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Unread 08-11-2010, 01:07 PM   #16
80cj
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Quote:
Originally Posted by Chewtoy View Post
I put 4 deg shims on my Dana 30 to move my caster from ~2 to ~6 and it made a world of difference on my '76 CJ5. Much less wander.
Yours too, huh? Makes me wonder why they put so little caster in at the factory. I had the stock suspension on mine when I had it measured.

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Unread 08-11-2010, 02:46 PM   #17
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Quote:
Originally Posted by Chewtoy View Post
I put 4 deg shims on my Dana 30 to move my caster from ~2 to ~6 and it made a world of difference on my '76 CJ5. Much less wander.
Just wait until you get some friction wear in there and everything starts moving around, creating a rolling deathtrap. Front shims are no different than installing blocks. The last thing you want is a tolerance stack at those locations.

The correct method to achieve larger jumps in caster values is to rotate the knuckle yokes as Foggybottom mentioned, as you do not create a stack-up and you retain (or even perfect) your pinion angle.
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Unread 08-11-2010, 03:50 PM   #18
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I've got a spare dana 30 and am willing to attempt rotating the axletubes. How much of a biotch is it to get them apart? is there a good thread on this?
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Unread 08-11-2010, 04:04 PM   #19
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I've got a spare dana 30 and am willing to attempt rotating the axletubes. How much of a biotch is it to get them apart? is there a good thread on this?
If you search for "rotate" in CJ Tech, you'll probably find the ones where this has been discussed. People have linked to writeups in them

Its quite a biotch, as it is a labor-intensive process to grind through the welds from the tube to the knuckle yoke. Having the axle out of the vehicle so you can turn it while grinding will be helpful, but you'll need to have it back in the vehicle and able to be under load before performing the final welds. (Estimate and turn the yokes, tack them, set the vehicle down, measure, possibly adjust, etc.)
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Unread 08-11-2010, 04:12 PM   #20
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The way I get inner knuckles to turn is this.
1) Grind the welds between the tube and the C (inner knuckle) with a grinding wheel till it is almost gone. You have to be careful to not grind into the tube.
2) Switch to a flat cutter wheel to grind down the side of the knuckle and along the tube to get the last part of the weld. I try to make a 90 degree angle at the joint between the tube and knuckle at this point.
3) Once I think I have the weld ground out (it won't be) I take two hammers (about 3 lb) and bang on both sides of the C so as to try to knock it off the end of the tube. This generally makes a tiny crack show somewhere along the joint between the tube and knuckle. The crack will be so thin that is is not easy to even notice. I'm talking width of a hair thin. Once you get a crack you can see where else you need to grind to get all the weld out.
4) Then you can knock off the C with the two hammers hitting the C on both sides toward the outside of the tube at the same time. Once you have the Cs off you can put them on at your desired angle.
5) Note that you do not want any difference in caster angle from one side to the other so spend whatever time it takes to get the angles as exactly the same as you can otherwise your steering will pull to one side when you put it back together.
6) Jeephammer says don't hammer on the cast Cs but I've done it 3 times with no problem and I can't find any other way to do this job with the limited tools I have in my garage. I have seen pictures of people actually turning a C while still on the tube but you would need a lot of force and a way to hold the axle to do this. The ones I have had were always on too tight to even think about turning them.
7) note that you have to set caster, pinion angle and spring perches all at the same time with respect to each other to get the geometry you really want. If you think about it a minute that will make sense.
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Unread 08-11-2010, 04:23 PM   #21
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hmm. i just assume find a dana 44 and shorten it for all that labor huh? i'm definitely not in a rush. it's like a freaking hundred degrees everyday in louisiana right now
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Unread 08-11-2010, 05:42 PM   #22
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Quote:
Originally Posted by waydownsouth View Post
hmm. i just assume find a dana 44 and shorten it for all that labor huh?
And then rotate the knuckles for proper caster?
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Unread 08-11-2010, 06:02 PM   #23
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There is a guy in Denver who will take a full size D44, cut off the knuckles, turn the tubes out of the knuckles he cut off and weld the Cs back on at whatever caster you want for less than $75. Because of that I am out of the knuckle turning business and just let him do it.
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Unread 08-11-2010, 09:10 PM   #24
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Originally Posted by PavementPounder View Post
Just wait until you get some friction wear in there and everything starts moving around, creating a rolling deathtrap. Front shims are no different than installing blocks. The last thing you want is a tolerance stack at those locations.

The correct method to achieve larger jumps in caster values is to rotate the knuckle yokes as Foggybottom mentioned, as you do not create a stack-up and you retain (or even perfect) your pinion angle.
I would think that installing a front shim would be not much different than adding on a leaf above the main leaf as long as the angle of the shim is not too steep (I wouldn't go beyond 4 degrees) and the shim is made of steel and bolted to the spring pack with the center bolt and captured by the U bolts. The 4 degree shim I have on my Jeep is no more than 5/16" thick at the center bolt location.

What about spring over conversions where the main leaf (that takes all the side loads, etc) is positioned an inch or more above the spring perch on a stack of leaves and the CG is raised substantially? Doesn't the situation become more severe as the spring arch increases?

I realize that in shimming an axle for caster correction, front U joint angles are compromised but in my case, I have a set of free wheeling hubs and when in 4WD, I seldom exceed 25 MPH so vibration is not an issue.

Last edited by 80cj; 08-12-2010 at 01:12 AM..
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Unread 08-12-2010, 11:03 AM   #25
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This is a scan from my Jeep FSM saying to use shims to correct caster problems.
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Unread 08-12-2010, 06:51 PM   #26
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Here's the thread that will tell you why degree shims on a front axle are dangerous. Its a little long:

http://www.jeepforum.com/forum/f8/wh...-loose-445430/
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Unread 08-13-2010, 07:09 AM   #27
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I just did the 4* shims.....

on my 83 CJ7. It went from wandering to nothing but straight line. Marked improvement.
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Unread 08-13-2010, 03:36 PM   #28
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I've had 4°, NAPA bought, shims in my front axles for over 20 years and it has never been a problem but has been one hell of an improvement when 33" tires went on. Steering returns to center when completing a turn and it goes nice and straight down the road no matter how many ruts and grooves there might be. I installed them back on the front axle now that I have rebuilt the entire Jeep and switched to 32" tires instead. Didn't want to discard a good thing when I had it and will always keep them because of the improvement they made. The only thing I bought was new centering bolts of longer length so the wedges stay bolted to the spring packs of the new Black Diamond lift kit.
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Unread 08-24-2010, 08:07 PM   #29
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I purchased 4* shims for my 76 CJ5. Haven't installed them yet but eager to give em a try. I have a brand new 4" lift kit in which the center pin is 3/8"dia and about 5/16" long on both sides for mounting on the perch/springplate. I hear people mention a leaf spring stud replacement. My new leafs dont have a bolted stud holding the spring pack together. Is it necessary?
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Unread 08-24-2010, 08:18 PM   #30
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You won't find anyone offering the opinion that shims won't "work". They'll certainly change your caster. That's what blinds people about this. They take the shortcut and play a Jedi Mind trick on themselves, thinking that since it worked it must be okay. (Think low-hanging fruit.) The proper way to make this kind of adjustment on the front axle of a vehicle already modified, lifted, and with increased forces acting everywhere in the suspension is to do it permanently and without adding any additional parts between your perches and springs by way of rotating and re-welding your knuckle yokes. Shims are fine on non-steering axles.


Quote:
Originally Posted by gelmhorst View Post
I purchased 4* shims for my 76 CJ5. Haven't installed them yet but eager to give em a try. I have a brand new 4" lift kit in which the center pin is 3/8"dia and about 5/16" long on both sides for mounting on the perch/springplate. I hear people mention a leaf spring stud replacement. My new leafs dont have a bolted stud holding the spring pack together. Is it necessary?
Take another look at your center pin. I believe you will find that one end of it has a round head and the other is threaded. It is a bolt.

If your center pin doesn't go all the way though your leaf pack with a nut on the other end, please post a picture and identify what brand the leaf packs are. I'd like to see that.
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