What should my caster angle be?

Breto31

Breto31

TJ Enthusiast
Joined
Nov 30, 2020
Messages
397
Location
Kentucky
I’ve got 33” tires on a 4” lift. I’m having a bit of a wandering issue in - mainly on 2-lane roads that aren’t as “flat” as the main roads. I have to work a little harder on these smaller roads to keep it in the lane. It seems to really react to the angle of the road and want to pull one way or the other. It’s fine running around town on the wider roads, but when I get on the backroads, it’s a little iffy.

Anyway, I’m not sure what my current caster angle is, but I’m wanting to get an alignment done and tell them specifically what to set my caster at. From other threads I’m thinking it needs to be around 6 degrees. Does that sound correct?
 
Your caster angle will be a result of what your pinion angle is. If you have no vibes at your current angle, leave it alone. Moreover, unless you have adjustable arms, you won't be able to set you caster anyway. Just set toe-in correctly to spec.
 
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taylormade73 said:
Your caster angle will be a result of what your pinion angle is. If you have no vibes at your current angle, leave it alone. Moreover, unless you have adjustable arms, you won't be able to set you caster anyway. Just set toe-in correctly to spec.
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I’ve had it aligned 2-3 different times, including once myself, and none of it helps this wandering issue….. I’ve been seeing lots of posts stating that caster needs to be around 6 degrees, and that caster and toe-in are the main causes for wandering.

It’s not bad enough that it feels dangerous, but it’s bad enough that I feel more comfortable driving with 2 hands when I’m on the smaller 2-lane roads
 
I've got a 4" lift and run 5.5 degress of caster with no vibes.

do you have the before and after print of your alignment?

Road crown will play into your wandering concern but should be considered somewhat normal. Wide tires with a short wheel base tend to catch the crown of the road.

I have customers that purchase the top of the line tahoe/suburbans with 275/55/20 tires and constantly complain the the vehicle feel like it wanders on the road. 99% of the time its due to road crown.
 
williambmac said:
I've got a 4" lift and run 5.5 degress of caster with no vibes.

do you have the before and after print of your alignment?

Road crown will play into your wandering concern but should be considered somewhat normal. Wide tires with a short wheel base tend to catch the crown of the road.

I have customers that purchase the top of the line tahoe/suburbans with 275/55/20 tires and constantly complain the the vehicle feel like it wanders on the road. 99% of the time its due to road crown.
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I don’t have the printouts. Threw the first one away, didn’t get one with the second alignment, and the 3rd one I did myself. I’m at the shop now having it aligned, so I’ll see what the printout looks like. They said they’d show it to me before adjusting the caster.

I think the road crown is definitely part of it. It seems like my jeep reacts MAJOR to play in the road. Like, if the road dips down to the right, my jeep wants to fall off right. I hate feeling like I have to 2-hand drive on these roads
 
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Breto31 said:
I don’t have the printouts. Threw the first one away, didn’t get one with the second alignment, and the 3rd one I did myself. I’m at the shop now having it aligned, so I’ll see what the printout looks like. They said they’d show it to me before adjusting the caster.

I think the road crown is definitely part of it. It seems like my jeep reacts MAJOR to play in the road. Like, if the road dips down to the right, my jeep wants to fall off right. I hate feeling like I have to 2-hand drive on these roads
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Hopefully, you don't have vibes after they adjust your caster. @williambmac has an LJ so his experience will likely be different than yours. If you do have vibes, then you'll need to adjust your pinion to where you eliminate or mitigate vibes and your caster will be what it will be. If you don't have vibes with your caster set to factory spec, then you're golden.
 
taylormade73 said:
Hopefully, you don't have vibes after they adjust your caster. @williambmac has an LJ so his experience will likely be different than yours. If you do have vibes, then you'll need to adjust your pinion to where you eliminate or mitigate vibes and your caster will be what it will be. If you don't have vibes with your caster set to factory spec, then you're golden.
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What is factory spec? 6?….. I’ll see how far off it is when they come back in. I’ve got brand new ball joints, so I can’t imagine that the actual alignment would be very far off after having done 2-3 since then.

I just can’t figure out any other reason that my steering would be fighting the way it is on these smaller, less-flat roads.
 
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Breto31 said:
What is factory spec? 6?….. I’ll see how far off it is when they come back in. I’ve got brand new ball joints, so I can’t imagine that the actual alignment would be very far off after having done 2-3 since then.

I just can’t figure out any other reason that my steering would be fighting the way it is on these smaller, less-flat roads.
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I believe 7deg +/- 1deg
 
Breto31 said:
What is factory spec? 6?….. I’ll see how far off it is when they come back in. I’ve got brand new ball joints, so I can’t imagine that the actual alignment would be very far off after having done 2-3 since then.

I just can’t figure out any other reason that my steering would be fighting the way it is on these smaller, less-flat roads.
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20210802_095512.jpg
 
Here’s what the specs were AFTER they aligned it. They didn’t mess with the caster any. They actually told me that caster can’t be adjusted on TJ’s, and informed them that they could. To their defense, they offered to adjust it to whatever I wanted after I explained that my CA’s were adjustable. I figured it was pretty decent, so I left it alone.

They did say my toe-in was pretty bad. Not sure why that is after I’ve aligned it twice, and I have brand new ball joints…. he even finished it and lowered it, then hooked it back up to show me my new numbers. When he hooked it back up he said that it was already a bit off from what it was when he finished the first time - so they realigned it again for me.

49F90AA3-A1FC-42C1-8F58-F332DFE63BBF.jpeg
 
How does it drive now? I wouldnt go back to that shop if they needed you to tell them you have adjustable CAs and they couldn't tell by looking at them. I'd find someone else more competent.
 
Factory spec is 7 degrees but the bigger the tire, the less caster angle that is needed. That printout's 4.87 degree caster angle is less than I'd like to see with 33" tires, I'd want more like 5.5 to 6 degrees.
 
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taylormade73 said:
How does it drive now? I wouldnt go back to that shop if they needed you to tell them you have adjustable CAs and they couldn't tell by looking at them. I'd find someone else more competent.
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It does drive better, so far. I’ll need to get it out on the other roads this afternoon after work. I’ll report back.

I didn’t expect a ton from them. It was just a Jiffy Lube. It’s new in town, and they get you in and out pretty quick, but I knew they could at least adjust the toe-in and tell me if my caster was way off.
 
Reviving an old post - I’ve taken my jeep to 2 different shops, and none of them seem to be too enthused to adjust my caster for me using the adjustable arms. One told me they wouldn’t do it because their system told them that jeep TJ’s don’t have adjustable caster specs (based on the stock information). One told me that adjusting it using adjustable arms is “way harder than the cam bolts, and going to be a lot more labor” so I just told them to scrap it.

So, if I’m adjusting this myself to add 1.5-2*, I need to SHORTEN the uppers, right?

Also, if I’m adjusting these do I remove BOTH uppers at the same time, adjust them, and then reinstall them? Or do I need to do one at a time?…. I feel like I remember people saying to do them one at a time, but that seems like it would be really hard to shorten the arms if one of them is still attached (I’d be trying to make one shorter, while the other is fighting against me to stay longer).
 
Jerry Bransford said:
And what size tires are installed? The bigger the tire the less caster angle that is required.
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I have 33x10.50, 4” lift. My caster is currently sitting at 5* according to the alignment shop last week. I’ve had it measured at 4.87* and 5* by separate shops over the last 3 months, and I’ve made no changes to anything.

I’m thinking I need to increase that to about 6.5*. I’m having some “walking” issues still. Vehicle tracks straight and doesn’t pull, but it really wants to dip/dive with the road. I wouldn’t say the steering is flighty. The steering feels fine - but when I’m on un-level roads, the whole vehicle dives left/right with the road like a roller coaster. I expect to notice that some with the shorter wheel base, but I wouldn’t think it would be as much as I’m feeling.

I’m thinking that when I replaced the fixed arms that came with the lift (from the PO), I must have slightly changed the caster angle. I got 3 of the 4 arms on myself, but I had to take it to a shop to get the last bolt put on because I couldn’t get the axle moved with my ratchet strap enough to align. My assumption is they just extended the arm out enough to line it up, which could screw with the caster. It makes sense that I couldn’t move the axle any to increase the caster if one arm was already too long and fighting against me.
 
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