Caster

Is there “too much” caster ?

 

Yes. If you rotate the forward axle too far, the pinion angle will no longer be parallel to the transfer case front output shaft angle.
This is a a great diagram and is valid for front, as well as rear, drive shafts.

 

Too much caster can also contribute to death wobble. 5-7 degrees is the typically accepted range.

 

Shopping cart wheel wobble.

 

Yep, as in death wobble!

 

Nice part is, you get to see it on the cart instead of clinging to the steering wheel of the Jeep at 50MPH trying to slow down before the windshield falls out.

I used to work in a Ford specialty shop. Front coils and radius arms were the WORST.

 

X2, The best driving truck I ever owned was a 1964 Ford F-100 with a front straight axle, leaf springs and manual steering. Man that truck could be steered with one finger, It went where you pointed it and stayed there without any input. None of my newer vehicles come close to driving as good. Wish I knew what the caster angle was.

 

Probably very little, like in the 0-3° range. They built manual steering rigs back then to steer easily, and the closer to 0° the caster, the easier it will steer at a stop because there’s little-to-no scrub. The discussion of bias-ply tires comes into play also. Radials need more caster than bias-ply tires do, so when radials became the norm, caster settings went up.

 

Early manual boxes had high steering ratio's which helped keep effort down.
And radials run much lower pressures and softer compounds, both contribute to higher steering efforts.

 

Now that you mention it I am Sure I ran bias ply tires back then too.
My 74 cj5 came with bias ply tires too. I measured the caster on it a while back with everything still stock and with no axle shims installed.
The best I could tell both sides were about 1 maybe 2 degrees positive. It drove reasonably well on the street that way too. But now with the wear of all the steering and suspension parts not so good anymore.

 

Yeah, it wasn’t by total coincidence that radial tires appeared along side power steering systems. Just by the nature of design, even at the same pressure, bias tires have a much smaller contact patch making steering easier.