Difference between revisions of "Geo Setups"
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Some starter guidelines although its really really complex stuff and dependent on many other factors; | Some starter guidelines although its really really complex stuff and dependent on many other factors; | ||
− | Increasing front camber from the default -0.1° to -0.5° each side will dramatically improve the | + | Increasing front camber from the default -0.1° to -0.5° each side will dramatically improve the understeer, although the inside edges of the tyres will wear slightly faster. Increasing past -1.0° is great for high speed corners but will compromise low speed cornering, will reduce breaking effectiveness and it will tramline on the road. |
Increasing rear camber from the default -1.8° to -2.0° (or higher) makes the car more neutral after you've removed the under steer. | Increasing rear camber from the default -1.8° to -2.0° (or higher) makes the car more neutral after you've removed the under steer. |
Revision as of 12:14, 9 October 2006
Some standard Geo settings
Geometry | Standard S1 & S2 | S2 135R | 340R Road | 340R Track | Exige S1 | Msport |
Ride Height F/R | 130/130mm | 120/120mm | 100/110mm | 100/110mm | 112/122mm | 100/110mm |
Steering axis inclination | 12° | 12° | 12° | 12° | 12° | 12° |
Front Castor | +3.8° | +3.7° | +3.8° | +3.8° | +3.8° | +3.8° |
Front Camber | -0.1° | 0° | -0.5° | -1.8° | -0.5° | -0.3° |
Front alignment/toe | 0.2mm OUT Overall | 0 mm | 0.2mm OUT overall | 0.5mm OUT overall | 0.1mm OUT overall | 0.2mm OUT overall |
Rear Camber | -1.8° | -1.8° | -2.0° | -2.7° | -2.4° | -2.0° |
Rear alignment/toe | 1.2mm IN each side | 1.2mm IN each side | 1.5mm IN each side | 2.5mm IN each side | 1.2mm IN each side | 1.2mm IN each side |
Bump Steer | 2.0° to 2.5° toe in |
converting from mm to degrees; divide the toe in mm by the wheel rim diameter in mm then ARC SIN the answer
Geo setting X does Y
Some starter guidelines although its really really complex stuff and dependent on many other factors;
Increasing front camber from the default -0.1° to -0.5° each side will dramatically improve the understeer, although the inside edges of the tyres will wear slightly faster. Increasing past -1.0° is great for high speed corners but will compromise low speed cornering, will reduce breaking effectiveness and it will tramline on the road.
Increasing rear camber from the default -1.8° to -2.0° (or higher) makes the car more neutral after you've removed the under steer.
Increasing front toe in helps with the sharpness of the turn-in
Increasing rear toe out cancels out the rear suspension flex when the tyre is loaded which leads to toe out - so running more toe in compensates for that - you don't want toe out at the rear.
Setting your own geo
Whilst a race prep specialist can charge £200 for a Geo you can DIY castor, camber and toe settings.
1. To baseline your current setup www.alignmycar.co.uk will find a local place with a Hunter alignment system who will provide a setup sheet showing castor, camber and toe for £15
2. If you dont have the S1 or S2 service manual suspension sections you really should get them as this is only a small part; http://www.sandsmuseum.com/cars/elise/experience/maintenance/alignment/alignment.html
3. Set the front castor by "shuffeling washers" on the top wishbone pivots (caster is not actually that important).
4. Set the front and rear camber by adding & removing shims; removing a 1mm shim plate will alter camber by approximately -0.25° at the front and -0.30° at the rear (see above for camber effects).
5. You could set the toe yourself, but since a quarter turn of the track rod alters toe by 2mm its a damned delicate affair without a real time readout (toe settings are cirtical for handling).
6. Back to the alignment centre to check your config for another £15 and set your front and rear toe for another £30. You can now alter the camber without materially affecting toe.
MEMO: Someone else can explain how to create a DIY geo rig and set bump steer !