Yes. Post #1, first paragraph, third sentence-
"The final amount of camber(which is the angle of the wheels relative to an imaginary perpendicular line from the ground expresses in degrees and fraction of a degree) is a function of the length of the lower control arm via adding or subtracting shims, the adjustment slots on the strut tower, and the car's ride height."

So the answer is yes, BUT, will need to lower the ride height substantially to get an appreciable gain. The compromise there is reduced usable suspension travel(stroke) and the ride will be harder over bumps since the damper is closer to bottoming out at lower ride height(reduced travel/stroke). For example, lowering front ride height 20mm = 0.5 degree. This example is generous, and the height-to-gain is not linear.

 

Please allow me to follow up on this. If for some reason such has requiring 0.2 degree of camber gain to keep a tire from wearing prematurely in order to complete the distance of a race then lowering by x amount will be well worth it as long as the lowering doesn't affect the balance of the car nor the lap time enough to equal to the time of a tire change. #racestrategy
Usually on a dual-purpose street/track car its better to have 10mm more suspension travel/ground clearance than 0.25 degree more camber, especially on a car that's a low as a GT4 to begin with. But only the setup person and the driver can make this call based on the situation.

 

Tom,

When you say the rubber bushing are friendlier on the subframe are you just referring to NVH or are you saying that spherical monoballs can have some other negative effect on the subframe?

 

Personally I'm just a little tiny bit reluctant to put monoball inner on my street car. The aluminium mounting tab is pretty thin(as shown in photo in post #7, courtesy of Mech33). In event of a hard lateral impact it can break. I'm not saying it will break, just saying the chance is higher than with rubber. But if such an impact is that hard then there are greater things to worry about...
I know plenty of people running monoball inners, some are my local customer who enjoy the benefit of more precise feel. Of course the possibility of breaking is higher during an impact but many find that the benefit outweights such possibility. Its a personal choice. The two companies mentioned that manufacture monoball inner both have great products and great support for their products. Don't smack the wheel against a high curb or a wall then no problems.

 

Thanks Tom. I am running the Tarret spherical monoballs on my GT4. It does have a somewhat more precise feel. I did a number of track days with the OE rubber bushings and found that the car is already pretty precise from the factory so I consider the monoballs an incremental improvement for this car.

 

Nice, proper setup is everything

 

I'm running -2.4/-2.0 (F/R) on my dual-purpose GT4. This is how much exposed thread I see on my OEM inners with 11mm shims up front:






I had to transfer the OEM front shims to the rear in order to hit -2.0 degrees.

 

Any need for caster pucks at that level of front camber? That amount of camber sounds about right for my usage.

 

I was fine at -2.5 F without pucks on the tracks I run. Just maxed out to 2.7 F with stock parts. So far no indication of any problems with stock wheels on street. However, when I swap over to my track wheels and new tires I will be checking carefully again prior to the next event.

 

I didn't get any rubbing on the fender liner with this setup so stock pucks are fine for now. I'll swap in adjustable thrust arm bushings up front after a handful of track days or when the stock rubbers develop noticeable play, whichever comes first.

FWIW, I am running Swift springs, Tarret v1 rear toe arms, and a corner balanced rake.

 

At -2.7 front camber via adding control arm shims, stock ride height, with OE top plate, full negative at front strut tower slots, the front caster should be around 10 degrees. I know that 10 degrees of caster is considered to be "out of spec" by OE street car standard, but so is anything more than -2.x degrees of front camber! I get a lot of phone and email inquiries on caster being "out of spec" with track level camber. Adjusting camber angle by adding shims changes caster angle, that's the physics of it. As far as I am concern, the published OE street car alignment specs doesn't cover the range that we hardcore track enthusiast prefer. So outside of the OE caster spec is what I expect with outside of OE spec camber.

On race cars we use increasing caster angle as a mean to lengthen a car's wheelbase for high speed stability. Adjustable caster bushing(aka thrust arm bushings, or compression arm bushings) such as the ones that we make can be used to adjust caster independent but usually its not necessary at under -2.7 front camber. Unless there's an oversized front wheel/tire combo that rubs a lot with increased caster, or unless there's so much caster angle that the steering wheel requires too much effort to turn, unless the car owner wants the front wheel to look centered in the wheel well.

 

Can I get greater than -3 up front with just the camber plates and me lowering the car?

 

Hi,

Could you post the part# for the Porsche Motorsport GT3 Cup inners? It doesn't show in the pic (while GT4 part# is there).

I have a part 997.341.541.0R for inner, is that the longer cup model? Looks like it.

 

Thank you So Much Tom for this valuable and nice write up !!
I personnaly have 15mm shim (+GT3 CUP camber pucks) with a camber of approx. -2.7°

Could you elaborate on the fact that 15mm is "safe" : Do you mean that the Stock Tie Rod is OK ? (sufficient thread lengh)

Thanks in advance !

Best regards

Mathieu

 

No, I meant 15mm is the maximum thickness of shims before the control arm studs run out of thread length as shown in post # 1.
Tie rod thread length is not in full correlation to camber shims. Other factors that dictate toe rod lengths are camber plate setting, type of camber plate, and ride height.
I *think* the OEM inner tie rod has 70mm of total thread length, the OEM jam nut takes up 10mm of thread length, the thread diameter is 14mm, so its ideal to have 150% of diameter as thread engagement as minimum into the tie rod(aka steering rod), which is 21mm of thread engagement. So in my opinion if the inner tie rods have near 40mm of thread length showing then its too close to danger zone. Which is why for the more aggressive track setups we make longer outer tie rods(aka steering rods) shown in images below.