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post #1 of 15 Old 11-12-2007, 05:30 PM Thread Starter
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Caster

I have a question about Caster.

Since my lift I am currently at 2.8* positive caster. I see that Jeep's Specified range is 6* to 8* on the JK.

So my question is, what kind of problems could come from this?

I know that the wheel does not return to a straight line as easy with less caster and may wander around the road more but I am ok with that affect as it is not too bad right now. What Caster angles are you guys running 4"+ seeing?

What else could happen? Are there any wear issues on tires or extra stress anywhere?
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post #2 of 15 Old 11-12-2007, 06:51 PM
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Quote:
Originally Posted by WTF_LOL View Post
I have a question about Caster.

Since my lift I am currently at 2.8* positive caster. I see that Jeep's Specified range is 6* to 8* on the JK.

So my question is, what kind of problems could come from this?

I know that the wheel does not return to a straight line as easy with less caster and may wander around the road more but I am ok with that affect as it is not too bad right now. What Caster angles are you guys running 4"+ seeing?

What else could happen? Are there any wear issues on tires or extra stress anywhere?
I'm 2 1/2" lift in front, Cam Bolts gave my alignment guy got a castor of 5 & he said that was right on for my needs. Drives just fine now.

Jim,
USMC 0311 - 1811 RVN (Dec 67 - Aug 69) DAV, DMZ "Leatherneck square"((To All The "November Charlie Foxtrot's" that think they know)) You Are Clueless
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post #3 of 15 Old 11-12-2007, 07:06 PM
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Quote:
Originally Posted by WTF_LOL View Post
I have a question about Caster.

Since my lift I am currently at 2.8* positive caster. I see that Jeep's Specified range is 6* to 8* on the JK.

So my question is, what kind of problems could come from this?

I know that the wheel does not return to a straight line as easy with less caster and may wander around the road more but I am ok with that affect as it is not too bad right now. What Caster angles are you guys running 4"+ seeing?

What else could happen? Are there any wear issues on tires or extra stress anywhere?
1) how did you manage to get that much caster change ?

Your return to center will suffer and you "may" get some funky tire wear as now your ackerman angle is not "right" when you turn. This also may affect your turn radius.
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post #4 of 15 Old 11-12-2007, 07:25 PM Thread Starter
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USMCDOC14,

~2.5" lift, maybe a touch more. Stock arms. No cam bolts.

You sound surprised to hear 2.8*? What should be expected at that lift? I remember hearing some TJ guys getting into negative caster (with larger lifts)

Last edited by WTF_LOL; 11-12-2007 at 07:34 PM.
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post #5 of 15 Old 11-13-2007, 05:37 AM
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Originally Posted by WTF_LOL View Post
USMCDOC14,

~2.5" lift, maybe a touch more. Stock arms. No cam bolts.

You sound surprised to hear 2.8*? What should be expected at that lift? I remember hearing some TJ guys getting into negative caster (with larger lifts)
I don't really remember but that seems too drastic a change from 6-8* down to 3* with only 2.5" of lift.
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post #6 of 15 Old 11-13-2007, 06:08 AM
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Quote:
Originally Posted by WTF_LOL View Post
Specified range is 6* to 8* on the JK.
Where did you get that from?

Factory spec for caster is:

+4.2 0.5

Mine is at about +2.5 and it feels just fine.
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post #7 of 15 Old 11-13-2007, 06:31 AM
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BTW Here's the rules regarding the drive shaft angles:

Good cancellation of U-joint operating angles is within 1degree.
Operating angles less than 3 degrees (U-joint system).
Operating angles less than 10 degrees for constant velocity joint.
At least 1/2 of one degree continuous operating (propeller shaft) angle. On one U-joint system less than 1 1/2 degree operating angle.


I am off and will be reducing the pinion angle by a couple of degrees shortly, which will also bring my caster down. But apart from cutting and rotating the knuckles, there is not much I can do about that.

If I bring the caster to within spec, my pinion angle goes too high and I get drive shaft vibration. Most probably not such a big issue for those running stock shafts, but with aftermarket shafts you will get vibration if they are too far off.
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post #8 of 15 Old 11-13-2007, 06:41 AM
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Does this relate to the terra flex 2.5 BB lift? I thought it did not change the castor that drastically? Oh and what is everyones opinion on cam bolts? good or bad?
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post #9 of 15 Old 11-13-2007, 06:51 AM
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Quote:
Originally Posted by mike_engle View Post
Does this relate to the terra flex 2.5 BB lift? I thought it did not change the castor that drastically?
It doesn't. If he's now at 2.8 and spec is +4.2 0.5 then he's actually only 0.9 out, which is not that much.

Quote:
Oh and what is everyones opinion on cam bolts? good or bad?
They will adjust out this kind of thing, but I personally don't see the need for them. Put some adjustable uppers and lowers in and you can correct the pinion angle and move the axle forward to where it belongs.
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post #10 of 15 Old 11-13-2007, 09:22 AM Thread Starter
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Quote:
Originally Posted by PhilD View Post
Where did you get that from?

Factory spec for caster is:

+4.2 0.5

Mine is at about +2.5 and it feels just fine.
Seems that that is the issue then. I got those numbers from calling the dealership so I am not surprised they are wrong

Anyway, sounds like we are at nearly the same so I feel better about it. Everything felt ok, just was worried that being that far off (from the numbers the dealer gave me) could cause problems.

Thanks PhilD, you da man!
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post #11 of 15 Old 11-13-2007, 09:40 AM
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Originally Posted by WTF_LOL View Post
Seems that that is the issue then. I got those numbers from calling the dealership so I am not surprised they are wrong
That explains it, I think factory caster for a TJ is +7.0 1.0 which would give you the 6-8 they gave you.


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post #12 of 15 Old 11-13-2007, 09:54 AM
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Quote:
Originally Posted by nam6869usmc View Post
I'm 2 1/2" lift in front, Cam Bolts gave my alignment guy got a castor of 5 & he said that was right on for my needs. Drives just fine now.
Jim, where did you get your cam bolts?

/jl

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post #13 of 15 Old 11-13-2007, 10:03 AM
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I'll have to dig up my alignment notes. FWIW, the factory measurements on a recently calibrated alignment machine were not even close on most measurements and way outside specs. Caster and Thrust angle were the two that come to mind as being the worst. And of course in stock form, there is little to nothing you can to about it.
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post #14 of 15 Old 11-13-2007, 12:37 PM
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Quote:
Originally Posted by John L View Post
Jim, where did you get your cam bolts?
"John L" here ya go,.....http://www.4wd.com/productdetails.as...7&partID=15495....
I've wheeled these hard & they are still rock solid. I have to agree with the Adjustable Control is the way to go, but I was spending $$$$ on other things at the time.

Jim,
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post #15 of 15 Old 11-13-2007, 02:16 PM
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Quote:
Originally Posted by nam6869usmc View Post
"John L" here ya go,.....http://www.4wd.com/productdetails.as...7&partID=15495....
I've wheeled these hard & they are still rock solid. I have to agree with the Adjustable Control is the way to go, but I was spending $$$$ on other things at the time.
Thanks for the link. Mine is a little darty, for lack of a better word, on the highway, I'll have the alignment checked first, then maybe put these in.

/jl

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