Hey guys. I really need some help with this tune. I built a Peugeot 308 for c class. First build was fwd. Had massive understeer that I could not work out with tuning. I started over and converted the car to rwd. My hope was that the rwd setup would make it easier to get rid of the understeer. The car still pushes.
Upgrades
Rwd conversion
3.7L V6 VVT Engine
Centrifugal supercharger
Street ignition
Street weight reduction
Race breaks, dampers, and roll bars.
Race trans and diff
Race aero front and rear.
Race tires with max tire width front and rear.
Sport style Fikse Profil 5S rims
Tuning settings
Tire pressure- 28 psi front and rear
Trans- FD @ 4.30 1st through 6 left at default settings.
Camber -2.0 front and rear
Front toe- out .2
Rear toe 0.0
Caster 5.0
ARB front 13.30
ARB rear 10.00
Front spring 756.8
Rear spring 571.1
Default ride height
Front rebound 9.9 Rear 7.5
Front bump 6.3 Rear 4.7
Aero default
Break setting default.
Diff accel 35 decel 17
These are my base tune settings. I have tried 4 different builds with variations on the tuning and the understeer persist. I am tuning on Silverstone GP with a target time of 2:25.0. Based on my skill level.
I have been working this car for a few days with no luck. Any help would be greatly appreciated.
Before you do anything add enough parts to use all of the PI you can. Unless I followed your build wrong I got 488 PI. Then once you’ve built it to 500 PI remove the aero until you’re finished tuning otherwise it’ll be hard to feel your changes.
As far as the tune goes the first thing to strike me as odd is that your front springs are over 200 in/lb stiffer than the rear on a car with a 54% front weight distribution.
However now that I’ve driven it, I have noticed a small amount of understeer, however just enough where when you use the gas it’s balanced in a corner. it actually drives quite well IMO. I ran a 1:06 flat on test track, which considering it’s not fully built is pretty good.
What is your assist setup just out of curiosity? Do you run even the braking line?
After looking at the build, I realized that i didn’t list the supercharger upgrade. Its been fixed. Thanks for pointing that out.
With this build the car is 3363 lbs and 57% front weight. Springs are set for balance.
Front 756.8. Rear 571.1. ( 756.8 + 571.1 = 1327.9 ) 1327.9 x .57 = 756.905 for front leaving 570.997 rear.
All assist are off. No race or breaking line. Normal steering. I have been driving this way since forza 3. I assume you are referring to the Airfield Test Track. I just drove it there and ran 1:05.239. Its not a track i do well on so I don’t know if that’s a good time. I always tune on Silverstone Gp. Better track to tune on for a good overall build. It will really highlight problems your having.
1:05 is a pretty brisk time for that track. LB times are at about 1:03 and my fastest cars only hit 1:04. I just noticed that I accidentally added a full roll cage. This brought the weight distribution back to 55% and made it pretty steerable. I think it drives better that way. If you build the stock engine you can get a little bit of weight off and move the weight distribution further back to 53%. I think that might be a better bet.
Try -ve (pointing inward) front toe instead of +ve (pointing outward).
Reason: in corners, the inside tire is unloaded and outside tire is loaded therefore outside has more traction. If the car has -ve front toe, the outside front tire has more traction and it is pointing INTO the corner which helps to point the car towards the apex.
This sorted out my Ford Escort RS nicely. If the car needs more cornering performance, then you can try putting on +ve toe to the rear (+ve toe will encourage the rear to come around faster, inducing oversteer).
Front ride height slightly lower than the rear also helps the car to turn in better.
+1 (get the weight out, even if you reduce other overall performance areas)
Your total spring rate to weight ratio is set to around 39-40%, you can probably go down to the 30-35% range and then split the F/R on %Weight distribution. Swap the Front/Rear ARBs…and, you can still probably go even higher on the rear. Bump is definitely too high…get around the 2-4 range.
EDIT - I have FWD and RWD that you can try out which I posted in a separate thread.
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