EFFECT ON

VEHICLE – POSSIBLE CAUSES

Straight Line Instability

* Too much rear wheel toe-out. * Not enough rear downforce. * Too much front downforce. * Not enough rear toe-in (under hard acceleration) –presumably for RWD. * Too much front toe (either in or out) – car darts over bumps. * Front ARB is way too stiff – car darts over bumps.

Instability Under Brakes

* Front end darts or wanders – too much front brake bias. * Car wants to spin – too much rear brake bias.

Response

* Car feels heavy and unresponsive. o Too much downforce. * Car feels sloppy and is slow to take a set in corners. o Too little shock. o Too much body roll (not enough spring and/or ARB). * Car responds too quickly, is twitchy, and slides easily. o Too little downforce. o Too much shock, too much spring, and/or too much ARB. o Too much tire pressure.

Understeer

* Corner entry understeer – car won’t turn in at all. o Front tires not wide enough. o Too much front roll stiffness – ARBs and/or springs. o Not enough front bump – shocks. o Not enough front downforce. o Too much dynamic camber on front wheels (not enough static negative camber). * Corner entry understeer – car turns in initially then starts to push. o Too much front toe-in. o Rebound too stiff – shocks (not enough droop travel). o Not enough front downforce. o Bump not stiff enough – shocks. * Corner entry understeer – car turns in and then darts. o Insufficient front suspension travel in either or both directions – shocks.