Rear Trouble?

[Mack B Mike]

Hello All

Took the B out for a ride today drove for about an hour varying speed between 30 and 60 mph without any issues until i got back to my house. I stopped at my driveway and started to back in and bout 10 foot in my rear axle locked stalled engine started truck again tried to continue backing up no luck would not move tried going forward again couldnt go forward either hit the GO pedal harder frame started flexing but truck wouldnt move, checked service and parking brake to make sure nothing was binding all is good there, touched the carrier and it was extremely hot!! sizzled water, also could smell burnt gear oil. Pulled drive shaft , ran engine and trans in all gears no problem there, could move truck bout 2 inches with drive shaft off but no pinion movement, any ideas of what could have happened would be helpful dont have much experience with the Mack Rears

Thanks,

Mike

[HK Trucking]

Did you check the lube level in the rear diff?

Sounds like it may have run dry and locked up.

[Mack B Mike]

Did you check the lube level in the rear diff?

Sounds like it may have run dry and locked up.

The last time i checked prior to today was ~ 5 months ago added a little bit at that time but nothing major, there were no puddles in the garage and just got it on the road the beginning of this month and probably put only 300 miles on it oil level in the rear seemed good just with horrible burnt smell

[Mike]

Hey Mike,

I'll have to backup what Herb said. If the rear grease had a bad odor it was past due on a change. Was the vent open and did you pull something overrated for the truck? It's possible that when you checked the grease level it was low. Sometimes we get in a hurry or when the grease is hot you can get an over run makes one think the level is full. Keep us posted.

Good Luck!

mike

[NoClueJoe66]

Hey Mike,

I'll have to backup what Herb said. If the rear grease had a bad odor it was past due on a change. Was the vent open and did you pull something overrated for the truck? It's possible that when you checked the grease level it was low. Sometimes we get in a hurry or when the grease is hot you can get an over run makes one think the level is full. Keep us posted.

Good Luck!

mike

I'm with them too on this, usually when i get a new vehicle "As in another toy to tinker with, work with, or just to drive" usually flush ALL fluids, check stuff grease, etc. Sometimes it slips our minds or not enough funds, but I usually run them a little then do a complete flush. Sounds like your gonna have to pull her apart. Keep us updated on it and good luck.

[Mack B Mike]

I'm with them too on this, usually when i get a new vehicle "As in another toy to tinker with, work with, or just to drive" usually flush ALL fluids, check stuff grease, etc. Sometimes it slips our minds or not enough funds, but I usually run them a little then do a complete flush. Sounds like your gonna have to pull her apart. Keep us updated on it and good luck.

Hey All,

pulled center section apart today i found that it was the inner pinion bearing that failed, the cage that holds the roller bearings in place got shredded somehow and a few of the rollers got out, it appears that 4 were missing and were getting chewed up, found two rollers and alot of metal shavings in the bottom of the carrier, fortuneatly all the gears are intact with the exception of one that has a small chip out of it hopefully i can just replace the bearings/races and get back on the road

Mike

[Mack B Mike]

Hey All,

pulled center section apart today i found that it was the inner pinion bearing that failed, the cage that holds the roller bearings in place got shredded somehow and a few of the rollers got out, it appears that 4 were missing and were getting chewed up, found two rollers and alot of metal shavings in the bottom of the carrier, fortuneatly all the gears are intact with the exception of one that has a small chip out of it hopefully i can just replace the bearings/races and get back on the road

Mike

of course as things go it could not have been a quick fix to replace the bearing/race. I found that the race for the inner pinion bearing had spun in the housing and also the inner pinion bearing spun and welded itself to the pinion. the removel of the old bearing was interesting had to use the hot wrench and carefully cut it off found some small gouges and high spots on the pinion, cleaned it up in the lathe and installed the new bearing all good there, now the pinion housing, the new race just dropped into the housing, this was not good so i cut down all the rough spots in the housing so the race would sit level there was some side to side play ~.0005 of an inch, two choices either bore the housing and install a bushing around the race to be able to press fit the parts or JB weld the new race in, i took the easier of the two... JB welded the race in, assembled pinioin/bearings to center the race and allowed to dry, installed pinion assembly this morning, filled with GO-J and were back on the road.... see pic of pinion housing where the race spun

[Mike]

Glad to hear things are back to normal. Keep us posted of the longevity of the truck.

mike

[mackmixer]

I hope the JB Weld works.

If it turns on you again and you have to go back in it again, you might consider cutting some brass shim stock, say 0.003 thick, the thickness of the race and wrap it on the inside of the race housing protruding up slightly out of the housing and then pressing the bearing race in the housing. I have successfully done this on smaller bearing races like a Ford truck rear carrier bearing where the race was about 2 - 2 1/2" OD

Or you can build up the housing with weld metal and turn it back to the correct ID.

[dougleonard]

To many good used housings out their to try a repair such as that, I would not suggest that type of repair.

[dougleonard]

To many good used housings out their to try a repair such as that, I would not suggest that type of repair.

[HK Trucking]

You also could use a prick punch and hammer, and do a home made "knurl" on the inside of the bore where the bearing cup fits.

I've salvaged some worn parts that way.

Make enough punch marks around the inside of the bore until the cup won't slide in, then coat the outside of the cup with loctite and drive the bearing cup in as you normally would.

[Mack B Mike]

You also could use a prick punch and hammer, and do a home made "knurl" on the inside of the bore where the bearing cup fits.

I've salvaged some worn parts that way.

Make enough punch marks around the inside of the bore until the cup won't slide in, then coat the outside of the cup with loctite and drive the bearing cup in as you normally would.

thats a good idea, i have done somewhat the same thing on small engine valve seats that would pop out, it worked great, ill have to remember that for next time, if there is one, so far the JB weld held it in without a problem

thx

Mike

[theakerstwo]

thats a good idea, i have done somewhat the same thing on small engine valve seats that would pop out, it worked great, ill have to remember that for next time, if there is one, so far the JB weld held it in without a problem

thx

Mike

Or take to machine shop mand say what should i do. They will either build up with brass and i have did this by brsing brass in there and remaching or they may consider making a salvage ring to go inther after cutting some stock out. glenn