Knuckle centering question (1 Viewer)

[The Punter]

I may get flamed for this, but here goes

Exactly how much variation can there be in knuckles. In the 3 sets I have to choose from for my disc upgrade the shims only varied by 1 or 2. If I choose a set and setup for preload only, am I courting disaster later? I've got the Marlin Crawler seals that deal with misalignment better for my buildup. Just trying to ascertain how much effort I put into finding, renting or buying a centering tool.

Cheers

 

[Bluegrass40]

From my experience, it's a crap shoot unless you know it has not been done in the past or it was done properly by the po. Mine were not close to centered on either side.

 

[Mr Cimarron]

I did not use the centering tool. Only preload adjusting with shims when going to 60 knuckles. I haven't put enough miles on yet to see if it will spring a leak. I'm not afraid of going back to correct if it starts leaking.

 

[SuperDuperCruizer]

If the axle shaft isn't centered from the differential to the knuckle, the inner seal can unevenly wear &/or potentially leak differential oil into the knuckle. I rebuilt an axle leaking at the knuckles. One side was spot on while the other was off. The inner axle seal was shot on that side too. I believe the axle was on its original seals and the knuckles were shimmed as they left the factory.

 

[Bluegrass40]

If the axle shaft isn't centered from the differential to the knuckle, the inner seal can unevenly wear &/or potentially leak differential oil into the knuckle. I rebuilt an axle leaking at the knuckles. One side was spot on while the other was off. The inner axle seal was shot on that side too. I believe the axle was on its original seals and the knuckles were shimmed as they left the factory.

Surprising to hear that one side was off if it had the factory shim pack in it. How far off was it? Was it outside of tolerance?

In order to be off it was either not set up well at the factory or there was deformation in the knuckle or axle housing tube (which seems unlikely). Could have been built on a Monday morning or Friday afternoon I guess

 

[php74]

You probably know but centering is done by bottom shims only...and preload by the top shims.

 

[The Punter]

You probably know but centering is done by bottom shims only...and preload by the top shims.

I do now, thanks!

 

[GRM]

You probably know but centering is done by bottom shims only...and preload by the top shims.

By adjusting preload, you also adjust the center of the knuckle.

One truck I have uses no top shims and a large stack of bottom shins. The last truck I owned was the opposite - lots of shims on top, none on th bottom.

I first set the preload - then measure the thickness of the combination of top and bottom shin stacks. Then I center the knuckle, doing a little math to determine what shims go on top and what ones on the bottom.

 

[SuperDuperCruizer]

I don't know the history of the truck but I could see there was a fender bender on the side in question. The original bumper was bent up but not enough to require a replacement. The fender was replaced & the panel w/blower box was too. I can't remember how far out of center the knuckle was but the seal was unevenly worn to one side. I doubt anything more than bodywork was taken care of with the insurance claim. The axle/knuckle could have been knock out of alignment from the accident.

I do remember playing with the shim combinations to get the desired total thickness. I wrote it all down somewhere. If I find my notes, I'll update with more details. My initial assumption was that someone set it up close enough and the fender bender wasn't the root of the problem.

Surprising to hear that one side was off if it had the factory shim pack in it. How far off was it? Was it outside of tolerance?

In order to be off it was either not set up well at the factory or there was deformation in the knuckle or axle housing tube (which seems unlikely). Could have been built on a Monday morning or Friday afternoon I guess

 

[php74]

Just use the shims that were already on the bottom (or measure them and duplicate the thickness with new ones). Then mess with the top ones with the scale until you have the correct preload.