R32 GTR Fast Road/Track Alignment

[Timmaz300]

Hello everyone. I am wrapping up the last bit of my suspension build. I am looking for recommendations for alignment specs to start with. I have an appointment in the middle of march to get an alignment and corner balance done by a shop at the Nurburgring. I've been reading through some of the past threads and have a general idea of what I should do, but want to confirm that I am going the right direction with my setup. My current setup is:

MCA Red series coilovers (11kg front, 7kg rear)

Factory sway bars

SPL castor rods, outer tie rods, front sway bar end links, rear upper control arms, traction rods, subframe bushings, and spherical knuckle bearings

GK tech front upper control arms

Superpro rear lower control arm bushings, rear sway bar end links bushings, front and rear sway bar mount bushings. 

Full Race ETS Pro 

Dunlop Dirreza ZIII (265/35R18) 200TW

From what I can tell I should start with

355mm front 345mm rear ride height

6 degrees castor front 

-3.25 degrees camber front

2mm total toe out front

-1.5 degrees camber rear

1mm total toe in rear

Any input would be appreciated. Thank you in advance 

 

[GTSBoy]

I would use zero toe at the rear, especially if you have solid ends on the arms.  I would also use slightly less toe in on the front.  -1 total, or even zero, especially if you have solid ends on the castor arms.  Your front camber target will be ace for fast corners, but will eat tyres on normal street driving.  Good for the 'ring but.

Tyre pressures are the big unknown here.  I would start with 38psi and consider going higher for a fast track.

The other big unknown is the suspension settings.  You will need to work out where to set the dampers to work with those springs and whatever tyre pressures you might end up with (assuming that you have an IR pyrometer and work out from tyre temps that you need different front to rear).

[Timmaz300]

Thanks for the reply. From my reading, I'm under the impression that toe is more of a factor than camber, when it comes to tire wear. Also from reviewing Sydneykid's posts, seems like toe out is desired on the front for better turn in. If your want stability under braking a little toe in is needed, but some toe out will help the back end come around better. Not looking for a track spacific setup, but a reasonable compromise for carving up mountain roads and doing some non competition track time. Still need to figure out tire temps once I hit the track.

[GTSBoy]

Everything Sydneykid has to say is essentially correct and well considered.  But it is mostly aimed at Skylines without suspension arms that remove all the bush compliance.

Toe in = stable, toe out = active (and therefore, effectively, unstable).  So, yes, toe out is recommended for enhancing turn in.  But at very high speeds that lack of stability can make the car very difficult to drive.  Better to start a little more conservative and adjust the alignment after discovering how it drives with something less likely to kill you.

Now, the other thing about toe-in & out is that stock suspensions have plenty of movement in them from all the squidgy bushes.  What that means is that when the car is moving forward, there is a load pushing the wheels backward, relative to the body.  If there is compliance in the bushes then the general response is for the toe-in to decrease.  So let's start at the rear.  If you set -1mm of toe-in at the rear and that decreases, you will actually end up with zero toe, or possibly even toe-out when the suspension gives.  If you have really stiff bushes or steel rod ends, then there is less deflection and you don't get the same effect.  Better to reduce the static toe-in to zero, to get the wheels pointing where you would want them to be from the start.  The aim of stock alignments on stock bushes is to get close to zero toe while under way.

Toe out at the back can make the car incredibly kill-deathy.  Depending on spring rates, ARB stiffness, damper settings and road bumpiness, it can make it super willing to rotate, sending you off into the furniture at high speed.  Again, better to start slightly conservative.

At the front, it's the same story.  Stock alignments are toe-in, compliance pushes that out to zero-ish.  With less compliance, set zero to get zero, or slightly positive when moving.

Neg camber = inside edge wear.

Toe out = inside edge wear.

Therefore Neg camber + toe out = much faster inside edge wear.  Usually, to even out tyre wear, alignment shops will use toe-in with neg camber to push the wear across the whole face of the tyre.  But if you want aggressive cornering turn-in and grip, you don't want the toe-in, so you have to accept the wear.

 

[KiwiRS4T]

I ran 3deg neg camber on the track and it was great - definitely faster through the corners. Having easily adjustable arms the theory was to return to neg 1 for the road but since you effectively need a full alignment with each change it didn't happen. So it was cr*p on the road - skittish and chewing out tyres. If you can manage a lot of track time in a short period it might be worth doing but otherwise best to go with a street friendly set up.