Return to Center Advice

HuskerJeep

HuskerJeep

TJ Enthusiast
Joined
Jan 17, 2019
Messages
268
Location
Omaha, NE
I am experiencing poor return to center on my '98 and I'd like some advice or thoughts on the issue. Here are the facts:
  • Steering wheel only returns back to 11:00 and 1:00
  • OEM Saginaw steering gear, 103,000 miles on the Jeep. It does have a small leak that isn't fixed with stop leak
  • I've installed (earlier this year) H&R springs that netted 1.5" of lift (I don't have a comparison of before and after for steering, I put the lift on pretty much right after I bought it)
  • 31x10.5 tires (running at 30 psi today, was a little lower than that before so I added some pressure to see if that did it, and there was no change)
  • I removed the steering damper to see if that was the issue, no change
  • I've replaced almost all of the front steering components, all the remaining ball joints are in good shape
  • Toe-in is slightly less than 1/8” closer in front
  • I measured the front pinion angle at 6* from 0 (as measured from the front inspection ports). Correct me if I'm wrong here, but based off the fact that the relationship between Pinion angle and Caster angle on a Dana 30 in a TJ is 12 degrees, that puts my Caster at 6* as well (I checked this as best I could with my angle finder and was also getting right at 6*).
All of that leads me to believe that Caster is ok for what lift I have, tire pressure is good, steering linkage is good, so it's probably the steering gear. Would you agree, or have any ideas on what else I should be checking first?
 
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It's difficult to correctly measure the caster angle, I'd either have that verified by an alignment rack or re-check it. 6 degrees of caster angle is enough but I'd verify what you have before assuming your steering box has gone bad. I doubt a 4x4 shop with an alignment rack would charge much to just tell you what your caster angle is. A chain-brand alignment shop would likely want to charge for an alignment just to measure the caster angle.
 
Thanks Jerry. What is it about measuring caster that I’m missing? If the angle relationship between the theoretical line through the ball joints and the pinion are fixed at 12* difference, then why isn’t it as simple as measuring the angle on the inspection points to the side of the differential? Assuming the Jeep is sitting on a flat surface.
 
Because of the word "theoretical". This is a Jeep. "Theoretical" and "actual" are often different. 🧐
 
And finding a place to measure caster isn't terribly easy for the home mechanic. The desirable caster changes with tire size. The optimal pinion angle takes precedence over caster.

At the end of the day, I still haven't figured out why the specific caster measurement matters once there is enough or it is what it is.
 
BuildBreakRepeat said:
Is the relationship between caster and return to center (if it could even be measured) linear? Does having an increasing amount of caster improve return to center or is it negligible at a a point.
Click to expand...

I can tell you that with a 4" spring lift, a Savvy raised skid, 33s and a 0° front pinion, the return to center is still quite pronounced.
 
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Steering gear problems are the most common cause of steering not returning to center. Next is toe. You could try more toe-in and see what happens. It's free to try right? You have set it at less than 0.125" and the factory spec is around 0.16" Personally I wouldn't measure or even consider caster on a fairly stock TJ. Most TJs with mild lifts don't need any caster adjustments and return to center just fine. You might have it tested at an alignment shop to see if something is really bent but I doubt that's your issue. It is simply much more likely that your steering gear is shot than your front axle is bent.
 
Just following up on this after a few recent changes. Here is what I've done recently:
  • Disconnected the steering stabilizer, put the front axle on stands and turned the front wheels by hand to see if I could feel the ball joints catching/dragging at any point. They felt smooth through the whole range of motion. Maybe I did that wrong, or that test sucks, but that was the advice from a local 4x4 shop to check if the ball joints were sticking.
  • I installed all new control arms (the Crown OEM-style kit). When I did that, I maxed out the cam bolts to improve my caster by about 0.3* on each side.
  • I also gave myself another 1/8" of Toe-In.
In the end, no change to my return-to-center issue. I'm still thinking steering gear and running out of options to check.
 
HuskerJeep said:
  • I installed all new control arms (the Crown OEM-style kit). When I did that, I maxed out the cam bolts to improve my caster by about 0.3* on each side.
  • I also gave myself another 1/8" of Toe-In.
In the end, no change to my return-to-center issue. I'm still thinking steering gear and running out of options to check.
Click to expand...
You gave yourself .3 degrees more caster, how much total caster do you have now? And you gave yourself an additional 1/8" of toe-in? The recommendation for toe-in is 1/16" to 1/8". How much total toe-in do you have now?
 
Jerry Bransford said:
You gave yourself .3 degrees more caster, how much total caster do you have now? And you gave yourself an additional 1/8" of toe-in? The recommendation for toe-in is 1/16" to 1/8". How much total toe-in do you have now?
Click to expand...
I haven't put it on a rack yet, so I don't know these measurements exactly, but if I assume the 12* difference between caster and pinion, then I should be about 6.3* of caster. I had right at 1/8" of toe-in before and gave myself another 1/8", so I'm right about 1/4". Probably too much, but I didn't notice any real driving difference and I'll probably move it back to where it was.
 
Your Profile doesn't mention any suspension lift height. If it's stock or maybe just a 1" spacer and your control arms are fixed length your caster angle is likely fine. If it is 6.3 degrees as you are guessing it is, that's fine. The taller the lift with fixed length control arms, the less caster angle you end up with.
 
Jerry Bransford said:
Your Profile doesn't mention any suspension lift height. If it's stock or maybe just a 1" spacer and your control arms are fixed length your caster angle is likely fine. If it is 6.3 degrees as you are guessing it is, that's fine. The taller the lift with fixed length control arms, the less caster angle you end up with.
Click to expand...
I'm at 1.5" of spring lift with the H&R Springs with fixed OEM length control arms, so I agree with you that I should be within spec on caster.
 
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With stock or non adjustable control arms your caster is what it is. You may want to play around with your tire pressure a bit too. Going up or down 2 psi at a time until you find the sweet spot. You will definitely know when you find your sweet spot.
 
Goatman said:
With stock or non adjustable control arms your caster is what it is. You may want to play around with your tire pressure a bit too. Going up or down 2 psi at a time until you find the sweet spot. You will definitely know when you find your sweet spot.
Click to expand...
My ‘98 has adjustable cam bolts on the front lower arms, so that’s how I adjusted the caster, it’s not much though.

For tire pressure, I’m at 30 psi now and was down at 27 before and the return to center wasn’t effected by going to 30. I think the ride is better at 27 though.
 
Ok, a little more info here. I took it to an alignment shop that has a lot of experience with Jeeps just to rule out any issues that I couldn't see. Basically, the toe-in was a little high (as I suspected since I added a little more last week). Caster is higher than I thought, at 6.6* and 6.8*, but I think that's good.

Getting the toe-in adjusted improved the steering slightly, but it still doesn't return to center all the way (comes back a little past 11:00 and 1:00 now).

Any issues with the numbers below?

Alignment_11-07-19.jpg
 
.08 toe-in (.16 total) is a bit light but it's within spec. .30 (.15 per side) is dead-on.

Ball joints? Do the tires move freely back & forth when you turn the steering wheel when the front tires are off the ground?
 
Jerry Bransford said:
.08 toe-in (.16 total) is a bit light but it's within spec. .30 (.15 per side) is dead-on.

Ball joints? Do the tires move freely back & forth when you turn the steering wheel when the front tires are off the ground?
Click to expand...
To check the ball joints, I put the axle up on stands, removed the steering stabilizer and then turned the tires individually by hand, not with the steering wheel. They were smooth throughout and I didn't feel any tough spots or sticking. I'm not sure how easy or difficult that should be though (easy or hard to move the tires through their range of motion). I'd say they felt tight, but I also expect things to be tight since I have almost all new steering linkage.
 
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