Theoretical-ish question - can you decrease understeer without increasing oversteer? Or is that the definition?

i.e., in general (autox), I'd like to increase front grip, turn in, steady state, without losing stability in other sections, i.e., slaloms, fast offsets.

Or is what I'm looking for just more grip in general?

 

Everything will affect relative understeer/oversteer balance but some things seem to increase cornering power overall without noticeable loss of cornering power on the other end.

Some of those things for me have been RCK, increased caster on front, stiffer big bushing on rear of front LCA, toe bushings on rear axle, rear trailing arm bushings, ACD flash. ACD flash though can probably go any direction.

While ultimately affecting understeer/oversteer balance by decreasing understeer, none of them seems to have caused decreased adhesion on the rear.

 

Stop thinking of it as oversteer and understeer. Start thinking about it as levels of grip. To get the car to "oversteer", you can increase grip in the front or reduce grip in the rear. The opposite is true for understeer.


Now with that being said, you shouldn't be looking to reduce overall grip. Ever. You should be looking to increase it as a system. You can start looking at it as "how can I increase grip in the front without reducing grip in rear which will net me more neutral dynamic balance without reducing overall grip". This should increase rotation which is really what you are looking for. Add in the dynamic power situation ( corner entry, mid-corner/mid-throttle, corner exit, etc. ) and it becomes even more complicated.

For example, oldest trick in the book for autocross is that if your car isn't rotating on a given surface, decrease front tire pressure until you start rolling over the edge of tread. If you still aren't rotating due to the increased grip, then start increasing pressure in the rear until it rotates. Not the right away to approach but easily managed in a parking lot for 30-60 second increments. This hurt overall grip but on autocross dedicated race tires on tight corners, rotation was at a higher premium than overall grip.

Whenever I tune/build a suspension, I am looking to get the static balance right based on tire size/compound and driving styles using spring rates, weight balance, and location of cg. Then using dampening settings and anti-roll bar adjustments to work on fine tuning dynamic situations which includes understanding power distrubution profiles ( think ACD flashes). From there, play with aero to maximize grip on whichever end I need to get the balance I want while all the time increasing overall grip. Then after the event, you go back to the drawing boards and figure out why statically you were pushing.

Remember, at the end of the day, it's about grip management. And grip is temperamental. It fluctuates wildly based on a number of factors ( road conditions/build, tire compound, heat, etc. ) and the best you can do is put yourself in the right ballpark with the component build. All the items that you can do to tweak grip ( tire compound, contact patch, aero for downforce, weight management, power distribution ( think ACD reflashes/repacked clutch plates), etc.) need to be towards a specific behavior or else you may end doing more harm than good.

At least that's my 2 cents.

 

cheapest and easiest way to increase oversteer in an autox only setup is adjusting rear toe. toe out in the rear will make the car rotate, but too much will make the car unstable at higher speeds-- you wont really be in those speeds in an autox course to be an issue though.

Ive personally never liked doing this since Ive frequented more road courses than autox events so Ive kept toe pretty much zeroed out. The best setup for fast high speed sweepers at a road course wont be the best setup for tight 1st gear turns on a autox.