Leaking drive hub seal

[aggies09]

I know this is a common occurrence and have read many posts related to same, but I have searched the threads looking for a step by step explanation of this repair process and haven't found it. If any of you know of such a thread would you mind referring me in that direction. After getting under the bus and looking around yesterday, I discovered that both inner drive wheels show signs of oil. One really bad, and one just showing. I figure that I might as well replace all before the summer drive season starts, but want all of the information at hand before I start. Thanks.

[Jon Wehrenberg]

Tony,

Hub seals are relatively easy to replace. I can outline it here in general terms or if you want I can do step by step over the phone.

To replace a hub seal you will need some tools, such as the big socket to loosen the nuts that hold the hub in place. The remainder of the project uses tools likely found in your tool box. It can be done solely by removing the large nuts and pulling the entire assembly of two tires, the hub, the brake drum off all at once, which requires a special carrier for pulling tires, or like I do, by pulling the wheels, drums, and then the hubs.

[AmeriStar]

Prior to replacing the seal make sure you have a new axel gasket and the proper seal driver for this application. Although a relative simple job it can be a backbreaking, finger pinching experiance if you're not prepared.
Although some mechanics use a silicone seal for the axel, it is best to use a gasket.

[Jon Wehrenberg]

Ditto on the gasket. All you have to do is order a 10 hole axle gasket. They know what it is.

As to the driver, some seal supply houses will allow you to use one if you buy the seals from them. I have used one once, but on the other 6 or 7 seals I replaced I used a block of wood on top of the seal and slowly and carefully tapped the seal evenly down into place. Not very elegant but so far none of the seals i installed have leaked. After seating the seal I always double check to make sure the inner portion of the seal continues to rotate within the outer part without binding.

There is one caveat when replacing hub seals and that is to insure the bearings will not run dry. I usually give them a coating of high temp bearing grease even though on the drive axle I tip it up so differential fluid flows sideways into the hub. We have had two instances in POG where the service shop did not insure the hub was filled with oil, Harry and Lew, and in both cases the buses twisted off the end of the differential due to bearing failure and both buses ended up on flat bed trailers. That never should have happened to these two guys but it shows how important keeping the bearings lubed is.

7907

When you pop your axle out (not a big deal, just sounds like it is) that is the pair of nuts that needs to be removed (the outer one has a safety lock) and the seal is at the rear of the hub.

It is a dirty messy job and as AmeriStar points out there is some grunting involved in pulling stuff apart. But if I can do it, so can you. In fact I just replaced my RH drive axle seal, the first failure on this bus at about 235,000 miles.

[aggies09]

I am assuming these are not Prevost specific parts and these parts can be picked up at my local truck service center. Is this correct?

[Jon Wehrenberg]

Correct. Seals are generic. So is the 10 hole gasket.

When you do the seal replacement it is the perfect time to scrutinize your brearings and bearing races. They are also generic if you find they need replacement.

[Orren Zook]

Tony

That 10 hole gasket is a dog - you'd better check with Prevost or a local charter fleet for it, the truck places might have only the 8 hole gasket available.

[aggies09]

Thanks Orren. By a "dog" do you mean they are weak, damage easily, or are otherwise inferior. If so, are there better alternatives?

[Orren Zook]

Thanks Orren. By a "dog" do you mean they are weak, damage easily, or are otherwise inferior. If so, are there better alternatives?

No, not a weak or inferior material, what I meant was that heavy duty trucks will use a more readily available 8 hole gasket. Prevost and MCI (perhaps other coach manufacturers too) have chosen to use a proprietary 10 hole gasket for their drive axle applications.

[Jon Wehrenberg]

Tony,

I always have a few of the 10 hole gaskets on hand along with at least one hub seal for each axle. For whatever reason hub seals will fail from time to time and there is no advantage to postponing replacement as you will see. The mess is just part of the reason to replace them. The damage done to your braking is the most important reason. If left long enough without maintaining the oil level in the hub or differential the damage to bearings and spindles gets very expensive.

By having the parts on hand I can deal with leaks ASAP. Unless someone has used gasket seal on your 10 hole gasket it may even be likely yours will be intact and suitable for re-use. I pulled an axle for demonstration at the POG rally in Santa Fe, and the gasket just came loose. I had brought a new one with me, but instead reused the old one and it never leaked. I just replaced it a month ago when I noticed my hub seal was leaking.

If you order them from Prevost just get an extra one or two. They are cheap.

[lonesome george]

I had a front hub seal leak last summer on a trip to Colorado, leaked about 1 ounce every 2/300 miles. I removed the trim cap and topped off the lube level from time to time until we got to the RV park where we were going to stay for a week or so. Did an evaluation of the resources at hand and concluded that this repair could be achieved with the stuff we had with the exception of a couple of tools we were able to round up in a near by town. So off I went to get this leak repaired and about time I got the bus cribbed up and the wheel off a crowd started to form of what turned out to be hub seal experts with lawn chairs and cold drinks to cheer me on and provide guidance, which I had not ask for I knew exactly what I was doing. In the end a couple of them were good sports and provided some chuckles. At any rate the seal replacement was successful.

Had the bus up on the ramps in my shop for an oil change and chassis service last month and low and behold I had another hub seal leaking, this time on the tag axle. Made the decision to change all of the remaining hub seals now rather than one at a time under less favorable conditions, after all the seals are the some age and have been exposed to the same conditions. As Jon mentioned these are not difficult to replace it's just that the parts are heavy and the most time consuming part of the repair is cleaning all the pieces for reassembly.

An additional benefit is having the opportunity to inspect the condition of the wheel bearings and the rest of the components that make this big ol' dude roll.

As far as seal installation tools go I have done it both ways and I think its a toss up, even with a seal driver there is no guarantee that the seal is going to go in straight without some care being taken when the seal is started in the bore.

Orren is right about Prevost Parts being the best place to get the 10 hole axle gasket, big truck parts suppliers will give you that "what are you talking about look " if you ask them for a 10 hole axle gasket.

The front and tag axles on my bus are the G.K.N. variety and the caliper mounting brackets are attached to the spindle with six 16mm diameter fasteners that are dipped in permanent lock-tite at assembly, these babies take the fun out of rotor removal in a hurry. Another thing about G.K.N.'s that I don't like is the outer bearing washer and adjusting nut design, it is real pain to get the washer positioned correctly to seat the bearings for adjustment. I ended up making a couple of tools to take the edge off this step. The Rockwell axles have a much better washer and adjusting nut design, straight forward and almost fool proof IMO.

[AmeriStar]

No, not a weak or inferior material, what I meant was that heavy duty trucks will use a more readily available 8 hole gasket. Prevost and MCI (perhaps other coach manufacturers too) have chosen to use a proprietary 10 hole gasket for their drive axle applications.

I have never walked into a 'truck parts shop' and found a 10 hole axel seal in stock. The best is to keep several on hand for your own use. The 10 hole rockwell is used on very few applications. Motorcoaches and fire trucks ar the most common.

[Jon Wehrenberg]

The seal is a 48690 for the drive axle on your coach Tony. There is a shop in Knoxville that sells bearings and seals and they always stock them, but the local Fleet Pride and Truck Pro do not.

[aggies09]

Jon, is that a Rockwell part number or a Prevost part number?

[Jon Wehrenberg]

It might be generic. I know it to be a Chicago Rawhide. Without doing some checking it might be a ScotchSeal number also unless they and Chicago rawhide are one and the same.

If you order from Prevost that is what you will get.

[Orren Zook]

Chicago Rawhide division of SKF markets their oil bath wheel seals under the 'scotseal' name, that 48690 is a C/R part number.

[aggies09]

Will the 48690 fit the steer and tax as well or is it a different seal?

[Jon Wehrenberg]

The seal for the tag and steer is the same, but not the same number as the drive. If you want that number I can go out to the garage and get it.

[aggies09]

Jon, at your convenience, I would like that part number. Don't make a special trip, but whenever would be great. I have ordered the gaskets and seals and am getting ready to start this project once everything gets here.

[Jon Wehrenberg]

If you need to replace the tag or steer seal you need the gasket that goes beneath the cap. I'll be out in the garage this AM so I will get all the numbers I can.

[Jon Wehrenberg]

Tony,

Steer and Tag hub seal.......presume disc brakes, solid axle........40086 Chicago Rawhide

Seal behind the cap...Stemco 3024
Seal at rear of drive axle hub.......3060

[aggies09]

Thank you.........