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ideal caster angle

camojeep88

NAXJA Forum User
Location
huntington beach
im tryin to figure out what caster angle is ideal im running deaver coils in front with custom long arms on 35" tires. so far it seems like 5* is ideal but everyone has a different opinion but i figured i would ask and see if anyone else has some experience here any advice would be great
 
id say as much positive caster as you reasonably adjust too really (otherwise you start to sacrifice pinion angle to a certain extent unless you cut and turn the knuckles...)

. Ive seen plenty of guys run 10* positive caster ( 7" coils, 39s, yota axles, etc)
 
5 to 7 degrees is good. But as mentioned, it becomes difficult to get there and get good pinion angle on stock axles with taller lifts.
 
Now that I think about it I have no idea what my caster angle is on mine. All the write-ups I've read used pinion angle which is really the same thing since changing one changes the other. But yeah my jeep has about 7-8" of lift and the pinion angle is
somewhere in the 5 to 7* range I guess. What I do know is that you can't just take it to shop and have them set it to factory specs and expect it to work, it's all custom from here on out in that respect. Too low and you'll get driveline vibs & possibly DW, too high you'll start to lose steering feel.
 
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5 to 7 degrees is what I always go for in a lifted xj. Never heard of the 1 degree per inch of lift. That means stock should be at zero! Stock specs are in the 4 to 5 degree range iirc.
 
My Jeep is lifted 6.5" and had near 0 deg caster after setting the front drive line angle. I believe stock is roughly 5 degrees. When I built the new axle I cut the c's free and reclocked them to give me 8 degrees. The extra caster helps compensate for the lift and bigger tires/wheels. It used to wander all over the place, now you can cruise down the road with 1 finger.
 
2000 FSM specs 7° as optimal caster with + 5.25° to + 8.5° as acceptable.
Most of us are lucky to get 5°, unless the Cs are cut and rotated.
Offset ball joints can gain 1-2°s of caster.

When adjusting, the FSM indicates that the front axle pinion angle has preference over caster. Better to get the pinion angle near zero to prevent vibs and damaging the front pinion bearing.
 
2000 FSM specs 7° as optimal caster with + 5.25° to + 8.5° as acceptable.
Most of us are lucky to get 5°, unless the Cs are cut and rotated.
Offset ball joints can gain 1-2°s of caster.

When adjusting, the FSM indicates that the front axle pinion angle has preference over caster. Better to get the pinion angle near zero to prevent vibs and damaging the front pinion bearing.

I stand corrected on the stock specs. just looked them all up on alldata and depending on what year you look at it varies a bit.

As for pinion angle taking prioroty over caster, I would agree in a stock application. I mean how far off was the pinion angle on every stock hp dana 30 produced for xjs? If you set the pinion angle right, the caster must be close.

HOWEVER. In a lifted application, I think safety, driveability, and handling take prioroty.
 
As for pinion angle taking priority over caster, I would agree in a stock application. I mean how far off was the pinion angle on every stock hp dana 30 produced for xjs? If you set the pinion angle right, the caster must be close.
HOWEVER. In a lifted application, I think safety, driveability, and handling take prioroty.
Pinion angle may not be as critical in a trail rig as in a DD. I regularly drive the XJ at 70MPH and are concerned with both caster and pinion angle. The caster angle should always be as high as possible.
In my XJ's case, at 4"s of lift, it only gets 5° of caster, when the pinion angle i correctly set, using offset ball joints.
I need to swap the LP with a HP D30 someday. More projects.

In my application, the front pinion angle was critical to preventing front driveshaft vibs. After re-gearing from 4.11 to 4.56, 1° of front pinion angle caused tremendous vibs when the driving at or over 55MPH (with 31"s) or 60MPH with the 33"s. The same pinion angle, on the 4.11s, had worked fine to 75MPH, as fast as I drive the XJ.
The increase in driveshaft speed made the difference. Everything in the driveline was tight. New axle bearings, a new driveshaft and the alignment was set to specs.
Getting the pinion angle to less than .25° eliminated the vibs. As a test, I bumped it up to .75° and the vibs came right back.
That was about 5000 miles ago and it's still quiet and steers fine, the result of spending a lot of time adjusting everything in the front end to handle and steer correctly. Every XJ seems to be a little different.
 
5 to 7 degrees, with 7 being on the more desireable end of the scale IMO. Unless you're lifting over 6" you should be able to get somewhere in that range and still have an acceptable pinion angle without cutting and turning the C's or using offset ball joints on an high pinion D30. Low pinion might be a different story, depending on your lift.
 
This is very apropos to my current situation. I have a 2000 XJ with 4.5" lift, short arm, on 31.5"-ish tires (265's) and less than 5deg caster. The steering is solid, no loose parts, ball joints or tie rod ends, etc., but it wanders badly on the road especially at freeway speeds.

I've been looking at the offset ball joints as a fix. Want to get around 7deg caster if possible. Sounds like that's the way to go. Any advice before I go order them? :)
 
D'oh!

I see. I do have adjustable lower arms. I guess I could try turning them out a turn and see what that buys me?
 
I'm running 6" of lift, adjustable UCA/LCA's and DB's, I have 6* caster on 35's and no issues. It cruises the highway comfortably and will carve up a KYA curvy mountain road.
 
Offset ball joints adjust camber. To get more caster you need to lengthen lowers by shims or adjustable arms or shorten uppers.

For a street rig, use the the adjustable control arms and or shims to locate the wheel's position in the fender and to set the ideal pinion angle.
If the resulting caster is 5 degrees or lower, an offset lower ball joint can be used to add up to 1-3/4 degrees of caster OR camber, depending on which way the joint is oriented. The adjustable ball joint rotates just the knuckle, leaving the axle housing's angle alone.
Below are a few examples of adjustable lower ball joints.
http://www.napaonline.com/Catalog/C...le-Lower-Front-Susp/_/R-NCP2643724_0318416994
http://www.jegs.com/i/Moog/719/K740...&cagpspn=pla&gclid=CLfirL7trLgCFeV7QgodJQsAeg

With my 2001 XJ's LP-D30 ( at 4" of lift and a pinion angle of less than 1 degree) using 1-3/4 degree offset lower ball joints is the only way I can get 5 degrees of caster without cutting and rotating the Cs. If I lift it anymore, the caster will be less than 5 degrees.
High pinion axles have more available caster at the same lift height.
 
Great info! Thanks!

My 2000 actually has a HP D30 swapped in, so that's a plus, but I only have adjustable upper control arms. I'm thinking I should be adjustable lowers as well in order to get the axle better positioned in the wheel well. It's a bit too far rearward and would certainly rub even though I'm only on 265/75's (31.6" dia or so).

I'm looking into both the control arm adjustments, shimming them and also the ball joints. Whatever I need to get the overall setup correct.

I really appreciate the input!
 
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