Dougster

Just got my wagon back and my settings are in degrees not mm.

How do these equate to mm?

Rear camber left : -1.17
Rear camber right : -1.06

Rear toe left : -0.03
Rear toe right : +0.07 Total : +0.05

Front camber left : -1.11
Front camber right : -1.17

Front toe left : +0.04
Front toe right : +0.04 Total : +0.09

I have the bumpsteer mod and MRT solid drop-links. I understand that max -ve camber looks OK but how close are my front toe settings to the +/- 1mm?

Many thanks for opinions in advance!

[Edited by Dougster - 5/2/2003 9:15:01 PM]

Leslie

I would have said that your present toe settings are as good as anything unless you get both rears balanced-but next to nothing in it. The cambers could be slightly better balanced too-there is enough tolerance in the rear suspension bolts to do that. I would imagine that the Prodrive settings take no account of the bumpsteer mod being done,

Les

[Edited by Leslie - 5/4/2003 11:27:37 AM]

Subarussian

Looks like you don't have any toe-in, front or rear.

As you saw from my thread Prodrive recommend 1mm on each wheel. TSL think it's too much and set my car to 0.8mm total at the front and a bit in the rear. I am very happy with the outcome!

If you are not too far from them it is definitely worth a visit.

Dougster

So what degree should I set front (and rear?) to equal the +1mm (or is it -ve) recommended?


[Edited by Dougster - 5/2/2003 5:39:51 PM]

Dougster

So basically you are saying leave it as is?

Leslie

It is very similar to mine without the ALK. I am more than pleased with the way mine handles so I would not touch it.

Les

Mycroft

As no-one appears to have answered you.. post the wheels size in inches and the tyre size and I'll post the info you want.

Dougster

18" ON 215/35s

Lars

You are running with zero too in and thats correct, as you have the Bump steering sorted out.
The Too in recommended by several people is to compensate for the negative effect from Bump steering ( Too out when spring is compressed) No bump steering and you do not need the too inn.
In my mind the best solution you can get.

Lars

GV27

I THINK this is one way to calculate toe:

I'll do .04 deg for the example. The radius of the tire is ~305mm for a Pirelli P-Zero Nero according to the TireRack.

Consider the triangle below:



Angle A is the toe angle (.04 deg), side AB is the radius of the tire (of course so is AC, but we can assume this problem away since the distance BC is miniscule) and side BC is the toe length. If Points B and C were the same, toe angle A would be zero.

Tan(A) = BC/AB. We know A (.04 deg) and AB (30.5mm) and we need to solve for BC. So:

BC = Tan(A)*AB = Tan(.04deg)*305mm = 0.213mm

Anyone want to check my math?

Chris

edited to put the decimal point in the right place!

[Edited by GV27 - 5/6/2003 5:05:21 PM]

Mycroft

With that size tyre 1 degree = 5.3mm (centre/perimeter)

So the numbers in parentheses are mm.

Rear camber left : -1.17 (-6.2mm)
Rear camber right : -1.06 (-5.6mm)

Rear toe left : -0.03 (-0.16mm ±0.02mm) best fit -0.14mm
Rear toe right : +0.07 (+0.37mm ±0.02) best fit +0.39mm
Total : +0.05 (+0.26mm 0.02mm) best fit +0.25mm

Front camber left : -1.11 (-5.9mm)
Front camber right : -1.17 (-6.2mm)

Front toe left : +0.04 (+0.21mm ±0.02mm) best fit +0.23mm
Front toe right : +0.04 (+0.21mm ±0.02mm) best fit +0.23mm
Total : +0.09 (+0.48mm ±0.02mm) best fit +0.46mm

All the numbers I have appended are hub (zero) to radius (the number provided)
I have to say that you should really use Degrees for cambers and mm for toe settings... this is the correct way to present meaningful figures.



Edited to provide 'best fit' tolerances. I don't like loose ends.
]

[Edited by Mycroft - 5/6/2003 1:30:37 PM]

GV27

Doh! That dang decimal point always bites me!

Dougster

Well that has just completely thrown me but will study it more!!

Still don't know whether to leave it the way it is as that was my original question!

Thanks for all the information guys.

GV27

I dunno about "shot to peices" - that's still within specs I believe. Though the specs are pretty wide from an enthusiasts point of view. Some shops like to run a bit of toe on one side to compensate for road crown and reduce tire wear.

Here's a link to some recommendations on performance alignments from some US tuners. Sorry the toe numbers are in inches. Note where it says zero rear camber they actually mean "no change" as the US Imprezas have no means of camber adjustment stock:

http://www.ravensblade-impreza.com/t...ign/align.html

As far as what it "should" be. It depends on what you want to do. All your numbers look pretty good for daily driving. I guess that one side (+.07 deg) toe in the rear could be a bit closer to zero.

For performance driving it's a bit touchier and really depends on the driver's needs and wants. Camber looks pretty good on yours. As far as toe goes, you can use it to destabilize the car for quicker turn-in and rotation. Of course that also makes it easier to put in the ditch if you screw up. The 1/8" toe recs in that link above is pretty radical - that's over 3mm! Probably more of an autocross setup. A lot of toe also means faster tire wear.

Here's a link to a table of handling adjustments, including geometry:

http://www.clubsi.com/suspension_tweak_table.shtml

Personally I run zero toe all around, and 1 deg negative camber all around on my WRX Wagon w/ STi RA suspension. I'll probably run a bit more front (1.5 deg maybe?) when my Noltec Caster/Camber plates arrive from "down unda". 1 deg is all we could get with the stock adjuster.

Chris

[Edited by GV27 - 5/6/2003 9:58:53 PM]

GV27

Mycroft, can you elaborate on "best fit"? I see where you're getting those numbers from but not sure why you chose to go + tolerence in some places and - tlerence in others.

Chris

Mycroft

Algebra... those figures in brackets work with each other and would get the results first shown in degrees... there are not many variable that fit within the confines of all the figures.

GV27

Oh, So you're saying with the tolerances built in to the siginificant figures those are "most likely" what the actual numbers are?

Dougster

bttt as I am going in for a Geo. check this week.

Could someone please give me advice in English (and degrees! ) as to what I should be running.

Thanks

Mycroft

Rear Toe is shot to pieces so that has to be deal with... I don't know the number of Bushes in you cars suspension but for each wheel count them and make a compound fraction of it with the number 15... so if you have 3 main bushes the you do 15/3 = 5.. that gives you the max time you are gonna have decent reliable settings for geometry.. over 5 years one or more bushes will need replacing...

This is a rule of thumb but is staggeringly good for serious drivers and their cars...


[Edited by Mycroft - 5/6/2003 8:03:53 PM]

Dougster

So camber settings OK but bring toe settings to as close to zero as I can get?

TSL settings have a little toe at the back and a little more at the front from what I can decipher from Trousers e-mail!!

[Edited by Dougster - 5/7/2003 2:08:53 PM]