HMMWV Hub temps?

[Army Kid]

Hey, I had a rear hub that was getting hot... too hot to hold your hand on the tie-rod connecting plate on the back for more than 10 secs. Jacked up, wheel didn't rotate too easily. Ripped it apart, replaced all bearings, races & seals.
There was only 1-thin shim previously on the upper bearing block/seal.
Measured with a micrometer , added shims, reinstalled to proper torque, repeat until I got the amount of play noted in the tech manual. 0.001" - 0.006" end play. (mine was ~ 0.004").
All reinstalled now. Still heats up.
The other rear hub was leaking and heating up less than the 1st one. Same rebuild = same result as #1. This one had more shims than the 1st, but I still had to add more to get the right amount of end-play. Heat is a product of friction, and so I am not pleased at this result obviously. I am in Arizona (108F yesterday), so currently I have been using the Lucas Hub-oil (stuff is thick like honey). I could switch to the Lucas synthetic stuff, but am doubting that that will result in a cooler hub. Plus that stuff seems to like to find new ways to escape the seals...
Question is... how hot do the hubs get on all the other trucks out there?? Anyone?

 

[Army Kid]

I'm gonna try to retorque the main wheel hub nut & use the lowest value I can get away with and see if that does any good. (I'm at the upper torque spec limit now) but advise still welcome.

 

[steelsoldiers]

Good question. I haven't checked the hub temps before. Do you have a infrared temp gun? If so, you could post some actual temps and we could measure ours for comparison.

 

[Army Kid]

Good question. I haven't checked the hub temps before. Do you have a infrared temp gun? If so, you could post some actual temps and we could measure ours for comparison.

Good thinking. I have a Fluke thermocouple probe I can check it with. I'll post something soon measuring from both sides (center of the exposed hub area looking at the wheel & on the backside - center of the where the tie-rod link cover is) Maybe after a 10min drive & 30min drive readout. All-4 wheels.
I can repeat after changing the hub nut torque from the high end to the low end of the spec to see if any change.

 

[Army Kid]

Good thinking. I have a Fluke thermocouple probe I can check it with. I'll post something soon measuring from both sides (center of the exposed hub area looking at the wheel & on the backside - center of the where the tie-rod link cover is) Maybe after a 10min drive & 30min drive readout. All-4 wheels.
I can repeat after changing the hub nut torque from the high end to the low end of the spec to see if any change.

OK here's the info.........
Conditions:
Lucas Hub Oil (the really thick stuff)
New bearings, seals, etc on both rear hubs, all torques to spec (high end) and shims / end play is perfectly in spec.
Never checked (yet) front hub bearings, etc (just changed oil so far)
Ambient temp = 94 F (at night)
Std 12-bolt rims; no-runflats; 37psi per tire; Goodyear 37" radials

Starting Hub temps: (outside center / hub cover- tie rod link)
LF= 100/101
RF = 98/99
LR = 98/99
RR = 97/98

After 10 minute drive avg 45mi/hr:
LF= 112/109
RF = 109/106
LR = 119/119
RR = 116/118
(from cold -> fronts increased ~10F and rears increased ~20F)

After additional 20 minute drive avg 45mi/hr:
LF= 113/115
RF = 110/109
LR = 132/131
RR = 127/130
(from cold -> fronts increased ~12F and rears increased ~30F)

So, with new bearings,etc,etc, the rears are rising in temp over 2x what the fronts are.
I will be changing out the rear radius rod assy soon, so I will remove the Hub cover and loosen the main hub nut to min torque spec, then remeasure comparing left rear & right rear to see if the looser one is cooler than the tighter one... TBD.

 

[Retiredwarhorses]

What are you torquing the spindle nut too?
That is a multi step process...it's almost finger tight....the tabs prevent it from backing off....

 

[Army Kid]

What are you torquing the spindle nut too?
That is a multi step process...it's almost finger tight....the tabs prevent it from backing off....

I used the tech manual for this... tighten spindle nut to 35-45 ft-lbs , rotate spindle 5-times CW, 5 times CCW, loosen nut, retighten to 23-27 ft-lbs.
I put both the left & the right hub nuts on to the upper end of the spec (27ft-lbs), but as I said above, I thought i'd try the low end on one of the hubs, so I took it back apart, and tried 23ftlbs (maybe 22). Haven't measured yet, but to my hand, they feel the same... strange.

 

[jwaller]

What are you torquing the spindle nut too?
That is a multi step process...it's almost finger tight....the tabs prevent it from backing off....

When I redid my stock hubs I switched to the H1 lock ring with set screw. When I inspected my alpha hubs that are now on the truck they have the same setup. I fell much better about them than I did about the tab's.

 

[Army Kid]

When I redid my stock hubs I switched to the H1 lock ring with set screw. When I inspected my alpha hubs that are now on the truck they have the same setup. I fell much better about them than I did about the tab's.

Yup, I converted to the Blue Hummer locking spindle nut kits. Pricey, but, pretty bulletproof design...
I see Predator now makes 'heat sinks' for their hub cover plates.... SUPER $$, but shows that these things do heat up (although I don't know why you would spend $500/ wheel on those things, seems absolutely crazy to me.) To each his own.
I'd make some on my milling machine if I thought they'd do much good, but I dont.

 

[happycamper]

Half my hubs are getting hot as well. Ever figure out the issue?

 

[Skrilex]

I wouldnt think 30° over ambient was bad for it

 

[happycamper]

My concern is how different my hubs are. I also had some wear on the washer (https://www.steelsoldiers.com/showthread.php?174425-HMMWV-M998-Hub-Washer-Wear)

My left side which I didn't disassemble are about 95 degrees after a 20 mile run.
My right side, which I might have over torqued get 120 degrees. Ambient 77 degrees.

I plan to replace the main bearings in case I damaged them. But if that doesn't fix it I'm out of luck, unless maybe the input bearings are failing and I just happened to catch it.

 

[DatGuyC]

I was advised that the hubs should not get hot enough to make them uncomfortable to hold your hands on for extended periods. When I rebuilt my hubs I found that the input bearings were a major cause of heat and I had to keep adding shims to the retainer till they ran cooler, the output bearings always ran cool if you follow the tightening procedure.

 

[spoonsc1]

I would expect the rears to be hotter than the fronts if all things were equal. The fronts are hit with the cooler ambient air and the rears are getting cooled by the heat soaked air the HMMWV is putting off. We all know how hot the tunnel get while driving!! I know my rear hubs are hotter than the front via non contact thermometer(FYI, same thing with the diffs)

 

[94M998A1]

Hey, I had a rear hub that was getting hot... too hot to hold your hand on the tie-rod connecting plate on the back for more than 10 secs. Jacked up, wheel didn't rotate too easily. Ripped it apart, replaced all bearings, races & seals.
There was only 1-thin shim previously on the upper bearing block/seal.
Measured with a micrometer , added shims, reinstalled to proper torque, repeat until I got the amount of play noted in the tech manual. 0.001" - 0.006" end play. (mine was ~ 0.004").
All reinstalled now. Still heats up.
The other rear hub was leaking and heating up less than the 1st one. Same rebuild = same result as #1. This one had more shims than the 1st, but I still had to add more to get the right amount of end-play. Heat is a product of friction, and so I am not pleased at this result obviously. I am in Arizona (108F yesterday), so currently I have been using the Lucas Hub-oil (stuff is thick like honey). I could switch to the Lucas synthetic stuff, but am doubting that that will result in a cooler hub. Plus that stuff seems to like to find new ways to escape the seals...
Question is... how hot do the hubs get on all the other trucks out there?? Anyone?

what page in the TMs have the specs for the plastic shims install? I can’t seem to find it

 

[REF]

I am concerned about your statement that your using Lucas Hub Oil - the stuff is thick like honey. Nothing against Lucas that have great product it's more about thick like honey. These hubs use strait cut gears, unlike helical cut gears that tend to pump oil from leading edge to trailing edge, strait cut gears tend to stack up on the oil as it passes through pushing the 2 gears apart causing more load on the bearings. I have worked with other high speed gearboxes with strait cut gears that would burn the bearings out if 90 weight oil was used instead of the 30 weight they called for. I would suggest draining the hub that is running the hottest and put in regular 85/90 gear oil ( synthetic if possible) and run you 20 mile test. providing your initial bearing preload is correct, I think you will be surprised.
If this test proves correct then your temperature differential in the other hubs can be explained by the amount of wear in the gears themselves , more worn will handle the thicker oil better ( cooler) tighter gears (less backlash) would run hotter.

Have been lurking on this sight for quite some time this is my first post, hope it helps.

 

[Bulldogger]

I am concerned about your statement that your using Lucas Hub Oil - the stuff is thick like honey. Nothing against Lucas that have great product it's more about thick like honey. These hubs use strait cut gears, unlike helical cut gears that tend to pump oil from leading edge to trailing edge, strait cut gears tend to stack up on the oil as it passes through pushing the 2 gears apart causing more load on the bearings. I have worked with other high speed gearboxes with strait cut gears that would burn the bearings out if 90 weight oil was used instead of the 30 weight they called for. I would suggest draining the hub that is running the hottest and put in regular 85/90 gear oil ( synthetic if possible) and run you 20 mile test. providing your initial bearing preload is correct, I think you will be surprised.
If this test proves correct then your temperature differential in the other hubs can be explained by the amount of wear in the gears themselves , more worn will handle the thicker oil better ( cooler) tighter gears (less backlash) would run hotter.

Have been lurking on this sight for quite some time this is my first post, hope it helps.

Note that the Original Poster hasn't been on in a VERY long time. (Click his name and then Profile) Doubt he'll reply. Just FYI. This thread is ancient.

I think most of us use the recommended gear oil from the TM.

Bulldogger

 

[DREDnot]

Note that the Original Poster hasn't been on in a VERY long time. (Click his name and then Profile) Doubt he'll reply. Just FYI. This thread is ancient. Bulldogger

Even so, it popped up and made me go check my hubs with the IR temp gun. They were all 25-30 degrees above ambient temperature. Im running Walmarts finest 80W90. Im satisfied with those temps.