I have a sports car project that's still in the planning stages. It's an older kit car that uses Mustang II rear leaf springs. I would like to go with something more adjustable and better suited to handling. I've been looking at both the torque arm and 3 link. The torque arm looks good, but the driveshaft is pretty short and I don't think the arm will be long enough to keep brake hop down. For that reason I'm looking at a 3 link. Most sources agree that they can be set up for some anti squat without inducing bad roll steer characteristics.

I've studied everything I can find, both in books and online, and see some sources recommending the upper link be 70% as long as the lowers while others don't mention it at all.

What is the reason for this length difference? I would think you would want them as close to the same length as possible to keep pinion angle from changing.