Does your lifted roxor like to not stay on the road? Here's the fix.

[DrunkenSlug]

Alright ladies. I finally made my roxor drive like a really good daily driver again. The fix? Getting rid of that bullshit 0 degree castor. Mine was actually at -.5 degrees after doing the BMF 5.5 SPOA lift. Brought it to get aligned a few times thinking it was that, it wasn't.

Anyway, I used the following. You only need to do the front 2 but these particular leaf spring bolts came fastest so I got 8. You might find something better for your homes shipping. But you need 2, not 8. You could probably get away with 4 degree shims, but the CJ guys were recommending about 5 degrees positive so this should have me right at about 5.5 right now.

Two notes

1. If you are spring under axle, the thick end goes to the front. If you are spring over axle (like in the picture), thick end toward the back.
2. The centering bolts are MUCH too long. Simply install them and cut the rest off with a cut-off wheel.
3. Drill the hole of the shim out a it, its just one or two sizes too small for the leaf spring center bolts.

Oh also I took out the smallest spring from both sides of the front (I have a 2025 HD) and that helped a lot with bumps!

Guys, when I say it now tracks perfectly, I mean it tracks perfectly. It drives better than at least half the trucks I've owned now. Even on the 38"s.

 

[Joebv]

Thanks for this. Probably a should do for me.

 

[DrunkenSlug]

Thanks for this. Probably a should do for me.

It’s night and day. Ever since the lift it’s been a chore to drive on roads. Now it drives like any other! Minus the low power (even with the tune it’s slow with these 38s ha)

 

[Samyguy]

Maybe a stupid question. I thought the wedge went between the spring and axle ?? Not on top.

 

[DrunkenSlug]

Make sure to check drive shaft angles when installing the wedges and / or longer shackles - especially on the rear axle.
If there’s a vibration in a narrow speed band (say as the vehicle accelerates through 30-35 mph), then the angles of transfer case output shaft and diff yoke are not being (mostly) parallel.

Zero vibrations (on my setup). The extra 6 degrees only affect the front driveshaft anyway which doesn’t rotate about 90% of the time anyway. But definitely check angles! Seems these things vary user to user.

Edit: well re-reading, that’s a lie. I’ve always had a bit of vibration on acceleration at certain rpms, but it’s under load and it’s been there since new. Unrelated to this

Maybe a stupid question. I thought the wedge went between the spring and axle ?? Not on top.

I could be wrong and am open to it! Everything I read/found was to do it like this. Then during, I was sending pics to ChatGPT and using the one post I saw where a guy installed shims on a roxor. He had spring under though.

I’ll say, feels perfect as is. Don’t think it’d get much better regardless of what I do, but you could be right on the location.

 

[DrunkenSlug]

I have a feeling he’s right and if I put the shim below the leafs I’d gain a bit more castor actually

Edit: thinking and looking at it some more, I think you’re right @Samyguy! Good catch. The way I have it does angle it slightly but I’d guess I’m just slightly positive at this point, not the full 6. I’ll take it apart again and move it and report back. Nice catch! My first time doing shims.

 

[DrunkenSlug]

@AZROX

Are you saying the wedge above the spring is actually rotating the entire axle housing through the U-bolts enough to increase positive caster?

 

[Colderweather86]

You have them installed incorrectly. All you have done is change the plate angle. The caster angle is still the same.

 

[DrunkenSlug]

You have them installed incorrectly. All you have done is change the plate angle. The caster angle is still the same.

Oddly enough, moving them didnt change the drivability at all, still feels great! I'm guessing with it on top it compressed that side of the spring a bit since it has so much clamp force and I was probably a bit positive castor anyway. You guys were 100% right though, goes under makes way more sense. I think what confused me was the picture of the spring under shim I was referencing. My first time doing it, thanks for the help! This did move the pinion more than it was before.

Updated the original post with new reference pictures for people.

Also thanks @AZROX

 

[USMC]

DrunkenSlug, I change my angles when I drive either Uphill or Downhill!

I run with 35 inch off road tires at 35 lbs. and it will get squirrely on a rough road but otherwise, it's only squirrely half the time!

 

[txroadkill]

DrunkenSlug, I change my angles when I drive either Uphill or Downhill!

I run with 35 inch off road tires at 35 lbs. and it will get squirrely on a rough road but otherwise, it's only squirrely half the time!

Too high for 35s with the weight of the Roxor. I bet it’ll drive much better at 30. 28 might even be a doable number, just need to chalk test it.

 

[AZROX]

For anyone who puts longer shackles on their rig and wants to check how much it threw off the xfer case output shaft and diff yoke out off parallel, do this:
1. Get a digital, magnetic angle finder of your choice
2. Take measurement A at the inspection cover at the back of the xfer case (round sheet metal cover)
3. Take measurement B at the back of the rear diff cover. There’s an about 1 in wide flat surface.
4. A-B is the angle the two are out of parallel. This is the degree wedge to install.
NOTE: wedges mostly com in 2, 4, 6, degrees. If you cannot get the exact degree wedge (e.g 3 degrees), get a wedge that points the diff yoke 1 degree further down towards the ground (e.g. a 4 degree wedge).
5. Repeat steps 3 and 4 for front axle.

Explanation:
Longer shackles rotate the spring and axle assembly a few degrees around the welded axle bushing (e.g. forward facing spring bushing at the rear axle and rear facing bushing at the front axle). Now, the diff yoke is looking up towards the sky a few degrees. Install a wedge left and right such that the yoke looks back to where it should.

Why does it matter, you ask? When the xfer output shaft and diff yoke are out of parallel, the u-joints bind ever so slightly in a certain spot as they rotate. You accelerate through 20-30-35 mph and notice a vibration in that speed range (and go way at lower and higher speeds). That’s the unhappy u-joints.

 

[USMC]

AZROX, can you explain that in Crayon for me????

 

[AZROX]

Better than crayons … checkout this YouTube video by GarageFab….. just watch to where he talks about the wedges and skip most of what follows (double cardan, and multi link suspension, …)

To visualize adding longer shackles and the diff / pinion pointing towards the sky - go to an extreme: imagine you jack up the rig, remove the spring shackle. The spring and axle will drop + pivot and the pinion at the dff will point up.

Pinion angle is …. What I called the angle of the yoke at the diff.