The ball joint end uses a high misalignment spherical bearing instead of a ball joint. The ball joint shank is extra-long and you can use spacers on the shank and bearing to fine-tune the roll center. The arm has no squishy rubber for accurate alignment under load and fast response. When adjusted correctly the arms can support up to 70 degrees of angle.
The heim joints on the chassis side of the car are screwed into sleeves that are right and left-handed threaded so the arm can be adjusted fore and aft, and in and out by just loosening the lock nuts and turning the center hex. The ends do not have to be unbolted from the chassis, greatly speeding alignment and setup. The huge flexibility helps adjust the caster, camber, and wheel position in the wheel well for maximum clearance and kingpin inclination. The arms also come with these spacers that can be placed fore and aft if you want to move the arms a lot in either direction. Back in the day, we would have to whittle custom spacers in a lathe to get the wheel centered. A lot of times angle kits would move the wheel too far forward in the wheel well causing rubbing so we would have to do this. GKTech makes this adjustment a piece of cake! The arms have up to 35mm in length adjustment so you can get the most clearance for steering angle without having to resort to the use of spacers that cause the wheels to swing in wider arcs which reduces for and aft clearance.
The GK Tech arms have adjustable steering stops! This is a super important feature in a rear steer car to prevent tie rod over centering which causes wheel wobble and steering sticking at full lock. If you were to shift from drift to grip, if you added wide tires, you could limit lock to prevent rubbing, then later, with narrower tires, allow more steering angle for drifting! We used to make our own custom steering stops which used shims to adjust the maximum allowed steering angle. With GKTech you can simply buy them!
7 comments
looks fanstastic! I always wondered about these arms and knuckles. Thank you for the in-depth review
“ Road racing cars need Ackerman in their front steering geometry and typically you want a gradually rising Ackerman curve that is slightly less than the geometric true Ackerman. For drifting, you want a digressive Ackerman curve. This tends to understeer in grip driving. GKTech makes 3 different knuckles. A grip driving one, a drift/grip one, and a super angle drift only one.”
^This really is ‘the secret’ to handling with rubber tires and their slip angles. In F1, I know that they even do an Anti-Ackerman setup!
https://www.f1technical.net/forum/viewtopic.php?t=8874
Until you understand these principles in theory and practice, you can’t really have a solid understanding of how to make a car handle.
It’s weird with open-wheel cars, We found that anti-Ackerman causes understeer in road racing in sedan-based cars.
I think it has everything to do with the tire. I am sure that F1 had to change up the anti-Ackerman when they switched to 18” wheel rims this year.
The ‘max lateral load’ (and associated ideal slip angles) for radial street tires is probably way different than the race rubber they run in F1. Also, downforce needs to be factored in.
My Holy Bible on tires is this book, if anyone that wants to race a car is serious about winning, or just being competitive, don’t get a HUGE REAR WING, please read the bleeping manual!
I ordered a copy and the author Paul Haney even signed it! What a guy! So happy for him to take my money!
https://www.standardsmedia.com/The-Racing-and-High-Performance-Tire-8627-book.html
I ordered the book!
they didn’t have it!
the book is out of print, considered a rare book and no one has it!