Knurled. said:rslifkin said:In reply to Knurled. :
A little bit of roll oversteer in the rear of a RWD vehicle can be useful. It requires you to stay on top of it, however. As in, reduce steering input a little when crossing the crown of the road on the street or when adding power. But it does mean less slip angle on the rear tires (as they're steered slightly outwards), so it can let you put down a bit more power coming off the turn.
A little bit, and only at low loadings. At high loadings it is spooky as all hell.
All manufacturers trive for roll understeer, not roll oversteer. Mazda played with roll oversteer (well, kinematic oversteer) in the FC RX-7 with their weird bushing arrangement in the rear suspension, but only under very light "whee!" side loads. (DTSS?)) Under light side loads, the outside wheel would toe out, steering you into the corner more. But under heavier loads, a different bushing would deflect and you'd get toe-IN. So basically a passive way of doing what Mitsubishi and Nissan tried with their computer controlled high performance four wheel steering setups. (And then after 80-100k or so the bushings are junk and the car just feels spooky until you replace the bushings ($$$) or use an eliminator kit, which turns it into a multilink Z31)
VW were the same way, all of their front drive beam-axle cars have ramped bushings so that under side loads, it steers the rear axle away from the corner. Negative feedback loops are predictable.
If you want interesting, Evan took a video of his rear tire while autocrossing his Miata on sticky-ish street rubber. The amount of toe-in in bump engineered into the rear suspension is mind-boggling!
Now, I have described a whole list of vehicles that are generally considered to have "GOOD" handling....
Early s2000's have dynamic toe out.
