Okay, I've done wheel bearings a ton of times and here's how I do it:
- Tighten the castle nut to a specified torque to seat the bearings, while spinning the rotor.
- Back off until the nut it is able to be moved by hand.
- Finger tighten the nut as much as possible. If the hole for the cotter pin is not accessible, back off the nut until it is.
In general, this has served me fine. However, I have bene chasing a front end looseness on my S10 for a while now, that had me thinking I had bad balljoints, as I was able to get movement from the wheel when I grabbed it at 12 and 6 and shook it. Couldn't see the ball joints move at all, though. Finally, I pulled the dust covers off the spindles, and tightened the castle nuts by 1/6 of a turn each, and that did the trick.
So, is my step 3 above wrong, and I should tighten past finger tight to get the cotter pin in, or is it a one off case with this truck? Or, am I going to destroy the bearings?
The bearings will heat up a bit while you're driving, and things expand with heat. You need to leave them just a tiny bit loose when you adjust them so that they don't expand and get too tight (and hot) in use. As long as the wheel turns freely with no binding and just a tiny bit of "looseness" when cold, is what you're aiming for.
I've never loosened on step three to make the cotter key hole, only tightened.
I've always used a wrench, snugged up, then backed off and turned down to where I just feel it snug up, which is a feeling more than anything. I then tighten to the next slot. Never lost a bearing on any of the hundred dozen cars I've repacked bearings on over the last 44 years.
They kinda changed the rules when disc brakes came along, because a bit of slack meant nothing with drum brakes. Discs, you can rattle the pads back with freeplay.
Tapered roller bearings are perfectly happy running with a bit of preload.
I think your exclusive use of your hand for tightening may not be correct. I don't think there is any need for the castle nut to be loose enough to be moved by hand, since the function is to preload the bearing. I haven't done one in a while, but I'm pretty sure that my castle nuts are too tight to turn with my fingers, so I use a small wrench.
I agree with Streetwiseguy's steps
Thank you. Okay, it sounds like I will leave it the way it is for now, and listen for any bearing noise. At least they are very cheap on old GMs if I need to replace them.
I look up the spec in the service manual, everyone's different.
wae
UltimaDork
8/11/24 12:04 p.m.
Last time I did that kind of bearing was on the motorhome a while ago. The book said to turn the wheel while tightening the nut to 12 ftlb to fully seat, back it off to "just loose", then hand-tighten, then loosen until the hole lines up, but no more than a half flat.
That was a 1993 P30 chassis, but I'd be a little shocked if that wasn't the same for all their trucks of that era.
On the '55 Chevy I just did, the spec was 30 ft.lbs and back off no more than 1 flat for the cotter pin hole. It has ball bearings and I ran it wrong for a few months before I discovered the difference in specs between tapered roller bearings and ball bearings. 
Well, I'm less certain now.
Well your S10 almost certainly has tapered bearings, no?
In reply to budget_bandit :
Yes, and you can't go wrong by the old "tighten while spinning until it stops setting everything, back off, finger tighten, back off until you can line up the cotter pin" method.
Some vehicles, however, suggest that you tighten the nut a certain torque (or certain effort to turn the hub, measured with a fish scale) and then just leave it there. Some people WANT it preloaded slightly Mazda
OP, on 70's and 80's cars (and trailers) I always did the same method you described in the first post. Only slight difference is if I could figure that the cotter pin was closer to fitting with a hair of tightening I'd do that instead of loosening the longer distance back to the cotter pin opening.
Everything I've done more modern than that has been sealed cartridges so far.
budget_bandit said:
......I'm pretty sure that my castle nuts are too tight to turn with my fingers....
This has the "Say What?" Magazine article feel all over it.
