Geo Setups

Geometry	Ride Height Front/Rear	Front			Rear
		Castor	Camber	Toe	Camber	Toe	Bump Steer
Standard S1 & S2	130/130mm	+3.8°	-0.1°	0.2mm OUT Overall	-1.8°	1.2mm IN each side
S2 135R	120/120mm	+3.7°	0°	0mm	-1.8°	1.2mm IN each side
340R Road	100/110mm	+3.8°	-0.5°	0.2mm OUT Overall	-2.0°	1.5mm IN each side	2.0° to 2.5° toe in
340R Track	100/110mm	+3.8°	-1.8°	0.5mm OUT Overall	-2.7°	2.5mm IN each side
Exige S1	112/122mm	+3.8°	-0.5°	0.1mm OUT Overall	-2.4°	1.2mm IN each side
Msport	100/110mm	+3.8°	-0.3°	0.2mm OUT Overall	-2.0°	1.2mm IN each side
Non-Standard Geo Settings
hbaumhardt S2 race	104/114mm	+3.6°	-1.4°	1 mm OUT overall	-2.6°	2mm IN each side

The standard settings are used when car is loaded with 2x75kg passengers and half tank of fuel.

Converting toe from mm to degrees:

1. Measure the rim diameter in mm as the size e.g. 17" is not the actual diameter your measurements are based on.
2. Multiply the result by PI to get the circumference.
3. Divide the result by 360 to get mm per degree.
4. Divide the toe mm by the mm/degree result to get toe in decimal degrees

Or Excel =DEGREES( ASIN( TOE_IN_MM / ( RIM_DIA_INCHES * 25.4 )))

Or use the calculator on this page, hypotenuse is the rim diameter the toe per wheel (total toe divided by 2) in mm is width (or toe in degrees is angle A). * http://joyfulcoder.net/sohcahtoa/

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 can 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 with front camber. Look at the rations on the standard settings and maintain the front/rear delta.

Front toe affects stability or responsiveness of turn in. Front Toe out (standard) makes the car more responsive turn in but causes additional drag in straights. Front toe in is more stable in straight line.

Rear Toe controls the stability of the rear through the corner. Rear toe in (standard) makes the car more stable and apparently the elise toes in more at the rear as the suspension compresses. Rear toe out causes the rear to steer out from the corner, reducing stability.

Factors affecting Geo

When asking questions about "the best geo for ..." the following need to be considred so make an effort to specify;

What you are using the car for (road, sprint race, endurance race) Tyre spec (section & compound) Spring rates Damper settings Ride height Current Geo settings Perceived problems with current setup

Setting your own geo

Whilst a race prep specialist can charge £200 for a Geo you can DIY castor, camber and toe settings. With a lot of variability in quality at alignment centres (and Lotus dealers !) for the best results put the effort in yourself and build a string based alignment rig which can be more accurate than a computerised laser system. To make a DIY geo/alignmnet rig see:Geo Alignment Rig (Home Made)

1. The Hunter computerised laser alignment system is one of the best (the variabiltiy is quality of the operator) http://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 (probably in dd:mm:ss rather than decimal degrees) for £15 and can set the front and rear toe for another £30.

2. If you are going to DIY you must have the relevant S1 or S2 service manual suspension sections. Setting castor and camber is straightforward as a caster washer and camber shim have fixed values, whereas toe is delicate - which way do you wind the flats and a quarter turn of the track rod can alter the toe by 2mm (e.g. just tightening the locknuts).

Absolutley critical to getting a good geo is having the right ballaat in the seats e.g. for a 780Kg race Elise the difference between empty and an 85Kg driver is 5mm ride height, 0.2° camber and 1mm toe. (Depending on Spring rates used) Don't let your alignment place guess the ballast

See Also

• http://forums.seloc.org/viewthread.php?tid=52913 - The pole & string thread by Randy
• http://forums.seloc.org/viewthread.php?tid=49382
• http://forums.seloc.org/viewthread.php?tid=106461