It seems now with my recent attempts tuning the 09 Solstice and 77 Firebird that cars with live axles behave differently than cars with independent suspension. I'm used to tuning old Pontiac and Chevy muscle cars with live axles cuz these are the cars I like the most. I can whip out a good tune for these cars in 10 to 20 laps but when I hop into a newer car with a fully- or semi-independent set up its totally different. While tuning the Solstice GXP tonight and the 77 T/A a couple of nights ago, around the Circuit Catalunya Full, I couldn't figure out why it was handling oddly through the corners. At times it seemed sluggish and slow and that was because spring offset is kinda high with being up to .8 or over on the outside springs. However, other times it seemed like it was riding stiff because there wasn't enough offset (.65) and the car, therefore, didn't have enough grip yet to lay down the power. I've tuned several cars at this track so I know that at that point in the turn is when to start gassing but I know If I do, the car will spin. The dampers are kinda messed up too, I think I had the resistance about right but then I drove over the rumble strips and the car will spin. It was crazy, I'd never had a problem like this that stays around.
Is there another approach for independent suspension tuning or knowledge about them I should know to make the right tune? Why do the spring rates act different through certain corners? And dampers? Do the roll bars play a different part? I know there are plenty of guys here that know about tuning these so please leave a reply. Its greatly appreciated for any thoughts or observations. What can I do to solve this guys?
Do Independent suspensions handle better when loose? and what offset should they have ?
Here are some stats for the 77 Firebird:
IFS, Live Rear
Stock Pontiac 6.6
A-Class, 700 PI
Race Tire Compounds
Rollcage
3,158 lbs
476 HP
54% FWD
Spring rates (lb/in)(F/R): 665.4/615.3
Ride Height (F/R): 5.2/5.2
Anti-roll bar setting(F/R): 18.54/13.01
Rebound (F/R): 6.4/5.7
Bump (F/R): 5.4/4.6
Downforce (F/R): 90/160
and 09 Solstice:
Fully-Independent suspension
50% FWD
A Class, 700 PI
Stock Engine
Race Tire Compounds
No rollcage
2,955 lbs
436 HP
Spring Rates (lb/in)(F/R): 600.2/705 (I know they should be the same and they were but loosening the front and stiffening the rear seemed to be a good idea. Previously they were both 675 lb/in)
Ride Height F/R): 4.0/4.0
Anti-roll bar setting(F/R) : 17.97/6.49
Rebound (F/R): 7.1/7.1
Bump (F/R): 5.0/5.0
Downforce (F/R): 85/155
Huge thanks to everyone that will really help me with this, I love Pontiacs and these are some of the coolest that FM7 has.
Edited by user Tuesday, July 16, 2019 11:53:16 PM(UTC)
| Reason: Finish up post