21 replies to this topic

[Nev]

The first thing to do is datum your drive. Mark your tyre locations with something like blue tack. Then drive away. Now use a 2.5m straight edge and spirit level between the 4 contact spots (marked by blue tack) and fit pieces of plywood or some such to level it. Then drive the car back onto the plywood and you are starting from a flat base.

 

You should also use a similar principle to work out your offsets for the chassis height vs driveway height so you can add/subtract this from your readings.

 

GL. Once you've done it once you realise how easy it is.

 

[Arno]

Don't forget that the 'book' values for toe/camber/caster for VX/Speedsters and Elises are all based on a car with:

 

- 75 Kg ballast in each seat

- 1/2 tank of fuel

 

Or  (on standard Bilstein suspension) it needs to be strapped down and ratcheted down to reach 130mm under the chassis beams.

 

Alignment machines like Hunters WILL note this ballast or ride requirement fact on their displays when selecting an Elise or VX/Speedster before starting the geo.

 

It's quite possible to maintain and set the values without doing this, but the absolute geo values between a ballasted and un-ballasted car can't be compared as the changes fromt he ballast in ride height will depend on the amount of bumpsteer and wishbone angles.

 

You do not need to ballast the car to set toe, but it will be on a different part of the bumpsteer curve, so you will need to adjust accordingly if you want to reach the 'book' values or may need to experiment more to find your sweet-spot handling-wise.

 

Oh.. And yeah.. This also means that if your car was geo'd following the procedures and you drive it with only one person then the passenger side will be a little 'off' from the driver's side. For this reason people who track their car often tend to have it geo'd with their (exact) weight in the driver's seat and depending on their preference more or less fuel (depending on the behaviour change you like better as fuel amount gets less and it gets lighter in the back)

 

Bye, Arno.