Caster angle seems disappointingly low, am I reading this right?

[AustyPosty]

For context, I have a 2.5 AEV dual sport with the geometry correction brackets in the “middle” position for 2.5”-3” lift. My reading of the pinion angle measured from the axle spreaders consistently comes up to around 87.4, what would this place my caster angle at? I assume it would be around 3-4, right? My floor is at an angle of 0.3, so it shouldn’t be throwing this number off too far. I also tried measuring at the bottom of the knuckles but could not get a consistent measurement.

I’m going to be setting the brackets to the max caster angle correction setting tomorrow, but if it doesn’t get me to at least 90 degrees (6 degrees of caster), what should I do? Jeep drives OK, it has a bit of bump steer and needs a bit more steering correction on the highway than I would like.

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[Thunderspud]

I might just bite the bullet and take it to a place with the good alignment machine (I am a fan of the Hunter Hawkeye machines) to get specific numbers before I went too much further.

I was never able to get reliably accurate caster measurements in my shop. Using the knuckles and that same Klein level. It always seemed to be less than I wanted. Probably user error, but I got tired of fighting it. The fancy alignment rack measured 6.04 and 6.08 (left and right), so I stopped wasting my own time and relegated the Klein level to our Roxor and farm trucks, lol.

 

[CrazyCooter]

Take it to a shop for actual reading because the angle you are reading is not an accurate caster measurement.

You might however note the difference between actual caster and the differential reading for future reference allowing you to set in in the future?

 

[MPMB]

You're measuring pinion angle rather than caster. I don't know if JT's have equal caster and pinion angles. Obviously they're tied together since it's solid axle.

A local tire shop alignment isn't very expensive.

Or you can do it at home. Put the axles on jack stands, remove the wheels, level the chassis based off hub heights, and you'll be able to measure caster more accurately.

Check caster on your Jeep at home with simple tools! DIY vs. Shop

 

[ShadowsPapa]

You're measuring pinion angle rather than caster. I don't know if JT's have equal caster and pinion angles. Obviously they're tied together since it's solid axle.

A local tire shop alignment isn't very expensive.

Or you can do it at home. Put the axles on jack stands, remove the wheels, level the chassis based off hub heights, and you'll be able to measure caster more accurately.

Check caster on your Jeep at home with simple tools! DIY vs. Shop

"The Internet" (as invented by a guy we all know) says that there's 6 degrees difference - and if you measure the differential housing, and get 0 (or 90) then your caster is 6.
At least that's what Wrangler people have been saying for years.

I'd rather let the shop give the real numbers. I've got more angle gauges than I can remember where I have them stored, still...........

 

[NewGladdyOWNR]

I’ll tell you right now it’s next to impossible to measure caster from a magnetic angle finder, whether it’s placed on your knuckles, diff, etc. Just get an alignment. Once you have your caster, place the angle finder on one of your front knuckles...this will NOT match the caster from your alignment shop and that’s fine. Your case is different because you don’t have adjustable control arms, but in my case to dial in my caster I put my jack under my front pinion to support it, loosened the front upper control arms and removed the adjustable end of the control arm from the frame, slightly lowered the jack, checked the angle finder then subtracted that measurement from my caster to figure out what the new caster was. There is math involved, just subtraction lol. It’s hard to write out, but it’s easy. You have just have to know what your actual caster is from a shop first.

 

[AustyPosty]

Got it, I’ll be taking it to a shop then! Thanks guys.

 

[CrazyCooter]

Back in the day when I spent half the day in the alignment pit, it was a game to screw with the old timers for me to look at "C's" on a strait axle truck/Jeep and guess the caster before we took readings. I was real good especially on the square body Chevys.

 

[Stan H]

For context, I have a 2.5 AEV dual sport with the geometry correction brackets in the “middle” position for 2.5”-3” lift. My reading of the pinion angle measured from the axle spreaders consistently comes up to around 87.4, what would this place my caster angle at? I assume it would be around 3-4, right? My floor is at an angle of 0.3, so it shouldn’t be throwing this number off too far. I also tried measuring at the bottom of the knuckles but could not get a consistent measurement.

I’m going to be setting the brackets to the max caster angle correction setting tomorrow, but if it doesn’t get me to at least 90 degrees (6 degrees of caster), what should I do? Jeep drives OK, it has a bit of bump steer and needs a bit more steering correction on the highway than I would like.

Hmm adjustable arms on top & bottom ?

 

[AustyPosty]

Update: I put the correction brackets to the 3-3.5” setting and it feels slightly better on the road, however I still have bump steer. I would have figured a 2.5” lift would be too low to experience bump steer like this, any idea what might be causing this or is this normal? I can confirm everything is torqued to spec, control arms, track bar, etc.

 

[Stan H]

Update: I put the correction brackets to the 3-3.5” setting and it feels slightly better on the road, however I still have bump steer. I would have figured a 2.5” lift would be too low to experience bump steer like this, any idea what might be causing this or is this normal? I can confirm everything is torqued to spec, control arms, track bar, etc.

Is the actual bump steer shock toast ? Mine was sad . Replaced with a dual system.
Happiness lives here now.

 

[ShadowsPapa]

I would have figured a 2.5” lift would be too low to experience bump steer like this, any idea what might be causing this or is this normal?

Lift may or may not experience that - depending on other factors. Have you changed the wheels - perhaps different wheel specs? Different "poke", or used spacers?
Lifts in themselves don't cause it - it's all the stuff that may or may not get done or changed in association with the lift, and how it was lifted.
It's not the height that matters - it's all the other stuff.

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