Caster Angle

[4x4rancher]

Thanks Dai. bit of a misunderstanding there, I wish to know the Datum, the fixed point from which the angles are taken.

[Ernest T Bass]

Bill, I dont know if this helps but its what MB have to say on castor value.

[4x4rancher]

It would seem then that castor angle is not easily measured,
This is how I was taught.
Castor angle results from steering axis incline,so the measured camber angle changes over a measured range of steering angles as the wheel is turned.
Thus measuring the change in camber angle over a measured range of steering angles allows calculation of the castor angle.
For each front wheel measure the camber angle at centre and 2 extremes of steering, mark a line on the workshop floor parallel with the wheel at each position. This allows an accurate measure of the steering angle.
The formula is then.
(180/pi) x (camber 1 - camber 2)/(steer 1 - steer 2)
The castor angle is the difference between the camber angle at the steer points.

[bwillie]

Thanks for all the good information guys!
The plan is to use an adjustable link end so it can be "tweeked" as needed to get things a close to stock as possible once they are installed. I will post pictures once it is completed, along with how it turned out in regards to perfomance.

[Hipine]

Kingpin inclination is the word used to describe camber in a solid axle. It's the angle that the steering axis is away from vertical as measured in a plane that is vertical and parallel to the axle shaft (like the front grille) To see camber, or kingpin inclination, you have to look at the kingpin from the FRONT of the vehicle and it'll usually be tipped inward at the top.

Caster (with an "E", not an "O" please.[:)]) is the angle that the steering axis is away from vertical in a plane that is perpendicular to the axle shaft (like the side door). To see caster you need to look at the kingpin from the SIDE of the vehicle and you'll usually see it tipped rearward at the top.

You're right, 4x4rancher. Caster can be measured as the difference between the camber measurements at each end of steering travel. I don't know why it works, and didn't want to think about it, but the instructions that came with the camber gauge I have say it can be done that way, and I've trusted those and found it to work just the way you describe. Sometimes that's enough. [:)]

A good rule of thumb to use with the G (works with LRs too due to similar front radius arm length) is that as you move the axle away from the chassis, like you do with a spring lift, you loose about 1/2 degree of caster for each inch of lift (same change occurs in pinion angle). Use the method of your choice to restore caster at that rate to get you back where you came from.

But as Karl points out, steering "feel" will be influenced by a LOT of things that all effect how much force the ground exerts on the tire in the opposite direction to vehicle travel, so just restoring the lost caster may not be the "most best" thing to do if you've also significantly changed rolling radius and tire centerline offset in your mods.

Since I touched on pinion angle earlier.... Especially with big lifts (like 6") on short wheelbase vehicles, it's often desirable to change caster and pinion angle by different ammounts. The only way to do this on the G is to cut and weld, or custom fab, the axle casing.

Good luck!

-Dave G.

[4x4rancher]

[quote]Hipine - 6/29/2005 2:29 PM
Caster (with an "E", not an "O" please.[:)])
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I'm not even going to rise to it,but on the 200th aniversery of the battle of Trafalgar you are going to correct my English, I think not. you will be telling me next that tyre is wrong.
Gadzoucks you knave.

QUOTE
Collons English Dicyionary and Hutchinson Encyclopaedia.

Caster: as applied to suger sprinkled on confectionery
Castor: as applied to a small wheel attached to furniture for ease of moving. or Castor oil as used in medicines and blending Castrol motor oils.
You make your own mind up what it is on a G Wagen.

[Ernest T Bass]

[quote]4x4rancher - 6/29/2005 5:58 PM

Hipine - 6/29/2005 2:29 PM
Caster (with an "E", not an "O" please.[:)])
------------------------------------------------------
I'm not even going to rise to it,but on the 200th aniversery of the battle of Trafalgar you are going to correct my English, I think not. you will be telling me next that tyre is wrong.
Gadzoucks you knave.

well since we are talking in English: the clue here is in the name [}:)][}:)]

Castor - wheel like device that helps you move the bed
Caster - a kind of fine sugar
Castor oil - .........[}:)][}:)]

You beat me to it Bill: but why is it still called English?
[:D]

[4x4rancher]

Proof positive.

[Dai]

Hipine, you seem to have struck a nerve.

-Dai

[Hipine]

4x4rancher - 6/29/2005 12:58 PM
....on the 200th aniversery of the battle of Trafalgar....

What's that got to do with the price of tea in....oh wait, sorry, another bad colonial-cum-aquatic metaphor.[:)]

But I mean, it's not like I'm asking you to call it "roulette", or "echador".

Besides, you can't tell me you're celebrating all YEAR! I thought it was October by the time Nelson got himself turned the right way 'round to ram old Villy's skiff?

You know me, nothing but big yellow smileys here. [:)] and the fullest respect for the traditions of my ancestors.

But as long as we're quoting dictionaries,
http://encarta.msn.com/dictionary_/caster.html

All the best, mates,

-Dave G.