You want to use as less shims as possible so you slam in the top strut plates and then add the necessary shims to reach the desired camber, it doesn't have to be exact down to 0.01 degree.
At almost -2.7 your caster will be out of spec. Once you cross -2.5 you are better off with camber plates. They add -1 degree and correct caster.

 

A bit of both actions here will work to achieve the desired goal. One is not necessarily better than the other. You can get up to about -3.0 of front camber with just shim but then you need solid LCA bushings to maintain caster. You can also add front camber plates to get the -3.0 as well but then don't necessarily need the LCA bushings. Of course the best scenario is to do both. You can then get up to at least -3.8 front camber like one of my friends just did this week. With all three things; the solid LCA bushings stiffen up steering response from the mushy OEM rubber ones and make the caster infinitely adjustable, the camber plates offer adjustment to keep the tires from rubbing on the fender wells, and then you can add shim to increase the front track for handling balance relative to the rear. It is not all just about the ultimate camber numbers.

I just had the car aligned again today. As I shave off another second or so on my lap times, I am of course rolling more speed into the corners, and the outside edges of the tires are wearing out a little more than the insides. Therefore, I added another -.2 degrees of camber in the front and was able to squeak out another -.1 degrees in the rear. The end result was -3.4/-2.8 of camber. There is no more to be had in the rear as the tires already stick out a bit and will rub if I go any further. Rear camber plates will be needed in the rear to go any further on the negative camber there. I also raised each coilover by one turn or 2mm for additional clearance to get the car back up to the full stock ride height. Needed to do that for the final adjustment after the Swift 60 Nm springs had settled a bit after installation. For the toe in the rear, I backed off from 15 min to 12 min to help the car rotate a touch more as it is already pretty stable under braking and in high speed corners. I can tolerate a moment of wiggle when braking from 130 mph. For the front toe, I added 2 min of toe out on each side from 0.00 to help the car turn in with a bit more bite.

These toe adjustment may seem so sight so as to not have an affect, but at the limit, they do. My car handles great, so I am only doing slight incremental adjustments here. I want to improve things a bit without upsetting the apple cart. My goal here was to get the tires flatter to the track surface for an overall increase in ultimate grip and then improve slower speed cornering where there was a hint of push at the limit.

 

What’s the recommended alignment specs for a bone stock gt4/spyder for aggressive street/canyon road use only?

 

You add track width when you shim the lca but having camber plates allow you to keep caster in line as mentioned. My current set up:

 

What tires and what pressures?

 

IMO.....

Front -2.5 with zero toe
Rear -2.0 with 2 mm toe IN each side

 

doesn’t -2.0 rear require aftermarket toe links?

 

One thing to keep in mind...camber is dependent on track and tires. You need to keep an eye on tires via temps and visual inspection in order to reach the camber numbers that work for the track and tires.
What works for me at my track may not work for your track and tires....but could be a nice starting point.

 

Yes....you will need them sooner or later....if it's a GT4/Spyder maybe source a set from the GT4RS. With those maybe you can reach -2 on the rear, they are a bit longer.
If you don't want any of the above solutions then go for max rear camber while hovering around the 2 mm toe IN on the rear....for the front just add -0.5 deg to what you have on the rear.

 

Yes...but if you add a meaty 265 up front the camber plate helps you tuck in that tire.

 

are the toe links and increased camber noticeable with street driving?

 

I wouldn't say they make a big difference, you have to be really moving to need more camber, and braking hard to notice the rear waggle on the street.

 

Exactly what I would say and ditto to the rest of JM's comments.

 

Nice set up. That is where I was but with 0.0 toe in the front before this last alignment. Tires are of course 265/305-19. Was lucky to get a couple sets of Goodyear Supercar 3Rs before they disappeared. The caster was about 9.25 with caster pucks.

 

Makes sense, thanks for the explanation. I was a bit worried at first that something was wrong.