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Wheel Bearing Temps High, grease & Preload Q's

BugEyeBear

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Hot hubs are generally caused by one of a couple of things: Dragging brakes, too much grease, or too tight of a wheel bearing adjustment.

-Chuck
I agree!

Could also be grease washout caused by a bad seal.

In MY case it was caused by a combination of too much preload and the use of the wrong grease.

Too hot to touch is TOO HOT!

Suggest that you pick up an IR Thermometer Gun to check your temps (available pretty cheap from Harbor Freight & other sources...). This will permit you to better locate the hot spots w/o burning your hands. It also gives you a more accurate number than you'll get w the "hand thermometer". You'd be amazed at how much you can learn about the condition of your truck by keeping an eye on the temps of ALL of the running gear (brakes, hubs, axles, diffs, xfercase, trans, PTO, winch, engine, etc.).
 

M35A2

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THANKS Guys for all of your answers & suggestions!

The repair shop has disassembled the rear wheel bearing assys again...
They are inspecting the bearings & races, and will be packing them with a non-Moly high temp grease prior to reinstall.

For your reference here's a data sheet that I found on the MIL-G-10924 Grease that is refererred to in the Lubrication Order.
GREASE, AUTOMOTIVE AND ARTILLERY GREASE
Appears to be a Lithium 12%, Polyalphaolefin (a polymer) 63%, Distillates 12% composition, with a boiling point of 700 degrees F, & a melting point of -70 degrees F.
So I would think that a High Temp Lithium Grease with similar properties should be a suitable replacement.

The repair shop is also going to modify their bearing preload procedure to include the 1/8 turn nut back off, as noted in the TM.
Here's the procedure they are now following:
1. Torque the inner adjusting nut to 150 ft-lbs while rotating the wheel at least 2 revolutions.
2. Relieve pre-load by backing off the adjusting nut 1/2 to 1 full turn.
3. Re-torque the inner adjusting nut to 50 ft-lbs.
4. Then back off nut 1/8 turn.
5. Install adjusting nut star washer, and outer adjusting nut .

6. Tighten outer nut 100-150 ft-lbs.
7. Bend over tangs of the star washer to secure the adjustment.

They are also planning on taking a close look at the outer seals to see if they are dragging on the race.
I'm not sure if they will attempt to modify these seals (mod noted in other threads), so IF the seal is dragging this might be something I'll just have to live with untill I can mod them myself.


I'm keeping my fingers crossed that THIS attempt will be successful! fat lady sings

I'll let you know what the outcome is....

-Bear-






When I've done wheel bearings I firstly pack them with a good Lithium based grease.

AS far as pre load goes, I will crank those bearings as tight as they will go while spinning the wheel at the same time to seat the bearing properly. Then slacken off so they have quite a bit of play in and then tighten up again, as tight as they will go spinning the wheel at the same time. I then slacken off again until there is some play in the bearing and then tighten up HAND TIGHT again, spinning the wheel. When you can't do it up anymore by hand take up a quarter of a turn and check end float. As soon as you can't feel any end float that's it. Back off nut slightly to take into account the fact that when you tighten the outer nut up it will also tighten the inner nut slightly. I've used this method with all my trucks and never had a problem.

I think your problem is the wrong grease (too thick) and pre load on the bearings. It's all very well having a figure of say 150 lbs, but it all depends on what condition the bearings are in, how much grease and what type is used etc. The best way I've found of doing these is by feel. Take your time (shops are on a deadline to get onto the next job so might rush through yours to get the next one underway - time is money). It took me all day to do the bearings on my Land Rover.

Hope you get it fixed.
 

Westex

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A report back. I got it to it's destination, but in this Texas heat, no telling what became of the bearings themselves. I could only keep my hand on the hubs for about 4 seconds. Too hot, I know. Before it moves again, I slip out the axles and do the repack. I suspect too much preload and gear oil through whatever seal was there, which washed out the grease, or a combination of the above. My purpose in posting this, is that our trucks are over engineered, which is a great thing. All of this while pulling my trailer with 7000 pounds of mesquite wood on it. I refused to load the truck bed with more wood because of the bearings.
 

stumps

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A report back. I got it to it's destination, but in this Texas heat, no telling what became of the bearings themselves. I could only keep my hand on the hubs for about 4 seconds. Too hot, I know. Before it moves again, I slip out the axles and do the repack. I suspect too much preload and gear oil through whatever seal was there, which washed out the grease, or a combination of the above. My purpose in posting this, is that our trucks are over engineered, which is a great thing. All of this while pulling my trailer with 7000 pounds of mesquite wood on it. I refused to load the truck bed with more wood because of the bearings.
If the seals leak badly enough to wash out the grease, you will usually have great wet drool marks down the sides of your tires. It isn't something you can miss.

Timkin roller bearings are perfectly happy with differential oil as a lubricant. They wouldn't run hot because of running a thinner lube than GAA.

Hot hubs are caused by: 1) excessive bearing tension. 2) dragging brakes. 3) excess grease. and a distant 4) excessively thick grease.... I'm not sure where you would find an excessively thick wheel bearing grease.

I pack the bearings with a #2 NGLI wheel bearing grease, or GAA. I do the packing by scooping a blop of grease into the palm of my hand, and kneeding as much grease as I can into the rollers with my fingers. I wipe a little grease on the seals, and butter in enough grease to fill in the sides of the cages/rollers, and that is it for the grease. It takes several minutes to pack the grease into the bearing. Using a bearing packing attachment is fine too... If you have one big enough. Do not stuff 5 lbs of grease into every nook and cranny in the hub. If you do that, you will cause the grease to be pumped around by the roller bearings, and that makes lots of heat. The only purpose for the grease is to lube the roller bearing cage, to provide a film of lubricant that cushions the rollers against the races, and to keep the dust and dirt away from the rollers... a problem that is not so critical with modern seals... more so with the old felt seals. The grease will push out of the way of the rollers almost immediately in operation. The grease acts as a sponge full of oil, and keeps a wet oil film on the bearing surfaces. That is all.

I put the hub back on the spindle, and tighten up the nut a bit beyond snug, while rotating the hub in each direction. Tightening a little more each time until I feel bearing rumble and drag. (The torque specs in the TM are really only good for brand new bearings and races, and for mechanics that can't be taught how to feel when a bearing is right. ) I then loosen the nut until the drag and rumble is gone, usually 1/8 to 1/4 turn, and there is a barely perceptible click feel when I attempt to "steer" the axle by pushing and pulling on the drum. You can't hear it, or see it, but you can just barely feel a little click as you change directions. Sometimes you have to repeat the tightening and loosening of the nut several times until you get the right feel.

Then is when you put on the lock tab, and tighten up the outer nut to spec. Tightening the outer nut will take up some of the "lost motion" set into the bearing when you adjust it, but I believe there should still be a very tiny amount (others disagree). If the bearing regains the rumble feel after you tighten the outer nut, it is adjusted too tight and you need to loosen it... and do the inner nut adjustment over again, looser this time.

One thing to note: I have never had a bearing fail from being adjusted a tad loose.... But they always fail when they are too tight.

-Chuck
 

Westex

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Stumps, your post is so good, I've printed it off and will use it as a guide when I go back out to Dryden for my 'fun in the sun' axle grease day.
 

OPCOM

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Old rule of thumb- if you can't hold your hand on the bearing cap due to the heat, it is most likely too hot. Could you have a brake shoe dragging that is causing the heat build up from the drum to transfer to the bearing caps? Just something to check.
I have had this. It does not take much drag either, if highway speeds are involved.
 

cattlerepairman

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Nope; they heat up too fast in short order, like 5 miles. This tells me it's the preload.
Did you compare wheel hub temp and brake drum temp? Unless the drums are cool, I respectfully disagree because "preload" is what I thought as well, with a wheel that drove me nuts for getting hot very quickly. All I did was back up the brakes all the way on this wheel - result: ice cold.

It taught me that very little brake drag (the kind that you would accept with car brakes, when they scratch just a little) is required to heat up the Deuce drums quite remarkably in only a few kilometres.
 

Westex

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cattlerepairman: Thanks for this post; Think I will check this out. Always wrong to assume one thing over another. I stand corrected.
 

cleb

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There is a thread around here somewhere I started, but it was the new seals from China that caused the high heat issue....I couldn't find all of the bearing races to bend the seal in a press, so I put a shim in. Not ideal, but it did the trick. This was after replacing bearings + races + seals 2 times :(. They need to do a better job of QC at the factory...
 

Beerslayer

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Great thread.

Hot hubs are caused by: 1) excessive bearing tension. 2) dragging brakes. 3) excess grease. and a distant 4) excessively thick grease.... I'm not sure where you would find an excessively thick wheel bearing grease.
I would like to add to your list

5) Worn bearing/pitted race

I always do a safety check when stopping on long trips. Last summer, 85 deg ambient temps all but one hub was around 100 deg, same temp as tires. Right front was 180. Started stopping frequently to monitor, when it got to 247 deg started running water on it to cool enough to get home.

Pulled to inspect, race was pitted. New bearings, lithium grease, now runs same temp as others.
 
S

Starbuck

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I work at a diesel truck and trailer shop, I currently don't own a deuce yet, is there a "crush sleeve" between the outer and inner bearings? If there is sometimes these are worn down too much and the factory specs do not work, and the hub will not spin freely. When I am in doubt or if there is not a crush sleeve I use a Dial indicator to measure end-play. Tighten down the inner nut to seat everything properly and back off a bit, use the gauge to measure until it is set between 1 and 5 thous of an inch, tighten the lock nut down and remeasure, tighten or slack off the inner nut until your final play is between 1 and 5, too tight will cause excessive heat and after a while the bearing will pile up, too loose is better than too tight as it will cause slower failure, perfect is better though!:beer:
 

BugEyeBear

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No crush sleeve from what I remember...

Measuring slack w the dial indicator sounds like a good idea.
(I relied on the "touchy feely" method, AND my IR gun to verify the running heat build-up.)

One thing to remember is that many of the afternarket repair parts used here have different tolerances than stock parts did... SO many of the factory specified procedures might not be exactly the best approach.

Good mechanic practices, experience, and using your head is the best course of action.
 
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Tinwoodsman

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Well, I have been reading "Hot Hub" related threads (No Not Hot Tub!!) for about two hours now. My bottom line question is this. Is there a source to buy seals from that are good to install without modification?
 

BugEyeBear

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Here's the IR/Laser Thermometer Gun that I bought at HarborFreight for checking the running gear temps on my MVs....
Non-Contact Laser Thermometer

GREAT TOOL for checking the temps of your hubs, diffs, xfercase, trans, etc.
Allows you to catch problems before they get TOO COSTLY!!

At this price ($25.99) I'm tempted to buy another one!!
 

wcolt45

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I too am having the hot hub problem after flipping my hubs,i'm pretty sure i simply have the bearings too tight,the grease i used was Lucas Red and Tacky,I gotta ask,is this grease acceptable for the wheel bearings in our Deuces?Has anyone else used if for theirs?
 
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