Xem Studiomeasured geometry

Library › Car design › Suspension geometry ·

Reverse (anti-) Ackermann

Why do some race cars use anti-Ackermann steering? · Standard part · basis: Design rules and figures from the cited sources; example geometry by Xem Studio

Also called: anti ackermann, reverse ackermann, parallel steer, anti-ackermann race car, negative ackermann, ackermann percentage, slip angle steering, parallel steering geometry

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

sizes
2 in table

Notes

  • At high cornering speed the outside front tyre carries more load and wants a larger slip angle, so pure Ackermann is not ideal. Some racing cars use reverse Ackermann to offset the slip-angle difference, which cuts tyre temperatures in fast corners but hurts low-speed performance (Wikipedia).
  • On RC cars, less Ackermann gives smoother turn-in, more mid-corner stability and more even front tyre wear (CompetitionX).
  • 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.

Reverse (anti-) Ackermann size chart

parametervalue or rangesource
Reverse Ackermann usehigh-speed corners; worse at low speedWikipedia
Less Ackermann (RC)smoother turn-in, more stable, even tyre wearCompetitionX

Where the files are

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

WikipediaAckermann steering geometrywebPublisher's page; dimensions are facts
CompetitionXRC Ackermann Steering ExplainedwebPublisher'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

anti-ackermann-geometryAckermann demo: inner wheel 30°, outer wheel per the Ackermann relation for wheelbase 260, track 190 (illustrative layout)STEP · STL
Let your AI pull this. Add https://xemstudio.com/mcp to Claude, ChatGPT, Cursor or any MCP client (free, no account, one minute) and it can look up exact sizes, mating fits and free STEP/STL from every chat.
Set it up →

Plain text: sheet.txt · JSON: /api/geometry?object=anti-ackermann

Reverse (anti-) Ackermann, isometric render of a generated part
Render of anti-ackermann-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

Is parallel steer the same as anti-Ackermann?

Parallel steer sits between the two; the sources describe reduced and reverse Ackermann for high-speed cornering.