Adding Weights prior to performing geometry and toe effect?

[NickT]

Tony

 

I've wondered why some manufacturers specify adding weights to the drivers seats or footwells of equal weight ie 70kg per side, when most of the time only a driver is in the car. What effect would this have to the geometry then if the mass of the driver was just added to the car and then the geometry done?

 

I'm curious as it alters the toe position and front to rear thrust angle on my vectra from unladen to when I sit in it (steering wheel clamped and brake pedal held down with a tool) I finish up changing the geometry with the boot empty and half tank of fuel so that when I am in the car the camber on all wheels and rear to front thrust angle c is zero and front to rear thrust angle is zero etc. I'm a bit obsessive about accuracy so I'd like to hear your opinion on this.

 

Thank you in advance

[Tony]

Nearly all German cars require ballast in order to get the suspension at mid point. The target datum has assumed this has been done but sadly most places don't have or add ballast.

 

Since every geometry is the manufacturers best guess it's the best overall target but it's not error free.  The only time i add additional weight is for competition cars where i add the exact human weight. Outside of the German arena i subliminally interview the driver if he/ she is of generous build and i take additional steps to compensate.

 

What is a surprise when only the driver is in the car is the upper parallelogram moves diagonally meaning the OSF camber just lowers ( no real gain ) but the NSF camber moves more negative.

[jammy]

I shall show them this too when I go back ?

[Tony]

Call their bluff and look around to see any weights?...We use keep fit weights but some use containers full of something like lead or even cement.

[jammy]

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