Glossary

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There are loads of terms that are used to describe suspension and car technology:

  • Ackermann
  • Camber
  • Caster
  • Roll Centre
  • Scrub
  • Scrub Radius
  • Slip
  • Steering Axis Inclination (SAI) / Kingpin Inclination (KPI)
  • Toe in / Toe Out

So why are they important ?

With donor parts taken from a number of manufacturers, chances are when they are assembled together there is much that can be improved with regards to handling.

How do I know what needs changing?

There are some general rules to follow, but as with many characteristic these rules can be contradicted by different road conditions, vehicle weights, tyre set-ups etc. They are for rough guidance only.

Loose Handling Everywhere

Verdict:  Very Poor

A car with ‘loose handling’ will be very hard to drive, compensations by the driver will do little to help. Much of the set-up may need changing. Stay with the changes that make the most difference.

  1. More front spring rate.
  2. Less rear spring rate.
  3. More sway bar or sway bar load.
  4. Lower the panhard bar.
  5. Less stagger. (circular race track only – involves different tyre diameters)

Tight Handling Everywhere

Verdict:  OK but slow

A car with ‘tight handling’ will be easy to drive but will also be slow on the track. Much of the set-up may need changing. Stay with the changes that make the most difference.

  1. Less front spring rate.
  2. More rear spring rate.
  3. Less sway bar or sway bar load.
  4. Raise the panhard bar.
  5. More stagger. (circular race track only – involves different tyre diameters)

Loose Entry or Loose Cut Zone

Verdict:  Very Poor

A car that has loose handling on entry to a corner will be a handful and may result in lose of speed through the whole bend or ever a spin. It is high priority to fix this.

  1. More front spring rate.
  2. Less rear spring rate.
  3. Less rear weight.
  4. More sway bar or sway bar load.
  5. Less rear brake bias.
  6. Lower the panhard bar.
  7. Less stagger (circular race tracks only).
  8. More front shock compression.
  9. Less rear shock compression.
  10. Less top link angle (less anti squat).
  11. More diagonal weight.
  12. Less trailing arm angle.
    • Left Hand Bend : Right Rear
    • Right Hand Bend : Left Rear
  13. Shorter A-arm.
    • Left Hand Bend : Right Front
    • Right Hand Bend : Left Front
  14. More toe out.
  15. More positive caster.
  16. Add anti dive.

Stable Entry / Tight Cut Zone

Verdict:  OK, but may have high driver involvement

Make smaller adjustments and monitor changes closely.

  1. Less spring.
    • Left Hand Bend : Right Front
    • Right Hand Bend : Left Front
  2. More spring.
    • Left Hand Bend : Left Front
    • Right Hand Bend : Right Front
  3. Raise panhard bar.
  4. More rear spring rate or spring below:
    • Left Hand Bend : Right Rear
    • Right Hand Bend : Left Rear
  5. Less diagonal weight.
  6. More stagger (circular race tracks only).
  7. More front camber if temperatures verify.
  8. Longer A-arm (maybe add static camber at same time).
    • Left Hand Bend : Right Front
    • Right Hand Bend : Left Front
  9. More rear weight.
  10. More caster split.
  11. More rear brake.
  12. Less shock compression.
    • Left Hand Bend : Right Front
    • Right Hand Bend : Left Front
  13. More LR shock rebound.
    • Left Hand Bend : Left Rear
    • Right Hand Bend : Right Rear

Stable Entry / Good Cut Zone / Tight Middle

Verdict:  Poor – The driver can make limited compensations.

Make smaller adjustments and monitor changes closely.

  1. More rear stagger (circular race tracks only).
  2. Raise panhard bar.
  3. Less spring.
    • Left Hand Bend : Right Front
    • Right Hand Bend : Left Front
  4. More spring.
    • Left Hand Bend : Left Front
    • Right Hand Bend : Right Front
  5. More trailing arm angle.
    • Left Hand Bend : Right Rear
    • Right Hand Bend : Left Rear
  6. Less diagonal weight.
  7. More shock rebound.
    • Left Hand Bend : Left Rear
    • Right Hand Bend : Right Rear
  8. Less shock compression.
    • Left Hand Bend : Right Front
    • Right Hand Bend : Left Front
  9. More Ackerman.
  10. More spring.
    • Left Hand Bend : Right Rear
    • Right Hand Bend : Left Rear
  11. More front camber if verified by tyre temperatures.
  12. More caster split.

Stable Entry / Good Cut Zone / Loose Middle

Verdict:  OK – driver can compensate in some conditions.

Make smaller adjustments and monitor changes closely.

  1. Less rear stagger (circular race tracks only).
  2. Lower panhard bar.
  3. Less trailing arm angle.
    • Left Hand Bend : Right Rear
    • Right Hand Bend : Left Rear
  4. More spring.
    • Left Hand Bend : Right Front
    • Right Hand Bend : Left Front
  5. Less spring.
    • Left Hand Bend : Right Rear
    • Right Hand Bend : Left Rear
  6. Less rebound.
    • Left Hand Bend : Left Rear
    • Right Hand Bend : Right Rear
  7. More compression.
    • Left Hand Bend : Right Front
    • Right Hand Bend : Left Front

Stable Entry / Good Cut Zone / Good Middle / Tight Acceleration Zone

Verdict:  OK – driver can make limited compensation in some conditions.

Make smaller adjustments and monitor changes closely.

  1. Less top link angle.
  2. Slightly more stagger (circular race tracks only).
  3. Small raising of panhard bar.
  4. Slightly more trailing arm angle.
    • Left Hand Bend : Right Rear
    • Right Hand Bend : Left Rear
  5. Slightly less diagonal weight.
  6. More shock rebound.
    • Left Hand Bend : Left Front
    • Right Hand Bend : Right Front
  7. More shock rebound.
    • Left Hand Bend : Right Front
    • Right Hand Bend : Left Front
  8. More shock compression.
    • Left Hand Bend : Right Rear
    • Right Hand Bend : Left Rear
  9. Less shock compression.
    • Left Hand Bend : Right Front
    • Right Hand Bend : Left Front
  10. Slightly less spring.
    • Left Hand Bend : Right Front
    • Right Hand Bend : Left Front
  11. Slightly more spring.
    • Left Hand Bend : Right Rear
    • Right Hand Bend : Left Rear

Stable Entry / Good Cut Zone / Good Middle / Loose Acceleration Zone

Verdict:  Poor – High driver involvement

Make smaller adjustments and monitor changes closely.

  1. More top link angle.
  2. Less stagger (circular race tracks only).
  3. Lower the panhard bar.
  4. Less trailing angle.
    • Left Hand Bend : Right Rear
    • Right Hand Bend : Left Rear
  5. More diagonal weight
    • Left Hand Bend : More Left Rear spring. (race cars – Right Rear spring softer than Left Rear spring by 10% +/-.)
    • Right Hand Bend : More Right Rear spring. (race cars – Left Rear spring softer than Right Rear spring by 10% +/-.)
  6. Less shock rebound.
    • Left Hand Bend : Left Front
    • Right Hand Bend : Right Front
  7. Less shock rebound.
    • Left Hand Bend : Right Front
    • Right Hand Bend : Left Front
  8. Less shock compression.
    • Left Hand Bend : Right Rear
    • Right Hand Bend : Left Rear
  9. Less Ackerman.
  10. More spring.
    • Left Hand Bend : Right Front
    • Right Hand Bend : Left Front
  11. Bigger sway bar or more sway bar load.

Stable Entry / Good Cut Zone / Good Middle / Good Acceleration Zone / Tight Exit

Verdict:  Good – In warm conditions with good tyres this can be ideal.

Check handling in all conditions before making small adjustments. Monitor changes closely over a period of time.

  1. Slightly less top link angle.
  2. Slightly more stagger.
  3. Small raising of panhard bar.
  4. Slightly more trailing arm angle.
    • Left Hand Bend : Right Rear
    • Right Hand Bend : Left Rear
  5. Slightly less diagonal.
  6. More shock rebound.
    • Left Hand Bend : Left Front
    • Right Hand Bend : Right Front
  7. More shock rebound.
    • Left Hand Bend : Right Front
    • Right Hand Bend : Left Front
  8. More shock compression.
    • Left Hand Bend : Right Rear
    • Right Hand Bend : Left Rear
  9. Less shock compression.
    • Left Hand Bend : Right Front
    • Right Hand Bend : Left Front
  10. More Ackerman
    • Left Hand Bend : Slightly more Right Rear spring (race cars – Reduce spring split in rear to 5% stiffer Left Rear or to equal rears).
    • Right Hand Bend : Slightly more Left Rear spring (Reduce spring split in rear to 5% stiffer Right Rear or to equal rears).
  11. Slightly less RF spring.
    • Left Hand Bend : Right Front
    • Right Hand Bend : Left Front

Stable Entry / Good Cut Zone / Good Middle / Good Acceleration Zone / Loose Exit

Verdict:  Poor – Slow, loose exit from corners will require high driver involvement.

Make smaller adjustments and monitor changes closely.

  1. More top link angle.
  2. Less stagger (circular race tracks only).
  3. Lower the panhard bar.
  4. Less trailing arm angle.
    • Left Hand Bend : Right Rear
    • Right Hand Bend : Left Rear
  5. More diagonal weight
    • Left Hand Bend : More Left Rear spring. (race cars – Right Rear spring softer than Left Rear spring by 10% +/-.)
    • Right Hand Bend : More Right Rear spring. (race cars – Left Rear spring softer than Right Rear spring by 10% +/-.)
  6. Less shock rebound.
    • Left Hand Bend : Left Front
    • Right Hand Bend : Right Front
  7. Less shock rebound.
    • Left Hand Bend : Right Front
    • Right Hand Bend : Left Front
  8. Less shock compression.
    • Left Hand Bend : Right Rear
    • Right Hand Bend : Left Rear
  9. Less Ackerman
    • Left Hand Bend : More Right Front spring (race cars – If Left Front is stiffer than Right Front think about equal fronts or softer Left Front).
    • Right Hand Bend : More Left Front spring (race cars – If Right Front is stiffer than Left Front think about equal fronts or softer Left Front).
  10. Bigger sway bar or more sway bar load.

Stable Entry / Good Cut Zone / Good Middle / Good Acceleration Zone / Good Exit

Verdict:  Excellent.

Put your spanners away and DRIVE IT!

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Seventh Heaven 16th September 2014

Files

Ford Sierra - Sectioned IRS DWG CAD
Front Suspension Sierra - DWG CAD
Front Suspension Cortina - DWG CAD

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