Massive gook buildup on brake drum

[Buffalo SpaceShip]

You folks here are an invaluable resource, I hope you know!

And we found another one this morning: My Mom was able to hook me up with an older gentleman at her church that has a large yard/ shop near here. He presently doesn't do the HD work, but runs a machine shop. But, he has a 1" impact and a lot of room. I'm taking the bus out there in a few hours and we're going to pull the duals off and see what's going on. The biggest downside is being away from the Internet (you folks) and my maint. manual. I will take the camera and maybe come back and fire off images here as need be.

If I can get the drum off (cross fingers), I can at least repack what's there, and maybe find a seal locally. I'm probably out of luck on new linings and special brake parts until I'm home... but I'll sure feel better knowing what I'm up against. My coach has stopped OK with it's present three drums. It appears that I've had this issue for many miles. But, I just can't let it continue on, rolling blindly home... with my precious kids onboard.

I also got a call from ChuckMC9, who lives here in Big D. I've been out of touch with him for several months, since he hasn't posted in awhile... but it made my day that he thought enough to call and give me some much-needed moral support. Thanks, Chuck!

It ain't always what 'ya know, but it's who 'ya know. And I'm so pleased to know all of you... and know that you are all trying to help me here. So thanks, as always... you guys rock!
Brian B.

[Runcutter]

Brian, I just got the board on to catch up.  I don't have a heavy schedule today, so I can bring the manuals to you - if you want.  I don't have a heavy schedule today, so I can come by.  Call me if you want to - nine seven two, four six six, four six one one.  I just got off the phone with JL Vickers - who also had a couple of suggestions.

Arthur Gaudet -- Carrollton

[Stan]

I am sure if you see a manual you will understand this better.

Pulling the brake drum only get you to the brakes. My opinion is that you can delay the brake work until you get home. If you want t get to the seals and bearings you do it by pulling the axle. Take the weight of the wheel with your axle jack and then take all the nuts of the axle bolts. Thump the end of the axle with a big hammer to get it loose. You may have cone washers on the axle studs that you have to remove. After you pull the axle out you can dis-assemble the seal and bearing setup.  If you have to get to the inner seal, it is gut busting work without the proper tools. To make it as light as possible, remove the wheels, the brake drum and then remove the hub.

I understand that you still don't know the source of the oil, but the quantities you are describing sound like a seal problem

You should be able to buy seals and bearings at any large bearing distributor. Look in the Yellow Pages for Bearings and or Drive line Components. If you are stuck for an axle gasket you can cut one out of a corn flakes box or just use a bead of silicon. HTH

I can't give your more help without knowing what kind of bearing setup you have. The GM gurus seem to indicate that both types were used  although opinions have been expressed that only one or the other were used.

[NJT5047]

I'm late to this thread, but if you must pull the duals, throw some plywood or something under the wheels that will let you lever the wheels off and on.  Jack only enough to get the wheel fractionally off the ground.
If you jack the bus up, and find that the wheel doesn't have any play in the hub, and the diff is full of lube, you could very likely drive the bus back.  If you have play, you'll have to make repairs.
The drive axle bearings are  lubed by diff lube.  The fronts may be grease, or if there's a plug in the center of the cap, they'll probably have grease in them.  Either works on an RV fine. 
As has been suggested, keeping up with the temp of the hub/drive wheel bearings is important.   If the bearings have failed, heatbuildup from brake and bearings could cause a fire.  You pix doesn't look like you have much more than the beginning of a seal failure...nothing "dripping" off the brake drum. 
Be sure and follow the manual on getting lube into the axle hub bearings if you replace the seal and bearings.  Once the wheels off the hub, you may want to jack the bus up so that the diff lube doesn't run out of the axle housing....it may not. 
If you pull the wheels and brake drum, be prepared to catch some heavy parts!  You'll need some help with the drum.   And don't let the wheels fall onto you!  Heavy suckers!

Good luck, JR

[mikeH8H-649]

To all concerned alot of gmc's came with grease packed rear axel bearings and there is a seal to keep the gear oil from getting into the bearings,this is not something I am guessing about I just did mine and it is a 79 h8h-649 and I bought the new seals ect from Luke since I could not find them anywhere else,I am not trying to be a smarta$$ here but if his bearings are grease packed and he is losing grease from the seal he would have problems quicker than with the oil fed brgs as the grease will not replenish itself as the oil ones will as long as there is gear oil and as he said his diff is full,so he needs to know what he has and then go from there  Mike

[Stan]

Mike8H8: Yiou must be as dumb as me (grin). The experts have told us numerous times that all drive axle bearings get their lubrication from the differential oil and you tell us that you just put grease packed bearingswith seals in your bus.  I was dumb enough to make the same mistake on a bus before I was told that I was wrong. I was really lucky to have the parts book with the seal numbers.

[NJT5047]

VERY Interesting!     That would explain the lack of wet gear lube?? 
Brian, did you get the bus cranked yet? 
The rear leak will be interesting...!
JR

[frank-id]

  My opinion is the rear axle housing vent is covered with lube grease and road dirt.  The rear housing has a large vent on the top of the housing.  Remove vent and clean.  Lots of brake clean will wash away all the lube , brake dust and rear dirt.  Before spraying loosen the slack adjuster as loose as possible.  After the big cleanup, check for cleanliness.  Simple green also removes heavy grease and oil.  After the cleanup readjust both slack adjusters.  My method of adjustment is to tighten adjuster snugly and loosen 3/4 turn.  Dragging brakes are not good and affect MPG economy.

[Buffalo SpaceShip]

Well, I spent a good chunk of the afternoon with the present electical issues. I finally went to Sam's to toss my 3-1/2 year old 8Ds for some fresh ones, but had to do some family stuff after that. We're crossing our fingers that it'll crank off tomorrow. Arthur/ Runcutter was kind enough to come by my folks' with his manuals for me to copy. He and I spent some time chatting about busses and conversions, and it was great to do so. I also spent some time on the phone with JL Vickers, a very kind a knowlegable busnut.

Via the manual, I confirmed that GMC' Buffs definitely have grease-packed bearings. Funny that Frank should mention the vent hole on top of the axle, because I spent some time having to clean off that area. The slack adjuster is also suspect, since most of the grease I found was sitting near it and on top of the rotor. I'd think a blown seal would leak out most of its goo downward. But maybe I'm just wishful thinking at this point.

I'm going to upload the pages from the manual for folks to peruse. I'll have to do it via my hosting service (links) so they're hi-rez enough to read. I do plan on cleaning the brakes as good as I can before heading out sometime this weekend. I'll also keep an eye on the axle temp by stopping every so often. I'm planning the longer Interstate Route... I-35 NB to I-70 WB. Takes me through OKC and Wichita, and numeroud KS towns. The typical Amarillo route could prove dicey if I have issues.

Be back in a flash...
bb

[Buffalo SpaceShip]

Here's what we got on Da Buffs rear axles...

http://www.thefamilybus.net/files/rearaxles.pdf

bb

[John E. Smith]

I just sent Buff an email...

As I told him, it is really a pretty simple job to replace an oil seal -- and with that much leakage, he really should check the bearings.  Personally, I wouldn't try to get home on it -- just from the reduced braking ability caused by the oil-saturated brake blocks. 

I think that the rear end would probably be ok, as long as he checked the lube level every couple of hundred miles and watched his rear end temp.  The problem is that any failure would happen on that wheel end, pretty far removed from the temp sending unit -- he could have serious damage by the time his temp guage went up enough to worry about.

[Buffalo SpaceShip]

I appreciate the thoughts, John. But let's take a look again at the pics (attached) and maybe you'll see why I'm leaning now towards an over-ambitious lubing of the slack adjuster's zerks:

The top photo shows the top of the wheel/ lining. Notice how the grease is built-up on the slack. Now, notice where the majority of the grease is... on the leading edge of the brake block and then travels upward. Exactly what would happen if grease is shooting out of the slack on every brake application as the wheel rotates forward. I also can see the rubber on the slack adjuster pivot point in the foregroud seems like it's still bulging with grease.

OTOH, the bottom pic shows just a thin film of grease. If the wheel seal had failed, I'd think that gravity would ooze the grease out of the bottom of the drum... and surely not deposit it way up and over on the slack adjuster.

I'm betting that someone filled up the slack... and then filled it up again with grease. It's probably been coming out for the last 6,000 miles. I had one hard service application when I had to "mash 'em" to stop for a quick yellow-to-red light back in March that may have started the oozing.

Also notice how dry the axle end area seems to be compared to the slack that's dark and moist on the bottom pic. On the top pic, there's a diagonal line of "soak stain" on the brake block going inboard to outboard... I'd think that a seal failure would show a mirror image of this.

Have I watched too many episodes of CSI??

bb

[Busted Knuckle]

Brian,
I'd like to agree with your conclusion, but the grease streaks slung outward all the way around the tire make me lean more in the bad wheel seal area from previous experiences that's what the tire usually looks like on a seal failure. Also if the grease is leaking onto the hub when you apply the brakes the leading edge is going to collect the majority of the grease! First thing I'd do is to clean it as I described before then take it for a spin and see if it starts to reappear! BK 

[Buffalo SpaceShip]

Bryce, I'm not trying to be contrary, but consider this... if I manually filled up the brake drum with grease (for some crazy reason) and then roll down the road at 495 revs. per mile (tire rpm), the centrifugal force of all of that grease is going to put the same streaks outward on the tire. The streaks just show us the direction of the grease leaving the drum from the force.

What we're debating about is the cause of the grease.

And wouldn't a wheel seal be oozing all of the time... not just when I apply brakes? Why would it collect way up and out there on the slack? And centrifugal force will fling the grease outward... not upward and inward. Fill up a paintbrush with water and start slinging it with a rope. Will you ever get wet?

Just some observations...
bb

[larryh]

Brian

We have gave you our honest opinion of 43+ years of being a heavy equipt experience. I don't want to be a smart $%^ but you have a grease seal leaking and need to replace it and the lining.

LarryH