Suspension set-up and alignment specs

[Boyscout]

i am currently installing a new suspension and need to know what other owners are using for alignment specs. the car is a R32 GTST and is going to be used for street driving and auto-X. does anyone know of a reputable shop in the Edmonton area that can do a quality alignment (without taking my car for a joy-ride...)

Front:
Apexi coilovers (lowered ~ 1.5")
FUCAs (adjustable)
Lower control arms (adjustable)
front tension rod (adjustable)
castor arms (adjustable)
upper strut brace

Rear:
Apexi coilovers (lowered ~ 1.5")
RUCAs (adjustable)
lower control arms (adjustable)
upper traction rods (adjustable)
HICAS lockout with adjustable tie-rods
upper strut brace

thanks for your help

[CanadianGTR]

Once you find a good baseline, I suggest buying a contact tire pyrometer and taking measurements on the track after each session. You will find that what tire you run + how you drive will affect the baseline numbers, so it's hard to really tell what a surefire bang-on setup will be unless the person has the exact same suspension, tire, race weight, driving style.

I suggest getting it corner balanced as well.

[Boyscout]

so i need someone to give me a good baseline.

[Transparent Skyline]

-2.5 camber
1/32 toe in
5 degress of caster

-2.0 camber
1/64 toe in

I am running 245/45/16 hankook RS2 i am about the same right as you an have compatible parts list so this should be alright. This Set up has worked well for me in the past at auto X and track days tyres dont seem to chunk and heat even....But with this little amount of toe in its kind of a bitch on the road..

[frankiman]

you can check out the GTR chassis setup database
http://forums.gtrcanada.com/gt-r-tec...ase-49559.html


and for the alignment, i just brought my car to the local Nissan dealer, the alignment guy also owns a skyline,
told him what specs i wanted, and he put it all on the dot

[fastbmw7]

For the rear toe setting, I like a little toe out... it makes for a nice crisp turn in. Try 1\32 toe out. Remember, what is optimal for the street will likely not be optimal for the auto cross track and vice-versa.

[Bugsly17]

Use oem specs.


and nothing else.

[Skym]

Factory alignment specs are good for factory suspension setup. But gives a good base to work from. Alignment specs depends on your setup (spring rates, shock valving, swaybars, ride height, tyre pressures, etc). Also application like street, racetrack, dragstrip, etc. Like for example on racetrack you tend to run more camber on rear for cornering, but on dragstrip you do the opposite when looking for maximum traction when rear squats.

Also I would get a tool to measure heat across tyre, as it tells you what's going on with the tyres and can make adjustments to alignment, tyre pressures to suit.

[plankworx]

I ran this for a couple of grip sessions, worked quite well;

front:
-2.2deg camber
1/32 toe-out
~8deg castor
with your adj. lca's, widen each side by 1/8-1/4"

rear:
-2.5deg camber
0 toe
stock track-width

[Boyscout]

ok, so if it is mainly street (summer only) and occasional track?

front camber: -2.5°
front caster: 7.0°
front toe: 0°

rear camber: -2.0°
rear toe: 0.5° in

[frankiman]

that actually a pretty good street/track alignment,

but again, it depends on your spring rates, damping rates, ride height and swaybar stiffness

[Skym]

Also tyre pressure. Note the tyre pressures the alignment was done with and use them. Digital tyre pressure gauge and foot or electric tyre pump are worth it.

Here's my cars alignment specs at stock ride height before suspension was upgraded and with HICAS lockbar -

Key: Left/Right

FRONT

Camber -0.3 / -0.5
Caster 5.5 / 4.9
Toe 1.1mm / 1.1mm
Set Back 0.15
SAI (KPI) 13.0 / 12.3
Included Angle 12.7 / 11.8

REAR

Camber -0.9 / -1.0
Toe 1.4mm / 1.6mm
Trust Angle -0.01

It was designed to eliminate some understeer into tight 90 degree corners (turning left) with stock suspension setup, lockbar (castor settings on front).

Another set of alignment specs can be found in this thread with 1.5" front, 2" rear drop in ride height -

http://forums.gtrcanada.com/gts-tech/t-car-pulls-to-the-rightleft-46585.html

It's so you can see what was changed alignment wise when car is lowered.

Or to save you the trouble of clicking on link -



Thanks goes to mfroese for those lowered alignment specs.

[GTR-Dad]

Remember that personal preference and driving style will affect what works best for you. Suspension components interact with alignment settings too.

I'd be interested in hearing from guys who have either a theoretical and/or experience basis for how each setting affects the car.

Front
Toe in -
Camber -
Negative camber tends to keep more of the tread surface in contact with the road during cornering. In general, the less body roll you experience the less negative camber you need. Tune this with a tire pyrometer and shoot for even temperature across the tread surface.
Caster - High caster settings help initiate turn in by adding more negative camber with steering input. High caster settings also increase steering effort and tendency for wheels to return to straight ahead.
Spacer -
Anti-roll
Stiffer (relative to rear anti-roll) will increase load transfer to outside wheel, reduce front grip capacity, and increase understeer.
Damper
- Increased damping sharpens transient response. I've found the car responds to steering inputs more quickly, but becomes becomes upset on irregular corners.
Tire pressure
-

Rear
Toe in - fastbmw7 likes about 1/32 toe out for crisper turn in. If outside (weighted wheel) has toe out it'll tend to make the rear end of the car move out of the turn causing the car to rotate into the turn quicker.
Camber
-As per front
Spacer -
Anti-roll
Stiffer (relative to front anti-roll) will increase load transfer to outside wheel, reduce rear grip capacity, and increase oversteer.
Damper
- Increased damping sharpens transient response. Harder settings make for twitchier rear end, particularly when exiting hard on irregular tracks.)
Tire pressure

[frankiman]

front toe in; helps stabilizes the cars during cornering
front toe out; increases ''turn in'' speed

also;
High caster creates camber as wheel is turned, which means you can run less static negative camber, which means you have a more flat tire when straight, good for acceleration and braking

rear toe in, stabilizes the car in straight line

rear camber, same as front camber, exept there is no caster, so static camber is primary, lots of negative camber increases rear traction, since often rear of car rolls more than the front, but lots of negative camber greatly reduces rear straight line traction during hard acceleraton as rear suspensino squats

and about swaybars, its all about balance
stiffer frotn than rear = understeer, as front inside wheel will tend to lift while rear wheels will stick
stiffer rear than front = oversteer, as rear inside wheel will tend to lift off the ground (tripod mode) while front will stick

[GTR-Dad]

Thx Frankiman. I'll update a 'master' post that should probably make its way to 'sticky'. Just need a couple explainations and clarifications.

front toe in; helps stabilizes the cars during cornering

How does toe in accomplish this?

front toe out; increases ''turn in'' speed

This seems counterintuative as the outside, weighted wheel, will tend to run wider than zero or positive toe-in. Please explain mechanism.

also;
High caster creates camber as wheel is turned, which means you can run less static negative camber, which means you have a more flat tire when straight, good for acceleration and braking

Yep.

rear toe in, stabilizes the car in straight line

Have you got a handle on why this is?

rear camber, same as front camber, exept there is no caster, so static camber is primary, lots of negative camber increases rear traction, since often rear of car rolls more than the front, but lots of negative camber greatly reduces rear straight line traction during hard acceleraton as rear suspensino squats

Just to clarify, I think the first case refers to cornering.

and about swaybars, its all about balance
stiffer frotn than rear = understeer, as front inside wheel will tend to lift while rear wheels will stick
stiffer rear than front = oversteer, as rear outside wheel will tend to lift off the ground (tripod mode) while front will stick

Yep.