ACTUAL WHEEL ALIGNMENT DATA - GTB

[jp928]

Seeing as nobody could tell me what actual settings they have, or have seen on a gtb, I will start it off.
I have a friend at a Bob Jane shop I have used for some time now with very good results, because he understands whats going on, will let an owner get involved , and will do his best to get dead on the desired settings. Unfortunately his machine (Italian Corghi) does not have settings for a GTB, or even a GT as late as 08, so I got data from the Gen IV WSM alignment section. I needed the alignment as I have just replaced all the Bilstein struts, and as expected the directional stability was off a bit.

These are (all for wagon, and figures as in 0.15 = 0 degrees 15 minutes):-
WSM obtained/observed
Left Right
Front Camber -0.15 +/- 0.30 0.10 0.10
Caster 5.40 6.00 5.40 Not adjustable
Toe +/- 2mm -0.1mm 0.0mm

Rear Toe +/- 2mm -0.1mm 0.0mm
camber not given -0.50 -0.50 Not Adjustable

Thrust angle 0 0.0
Track difference?? -0.20 Dont know quite what this is - crabbing indication?

We have gone for 0 toe to see how it feels, and it wont take long to change a little. He spent nearly an hour, I gave the underside a good inspection (no signs of lower control arm rear bush cracks, no oil leaks), tied down the aircon drain so it didnt go all over the left LCA bush. $65. Interesting to watch how adjusting one thing affected another - initially the rear camber was -1.1 and -0.40, but after adjusting the toe, they converged to the -0.50 above.
Only have a couple of 25km runs to work and back so far, but it feels fine to me. Need to do a clear freeway cruise to really check stability.

Anybody have any actual data , and feedback to pass on please?

jp 08 gtb 6mt wagon.

[kiks]

Few things:
The track width changes between sedan and wagon. No big thing to be worried about.
Thrust angle should be 0.
0 toe all around is actually not that stable unless you have a compensation of about +1deg caster on the right front to allow for camber of the road.
If anything I'd be going 0.5 to 0.75mm toe out per degree of negative camber on the front, and if you want the car to behave like stock, 1-2mm toe in on the rear. 0 for the best tyre life on the rear, and 2-3mm toe out for the car to grip mid corner and artificially remove some of the mid to late corner power on understeer.

Caster in the front you want as positive as possible and as little negative camber as you can get with road tyres. The stickier the tyre the higher the spring rate and higher the camber you can run until braking decreases any noticeable amount.

Im no expert, but from my own playing around a shitload I've definitely found the extremes on whats worth doing, but I have little regard for tyre life. Im sure others can sway in, but without messing with spring rates and track widths there is only so much you can do.

[Robbks]

Few things:
0 toe all around is actually not that stable

as little negative camber as you can get with road tyres.

I found the slight decrease in straight-line stability going to 0 toe all round, but it did make for better cornering than the stock, toe in settings.
i found that front toe-out was too wandery for everyday driving.

also i found the -ve camber up front helps with the mid-corner grip as it reacts with the caster angle to give more dynamic camber once you get some steering angle into it.
Also helps keep the outer edges of the tyres in tact for longer

personal preference and driving style/ conditions/ roads also dictate what you need.
Tassie doen;t have any straight roads, so these settings seem to suit me in my situation,
the car also changes direction much nicer with 0toe

[jp928]

This is good stuff coming out, just what i wanted. I think I felt a slight loss of directional stability when I went to ET 48 wheels (from factory 55), but that may be because I was expecting a change like that. In ~150kms since the change, I havent been unhappy with the handling so far, but will run it for a month before looking at changes. For some cars there is lots of data out there...eg MX5 - increasing negative camber 0.25deg can transform the turn in - the outer wheel has more grip as its flatter to the road, but tyre life doesnt suffer significantly.
Keep the ideas coming please. Anybody else in Melb wants to try things, see Anthony at Bob Jane Elizabeth St. He also does STI alignments for Docklands...
jp 08 gtb 6mt wagon.

[augo]

Gday I got a wheel alignment done today, I asked ol mate to set the front at 1mm toe out, my read out says Half toe -1mm.
Would negative be toe out or toe in?
Cheers

[bass_straitener]

I recently had my suspension looked at by Trutrack Suspension in North Melbourne.

Here are the numbers he gave me for my setup.

FRONT L/H R/H
Camber -0.57 -1.07 MAX
Castor +3.32 +3.45
Toe In 0.5 0.5

REAR
CAMBER -1.13 -1.40
TOE IN 0.7 0.7

Not sure if suspension type etc matters but I'm running coilovers with braces etc and JSpeed LCA bushes. Car is also lowered possibly 25mm less than standard.

[augo]

Yeah I actually saw that before I went in and used it as a guide
Just trying to work out if toe out reads as "negative" on the data sheet?....
Negative sounds like toe in to me, I could be wrong.

[bass_straitener]

Perhaps these sites will give you the more answers.

http://www.ozebiz.com.au/racetech/theory/align.html
http://en.wikipedia.org/wiki/Toe_%28automotive%29

These state:

"Negative toe, or toe out, is the front of the wheel pointing away from the centreline of the vehicle."
"Positive toe, or toe in, is the front of the wheel pointing in towards the centreline of the vehicle."

Or come over and drive my car and see what you think and how it compares to yours.

PM me.

[augo]

Nice one bud. The power of searching...