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Roll centre

What is the roll centre and how does it affect handling? · Standard part · basis: Design rules and figures from the cited sources; example geometry by Xem Studio

Also called: roll center, roll centre height, instant centre, rc roll center, roll axis, roll moment, double wishbone roll centre, panhard roll centre, camber link roll center

Exact dimensions. True size, with no printing tolerance added.

sizes
3 in table

Notes

  • The roll centre is the point about which the body rolls on its suspension; on a double-wishbone layout it is found by extending the arms to their instant centre and drawing lines to the contact patches (Formula1-Dictionary; Suspension Secrets).
  • Lower roll centres give more roll; as the suspension compresses the roll centre rises and the roll moment shrinks (Formula1-Dictionary). On a solid axle with a panhard bar, the roll centre is the mid-point of the bar (NC4x4).
  • On RC cars, upper shock-tower link holes lower the roll centre and add corner-entry steering; lower holes raise it for high grip (Tekno).
  • The file is a reference example built by Xem Studio from the numbers above (Reference 1/10 touring car: wheelbase 260 mm (AARCMCC ISTC 250-270), track 190 mm (EFRA width without body), 50 mm = EFRA rim limit.). Sizes the sources do not fix are illustrative; scale the example to your own vehicle.

Roll centre size chart

parametervalue or rangesource
Panhard axle roll centremid-point of panhard rodNC4x4 forum
Roll axis nose-downtends to oversteer; nose-up tends to understeerFormula1-Dictionary
RC upper tower holeslower RC, more entry steeringTekno setup guide

Where the files are

Other publishers' files are linked, not hosted. "verify" = check the license at the link before commercial use.

Formula1-DictionaryRoll centerwebPublisher's page; dimensions are facts
Suspension SecretsSuspension geometry explainedwebPublisher's page; dimensions are facts
NC4x4 forumGeneral 4 Link Suspension Design InformationwebPublisher's page; dimensions are facts
Tekno RCTekno RC Setup GuidewebPublisher's page; dimensions are facts
CompetitionXRC Quick Setup GuidewebPublisher's page; dimensions are facts

Free files

★ Free files 1 parts. Xem Studio design: free to use, print and sell things from; not to be republished as files. Xem Studio Design License. index.json

roll-centre-geometryroll centre demo: front axle, track 190 mm, Ø50 tyres, 0° (illustrative layout)STEP · STL
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Plain text: sheet.txt · JSON: /api/geometry?object=roll-centre

Roll centre, isometric render of a generated part
Render of roll-centre-geometry from the free STEP; not to scale.

Fits with

Camber angle, isometric render of a generated part
Camber angle4 sizes★ 1 file
Caster angle, isometric render of a generated part
Caster angle5 sizes★ 1 file
Front kick-up (RC), isometric render of a generated part
Front kick-up (RC)4 sizes★ 1 file
Front toe (toe-in / toe-out), isometric render of a generated part
Front toe (toe-in / toe-out)3 sizes★ 1 file
Rear toe-in, isometric render of a generated part
Rear toe-in3 sizes★ 1 file
Ackermann steering geometry, isometric render of a generated part
Ackermann steering geometry4 sizes★ 1 file

Questions

Why raise the roll centre?

Less roll and quicker response; Tekno uses lower tower holes (higher roll centre) on high-grip tracks.