Help Please - Manual Hubs Hot to Touch!

[mmesa005]

My son had the 4 wheel drive system engaged today as it was raining pretty heavily. He never went over 35 mph and drove about 10 miles going to and from school. When he came home he asked me to unlock the manual hubs and when I touched each hub they were very hot!

Earlier in the week he told me the brake / anit-lock lights went on when he depressed the brake pedal. I checked the bake fluid and found it low so I added fluid and the light extinguished. No leaks detected. Not certain if there is a connection here?

I did some preliminary searching through the archives and read that a number of things can contribute to the hot temperature of the hub but I would appreciate any validation that I am on the right track or if I missed something?

The Bronco is an 89 XL, automatic with manual hubs. PS/PB. I have owned it for about 2 months. Changed all the fluids, flushed the brakes with fresh fluid as I replaced RABS as the rear brakes were not engaging. Replaced front brake pads/rotors. Rear drums were fine.

 

[dirtcowboy]

check front bearings for torque? as in way too tight? Just sayin'

 

[mmesa005]

check front bearings for torque? as in way too tight? Just sayin'

Turned out to be the slide pins were gunked up and hanging the calipers. I did take the hubs off, cleaned, inspected, and repacked the bearings. They were put on correctly, not over torqued.

Thanks for responding!

 

[ab_slack]

I would say look for brakes dragging. That would heat up the rotors and heat the hubs.

Bearings too are a possibility....generally hubs will be a bit hotter unlocked than locked since when locked the bearings in the hub aren't turning.

I had a similar issues and it was a collapsed brake line (the rubber one). They have multiple layers and inner part can act line a check valve and not allow brake pressure to be relieved. You say the caliper slide pins, that make sense. Obviously it wasn't linked to hubs being locked.

Now if it got very hot, then it is possible the grease in the bearings got toasted. I know it did on mine. I ran it for awhile but eventually I replaced both bearings at the rotor. The one on the outside and the one on the axle shaft behind the rotor (often forgotten). If the grease has gotten burnt, replacing the bearings isn't necessary but new cleaning them and re-packing with grease would be good.

As for the four wheel drive system being engaged...hubs locked no big deal, but if your son was actually engaging 4WD while driving, normally rain doesn't have enough slip so I wouldn't advise using 4WD under rain condition except in specific cases because in turns there must be some slip. The only time I use in rain is when stopped and want extra traction accelerating (without turning).

 

[mmesa005]

I would say look for brakes dragging. That would heat up the rotors and heat the hubs.

Bearings too are a possibility....generally hubs will be a bit hotter unlocked than locked since when locked the bearings in the hub aren't turning.

I had a similar issues and it was a collapsed brake line (the rubber one). They have multiple layers and inner part can act line a check valve and not allow brake pressure to be relieved. You say the caliper slide pins, that make sense. Obviously it wasn't linked to hubs being locked.

Now if it got very hot, then it is possible the grease in the bearings got toasted. I know it did on mine. I ran it for awhile but eventually I replaced both bearings at the rotor. The one on the outside and the one on the axle shaft behind the rotor (often forgotten). If the grease has gotten burnt, replacing the bearings isn't necessary but new cleaning them and re-packing with grease would be good.

As for the four wheel drive system being engaged...hubs locked no big deal, but if your son was actually engaging 4WD while driving, normally rain doesn't have enough slip so I wouldn't advise using 4WD under rain condition except in specific cases because in turns there must be some slip. The only time I use in rain is when stopped and want extra traction accelerating (without turning).

We caught it early enough that the bearings were fine so we cleaned out the old grease and put in new. We pulled both bearings and replaced the rear seal as part of the service.

 

[Jim Oaks]

Turned out to be the slide pins were gunked up and hanging the calipers. I did take the hubs off, cleaned, inspected, and repacked the bearings. They were put on correctly, not over torqued.

Thanks for responding!

Fortunately it was just the slide pins. Slide pins are cheap, so it's best to replace them when they start looking rough. Don't forget the pin grease.

Usually, hot hubs are caused by bad or improperly adjusted wheel bearings. Looks like you dodged the bullet.

 

[mmesa005]

Fortunately it was just the slide pins. Slide pins are cheap, so it's best to replace them when they start looking rough. Don't forget the pin grease.

Usually, hot hubs are caused by bad or improperly adjusted wheel bearings. Looks like you dodged the bullet.

Will definitely be part of the scheduled maintenance!