Camber question

[leorest]

I have the capability to measure camber angle accurately in degrees.

I have been told that castor is calculated from two camber measurements…
A) with the wheel turned 20 degrees left and
B) with the wheel turned 20 degrees right.

So far, so good.

My question is…
What is the equation?
I have been told that it is as simple as subtracting one from the other but what confuses me is that I have seen camber/castor gauges that have different scales, implying that there is some further calculation.
I was expecting to use trig.

Any recommendations of books or web sites covering suspension geometry mathematics for dummies?

Leo

[madrabbit]

One book you could try is, the Race and Rally source book, which has calculations in abundance for working out such things as Castor/camber, kingpin inclination, spring rates and other mind boggling, magical, mystical and mythical calculations.

[leorest]

madrabbit said:

One book you could try is, the Race and Rally source book, which has calculations in abundance for working out such things as Castor/camber, kingpin inclination, spring rates and other mind boggling, magical, mystical and mythical calculations.

Thanks for that.
I'll get it the next time i'm ordering from Amazon.

I've been thinking about the method of calculating castor by subtracting A) camber at stearing 20 deg left from B) camber at stearing 20 deg right.
This must be an approximation.
It will only be true if the castor angle is zero i.e. A=B
If the castor angle was 90deg then...
A=20 B=-20 so A-B=40 error of 50deg!

As castor angles are normally nearer to zero than 90 It probably is a reasonable approximation with insignificant error but as I'm making a spreadsheet to do the maths I may as well do it right.

Anyone out there done this maths at school?
Leo

[leorest]

OK
I think I've researched the answer for this on the internet.
After reading this... www.hunter.com/pub/undercar/2573T/index.htm
I've come to the conclusion that this formula is close enough.

Caster(deg)=(180/3.1415)*[(camber1-camber2)/(turnangle2-turnangle1)]

Also found this interesting...
www.quadesl.com/miata_alignment.shtml

If anyone out there is interested I made a spreadsheet to do the maths. Email me via profile if you want it.
Leo


>> Edited by leorest on Thursday 6th January 13:43