OS entry vs. OS exit - need tuning advice

Aston Martin V12 Vantage - class A.

I had already applied a baseline tune that was pretty good. I built in a decent amount of OS for help in corner entry, since I was initially getting slow response (US) to turns and even hairpins at slow speeds were not turning in as well as I liked. I adjusted the Springs by lowering the F and raising the R. I then noticed a bit of bobbing and ‘floatiness’ in addition to getting a good deal of OS on corner exit. It’s not sudden OS, and the rear doesn’t slip much, if at all, this just happens during acceleration out of the corner and starts the car a little sideways. When I start to counter, I get into a bad state where I am then fighting to keep the car on the track. The OS usually occurs about 1/3 - 2/3 through my acceleration in the gear I’m exiting with (typically 2nd).

In response;

  • I raised the F & R rebound about 2.0 each to eliminate the ‘floatiness’. ← this worked
  • I then lowered the F rebound 0.3 and raised the R rebound 0.3 for the corner exit oversteer. ← didn’t work and resulted in corner entry US again
  • I lowered the F bump 0.2 and raised the R bump 0.2 for the corner exit oversteer. ← didn’t work and resulted in corner entry US again

Yes, I realized I broke a cardinal rule by adjust for two problems at the same time, but it was late and I was going OCD about getting it straightened out before going to bed. So, then I was caught fighting the corner entry US by adjusting the Springs (F - down, R - up) and then trying to dial out the corner exit OS subsequently with the Dampers (rebound/bump F - down, R - up).

But, things just got worse. I was up really late last night, so perhaps I’m missing something, but can anyone give me a bit of advice on how to get out of this quandry (OS to aid corner entry, remove exit OS for smooth acceleration away)?

In case you need to know, I have it built to SHALB values of 8.0 / 6.5 / 7.8 / 8.0 / 6.4 - (no option on upgrading brakes)

Springs: Race
F-ARB: Race
R-ARB: Race
Diff: Race
Compound: Race
F-Tire: 245 (default)
R-Tire: 315
Rims: Lexani LTC-704
F-Aero: Forza
R-Aero: Forza
Tranny: default
Wgt. : ~3740 lbs
F-wgt: 51%
Power: 518 hp
Torque: 425 lb-ft
Lat. G’s: 1.118

I don’t remember my Spring or Damper values (and I don’t have my notebook with me), but I remember my Diff is A/D: 48% / 20%


When you raise the rear springs it puts more force on the front, so by increasing the rear and lowering the front, you double lowered the front. The floaty feeling is having too low of springs, raise your spring rate first off. Once your springs are set create oversteer by adjusting the rear rebound. ADD before you take away, this is a good rule of thumb when tweaking a stock tune. They’re always on the soft side to aid beginners. I always think of the bump as how the car gets set when it squats in a corner, the rebound is how the car pushes off its squat position, and the difference between the front bump/reb and rear bump/reb is how hard it transitions. On an aston martin with 51%, you can’t really force too much oversteer without sacrificing traction. They have the same problems any big motor front engine RWD have, too much weight over the front away from the center of gravity. Whips the ass end about a lot.

Try dropping the rear roll bar one click too, sometimes giving it a little play helps it stick out of corners.

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Thanks for the detailed suggestions.

I tend to set up for general OS/US with the Springs, adding OS for corner entry in this case, and then I start fixing the bits where I’m applying force to the car (weight transition, braking, torque to the wheels, etc.). Typically, I’m adjusting caster for stability, the brake bias if I’m having issues coming in smoothly to a corner (decelerating) and for corner entry/exit issues revolving around decel/accel/stability, I adjust the rebound and bump. When I have shifting issues where downshifting quickly = locking up, or upshifting and having the wheels break loose, I start adjusting the differential.

Straight out of the box I’d change that diff to say 28-30% acc and about 5% dec. Should help with both entry and exit.

I’d up the size of the front tires, see if that improves things.

If i remember right that car is a tricky one to tune, have you tried some weight reduction and sport tires with more width instead of using race tires? being that heavy might be part of the problem, i tend to go back n check the build when the tune/finetuning doesn’t seem to work well.