Caster Issue?

JohnBoy

JohnBoy

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Joined
Jul 1, 2021
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8
Location
Ancho NM
Just got my first Jeep about a year ago. It had a few issues. That explains the price. Any way, it drive like crap on the road. I believed the problem to be alignment so I didn't freak over it too much. I spent the last year ironing out all the wierd crap the the last owner screwed up. Now I finally getting to the road stability. Has a new steering gearbox. Tow is set fine. Still crappy on the road. Symptoms point to caster. My shop manual says that caster should be +7 degrees. According to the angle finder the drivers side was -8 and the passenger side was -2. It has a full 4" lift. The entire suspension is from the lift kit. Now the problem. If I adjust the caster to +7, the u-joint is going to be way up in the air. I stopped at +2 and it already seems too high to me.
I have discovered in my adventures the past year that some parts are CJ, not TJ.
Not sure if that would make a difference or not. The only adjustment for the caster is the upper control arm.
Does the caster specs change with a lift?
I don't dare go any more +.
It's a 2000 tj. Tires are 33x12.5x15
Comments, thoughts and ideas welcome.
Oh, it doesn't have a salvage title but it was definitely build from misc parts. I have everything else as good as new. Except this.🤠
 
I like the color combination of your Jeep; I am biased...
Caster should always be as close to spec as possible.
When caster is off by that many degrees; the steering will feel light and drift on the highway.
Most regular alignment shops will not work outside the bubble to align the vehicle to what it needs...
You need to take the Jeep to a shop that specializes in Off Road vehicles such as your Jeep where they will adjust the control arms to the correct length for caster and pinion angle.
 
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Alignment tech here.

From reading your post it sounds to me like you could benefit from a set of offset ball joints. A negative 6 split to the left will make it ride like hot garbage. Although true that you might be able to bridge the gap with just adjustable control arms, its hard to twist a solid axle to get the caster in spec if that split is that high.

As Charles said, I would recommend bringing it to a trusted 4x4 alignment shop and request a complete shakedown of the front end to cover as many bases as possible.

Aligning these TJ's aren't difficult, but depending on what's going on it can get time consuming.


Good Luck!
 
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Thanks for the reply Charles.
I have always had a car project in my garage. Pay 500-1000 for a pile of junk. Throw money and time at for 2-3 years. Drive it for a summer sell it and do it all again. This is the first(and last) time I've bought one that someone else has modified. Nothing was done right or even complete.
Never needed anyone else to do an alignment before. Not going to start now. Never had one lifted, thought the caster might need to be different for s lift. I live out in the desert. The nearest anything I need is 90 miles away. I'll get it done. Nothing like a challenge huh.🤠
 
JohnBoy said:
Just got my first Jeep about a year ago. It had a few issues. That explains the price. Any way, it drive like crap on the road. I believed the problem to be alignment so I didn't freak over it too much. I spent the last year ironing out all the wierd crap the the last owner screwed up. Now I finally getting to the road stability. Has a new steering gearbox. Tow is set fine. Still crappy on the road. Symptoms point to caster. My shop manual says that caster should be +7 degrees. According to the angle finder the drivers side was -8 and the passenger side was -2. It has a full 4" lift. The entire suspension is from the lift kit. Now the problem. If I adjust the caster to +7, the u-joint is going to be way up in the air. I stopped at +2 and it already seems too high to me.
I have discovered in my adventures the past year that some parts are CJ, not TJ.
Not sure if that would make a difference or not. The only adjustment for the caster is the upper control arm.
Does the caster specs change with a lift?
I don't dare go any more +.
It's a 2000 tj. Tires are 33x12.5x15
Comments, thoughts and ideas welcome.
Oh, it doesn't have a salvage title but it was definitely build from misc parts. I have everything else as good as new. Except this.🤠
Click to expand...
How are you checking caster?
 
Maybe I'm confused but adjusting for more positive caster should make the diff yolk go down towards the ground not up. Your statement about the u-joint going too high is confusing. Is your yolk too high or is the driveshaft angle too high?
 
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🤣No not the u-joint. The bottom of the axle where the kingpin would be if it weren't a 4x4.
Probably be better seting the pinion angle. That should get the caster pretty ok. At least a lot better than it was/is. Then go from there.
 
JohnBoy said:
Smoothest part at the bottom joint.
Click to expand...
There is only one place you can get a reliable reading. You have to take a 2" wide spacer about 1/8" thick and stick it on the flat spot machined into the bottom of the inner C. Put your angle finder on that taking care to keep it pointed squarely front to back. Do that on both sides to see if you really have that much side to side difference.
 
Jezza said:
Maybe I'm confused but adjusting for more positive caster should make the diff yolk go down towards the ground not up. Your statement about the u-joint going too high is confusing. Is your yolk too high or is the driveshaft angle too high?
Click to expand...
The illustration in my shop manual shows positive caster to be forward at the top. But, apparently not so cause this simply is not right. Way too much pinion angle.
 
mrblaine said:
There is only one place you can get a reliable reading. You have to take a 2" wide spacer about 1/8" thick and stick it on the flat spot machined into the bottom of the inner C. Put your angle finder on that taking care to keep it pointed squarely front to back. Do that on both sides to see if you really have that much side to side difference.
Click to expand...
Will do. Thanks.🤠
 
Positive caster is where the steering pivot is angled back toward the driver. Picture a kids big wheel. Lots of caster very stable.
 
Rolling LJ said:
Alignment tech here.

From reading your post it sounds to me like you could benefit from a set of offset ball joints. A negative 6 split to the left will make it ride like hot garbage. Although true that you might be able to bridge the gap with just adjustable control arms, its hard to twist a solid axle to get the caster in spec if that split is that high.

As Charles said, I would recommend bringing it to a trusted 4x4 alignment shop and request a complete shakedown of the front end to cover as many bases as possible.

Aligning these TJ's aren't difficult, but depending on what's going on it can get time consuming.


Good Luck!
Click to expand...
Good post and glad you are here and understand your trade.

......offset ball joints are cool and only move the knucke so that preserves pinion angle.

pinion angle on the front isn't as touchy as the point of rotation, length of shaft and the double cardan compensate a good bit as a team so to speak

Lifts roll the axle forward (edited), and caster goes out the window and it wonders, floats and typically has a light feel at the wheel.

Tjs arent hard to get right, just easy to mess up. To the point I’m cautious the first time drive one I’m not familiar with.

What bothers me is so many people accept bad steering because they do not know how good these can be, even lifted.
 
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AndyG said:
Good post and glad you are here and understand your trade.

......offset ball joints are cool and only move the knucke so that preserves pinion angle.

pinion angle on the front isn't as touchy as the point of rotation, length of shaft and the double cardan compensate a good bit as a team so to speak

Lifts roll the axle back, and caster goes out the window and it wonders, floats and typically has a light feel at the wheel.
Click to expand...
Lifts roll the axle forward at the top which takes away the caster we need.
AndyG said:
Tjs arent hard to get right, just easy to mess up. To the point I’m cautious the first time drive one I’m not familiar with.

What bothers me is so many people accept bad steering because they do not know how good these can be, even lifted.
Click to expand...
 
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