Upper Control Arms
Upper control arms (A-arms) locate the top of the front suspension on a race car and set key geometry like camber and roll centre. This range from Keyser and TWM covers standard arms, ball joint arms and cross shaft and plate components used to build or rebuild an upper arm assembly.
Lengths run from around 7-3/4 inches up to 11-1/4 inches, and ball joint arms are available in different angles, including 13 degree versions, which changes how the arm geometry behaves through suspension travel. Some arms use a bolt-in ball joint with an aluminium shaft, others use a threaded ball joint or dual bearing design, so match the arm type to the rest of your front end setup.
- Standard 4-bolt upper arms
- 13 degree ball joint upper arms, including dual bearing versions
- Cross shafts and ball joint plates for rebuilding arms
Frequently asked questions
How do I choose the right length upper arm?
Arm length affects camber gain and roll centre, so it needs to match your car's front end geometry and chassis setup. Check what length the rest of your suspension is designed around before swapping arms.
What does the ball joint angle (like 13 degree) change?
The angle of the ball joint affects how camber changes as the suspension moves through travel, which influences handling balance through a corner.
Can I rebuild an existing arm instead of replacing the whole thing?
Yes, cross shafts and ball joint plates are sold separately so you can rebuild or modify an existing upper arm rather than buying a complete new one.
