4-degree spring shims - location?

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Jul 4, 2021
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Clemson SC
Hi Everyone,

Maybe a stupid question, but before I make a mistake, the 4-degree shims for a raised suspension go on the front axle, correct? I bought mine from CCOT and their directions state:

HFS Spring shims counter problems caused by installing taller than stock height shackles. Caster correction Shims help correct drive shaft angles to relieve stress on U-joints by rotating axles upward. This changes the driveshaft angle, which ultimately reduces the pinion angle and reduces driveshaft vibration. Shims correct steering caster angle. Shims reduce wear on knuckle, bearings & tie rod ends. Shims help stabilize steering and reduce road wander.

Install thick part of the shim to the front of the rear axle. Shim installs on center pin of the spring stack.

I called and talked to Manny at CCOT and asked if it really goes on the back axle, as that doesn't make sense to me. He said he would call me back after he asks somebody. I didn't get a callback before they closed. I plan to install them tomorrow. Can anyone help me tonight?

Thanks!

Mark in Clemson SC
 

1911

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You've got two different problems going on with a lifted suspension, both of which can usually be solved with angled shims, so it may be easy to confuse them.

You put angled shims on the front axle spring perches to correct the steering caster.

You put angled shims on the rear axle spring perches to correct the working angles of the u-joints in the drive shaft.

In both cases, you want to measure and get the right angle (in degrees) of shims; you can't just put in 4-degree shims because some sales guy said to. Just FYI, not trying to rag on you.
 

Shark56

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As said above. What are your symptoms that you need shims for?
Most of the time, (not always), shims are needed in the front for handling issue, vibrations or steering wander. Some times they are also needed in the rear, usually because of lifted shackles causing vibrations. From my limited experience, it is usually front end wander that requires a shim to correct.

4⁰ will probably get you where you need to be.
 
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Joined
Jul 4, 2021
Messages
53
Location
Clemson SC
You've got two different problems going on with a lifted suspension, both of which can usually be solved with angled shims, so it may be easy to confuse them.

You put angled shims on the front axle spring perches to correct the steering caster.

You put angled shims on the rear axle spring perches to correct the working angles of the u-joints in the drive shaft.

In both cases, you want to measure and get the right angle (in degrees) of shims; you can't just put in 4-degree shims because some sales guy said to. Just FYI, not trying to rag on you.
Thanks 1911. This is helpful.
As said above. What are your symptoms that you need shims for?
Most of the time, (not always), shims are needed in the front for handling issue, vibrations or steering wander. Some times they are also needed in the rear, usually because of lifted shackles causing vibrations. From my limited experience, it is usually front end wander that requires a shim to correct.
Thanks 1911 and Shark56,

It's steering wander. I don't have any unusual vibrations that I can feel. I have a 350 with a Saginaw steering unit. Before the lift, it was a small pucker factor.. ( the springs, perch pins and shackles were 100% gone, the suspension was rusted into one piece, it literally wouldn't budge going over anything, it was like a solid frame go-cart. I had to cut it to remove it.) I installed an HFS 4-inch lift with greasable hanger pins, an extended pitman arm, a new steering stabilizer, etc. There was play in the steering, which I pretty much removed by adjusting the screw on top of the Saginaw box. But anything over 35 MPH is like driving on ice with a high pucker factor. All the stuff I read here on the forum suggested the shims. It seemed like a cheap way to see if something would help, so I went for it.
 

rkymtnflyfisher

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You've got two different problems going on with a lifted suspension, both of which can usually be solved with angled shims, so it may be easy to confuse them.

You put angled shims on the front axle spring perches to correct the steering caster.

You put angled shims on the rear axle spring perches to correct the working angles of the u-joints in the drive shaft.

In both cases, you want to measure and get the right angle (in degrees) of shims; you can't just put in 4-degree shims because some sales guy said to. Just FYI, not trying to rag on you.
All of this ^^^^^
 

Shark56

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I think for sure you need a shim up front. If you can check your pinion angle it will give you a good idea of what degree shim you need.
 
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Clemson SC
I think for sure you need a shim up front. If you can check your pinion angle it will give you a good idea of what degree shim you need.
Thanks, Shark. I think my plan will be to try to figure out how to measure my pinion angle, ( I am sure there should be a post on this somewhere) and if it is close enough to 4 degrees, just go ahead and add the shims and see what happens. This isn't a daily driver and I can modify the shim with the equipment I have, so I'll give it a whirl. The main question on what shims on what axle and the effect they make was answered, so it gives me someplace to start. I truly appreciate you all helping me. I'll let you know what I find out and hopefully, it will help the next guy.
 

pb4ugo

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Typically, You should determine what your caster angle is, then install the proper shim to get positive caster. 4° degrees will probably get you close. The shims should be made of steel. Aluminum ones will crack and crumble.
 
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Great Day! I went ahead and installed the CCOT aluminum 4 degree spring shims ( I understand steel is the way to go, but the hassle of return, while I can test what I have is a wash). The difference in steering was a total game-changer. I can now run above 45 mph without fearing death. It's really like night and day. I haven't gone back and studied the geometric reason why there is such a difference, but I will, I saw the posts explaining why. I would think that the sellers of these suspension lifts would at least mention that you may need the shims, or give you the option of the angle that you may need.

My rig went from something I couldn't drive more than to town, to something I have no issues with ( at least steering-wise) .. thanks for the help everyone. if there is another source for steel shims other than Valley Hybrids, please let me know.

Beer Time.

Mark
 
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Great Day! I went ahead and installed the CCOT aluminum 4 degree spring shims ( I understand steel is the way to go, but the hassle of return, while I can test what I have is a wash). The difference in steering was a total game-changer. I can now run above 45 mph without fearing death. It's really like night and day. I haven't gone back and studied the geometric reason why there is such a difference, but I will, I saw the posts explaining why. I would think that the sellers of these suspension lifts would at least mention that you may need the shims, or give you the option of the angle that you may need.

My rig went from something I couldn't drive more than to town, to something I have no issues with ( at least steering-wise) .. thanks for the help everyone. if there is another source for steel shims other than Valley Hybrids, please let me know.

Beer Time.

Mark
If George doesn’t have them I can point you to another source.
 
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If George doesn’t have them I can point you to another source.
Valley Hybrids do have them. $24.00 for each shim and $4.98 for the longer bolt. My aluminum ones for the pair with the bolt were $25.00 from CCOT. I may just wait till the aluminum ones start to fail and then replace them at this cost. I get that they have to be fabbed and stuff, so I think the price is reasonable, I just need to get my already spent $25.00 out of use on the aluminum ones.
 

pb4ugo

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They can crack during installation. The spring is curved and usually the shim isn't. You might have to shorten the sping to the perch. Good luck.
 
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Blue77FJ40

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I’m surprise no one has mentioned which way the fat side of the shim goes. For the front axle, it needs to face forward to lower the diff for a stock sprung under setup. Worked well for my squirrelly steering post lift.

For steel shims you can also try Roger Brown at 4Crawler.com
 
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