Leaking drive hub seal

[MyPrevost]

I know this is a common occurrence and have read many posts related to it, 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, could you please refer me to it? 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 I might as well replace all before the summer drive season starts but want all the information at hand before I begin.

Thanks.

[MyPrevost]

Tony,

Hub seals are relatively easy to replace. I can outline the general steps here or provide a step-by-step guide over the phone if you prefer.

You’ll need some tools, such as a large socket to loosen the nuts holding the hub in place. Most of the remaining tools will likely be found in your toolbox. You can either remove the large nuts and pull the entire assembly (two tires, hub, and brake drum) all at once using a special carrier for pulling tires or, as I do, by pulling the wheels, drums, and then the hubs individually.

 

[MyPrevost]

Prior to replacing the seal, ensure you have a new axle gasket and the appropriate seal driver for the job. While the task is relatively simple, it can be backbreaking and tricky if you’re not adequately prepared.

Although some mechanics use silicone sealant for the axle, it’s best to use a gasket for a more dependable seal.

[MyPrevost]

Ditto on the gasket. Just order a 10-hole axle gasket, and they’ll know what it is.

As for the driver, some seal supply houses will let you use one if you purchase the seals from them. I’ve used a driver once, but for most seals I’ve replaced, I’ve used a block of wood on top of the seal and tapped it evenly into place. It’s not the most elegant method, but none of the seals I’ve installed have leaked. After seating the seal, I always double-check to ensure the inner portion of the seal rotates within the outer part without binding.

One caveat when replacing hub seals is ensuring the bearings don’t run dry. I usually coat them with high-temp bearing grease, although on the drive axle, I tip it up so the differential fluid flows sideways into the hub. We’ve had two instances in POG where service shops didn’t ensure the hub was filled with oil, resulting in bearing failure and the buses being hauled away on flatbed trailers. It underscores the importance of keeping the bearings lubed.

When you pop your axle out (it’s not as daunting as it sounds), you need to remove the pair of nuts (the outer one has a safety lock). The seal is at the rear of the hub.

It’s a dirty, messy job, and there’s some grunting involved in pulling everything apart. But if I can do it, so can you. I just replaced my RH drive axle seal, the first failure on this bus at about 235,000 miles.

[MyPrevost]

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?

[MyPrevost]

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

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

[MyPrevost]

Tony,

The 10-hole gasket is quite a challenge—it’s best to check with Prevost or a nearby charter fleet for it. Truck supply stores may only carry the 8-hole version.

 

[MyPrevost]

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

[MyPrevost]

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

The issue isn’t about material quality; it’s that heavy-duty trucks typically use an 8-hole gasket, which is more common. Prevost and MCI, along with possibly other coach manufacturers, use a proprietary 10-hole gasket for their drive axle applications.

 

[MyPrevost]

Tony,

I always keep a few 10-hole gaskets and at least one hub seal for each axle on hand. Hub seals can fail unexpectedly, and replacing them promptly is crucial to avoid mess and, more importantly, to protect your braking system. If you let issues go unchecked and oil levels drop in the hub or differential, it can lead to costly damage to bearings and spindles.

Having spare parts allows me to address leaks quickly. If your gasket hasn’t been sealed with gasket sealant, it’s likely still usable. At the POG rally in Santa Fe, I demonstrated by pulling an axle; the gasket came off easily, and I reused it without any leaks. I only replaced it a month ago when I noticed a hub seal leak.

When you order from Prevost, consider getting an extra gasket or two—they’re inexpensive.

 

[MyPrevost]

Last summer, while on a trip to Colorado, I had a front hub seal leak, losing about an ounce every 2-300 miles. I managed to top off the lube level occasionally until we reached an RV park where we planned to stay for a week. I assessed the situation and determined that with the tools and resources at hand—plus a couple of additional tools I found locally—I could handle the repair.

When I started the repair, a crowd of hub seal “experts” with lawn chairs and cold drinks gathered to offer unsolicited advice. While their enthusiasm was amusing, I knew what I was doing and the repair went smoothly in the end.

Fast forward to last month: during an oil change and chassis service in my shop, I discovered another hub seal leak, this time on the tag axle. Given the age of all the seals and their exposure to similar conditions, I decided to replace all of them rather than tackle them individually under less ideal conditions. As Jon pointed out, the process isn’t difficult, but the heavy parts and time-consuming cleaning for reassembly are the main challenges.

Replacing the seals also allowed me to inspect the wheel bearings and other components, which was an added benefit.

Regarding seal installation, I’ve done it both with and without a seal driver. Regardless of the tool, careful alignment is crucial to ensure the seal goes in straight.

For the 10-hole axle gasket, Orren is right: Prevost Parts is the best source. Big truck parts suppliers often don’t carry them and might give you a confused look.

On a related note, my bus has G.K.N. axles with caliper mounting brackets secured by six 16mm fasteners with permanent lock-tite, making rotor removal quite challenging. I don’t like the outer bearing washer and adjusting nut design on these axles, so I made a couple of tools to simplify this step. In contrast, Rockwell axles have a much more user-friendly washer and adjusting nut design, which I find almost foolproof.

 

[MyPrevost]

No, it’s not about material quality. What I meant is that heavy-duty trucks commonly use a more readily available 8-hole gasket. Prevost, MCI, and possibly other coach manufacturers use a proprietary 10-hole gasket for their drive axle applications.

I’ve never found a 10-hole axle seal in stock at a truck parts shop. It’s best to keep a few on hand for your own use, as the 10-hole Rockwell is used in only a few applications. Motorcoaches and fire trucks are the most common users.

 

[MyPrevost]

The seal you need for the drive axle on your coach is a 48690. There’s a shop in Knoxville that stocks these bearings and seals, but local Fleet Pride and Truck Pro locations do not carry them.

 

[MyPrevost]

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

[MyPrevost]

It might be a generic seal; I know it as a Chicago Rawhide 48690. It could also be listed under ScotchSeal, unless Chicago Rawhide and ScotchSeal are the same. If you order from Prevost, that’s what you’ll receive.

 

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