Why does the rear end step out?

[Mike Grace <mgrace@domain.elided>]

Reading in Millikan's book "Race Car Vehicle Dynamics", I'm wondering why
the rear end steps out when going over bumps in my solid-axle Giulia? Is it
bump steer at the rear-end or something else? I have newly installed poly
bushings in the rear which make my car handle much better than before, but
bumps are still it's undoing. BTW, the book describes the Alfa's four-link
(T-arm is equivalent to two links), lower-parallel-arm design as generally
inferior to other solid axle suspensions. Based on driving Alfas and
mid-60's Chevy's with supposedly *better* designs, there's a lot I clearly
don't understand about suspension dynamics.

Mike Grace
Santa Barbara
'74 GTV

------------------------------