Note: high-speed instability in RR cars is a known challenge — especially in older or less aerodynamically advanced models like classic Porsche 911s or rally-style RR cars (Renault Maxi 5 Turbo).

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When it happens most often:

• Over crests or bumps at speed

• During high-speed direction changes

• Under full throttle with aero lift

• When braking hard at high speeds

 

Causes

 

1. Rearward Weight Bias

• engine sits behind the driver - less weight over the front - makes rear heavy and reactive

• at high speeds, the front can feel too light, especially under acceleration.

 

2. Light Front Axle

• reduces steering stability - front may wander or feel vague

 

3. Aero Imbalance

• too much rear downforce vs. front causes front-end lift

• too little rear downforce causes yaw instability or tail wiggle.

 

4. Suspension Stiffness / Softness

• too soft front - floaty steering

• too stiff rear - nervous on bumps, especially in fast corners

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Fixes

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• increase forward brake bias (Helps stabilize the car during high-speed deceleration by preventing rear-end lightness or rotation)

• increase front aero (keeps the front planted for high speed stability / steering)

• rear aero - balance - don't increase too much (keeps rear planted without overpowering front)

• stiffen front springs (prevents excessive lift and roll at speed and improves directional stability)

• stiffen front damper compression (improves responsiveness and stability at high speed)

• stiffen front damper rebound (stabilizes steering especially over crests and under braking)

• slightly soften rear damper rebound (reduces rear bouncing / twitchiness and keeps more stable / planted at high speed)

• slightly stiffer front ARB (adds front end stability)

• increase front negative camber (to increase grip on cornering and maintains front end control)