Toe out at the front, imho, seems a bit odd for a fast road car.
The loaded outside wheel will actually take longer/more lock to get a slip angle for lateral force than it did before. I'm not really sure on the intricacies, but on a track with slicks where you want to be on the ball all day long, great, a bit more response, but on a road car with softer tyres and fundamental setups for toe in compromises means going out might be a bit odd!?
I'd not add front camber all at once.
ONE change at a time seems a sensible course to take. The Alpina thread is a tad inaccurate too, a stiff front ARB will add understeer. Alpina likely do that to cancel out the loss of rear camber. They lose the lateral thrusting and movement, but keep it neutral/understeery.
Pretty sure it is toe in at the rear already.
Lastly, half the issue of the car is the kinematics, iirc, the Z4 puts on negative camber two to three times faster than the front under bump, so the back end get alot of grip benefit vs fronts when you roll onto the outsides in a bend.
What you need to do is find the sweet spot.
*Personally* I'd use good old scientific method to get where I want to be. BMW will have done road tests, changed one variable, tested again, changed one thing, tested again.
Of course, this is tough to do and expensive potentially, but it will get you what you want imho.
How about getting it done with 0.75deg less rear camber to start with, and everything else OEM?
See how it goes. You can always wind on/off equal amounts on the control rods once it is setup right. Work out which way to add/remove rear camber, and have a play yourself. Just note down the changes you make from OEM settings. Ask the operator when setting it up to get to OEM, then adjust to 0.75deg less rear camber, and note the amount of turns to get an idea of the adjustment sensitivity in that range.
Then you can have a play.
Making ALL those other changes in one go may feel terrible, and you will have no idea what bit is making it like that.
Alpina took out rear camber = oversteer, then added front arb = understeer... so cancelling the change out. BUT, they added a bit more worse front end ride comfort on bumps (less independence of front suspension movement, not a huge cost), with much improved lateral thrusting/ride comfort from the back by getting away from oodles of neg rear camber!
That said, what springs are you using again, same stiffness or different? Being lower you will have added more rear camber than at the front to start with due to the kinematics of the suspensions.
Personally on that I'd be very sensitive to changes. You could end up with a complete mess if you change too much all at once without really considering each change one at a time
It's easy to think of things as statics, but the dynamics is what matters more. Where the wheels move when the suspension moves, not just how it looks steady state when sat still!
Dave
