Wheels / Tires: Front wheel bearing adjustment

[jackb]

A few things..... I'm unable to find my answer by the search function. Someone, sometime, posted a torque value for setting front wheel bearing adjustment. Is this a good way to set them ? The good book says to bind the bearings, then loosen nut one castellation. When I do this, I still get some play. Once adjusted correctly, should the hub generate any heat (to touch) under driving conditions ?

[DEEPNHOCK]

(Long reply)
A couple things to remember.
The bearing manufacturer sets the industry standard adjustment requirement,
The method you stated is one of the accepted methods to prevent the dual taper bearings from being adjusted too tight.
Use that method, as it is published in the Studebaker service manual.
Now, to get technical and explain the 'why'...
Tapered roller bearings (as installed in opposition to one another, like on a spindle).
(disclaimer): Industry standard procedure is TMC (Technology Maintenance Council) RP618.
This has been developed by the bearing manufacturers and adopted by the TMC to reduce wheel end bearing failures on HD trucks.
But the cause and adjustment also applies to almost any tapered bearing spindle setup.

RP618 states that the proper adjustment for tapered roller bearings in opposition is +.001" to + .005" positive end play.
This number is the distance between the big end of the tapered roller to the flange on the inner race.

So, in a nutshell (a technical term)...
If your bearing adjustment is too tight, the end of the roller is pushed so hard into the shoulder of the inner race that the lubricant will be pushed out, and the rotating face friction will increase to a point where metal failure will occur.
That is why the spec is +.001" to +.005". You can measure this number with a dial indicator. Fact-based and verifiable.

But 98.5% never get measured. And, to boot, the ideal adjustment for a tapered bearing (as stated by the bearing manufacturers) is actually 'pre-loaded' -.002" to -.003".
The problem with that number is that without special tools NOBODY can 'feel' preload.
Once you get the adjustment to .000" YOU CAN'T MEASURE IT.
So a positive number on end play is chosen. As close to zero as you can get... But not zero.
If you measure your end play and it is zero, you have no idea (without special tools) if your preload is -.001" or -.008", which will lead to premature bearing failure.

Equipment manufacturers know this and set their procedures so the average technician (you) can adjust the bearings for long life without raising the odds of a premature failure. That is why the 'norm' is to snug it up (take it to .000" end play) and back it off a small amount to achieve +.001" to +.005" end play.

How much you back it off is dependant on the pitch of the thread for the retaining nut(s). A course thread will require less rotational back off that a fine thread. There are spec's for this (get out your Machinist Handbook) but manufacturers simplify this by using the flats on a hexagon.

Clear as mud, right?
But this explains the 'why'.
Teach this stuff for a few decades and you won't forget it.
Jeff

[Bud]

There will always be a small amount of heat generated from rotating bearings working under a load. The recommendations in the book do work and the bearings will live a long life if the bearings are properly lubed with a good quality grease. I replaced the original castle nuts on my cars with nuts and adjusters used on 60's and 70's Fords. The Ford nuts do not have castellations on the nuts but use an external cap with numerous cotter pin holes that are offset to make a more accurate adjustment. Cars equipped with disc brakes do not like any play in the wheel bearings as that can effect disc brake operation. Bud

[altair]

Some European cars have a split nut with a threaded screw through it, to get just the right clearance, bring the nut up then tighten the locking screw. With our cars there is nothing to adjust, bring it up snug and then back it off the first castle and insert the pin.

[jackb]

good and thx

[Big Dan]

And Just FYI, tightening then backing off to the next castellation works for BALL BEARING wheel bearings as well! The are the '48 Buick Special Wheel Bearings on my Boat Trailer! (and yes, I replace those, the races, and seals)

[E. Davis]

If you are in doubt just remember that a little to loose bearing will run longer than a too tight one.

[ColoradoHawk]

I was looking for an answer to that very same question a number of months ago, and came across a post that I took a screenshot of a keep in my phone for future reference.

[dpson]

Picked up this Wheel Bearing Adjustment tool years ago and have never used it. Looks like a mini-torque wrench (beam type).