Gravesdiggerxj
NAXJA Forum User
- Location
- Salt Lake City, Utah
I added this here to help repay all the tech I've used here on
:kissyou:Here is another good resource I wrote for explaining caster, Specifically in reference to the Ford Style Radius arms with a "C" style bushing. :read:
Caster angle helps determine how quickly a vehicles steering returns to center and how easily it turns:
Less caster usually means it is easier to turn but steering doesn't recover from bumps or return to center as easily.
Most "E-knowledge" is agreed that between 5*-7* of caster is ideal for Ford, IH, Chevy, etc or Jeep 4x4's with Dana front axles.
One good way I visualize caster is to imagine a bicycle front fork: it tilts backwards: this is your kingpin angle or caster angle as shown in the bottom most picture.
As this angle increases the wheel stays straight easier and is more difficult to turn (like a chopper)
. As it decreases it becomes easier to turn but has less stability (like the front wheels on a shopping cart).
With Radius arm style suspension as the axle descends (droops) the caster angle actually changes i.e. decreases, which is ok in slow speed environments such as rock crawling but can cause strangle handling at high speeds.
This is why when a vehicle is lifted it is essential to adjust the caster angle because the axle is pushed away from the body. This usually moves the wheel backward in the wheel well and causes the caster angle to decrease... thus increasing the potential to "death wobble". :explosion
Additionally Pinion angle usually decreases as caster angle increases so it is essential to find a good balance between caster and pinion (especially on late model Jeeps without unlocking hubs). Too little pinion angle can cause driveline vibrations. :nono:
Additionally as a vehicle is lifted the radius arm angle (or control arms angles) are increased causing road noise, bumps, cracks, etc to transfer "up" into the cabin of the vehicle instead of "across" the chassis. This tends to cause a harsher ride... this is why many 4x4 enthusiasts choose to install "long arms". Longer control arms effectively decrease the angle on the arm and decrease the amount that the pinion angle changes during suspension travel (this is known as "swing radius").
Next suspension chapter soon to come.
There are more complicated terms that can change when caster is changed such as scrub radius, but they aren't something most of us will worry about.
As always please forgive errors in spelling, diction, and terminology, if you notice a mistake let me know.
atriot: © 2008 GravesdiggerXJ
photos used from Google.com photosearch
