and transitions.
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Will
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Report this Post06-17-2003 01:03 PM Click Here to See the Profile for WillSend a Private Message to WillDirect Link to This Post
 
quote
Originally posted by The Aura:

Maxing the Front Castor increases steering effort a lot but helps transfer weight for better cornering and transitions.

Actually, it helps caster induced camber gain in tight corners. The front toe out is responsible for rapid transitions. I prefer somewhat less caster to get a better feel for what the front contact patches are doing. Try it both ways (buying a lifetime alignment is a good idea) and see which one you like.

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Formula88
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Report this Post06-17-2003 01:23 PM Click Here to See the Profile for Formula88Send a Private Message to Formula88Direct Link to This Post
I take it the front toe OUT is what causes the on-center twitchy-ness? In that case, for a high-performance street setting how about:

Front Camber: -1
Front Caster: +5
Front Toe: 1/16-1/8" toe-IN

Rear Camber: -1 to -1.5
Rear Toe: 1/8" toe-in

How's that sound? I do a lot of highway driving, so the twitchiness would get aggrivating after a while. I want to get the best handling I can, but maintain decent tire life, and not have the car twitchy.

Also, any "track-only" settings are welcome, too. Please mention if you use your settings on the street or track, and if you've noticed driveability or tire life changes.

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Mach10
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Report this Post06-17-2003 02:12 PM Click Here to See the Profile for Mach10Send a Private Message to Mach10Direct Link to This Post
I'm not so sure about toe'ing in the front... On the corners, the toe-in would make the front end slip a little easier... If anything, I'd leave it neutral.
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Formula88
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Report this Post06-17-2003 02:19 PM Click Here to See the Profile for Formula88Send a Private Message to Formula88Direct Link to This Post
ok. Well, I'd be looking for good high-speed stability as well as good cornering, so it may be a bit of a trade-off. For sure, it's going to be close to 0, I would guess. Probably 1/16" either toe-in or toe-out. Just not sure which would be better.
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Fredrik
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Report this Post06-17-2003 03:50 PM Click Here to See the Profile for FredrikClick Here to visit Fredrik's HomePageSend a Private Message to FredrikDirect Link to This Post
Is there any meaning goin more than -1 deg. camber? Ex -1,5deg

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*GT 87 3800 in progress.*
*Formula 88 Std.*

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vse1fiero@cox.net
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Report this Post06-17-2003 08:35 PM Click Here to See the Profile for vse1fiero@cox.netSend a Private Message to vse1fiero@cox.netDirect Link to This Post
 
quote
Originally posted by Mach10:

I have -1º camber on all four, 1/8" toe-out front, 1/8" toe-in rear. Didn't touch the castor.

Impressions? It REALLY likes to corner. But straight-line stability is reduced quite a lot. The car will wander a little more from road-surfacing, and steering feels REALLT twitchy. Once the car gets into the corner, it feels rock-stable, though.

Streetable? Yep. I just wouldn't try and WOT runs in 5th gear

First of all I respect your many posts Mach10...
Shark is the authority and following his advice I have a streetable track car that handles, and corners awesome and is stable and tracks dead on even above 120 mph. A small amount of increased steering effort is nothing compared to the advantages of 5 or so positive caster.
1)Hi speed stability
2)Lower speed hard cornering is improved because the tire is held more square to the road...more patch contact. etc.
Read 8shark web pages on set-up and do it...he's right on.

Mach10, try changing your caster setting only to +5 and tell us what you feel.

I've run at Willow Springs racetrack with my daily settings with fantastic results and absolutly even wear...inside & out...side to side. here it is;
Front -1 camber, +5 to +6 caster, 0-1/16 inch toe out...not more for street or road racing...up to 1/8 toe out for autocross.
Rear -1.5 camber, toe in not less than 1/16 up to 1/8

JD

[This message has been edited by vse1fiero@cox.net (edited 06-17-2003).]

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Report this Post06-17-2003 08:54 PM Click Here to See the Profile for vse1fiero@cox.netSend a Private Message to vse1fiero@cox.netDirect Link to This Post

vse1fiero@cox.net

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quote
Originally posted by Formula88:

ok. Well, I'd be looking for good high-speed stability as well as good cornering, so it may be a bit of a trade-off. For sure, it's going to be close to 0, I would guess. Probably 1/16" either toe-in or toe-out. Just not sure which would be better.

Its not new news that toe-in in front can be dangerous (twitchy) for fieros. Just like not having enough rear -camber or being toed-out in the rear is very dangerous...unless you like merry-go-rounds.
I think it important to say as other times when this topic appears that if you have'nt gotten new suspension parts ie
ball joints, ty-rods, A-arm bushings and springs your not ready to much benefit from this info because your car won't hold settings well anyway and won't be safe to push hard. JD

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Will
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Report this Post06-17-2003 09:06 PM Click Here to See the Profile for WillSend a Private Message to WillDirect Link to This Post
You want more toe IN in the rear than in the front to help tame the Fiero's infamous lift-off reaction.

Toe in would increases slip angle and traction in the front (increasing oversteer). Toe in in the rear increases rear slip angle and traction in the rear, reducing oversteer.

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vse1fiero@cox.net
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Report this Post06-17-2003 09:20 PM Click Here to See the Profile for vse1fiero@cox.netSend a Private Message to vse1fiero@cox.netDirect Link to This Post
 
quote
Originally posted by Will:

You want more toe IN in the rear than in the front to help tame the Fiero's infamous lift-off reaction.

.

Again, you don't want ANY toe-in in front.
0- 1/16 out. Some go with more to make up for the instability of worn suspension parts. But wear(scrub) increases with more.
JD

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Will
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Report this Post06-17-2003 10:59 PM Click Here to See the Profile for WillSend a Private Message to WillDirect Link to This Post
I said more toe IN at the rear. That means that the rear should be toed in further than the front whether that's neutral at the rear with excessive toe out in front or whatever, the balance is what's more important, as verhicles are EXTREMELY sensitive to rear slip angle.
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shark93726
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Report this Post06-17-2003 11:44 PM Click Here to See the Profile for shark93726Click Here to visit shark93726's HomePageSend a Private Message to shark93726Direct Link to This Post
If you have more adjustment range, front camber can be set as high as 2-1/2 degrees negative, especially if you are using oem rubber bushings. Ditto on the rear. That much would start to affect tire wear a lot though.

If you are experiencing "twichiness", you may have worn out rubber bushings in the rear a-arms, or some other worn suspension part. A Fiero with toe-out on the front and toe-in on the rear should be fairly stable under most conditions, although it "could" do that on a rough road, if you have quite a lot of toe.

Actually, toe varying from zero will probably cause more tire wear than aggressive camber and caster settings. Large amounts of toe "drag" the tire sideways down every straight, but camber and caster correct the tires during hard cornering, actually reducing tire wear from what you would otherwise get.

Most aggressive drivers get more even tire wear with added camber and caster, instead of wearing out the outside edge of the tread first.

The toe settings are to reduce "dartiness" on the front from steering inputs, and to help reduce trailing throttle oversteer on the rear. If you are concerned with tire wear, set those both closer to zero, the camber and caster will improve handling (cornering speed) more anyway.

Hope this helps ya.

------------------
Gerald Storvik
http://www.8shark.com

[This message has been edited by shark93726 (edited 06-18-2003).]

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