Your front suspension arms' sweep refers to how "swept" they are backwards (forward sweep is not generally used.)
Front sweep is set by changing the angle of the lower suspension pins so they angle slightly inward or outward when viewed from above. This will result in the arms angling slightly forward or rearward.
Changing the angle of the arm changes the car's wheelbase and, if you don't change the length of the steering links, will change your toe angle as well.
More sweep (arms farther back)
- More on-power steering
- Easier to drive on corner entry
- For high-grip tracks
Less sweep (arms closer to straight)
- More off-power steering
- For bumpy or low-grip tracks