Questions About my Castor Angle - JeepForum.com
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post #1 of 19 Old 07-22-2021, 09:58 PM Thread Starter
Mayday-Joey
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Questions About my Castor Angle

Hi, I have an 85' CJ-7 with a ~2.5" shackle lift. I've been trying to get it to drive more straight lol. I finally got around to checking my castor, see the pic attached. Seems to be about 6 degrees but am I measuring it in the correct location?

I put the indicator on a flat spot on the diff, I thought I had read somewhere before on this it's a good place. But if there's a better location let me know.





Other:



BTW, Before people go on an off topic rampage, I've already checked tire pressure, ball joints and tie rod ends.


I however am going to loosen the u bolts and re-torque them and the shackles. The rear axle is shifted about 1-2" to one side and the front passenger side is tilted.



my hope is I can shore up the suspension before I replace it, I don't drive it enough to replace the suspension, yet.


Second pic is just for run, not related.

Attached Thumbnails
castor1.jpg   WnyoOK3.jpg   2020-12-14.jpg  

85 CJ-7 4.2, a lot of unknown parts. My first Jeep!

Last edited by Mayday-Joey; 07-23-2021 at 12:19 AM.
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post #2 of 19 Old 07-22-2021, 11:10 PM
jurgen24
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Hard to see where you are measuring. If you draw a line through the lower/upper ball joint, that would be the caster.


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post #3 of 19 Old 07-23-2021, 12:44 AM
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I'm going through the same issue with my CJ7.

From everything I have read, you should check from the top of the upper ball joint on the knuckle.

Per the 1978 FSM, CJs came at +3* caster. Most folks go anywhere from 4-8*. I know, huge range.

Measuring from the pinion wouldn't give you the actual caster; there's some difference, usually about -2* from what I have read, baked in. It may be more or less.

There's a really good thread here about dealing with caster.

I put in the shims, but it's pouring cats and dogs here now, not to mention it's almost midnight. I'll take my beast out for a spin on Saturday to see if the 4* shims I installed helped.

Luck to you!

Dave
Mesa, AZ

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post #4 of 19 Old 07-23-2021, 02:05 AM
keith460
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You can't measure castor angle off the cast iron tab for the front axle bump stop. Plus, what you show is the opposite of what you need for castor angle.

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post #5 of 19 Old 07-23-2021, 02:28 AM
80cj
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I've seen people put a socket on the upper ball joint nut and sit the protractor on top of the socket. Probably better to take the Jeep to an alignment shop and have them measure caster, camber toe in/out.
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post #6 of 19 Old 07-23-2021, 07:02 AM
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Yes, thats what I found easiest. Theres not much room on the top of the "C" so putting a socket over the nut gives you a new flat spot to measure from. Your caster should be in the 5-7 degrees positive range, which means the top should be tilted back compared to the bottom.

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post #7 of 19 Old 07-23-2021, 10:30 PM
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My method is pretty EZ

If your front shackles are taller than the original shackles (even grossly taller)

You may have a caster problem!

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post #8 of 19 Old 07-23-2021, 10:43 PM Thread Starter
Mayday-Joey
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Lol, It does have shims, but after reading how bad shackle lifts are it's still going to have issues. But I'll try measuring it off the C hub tomorrow.



Eventually the suspension will get replaced but likely not till next year.



Quote:
Originally Posted by JEEPFELLER View Post
My method is pretty EZ

If your front shackles are taller than the original shackles (even grossly taller)

You may have a caster problem!

-----JEEPFELLER

85 CJ-7 4.2, a lot of unknown parts. My first Jeep!
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post #9 of 19 Old 07-23-2021, 10:44 PM Thread Starter
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I'll have to try it off the C hub tomorrow and see what I get.


I'll report back with what I find.

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post #10 of 19 Old 07-24-2021, 12:46 AM
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Quote:
Originally Posted by Mayday-Joey View Post
Lol, It does have shims, but after reading how bad shackle lifts are it's still going to have issues.
That's a common misnomer. It's the poor installation that is bad. Three inch shackles isn't some magical length. Many vehicles have different lengths. Even some Jeeps used 2". Wranglers use 4". Some pickups use 5" or larger. Jeeps actually benefit using longer shackles by gaining more flex. But it has to be done right and thats where people fail and give shackles a bad rap.

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post #11 of 19 Old 07-24-2021, 08:36 AM
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Quote:
Originally Posted by Renegade82 View Post
That's a common misnomer. It's the poor installation that is bad. Three inch shackles isn't some magical length. Many vehicles have different lengths. Even some Jeeps used 2". Wranglers use 4". Some pickups use 5" or larger. Jeeps actually benefit using longer shackles by gaining more flex. But it has to be done right and thats where people fail and give shackles a bad rap.
Not to get off topic, but I mildly disagree with this statement. Longer shackles do more than shift caster angles, they increase lateral flex as well. This can cause steering slop. They also increase the lateral load on the front spring hangers. Not such a big issue on earlier CJ's, but on 76 and later rigs with bolt on hangers, they can flex them at the frame mounting point and eventually possibly cause loose hangers, bolt breakage, frame damage, and hanger damage. The longer the shackles, the worse the effect.
Back on topic:
I agree with 80cj. Spend the money and get a professional to run a readout and adjust the toe in. This would give you an accurate starting point for any further adjustments.

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post #12 of 19 Old 07-24-2021, 11:36 AM
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Quote:
Originally Posted by jeepdaddy2000 View Post
Not to get off topic, but I mildly disagree with this statement. Longer shackles do more than shift caster angles, they increase lateral flex as well. This can cause steering slop. They also increase the lateral load on the front spring hangers. Not such a big issue on earlier CJ's, but on 76 and later rigs with bolt on hangers, they can flex them at the frame mounting point and eventually possibly cause loose hangers, bolt breakage, frame damage, and hanger damage. The longer the shackles, the worse the effect.
Back on topic:
I agree with 80cj. Spend the money and get a professional to run a readout and adjust the toe in. This would give you an accurate starting point for any further adjustments.
No, we don't disagree at all. You make my exact point. Poor installation! You can't just swap shackles and be done with it. Just as in other "systems" you need to beef up all parts involved, plus shim if necessary. The mounts are notoriously weak parts and should be replaced even if no suspension change is made.
And yes, to compound that basic flaw the longer shackles do just that. They add additional lateral torque that can twist them and/or help to make that inevitable crack at the rivot hole happen sooner.
And with that additional lateral movement you need to use poly bushings, properly sized poly bushings, preferably with a steel sleeve for proper spacing for tightening of the shackle itself. System flex is the job of the bushings. Rubber is too compressible. Grease bolts are a plus for added smoothness when the suspension cycles.
And then theres the shackles themselves. Two straps of 1/4" steel and 2 or 3 bolts don't cut it. These need at a minimum 3/8" sides and a block between them to keep the sides parallel, bolted or preferably welded. You want a solid part that stays rectangular, just as the factory ones did by using a 3 sided one piece and shoulders to keep the removable side 90 degrees to the bolts. Length, I addressed that in my earlier post.
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post #13 of 19 Old 07-24-2021, 02:36 PM
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Quote:
Originally Posted by Renegade82 View Post
You want a solid part that stays rectangular, just as the factory ones did by using a 3 sided one piece and shoulders to keep the removable side 90 degrees to the bolts. Length, I addressed that in my earlier post.
The factory ones aren't all that bad a design. Just wish they were a little heavier. I'm still running mine after 40 years and no problems.
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post #14 of 19 Old 07-24-2021, 02:44 PM
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Dave, had a little break in the weather here, and interested to see if you had a chance to get Klooge out for a test run, after installing the front shims? What was the result?

[QUOTE=Mongo228;41318977] I'll take my beast out for a spin on Saturday to see if the 4* shims I installed helped.
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post #15 of 19 Old 07-25-2021, 08:41 AM
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[quote=devildog80;41320031]Dave, had a little break in the weather here, and interested to see if you had a chance to get Klooge out for a test run, after installing the front shims? What was the result?

Quote:
Originally Posted by Mongo228 View Post
I'll take my beast out for a spin on Saturday to see if the 4* shims I installed helped.
They helped, but didn't solve the problem. I'll drop you an email.

Dave
Mesa, AZ

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