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Caster help

JMOliver

NAXJA Forum User
Location
North Carolina
Ok I’m brain dead from reading looking for help

99xj hpd30

Jeep drives ok but a bunch of wondering, I’m assuming it cause of caster. I’m at 7” lift pinions is 1-3 degrees off but no vibes ( pinions down a tad ) positive negative caster explain. Looking at Val joints there in line up and down, should bottom ball joint be further back or forward?

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Positive caster is what you need i.e. the lower ball joint forward. The 'U' joint is at a bad angle. You need to try to get it aligned better so it live a longer life. What is the caster angle? I think 7derees +/- is the ideal.

My XJ at 4.5" lift is about 5.5 degrees with no wandering except when in deep ruts created by heavy trucks on the highway especially shortly after a rain fall. Well, it also to have the toe out reduced a little.
 
So I need to turn my pinion up, but the springs will look forward more


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turn the pinion down to add positive castor... more positive castor is what will help fight wandering.

you will reach a point where drive line vibrations become a thing. take a little positive castor out of it and see if you can live with the wandering. thats about the best you can do without lowering your lift height.
 
That’s what I thought to much reading gets me confused lol, yes I don’t want to turn the pinion down anymore cause right now there’s no vibes unless running over 90mph


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That’s what I thought to much reading gets me confused lol, yes I don’t want to turn the pinion down anymore cause right now there’s no vibes unless running over 90mph


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I guess if you do not have vibes from the front drive shaft then it may be ok to run it that way. I set my drive shaft at/close to the recommended 1 degree U joint angle. I get no vibes over at over 80MPH and at 5.5 degrees of caster I get no wandering.

The drive shaft angle look steep in the picture. Do you have a T case drop? When the back of the T case is dropped, the front out put to the differential goes up.

With the amount of lift you have, you may have to compromise between drivability and drive shaft vibration unless you do a cut and turn or install offset ball joints.
 
I guess you could call it more of jerky gotta turn the wheel slowly, real responsive, almost to tight! All steering is new basically. Jcr steel spacer , new steering box, boostworxs steering brace, cavfab steering, ota trackbar. If the wheel is straight and you try to turn just a tad left or right it’s instant. So I would recall it wondering more like a tad of bump steer / body roll steering if that makes any sense


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I guess if you do not have vibes from the front drive shaft then it may be ok to run it that way. I set my drive shaft at/close to the recommended 1 degree U joint angle. I get no vibes over at over 80MPH and at 5.5 degrees of caster I get no wandering.



The drive shaft angle look steep in the picture. Do you have a T case drop? When the back of the T case is dropped, the front out put to the differential goes up.



With the amount of lift you have, you may have to compromise between drivability and drive shaft vibration unless you do a cut and turn or install offset ball joints.



I had Oliver’s in town make new driveshafts front and back there beefy so that might be why I don’t have any vibes? Idk


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I guess you could call it more of jerky gotta turn the wheel slowly, real responsive, almost to tight! All steering is new basically. Jcr steel spacer , new steering box, boostworxs steering brace, cavfab steering, ota trackbar. If the wheel is straight and you try to turn just a tad left or right it’s instant. So I would recall it wondering more like a tad of bump steer / body roll steering if that makes any sense


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Yes, I do remember that quirky handling when my XJ had only 3 degrees of caster. On a well known road I knew exactly when my XJ would need steering correction left or right and the response to steering correction was instantaneous. Those days, I tried to keep off the highway (yes, I am a chicken). Try to add some more caster. If you develop vibes remove the front drive shaft.
What is the measured front drive shaft angle?
 
take the driveshaft out and throw a to of castor at it just to see what happens.

also, looking at your photos... when i ran drop brackets i pushed the axle as far forward as i could in the adjuster on the LCA mount to get a bit of "stretch". you have adjustable uppers. if you remove the drive shaft and find that more castor helps your issue, you could push the LCA forward and dial the castor back in with the adjustable upper. even though its not much, that little bit of a push might help with driveshaft vibes if you find that more castor is beneficial.
 
Bottom ball joint should be forward. There is an app available from the play store to turn your phone into a level which can be placed onto the bottom of the C.

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