Adjustable Control Arm Question

When changing to adjustable LCAs, is it unheard of to only change the front or the rear arms? I imagine that for serious builders, it comes down to an alignment spec being limited by the LCAs from the desired setting and changing that component. But in general, is there any convention that, maybe, adjustable front arms are more essential than the rears, or visa versa?

Depending on how the car is lowered, the rear camber can max out around -2 +or- a few minutes whilst being able to achieve the correct toe. Most people are happy. Adding adj LCA would add another -2 of range It's typical to do front adj LCA's only to get > -1.8 I had Front's only for years, then replaced the front adj LCA's with new and moved the old F adj LCAs to the rear. Didn't change the feel as I stuck with -2 to -2.1 in R and I'm just a canyon carver now days If I had to do it again, I'd do front's with Tarrett LCA's with GT3 OEM rubber as they seem reliable and are half the cost of OEM

I have GT3 style LCAs up front and the OE ones in back. I’ve been able to get the level of camber that I want with this setup (-2.8 F and -2.4 R). I had originally thought that I would need GT3 style LCAs in the rear to get the camber I want, but since I lowered the car a bit by installing coilovers, the camber became more negative simply from the suspension being lowered a bit. I did need adjustable toe control links in the back because the OE ones aren’t adjustable. So if you are considering getting LCAs at all four corners, but keeping the OE dampers, you might consider upgrading to coilovers which drop the car about 20 mm and then foregoing the rear LCAs. The saving from keeping the OE rear LCAs will partially offset the cost of the coilovers. Having adjustable coilovers is a game changer in how our cars drive in my view.

For street alignments rear components are almost never needed. You can adjust and the camber and toe as needed in the rear for negative ~2 degrees and get the toe within spec. The front is where LCAs are needed.

The rear toe links are adjustable via the eccentric mounting bolt. Once you go past -2ish camber you can have trouble adjusting the toe. Lowering the car takes camber away rather than adding it. This an issue with strut based cars in general and our Caymans have them at all 4 corners. This is why we have to run a lot of static camber; once the car loads up in a corner the bump reduces camber further. In the front castor factors into that but not the rear.

Thanks for the input. The car is lowered via Ohlins and has front camber plates and rear adjustable toe-links. I was considering options for the next step in the setup. But, adjustable LCRs on all four corners could be a significant investment.

Are you wanting/needing more rear camber? For the front it's a solid move, the rear just depends. Happy to help you out with Tarett or Elephant LCAs: Cup-Series STREET Control Arm Kit Introducing Tarett's new GT3 Spec Cup-Series lower control arms for your Porsche 996/997/986/987/981 & 991 (not GT4 or 991 GT3). Now certified by PCA & POC as a class legal substitute for the NLA OEM Porsche 996 GT3 arms. Much more than just another billet replica of the GT3 arm; this design is... www.arcflashllc.com Elephant Racing GT3 Control Arm Kit (Pair), 996/997/986/987/981/991/71 GT3 Lower Control Arms (LCA) 996 and 997 GT3 cars came equipped with adjustable type lower control arms fit to the front of the car. This two-piece design allows the fitment of shims between inner and outer halves, enabling the control arm to be extended. This has the effect of both increasing... www.arcflashllc.com Elephant only does front arms in the GT3 style for the Cayman just FYI. LMK if you have any questions!

Joshua, in your diagram of the suspension, the damper is not angled. It’s completely vertical. In our P cars, don’t we have a setup where the damper/coilover is angled? If this part of the triangle is shortened as happens when a car is lowered with coilovers, wouldn’t it cause the camber to become more negative?

Sorry for the slow response. We're inundated with race cars getting ready for the season! You're correct Greg. I'm going to eat some crow here. We have a 991.2 GT3 RS in for some brakes and engine performance work. The last of the best mac strut cars! So I measured up the suspension and modeled the camber curve. To my surprise over 3" of compression travel there was 0.8 degrees of negative gain. Most of it in the first inch, less than 0.1" in the 3rd inch and loss past that. But these only have ~3.5 inches of compression travel so that part is negligible. This is all based on a ride height that nets horizontal LCAs at static ride height. Lower the car and the camber curve is really bad during the compression stroke. The other thing that is noteworthy here is this only tells the story of the net camber angle when the car isn't moving. Body roll counter acts the camber seen by the tire. So with a camber curve that reduces in compression you quickly go from ideal camber at the tire to positive camber at the tire. Whereas a double wishbone setup, like the 992 , has progressive camber gain in compression to account for roll. Needing less static camber, which translates into more straight line acceleration and braking traction.