More Hot Rear Axle Hubs

[Tow4]

I recently did a brake job and repacked all wheel bearings front and back. I also replaced the hub seals on the rear axles.

The hubs on the rear axles are running what I consider too hot. After running down the highway at 50mph, the rear hubs are too hot to hold your hand on for 5 seconds. I put a little water on the hubs and it doesn't boil off, so they are less than 212 degrees; but the exact temperature is unknown. I read that bearing temps should not be more than 50 degrees above ambient temperature. Since it's been in the nineties here, that would make it almost 150 degrees. I don't know if you should be able to hold your hand on 150 degrees for 5 seconds. Maybe someone knows a rule of thumb for judging temperature.

The front hubs are cool to the touch. I adjusted all the bearings same way; the only difference is the rear hubs have outer grease seals that the front do not. The brakes aren't dragging since the drums themselves are not hot.

I've read the grease seals can make the hubs run hot. Question is; can the grease seals make that much heat? I also noticed after driving about 200 miles over the weekend the temperatures seemed lower. However, the last couple of miles I was only going about 35mph so that may account for the difference.

 

[gringeltaube]

.......................Question is; can the grease seals make that much heat? I also noticed after driving about 200 miles over the weekend the temperatures seemed lower. However, the last couple of miles I was only going about 35mph so that may account for the difference.

My answer (again) is: YES!
If still in doubt, take one of them out, drive for a while and compare temps.

Eventually they will "wear in" or better say burn out, soon! Then hub temperatures will be back down to "normal", at the price of reduced sealing capability, at best...!

G.

 

[bsorcs]

This seemed the appropriate thread to tie into.

On the last recovery leg from Redstone, rearmost axle hubs were noticeably warmer than the front rears...could hold my hand on 'em for as long as desired, but they were significantly warmer. They cooled down and stabilized over the last 130 miles, as I ran slower. I'm looking for some pragmatic counsel re prioritization, as I have a USN motor whale boat recovery trip ahead...about 1200 miles each way. Already adjusted the floppy parking brake shoes and installed new belts. Might should order a hose or three. Engine running well.

Issues are as follows: 1) above-noted heating; 2) relatively minor leaking from the rearmost axle wheel cylinders; 3) today-noted red grease on the inner front tire...ie knuckle boot. Bottom line has to be fix 'em all...no-brainer; 4) yesterday heard/felt a 'clunk' at the left front hub on turning right at very low speed. Questions are: which to tackle first; how much effort re the rear hubs; what the heck might that be up front left?

Been reading and re-reading the stepXstep ta's re fronts, rear bearings, and cylinders...stellar stuff. Since the rears have to come off, I'll conceivably kill 2 birds...cylinder rebuilds and at least bearing repacks. The truck has 46k miles, so it would seem reasonable to do a complete job...rear seals, bearings, races, washers...as opposed to simple repacks. I likely can hit this part fairly quickly, as I have the Timken numbers for the bearings and races and should be able to get 'em locally. Need Timken/NAPA/??? i/o seal numbers to go with these. Have to order cylinder kits for the rear and seal and boot for the front.

Seems clear I've a bit of work ahead, but it's pretty straight forward, particularly with the info resources available. Am I on track? Am I missing something obvious/simple? If I go for both boots, am I likely to find what's making the clunk?

Heck of an intro to maint/repair, no! In for a penny, in for a pound. Has to be character building.

bs

 

[Heavysteven]

I did the front, it was a work out. Took me and 2 guys 6 hours. Did alot new boots, cleaned greased king pins, brakes, bearings, and seals. The step by step directions on this site are perfect.

I would put it up on jacks and do all six in 2 days.

 

[gimpyrobb]

Which to tackle first BS? The brakes! Start there and work your way out.

 

[RAYZER]

Bs, dont worry,this stuffs real easy to figure out and work on, the pop up front could just be suspension, mine doesit all the time, but could be a axle u joint, you'll know once you get in there, you can pull the front and rear hubs without removing the wheels which will save you some time but its a big wrestling match without a wheel dolly, buy a wheel bearing packer to make things less messy, you will need about 10 cans of brake cleaner,10 rolls of paper towels and a hazmat tray, good luck!!

 

[bsorcs]

H/G/R,

Thanks, gentlemen. In a somewhat perverse way I'm actually looking forward to this! Parts hunt starts tamale for this former govt scientist.

bs

 

[zak]

There's a post about putting a spacer between the bearing and seal. It worked for me.

 

[Bill W]

Zak/Larry
What did you use for a spacer?
I was gonna grind the tabs off one of the old nut locks and try that

I did all brakes and seals on my deuce and the left rear is running about 15° hotter then the other rears which is funny as that was the same hub that ran hot on my last ( untouched) deuce??, its also the only rear hub where I installed new cups and cones.
Bill

 

[zak]

I found a washer/spacer from McMaster-Carr and turned it down in a lathe to about .080. I don't know if I'd worry about only a 15 degree difference. Mine was so hot you could'nt hold your hand on it. My truck had a leaking seal when I got it. I repacked the bearings put new seals in and the trouble started. No matter how I adjusted the bearings the hub would run very hot. I even tried new bearings. I read here about the seals being a problem so I made the spacer. It worked. The hub is now the same temp as the others and no leaks after about 300 miles.

 

[Bill W]

I'm starting to think its more then just a tight seal, I readjusted the bearings put in another seal ( same brand though ) drove her about 5 mile and that hub was 25° hotter then the rest, I don't think a tight seal would cause that kind of temp difference in that short of miles. I did notice that the drum was hotter then the rest but wheel turned nice and smooth when I had axle out so I'm thinkin out loud here that maybe that brake is working fine and that the other rears aren't doing their part causing more load on that wheel so even though the truck brakes evenly I'm gonna bleed and readjust all the rear shoes. All the outer seals on my deuce are New star I think its odd that just one is acting up, but I have been ( oh so ) wrong before

 

[Wildchild467]

my deuce had new wheel cylinders installed by uncle sam before i bought it. plus the rear rear axle looked like it was replaced, and that rear rear axle has hotter hub temps than the rest. I would think when they replaced the wheel cylinders they packed the bearings and stuff. i put 3000 miles on it since i bought it in mid april, so it could be a good idea. i dont totally think that a tight seal could cause the extra heat, but more than one person has said that and me being new, i believe ya'll. i still would love to pull them all apart and pack the bearings and give everything a look though.

 

[rlwm211]

Adjusting bearings properly is key to maintaining cool hub temps. Also if a brake shoe, or shoes are dragging, you are guaranteed to have a hot hub. I would add that if you have one axle doing the majority of the braking those hubs will consistently be hotter.

It is very easy to adjust your bearings too tight. An old timer told me, a very long time ago, that a loose bearing will not burn up, but a tight one will. Now, obviously, a super loose bearing is a problem waiting to happen, but this makes sense to be honest that a bearing needs to be adjusted just tight enough, and not any more.

Lots of new bearing systems use a lot of preload. The older bearing and race systems do not require more than is enough to stop the bearing from slopping in the race. Attention should be paid to make sure the bearing and race are in good condition and do not have any rough spots nor should the bearing have any sense of pitting, or any feeling of roughness when it turns in the race. That test is a part of the bearing packing procedure.

If I had a hub running hotter than the rest, I would take it apart and find out why. Some of the parts are expensive, and you could have a failure on the road and a tow is very expensive if you break down.

This kind of problem is a pure and simple detective job, and once the brakes hanging is eliminated, you have only a couple of other possibilities to look into.

RL