Difference between revisions of "Geo Setups"

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== Some standard Geo settings ==
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== Standard Setups ==
  
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<table x:str border=0 cellpadding=0 cellspacing=0 width=655 style='border-collapse:
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===Elise/Exige===
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collapse;table-layout:fixed;width:493pt'>
+
 
−
<tr height=17 style='height:12.75pt'>
+
{| border=1 cellpadding=5 align=center
−
  <td height=17 class=xl24 width=158 style='height:12.75pt;width:119pt'>Geometry</td>
+
|- style="background-color:#fed200; face:bold;"
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  <td class=xl25 width=122 style='width:92pt'>Standard S1 &amp; S2</td>
+
| rowspan=2 | Geometry || rowspan=2 | Ride Height<br />Front/Rear || colspan=3 align=center | Front || colspan=2 align=center | Rear
−
  <td class=xl25 width=125 style='width:94pt'>S2 135R</td>
+
|- style="background-color:#fed200;"
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  <td class=xl25 width=125 style='width:94pt'>340R Road</td>
+
| Castor || Camber || Toe [Degrees] || Camber || Toe [Degrees]
−
  <td class=xl25 width=125 style='width:94pt'>340R Track</td>
+
|-
−
</tr>
+
| Standard S1 & S2 || 130/130mm || +3.8° || -0.1° || 0.2mm OUT Overall [-0.03°] || -1.8° || 1.2mm IN each side [0.16°]
−
<tr height=17 style='height:12.75pt'>
+
|-
−
  <td height=17 class=xl26 style='height:12.75pt'>Ride Height F/R</td>
+
| S2 135R          || 120/120mm || +3.7° || 0°    || 0mm [0.00°]              || -1.8° || 1.2mm IN each side [0.16°]
−
  <td class=xl27>130/130mm</td>
+
|-
−
  <td class=xl27>120/120mm</td>
+
| 340R Road        || 100/110mm || +3.8° || -0.5° || 0.2mm OUT Overall [-0.03°] || -2.0° || 1.5mm IN each side [0.20°]
−
  <td class=xl27>100/110mm</td>
+
|-
−
  <td class=xl27>100/110mm</td>
+
| 340R Track      || 100/110mm || +3.8° || -1.8° || 0.5mm OUT Overall [-0.07°]|| -2.7° || 2.5mm IN each side [0.33°]
−
</tr>
+
|-
−
<tr height=17 style='height:12.75pt'>
+
| Exige S1        || 112/122mm || +3.8° || -0.5° || 0.1mm OUT Overall [-0.01°]|| -2.4° || 1.2mm IN each side [0.16°]
−
  <td height=17 class=xl26 style='height:12.75pt'>Steering axis inclination</td>
+
|-
−
  <td class=xl27>12°</td>
+
| Exige S2        || 130/130mm || +3.8° || -0.3° || 0mm [0.00°]              || -1.8° || 1.5mm IN each side [0.20°]
−
  <td class=xl27>12°</td>
+
|-
−
  <td class=xl27>12°</td>
+
| Exige 240R      || 120/120mm || +3.8° || -0.3° || 0mm [0.00°]              || -1.8° || 1.5mm IN each side [0.20°]
−
  <td class=xl27>12°</td>
+
|-
−
</tr>
+
| Exige V6 Cup      || 130/136mm || +2.8° || -0.4° || 0.4mm OUT Overall mm [-0.06°]              || -1.9° || 2.5mm IN each side [0.30°]
−
<tr height=17 style='height:12.75pt'>
+
|-
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  <td height=17 class=xl26 style='height:12.75pt'>Front Castor</td>
+
| Exige 380/410/430 Cup  || 130/136mm || +2.8° || -0.8° || x.xmm OUT Overall mm [-0.12°]              || -2.10° || x,xmm IN each side [0.6°]
−
  <td class=xl27 x:str="'+3.8°">+3.8°</td>
+
|-
−
  <td class=xl27 x:str="'+3.7°">+3.7°</td>
+
| 111R            || 130/130mm || +3.8° || -0.1° || 0mm [0.00°]              || -1.8° || 1.2mm IN each side [0.16°]
−
  <td class=xl27 x:str="'+3.8°">+3.8°</td>
+
|-
−
  <td class=xl27 x:str="'+3.8°">+3.8°</td>
+
| 211              || 100/110mm || +4.0° || -1.4° || 0mm [0.00°]              || -2.5° || 1.2mm IN each side [0.16°]
−
</tr>
+
|-
−
<tr height=17 style='height:12.75pt'>
+
| Msport          || 100/110mm || +3.8° || -0.3° || 0.2mm OUT Overall [-0.03°] || -2.0° || 1.2mm IN each side [0.16°]
−
  <td height=17 class=xl26 style='height:12.75pt'>Front Camber</td>
+
|-style="background-color:#fed200;"
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  <td class=xl27 x:str="'-0.1°">-0.1°</td>
+
| colspan=7 | Non-Standard Geo Settings
−
  <td class=xl27>0°</td>
+
|-
−
  <td class=xl27 x:str="-0.5° "><span lang=EN-GB>-0.5°<span
+
| a forum hero S2 race || 110/115mm || +3.6° || -2.0° || 0.5 mm OUT each side [-0.07°] || -3.0° || 1 mm IN each side [0.13°]
−
  style='mso-spacerun:yes'> </span></span></td>
+
|}
−
  <td class=xl27 x:str="'-1.8° "><span lang=EN-GB>-1.8°<span
+
 
−
  style='mso-spacerun:yes'> </span></span></td>
+
The standard settings are used when car is loaded with 2x75kg passengers and half tank of fuel.
−
</tr>
+
 
−
<tr height=17 style='height:12.75pt'>
+
===Evora===
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  <td height=17 class=xl26 style='height:12.75pt'>Front alignment/toe</td>
+
 
−
  <td class=xl27 x:str="'0.2mm OUT Overall">0.2mm OUT Overall</td>
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{| border=1 cellpadding=5 align=center
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  <td class=xl27>0 mm</td>
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|- style="background-color:#fed200; face:bold;"
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  <td class=xl27>0.2mm OUT overall</td>
+
| rowspan=2 | Geometry || rowspan=2 | Ride Height<br />Front/Rear || colspan=3 align=center | Front || colspan=2 align=center | Rear
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  <td class=xl27>0.5mm OUT overall</td>
+
|- style="background-color:#fed200;"
−
</tr>
+
| Castor || Camber || Toe || Camber || Toe
−
<tr height=17 style='height:12.75pt'>
+
|-
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  <td height=17 class=xl26 style='height:12.75pt'>Rear Camber</td>
+
| Standard || 125/147mm || +5.2° || -0.3° || 0mm || -1.6° || 1.5mm IN each side
−
  <td class=xl27 x:str="'-1.8°">-1.8°</td>
+
|-
−
  <td class=xl27 x:str="'-1.8°">-1.8°</td>
+
|}
−
  <td class=xl27 x:str="'-2.0° "><span lang=EN-GB>-2.0°<span
+
 
−
  style='mso-spacerun:yes'> </span></span></td>
+
 
−
  <td class=xl27 x:str="'-2.7° "><span lang=EN-GB>-2.7°<span
+
Converting toe from mm to degrees:
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  style='mso-spacerun:yes'> </span></span></td>
+
 
−
</tr>
+
# Measure the rim diameter in mm as the size e.g. 17" is not the actual diameter your measurements are based on.
−
<tr height=17 style='height:12.75pt'>
+
# Multiply the result by PI to get the circumference.
−
  <td height=17 class=xl26 style='height:12.75pt'>Rear alignment/toe</td>
+
# Divide the result by 360 to get mm per degree.
−
  <td class=xl27 x:str="'1.2mm IN Overall">1.2mm IN each side</td>
+
# Divide the toe mm by the mm/degree result to get toe in decimal degrees
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  <td class=xl27>1.2mm IN each side</td>
+
 
−
  <td class=xl27>1.5mm IN each side</td>
+
 
−
  <td class=xl27>2.5mm IN each side</td>
+
Or Excel =DEGREES( ASIN( TOE_IN_MM / ( RIM_DIA_INCHES * 25.4 )))
−
</tr>
+
 
−
<tr height=17 style='height:12.75pt'>
+
−
  <td height=17 class=xl26 style='height:12.75pt'>Bump Steer</td>
+
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/
−
  <td class=xl27></td>
 
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  <td class=xl27>2.0° to 2.5° toe in</td>
 
−
  <td class=xl28></td>
 
−
  <td class=xl27></td>
 
−
</tr>
 
−
<tr height=0 style='display:none'>
 
−
  <td width=158 style='width:119pt'></td>
 
−
  <td width=122 style='width:92pt'></td>
 
−
  <td width=125 style='width:94pt'></td>
 
−
  <td width=125 style='width:94pt'></td>
 
−
  <td width=125 style='width:94pt'></td>
 
−
</tr>
 
−
</table>
 
−
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 ==
 
== Geo setting X does Y ==
−
Some guidlines although its dependent on many, 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 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 braking effectiveness and it will tramline on the road.
  
−
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 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 ratios on the standard settings and maintain the front/rear % delta.
  
−
Increasing rear camber from the default -1.8° to -2.0° (or higher) makes the car more neutral after you've removed the understeer.
+
* 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.
  
−
Increasing front toe helps with the sharpness of the turn-in
+
* 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.
  
−
Increasing rear toe cancells 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.
+
== Factors affecting Geo ==
 +
When asking questions on the forums 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 spec and settings
 +
* Ride height
 +
* Current Geo settings
 +
* Perceived problems with current setup
  
 
== Setting your own geo ==
 
== Setting your own geo ==
−
Whilst a race prep specialist can charge £200 for a Geo you can DIY castor, camber and toe settings.
+
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. 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
+
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 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.
+
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).
  
−
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).
 
  
−
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.
+
'''Absolutley critical to getting a good geo is having the right ballast 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'''
  
−
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.
+
==See Also==
 +
* http://arc.seloc.org/viewthread.php?tid=52913 - The pole & string thread by Randy
 +
* http://arc.seloc.org/viewthread.php?tid=49382
 +
* http://arc.seloc.org/viewthread.php?tid=106461
 +
* http://forums.pelicanparts.com/porsche-911-technical-forum/581498-stringless-wheel-alignment-diyers.html
  
−
MEMO: Someone else can explain how to create a DIY geo rig and set bump steer !
+
[[Category:Suspension]]
 +
[[Category:Lotus Elise]]
 +
[[Category:S1]]
 +
[[Category:S2]]
 +
[[Category:Lotus 2-Eleven]]
 +
[[Category:S2 Exige]]
 +
[[Category:Lotus Europa]]
 +
[[Category:Lotus Evora]]
 +
[[Category:VX220]]

Latest revision as of 13:44, 4 August 2023

Standard Setups

Elise/Exige

Geometry Ride Height
Front/Rear		 Front Rear
Castor Camber Toe [Degrees] Camber Toe [Degrees]
Standard S1 & S2 130/130mm +3.8° -0.1° 0.2mm OUT Overall [-0.03°] -1.8° 1.2mm IN each side [0.16°]
S2 135R 120/120mm +3.7° 0° 0mm [0.00°] -1.8° 1.2mm IN each side [0.16°]
340R Road 100/110mm +3.8° -0.5° 0.2mm OUT Overall [-0.03°] -2.0° 1.5mm IN each side [0.20°]
340R Track 100/110mm +3.8° -1.8° 0.5mm OUT Overall [-0.07°] -2.7° 2.5mm IN each side [0.33°]
Exige S1 112/122mm +3.8° -0.5° 0.1mm OUT Overall [-0.01°] -2.4° 1.2mm IN each side [0.16°]
Exige S2 130/130mm +3.8° -0.3° 0mm [0.00°] -1.8° 1.5mm IN each side [0.20°]
Exige 240R 120/120mm +3.8° -0.3° 0mm [0.00°] -1.8° 1.5mm IN each side [0.20°]
Exige V6 Cup 130/136mm +2.8° -0.4° 0.4mm OUT Overall mm [-0.06°] -1.9° 2.5mm IN each side [0.30°]
Exige 380/410/430 Cup 130/136mm +2.8° -0.8° x.xmm OUT Overall mm [-0.12°] -2.10° x,xmm IN each side [0.6°]
111R 130/130mm +3.8° -0.1° 0mm [0.00°] -1.8° 1.2mm IN each side [0.16°]
211 100/110mm +4.0° -1.4° 0mm [0.00°] -2.5° 1.2mm IN each side [0.16°]
Msport 100/110mm +3.8° -0.3° 0.2mm OUT Overall [-0.03°] -2.0° 1.2mm IN each side [0.16°]
Non-Standard Geo Settings
a forum hero S2 race 110/115mm +3.6° -2.0° 0.5 mm OUT each side [-0.07°] -3.0° 1 mm IN each side [0.13°]

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

Evora

Geometry Ride Height
Front/Rear		 Front Rear
Castor Camber Toe Camber Toe
Standard 125/147mm +5.2° -0.3° 0mm -1.6° 1.5mm IN each side


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 braking 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 ratios 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 on the forums 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 spec and 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 ballast 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

See Also

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