Front Hub Grease

[Fredward]

My MC-5 manual shows what the lubricant level is supposed to be in the front hubs. But I can't tell from the picture what the level is really supposed to be. (Mine still have grease not oil.) I don't want to unload/reload my bearings, they were serviced three years ago so I think they are set up OK and they have grease in them. But there is no extra grease in the hub. I can pop the plug out of the hub and pump more grease in but I'm not sure if I should do that or not? Would there be any harm in pumping a bunch of grease into that hub and sticking the plug back in?
Fred

[John316]

Interesting. In our we have oil in there (Lucas). You just fill up the oil to the bottom of the hole (basically as much as goes in there without coming out), and then put the stemco back in...

God bless,

John

[Dallas]

Fred, there is no extra grease when you have those type hubs.
Don't pump extra in either.. you'll only end up pushing it out the grease seal onto the brakes.
Greased bearings are meant to be packed, usually by hand, or if your really lucky, with a pneumatic or hydraulic bearing packer. Any extra is just thrown out of the bearing and never touches anything again, unless it's forced through the seal onto the brakes.

On my old bus, depending on the amount of miles, I try to pack the bearings once a year. If I were to put on 20 or 30 thousand miles per year, I'd probably do it twice.

[John316]

Dallas,

Interesting. Thanks.

God bless,

John

[johns4104s]

After finding rust on one side of my front wheel bearing i changed them over to grease. I feel if the bus stands for any length of time grease is a better bearing protector.

john

[John316]

John,

What is "any length of time?" Does that mean, a month, five months, a week?

Thanks.

God bless,

John

[DaveG]

John 3:16-I don't think you fill hub cavities to full (like rear end or trans). There is a specific fluid level. When filled as you describe, the lube will often come out the vent in the plug (Stemco pinkie) as it heat/expands.

Other John-service intervals are best determined by useage. Many folks (busnuts) probably don't put enough miles on in their lifetime of bus use to warrant changing out rear end lube or repacking wheel bearings...not to say that it couldn't/shouldn't be done, just that if it is neglected there probably won't be any problems.

Just trucker stuff. Take it for what it is worth. Don't get too hung up over getting your wheel bearings repacked after you know they've been done correctly at least once.

Dave

[gus]

Fred,

You need to consult your manual for the specific way to grease your hub.

Bearings are pretty much the same for all, but hubs can differ.

Some hubs require the cavity to be packed full and some just require a thin coating of grease. Same for the hub cap or cover.

My 4104 was packed full and it has leaked grease for three years, not as now much as in the beginning though. It should have had just a thin coat.

Whenever I pack a hub that I have no manual for I use the thin coat method.

[bevans6]

My bus has oil in the hubs.  I can't read a level indicator on the vaguely transparent cover that lets you see the oil level.  I don't think it should be full up to the fill hole, when it expands when hot it will leak.  I have mine full to just below the bottom of the plug.  My thinking is that even the plug will leak if oil is sitting against it all the time.  They aren't the newest of plugs, a tad crispy.

So what is the correct oil level, and where can I get new plugs?  It's a MC-5C

Thanks Brian

[Airbag]

My MC-5 manual shows what the lubricant level is supposed to be in the front hubs. But I can't tell from the picture what the level is really supposed to be. (Mine still have grease not oil.) I don't want to unload/reload my bearings, they were serviced three years ago so I think they are set up OK and they have grease in them. But there is no extra grease in the hub. I can pop the plug out of the hub and pump more grease in but I'm not sure if I should do that or not? Would there be any harm in pumping a bunch of grease into that hub and sticking the plug back in?
Fred

Fred if it makes you feel any better my 5A has grease in there also. The grease looks clean and red in color. I pulled out the rubber plugs expecting to find oil as well. If it ain't broke don't fix it.

[John316]

First off, a correction. I meant to say that we fill ours up the the bottom of the plug. So that is really only half full.

Brian, we got ours from MCI, but I think that any truck store will have them. We have always called them Stemco's but that is probably just a name, I don't know.

Dave G, Sorry I mistyped . Really, we only fill it up to the bottom of the plug, and we never leak .

God bless,

John

[Dallas]

John,

If you are filling your hubs up to the bottom of the plug you are putting in WAYYYY too much.
See the photo I've included for the full and add marks.



the low mark is about two thirds of the way from the plug down to the edge and the full mark is about a quarter inch closer to the plug. By over filling, your inviting seal failure, especially if the vent hole on the plug becomes plugged.
The seal isn't really meant to be run IN the oil, it's meant to retain the oil on the lower metal portion and act as a wiper and seal on the rubber part.
Only the part of the bearing is actually always in the oil and that picks up the oil with the rollers and splashes it the rest of the way through the bearing.

[DaveG]

Couple of things:

Stemco is a manufacturer of wheel seals, hubcaps, etc. similar to Chicago Rawhide and National. So the "stemco" ya'll are refering to is actually the little soft pink/red plug that goes into the window portion of the hubcap.

As far as methods to grease bearings/hubs, an industry standard is to pack both bearings, coat the spindle, and fill the hub cavity 1/3 full.

There is also some SF grease out there, SF as in semi-fluid...kinda a cross in consistency between gear oil and grease...maybe not a bad way to go.

[John316]

Dallas, Thanks, good info.

God bless,

John

[NJT 5573]

I have not heard of thin coating of grease method, but anything is possible. Here is what my old Freightliner Manual says.

"Pack the bearings with a pressure packer if possible. If a packer is not available, pack them by hand, forcing the grease into the cavities between the rollers and the cage from the large end of the cone. Pack the hub between the two bearings with grease to the level of the cups smallest diameter. If the hubs contain oil it is still necessary to pack the bearings with grease".

This means pack the entire circumference of the hub with grease, above the level that the bearings turn, so that if/when the grease gets hot it cannot escape the rolling bearing surfaces. The outside bearing normally sets inside the smallest cup, so the top lip above the rollers would be the proper level to fill the hub for a bearing running in grease.