What is best caster setting?

After my D30 swap I was faced with a trip to Idaho and a need for wedges immediately.I got a set of 4° steel wedges from Bluetorch to add to an assumed 1° positive caster. This should have got me 5°+ positive caster. It was aggressive but tolerable. I recently added a set of Mcruff's shackles. These are about an inch longer than stock and tipped me back to the barely controllable realm of steering. I'm going to ask Mike to make me a set after I get the exact measurement.

So to the original question, with a range of +5-7°, what's best? I already know 5° is too little for my style of driving. When does it start getting hard to turn?

 

Due to early Jeeps running bias ply tires, there was little caster angle at the knuckles. With the advent of radial tires, the caster setting went to around 7°.

Adding longer shackles in the front is a bad idea. This will take away caster angle and lead to increased sensitivity in the steering. Go back to the stock length shackles.

 

I don't like more than 7 degrees static. Any more makes it harder to turn at slow speed, increases tire wear when turning, and can cause high speed instability. Remember also that caster and toe change during suspension movement so you are looking for a running average.


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So Nick do you think I should just midline it at 6*?

 

Up to 7 degrees static is fine. If running wider than stock tires it helps with rutted roads and what not. Just don't go more than that if at all possible. Also keep in mind the more positive the caster the more the pinion will be pointing downward so u joint angles is something to consider.


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One last question. Should I get unequal wedges to exactly even out both sides?

 

Solid axle. If caster is unequal there are other issues. All you would do is put the springs in a twist preloading them and potentially damage the spring pads on the axle housing. Use even wedges both sides


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This claim surprises me.

If you look at the Easy Rider bikes, for example, they have very long forks which give them very high caster numbers, like 30 degrees. I had thought this was done exactly for high speed stability. The scenes of hands-off riding demonstrate that.

 

After reseting the caster angle last year (did it on dana 44 by unwelding the "c" knuckle) I bring it to the align center and ask them for 6 degree. Now I’m running 36” tsl bias, I’m drinving the jeep at 60 Mph’s with one finger on the steering wheel.
Before going with coil suspension, I put a 6 degree wedge and the jeep was going just fine on the road.

 

It's more than just the angle of the forks. It's how far the wheel follows the turn point. If too much it can cause high speed wobble. If too little it can cause wander and instability. Steering axis inclination plays in here too. More is not always better, like anything it is a balancing act.

 

At this point you learn fun words like Ackerman angle....

 

And scrub radius, and toe out on turns (toot), and included angle, and the list goes on


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Snicker, snicker. Nick said toot.

 

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Nick, could you expand on this comment? I have a freind of a friend who with a similar set up as Rocky and has not been able to resolve his steering issues nor has anyone else.

 

Do you have a specific question? Wayyyyyy too much to try and type on here.


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I found my answer. Thanks.

 

I am also surprised at the "can cause high speed instability". Typically the more caster, the better the high speed handling. Dragsters run up 18+ degrees, when the idea is to go straight at 300+ MPH.

I have a 70 Wagoneer D44 front and it came from jeep at 0 degrees (for the bias tires "bubble" I presume) My plan is set up around 6 degrees, glad to hear so many of you guys happy at 6. Thanks for this post!

 

I did it with a scout d44. Caster was set to 0 degrees, i grind the weld on the " C " knukkle, and i bring it to 6 degree. I can run the jeep a 60-65 mph's without any problem, and just to let you know i'm running 36" tsl bias and i can't complaint about anything.