Trouble with pinion bearing preload

[Raiph]

I'm trying to use a crush sleeve eliminator kit from yukon and I can't get the preload right. Using the solid spacer and a .020 shim I wind up with 24-25 in/lb of preload but with .021 worth of shims I wind up with 9-10 in/lb of preload. Certainly the tolerances aren't so tight that .001 should make that big of a difference in preload right?

I'm holding the yolk steady with a big pipe wrench wedged against the ground and then using an 18" breaker bar to tighten the nut. Once I got the .0210 shim up to 10 in-lbs I added a `3' cheater pipe thinking if I could get some real torque on the pinion nut it might get up where I needed it but that was a no go.

I've got no instructions with this, so just to make sure I've got this in the right order I've got the solid spacer against the shoulder of the pinion and the shim/s on top of the spacer, then the bearing sits on top of the shims and the yolk presses down on the bearing through the seal. Do I have those out of order and that's causing the preload not to be consistant?

I don't have any more ideas on what to do next, any help?

[sccacuda]

Using a solid spacer, the torque of the pinion nut does not affect rotating torque. The pinion nut needs to be torqued to spec, and then the rotating torque measured without any axles in the diff. New bearings, your looking for 25-30 in-lbs. Used bearings will be tough for you. But if you were just replacing the crush sleeve with another, you would have measured rotating torque before, replace, and add 5 in lbs.

All the shims/spacers should go before the bearing. Yoke is last, and might have an oil shim after, but again, on the yoke side of the bearing your only spacing the yoke out, not changing rotating torque.

[Raiph]

So are you saying I should have a total of 25-30 in lbs with the differential and ring gear installed too or just on the pinion by itself?

It's all brand new: ring and pinion, differential, bearings and races and seals.

[sccacuda]

Just the pinion installed, nothing else. 25-30 in-lbs rotating torque. Did you already measure pinion depth? You'll probably need to fine tune. I'd suggest reaming out your old lower pinion bearing to a slip fit. Install the pinion to the correct depth with shims under the bottom bearing based on your measurement. Do not install the oil seal. Install your spacer and shims to to get 25-30 in-lbs of rotating torque. After installing and before measuring, roll the pinion several times, then check rotating torque. Then install the diff with ring gear. I'm assuming your using roll adjusters on the side bearings? I don't know what type of rearend this is. If using roll adjusters, i like to snug down the caps and then set backlash by rolling the adjusters. They need to be torqued to 75 ft-lbs. for bearing preload. So caps snug, set backlash, torque roll adjusters and then torque caps. Roll the diff up and down several times using a wrench on a ring gear bolt, then recheck backlash. If it is correct, move on. If not, repeat until it is. Run the pattern and see where the gear mesh is. High/low, heel/toe. Adjust the pinion depth if necessary by removing or adding a shim under the lower pinion bearing. This will not affect rotating torque, as you are shimming under the bearing. If it is shim adjusted diff, let me know, and I'll go over that.

This is why I charge 4-5 hours to set-up a rear. Special tools, dummy bearings, pinion depth tools, etc...

[Raiph]

It's an 8.5" 10 bolt. I've already got the backlash and pinion depth adjusted using new shims but I didn't realize that 1/8th of a turn on the pinion nut could take me from 6 in/lb preload to 32 in/lb so I had to ditch the over crushed collar and instead opted for this crush sleeve eliminator kit that is also giving me fits.

The yukon booklet claims the preload for new bearings for this rear end should be 14 - 19 in/lb but the difference of .001 in shim on the solid spacer for the crush sleeve eliminator takes me from way below that spec to way above it.

[MonzaRacer]

Personally as for me for rebuilding a rear end is take your pinion to a machine shop that preps cranks, get it crank polished so that you and smack pinion on 2x4 to install the bearing or at least press it on with arbor press.
Then if you need to change shims you simply tap it on piece of wood and bearing comes off easy to swap shims.
Been building rear ends for years, never had one fail from doing this. Set pinion depth, torque nut, use dial or beam inch pound or digital wrench to read rotating torque.
A little tight I have little issue with. I have used dead blow rubber hammer too settle the bearings. OR I have actually spun the pinion with an impact (ie I always lube bearings while assembling anyway so spinning them shouldnt hurt) dont do it for minutes of time, just few seconds. This lets it sort of knock the high spots down so to speak.

[bryant]

one thing that effects the rolling resistance is the lubricant on the bearings while you are checking. I use a heavy sticky grease. i will shoot for 22-24 inlbs on a cool day. on a hot day the grease is thinner and i shoot for 18-20 inlbs. ive seen where gear oil is used and that shouldnt be over 12 inlbs on new bearings. the grease makes it a lot easier to get a good measurement with.