Dave is right. Torque steering (more correctly rear steering in our case) is due to the momentary change in wheelbase caused by the compression of one side of the rear suspension and the drooping of the other under acceleration/decelleration. The rear links on the compressed side tend to lengthen the wheelbase a bit compared with the drooping suspension, effectively "steering" the the rear axle away from perpendicular to the chassis. This momentarily changes the direction the rear of the vehicle takes wrt the front of the vehicle, and requires the driver to steer towards the drooping side to maintain the correct track.

This affects all londitudinal link based suspension systems (3, 4, and 5 link, and all variations of them) to greater or lesser degree, generally the longer the links, the less the steering issues will be. It also applies equally to suspensions on front beam axle vehicles (independant of normal steering inputs).