Wheel bearings

The post above counterdicts itself several times, I really don't understand.

No bearing will survive under 100 ft lbs of torque, I mean lets get reality here. The 100 lbs plus or minus is what it took to crush the sleeve, and that was on new bearings only. Used pinion called for a "slight preload" ???? been too long.
All my info on front wheel bearings came from General Motors Training center in San Leandro CA in the 70's. I too was a GM tech all thru the 60s and 70s.

But in short, do what works for you. Even official pros have different ideas, all of which may be the best way.

RJsfishin wrote:
You can use a little logical thinking in the case of wheel bearings.
In some places, tapered roller bearings DO require a slight preload, such as pinion bearings. And that is tolerable only because they run in oil.
Any greased bearing w/ zero clearance or preload on it, in theory has no room for grease, therefore will suffer an early failure. This was proven when disc brakes first came out, and a preload was called for to keep the brakes from dragging. But there was massive bearing failure because of the "NO ROOM FOR GREASE" A year (or less) later the preload spec was dropped, and so did the bearing failure.
NEVER run a preload on a greased bearing, it will fail from lack of lubrication.

Over 100 ft. lbs of torque on a pinion bearing is not slight.
As an example of your no grease theory, my F53 with grease packed front wheel bearings has been running for 92K miles with preloaded bearings. The OEM bearings failed at 38K miles, they were loose.
You are right about over torqued bearings on the new disk brakes. I was working in the auto industry when that happened. Ford specked the torque at 15 ft. lbs. and they failed. As you indicated, the specs was DROPPED, but you didn't include the whole story. The specs was DROPPED to a lesser number, but still preloaded and all was well.

Your mileage may vary.

Richard

Check youtube.

Too much preload is a cause for early failure on wheel bearings, nearly all the greased wheel bearings call for 0.00"-0.02" of end play.

I torque mine to 50ft/lbs and then back off 90, and the back up to where the torque starts to increase and then move as little as necessary to get the castle nut or pin to align.

My truck uses an outer sprinkle nut as well and that adds preload too.

As far as my TT it has about 7K miles on it and I so far have just been adding grease. I plan to inspect the bearings here soon.

You can use a little logical thinking in the case of wheel bearings.
In some places, tapered roller bearings DO require a slight preload, such as pinion bearings. And that is tolerable only because they run in oil.
Any greased bearing w/ zero clearance or preload on it, in theory has no room for grease, therefore will suffer an early failure. This was proven when disc brakes first came out, and a preload was called for to keep the brakes from dragging. But there was massive bearing failure because of the "NO ROOM FOR GREASE" A year (or less) later the preload spec was dropped, and so did the bearing failure.
NEVER run a preload on a greased bearing, it will fail from lack of lubrication.

RLS7201 wrote:
Hold the bearing up to the sun light and look for sparkles in the grease. Sparkles indicate metal in the grease. If they pass that test, wash them, look them over carefully for defects, repack if good and reinstall. Tapered roller require a slight preload to keep the rollers in full contact with the races. If left loose, they hammer themselves to death. Ball bearings from the pre 60s did require a slight clearance and that ideology carried over to tapered rollers.
Roller bearings have run many thousands of miles with no preload but would have run longer if installed properly.
Seals also last longer if they don't have to tolerate movement between components.
If you ever have the opportunity to talk to a real bearing engineer, he will concur with my statement.

Richard

Interesting note about preload on TRB's. Amost everywhere else you see them used, there is a recommended pre-load mentioned. As far as I can tell, no one is claiming such for wheel bearings, but always wondered why. Given that they are made to take thrust loads as well as radial loads, you'd think they'd need a little more than just "possible" contact, "half" contact, "intermittant" contact, etc., to distribute the thrust load around the race. Yet, time and again, zero pre-load is recommended. Not saying it's right or wrong, just saying, "hmmmmmm?".

OTOH, I know a guy who went through rear wheel bearings on his Ford Fiesta like candy until he stopped preloading them. Until I hear differently from a reliable source, as close to the light side of "zero" is what I'm using. Hasn't failed me yet.

Hold the bearing up to the sun light and look for sparkles in the grease. Sparkles indicate metal in the grease. If they pass that test, wash them, look them over carefully for defects, repack if good and reinstall. Tapered roller require a slight preload to keep the rollers in full contact with the races. If left loose, they hammer themselves to death. Ball bearings from the pre 60s did require a slight clearance and that ideology carried over to tapered rollers.
Roller bearings have run many thousands of miles with no preload but would have run longer if installed properly.
Seals also last longer if they don't have to tolerate movement between components.
If you ever have the opportunity to talk to a real bearing engineer, he will concur with my statement.

Richard

around page 60 here

We had problems with our wheels off & on for years. Last fall we finally found a TT service guy who knew what he was doing. He definitely does finger tight after the backing off. He found one of our wheel hubs torqued so tight it was deforming the bearings.

You should refer to the axle mfg literature if you have it. Mine (Dexter) says to torque the nut to 50 foot pounds, back off the nut then finger tighten it.