How to calculate rake angle in MoTec

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what is rake and why should you care?

To put it simply, the rake is the difference between the front and rear height of the car. If you draw a horizontal line below the line created by the floor plane of the car – the angle between those lines is rake angle:

rakeready

Positive rake angle means that back of the car is higher than the front.
A negative rake angle means the front of the car is higher than the back.

A positive rake can create additional downforce but can also make the car more unstable if it’s too big. When a car is on the track, this angle is constantly changing, depending on what is currently happening. For example, when you are breaking – the rear of the car is rising, at the same time increasing the rake angle.

All these changes affect the aerodynamics and downforce of the car. We are mainly interested in moments when rake becomes negative, as then aerodynamics is changing the most, often leading to understeering. I’m going to show you how to use MoTec to calculate our rake angle at any position of the track.

How to get rake angle in moTec:

First, you will need to download my MoTec workspace – all required calculations are already created there.

If MoTec is installed on your computer, just click twice on the downloaded file, and it will ask you if you want to Install the archive:

image 6

Once that is done, you should see new workspace in your MoTec – Adam_ACC – just open it:

image 7

Next, you need to find out what is the suspension travel distance when car is standing still for front and back.
Load lap where you were standing still. (If you changed configuration later, you need to select lap after configuration change).
Press 7 to open Susp trv tab.
Find a place where your car is standing still:

image 2

When Susp trv tab is open – press Ctrl+M to go to Maths editor.

Then, select source “User” and type “Constant“:

image 3

We need to input 5 values to have proper calculation.
Just click 2 times at each value and put proper measurements:

  • sus travel at rest Back – back suspension travel distance when car is standing still – that’s what we have in Susp trv tab.
  • sus travel at rest Front – same as above, but for front suspension.
  • Vehicle Height back – back height of vehicle set in tuning tab in game.
  • Vehicle Height front – same as above, but for front side of vehicle.
  • Vehicle Wheelbase – distance between front and back wheel. I couldn’t find any database with each vehicle wheelbase. I guess we need to find out from other sources.

That’s it! You’re done!

When all that is filled in, you can close the Maths editor, and head back to Susp trv tab.
There will be a graph showing your current rake angle at any position of the track:

image 5

You can also press 9 to go to Negative Rake Report tab, to see where on the map your car has a negative rake angle:

image 4

I hope this will help to make you a better and faster driver!

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