How To Replace Your Rear Axle Seals

Are you the proud owner of an axle that’s leaking diff fluid out the axle tube? Or are you converting your rear drum brakes to disc brakes? Either way, chances are you need to change the rear axle seal. We’ll show you how.

What Is A Rear Axle Seal?

rear seal
Image Credit: YotaTech

Axles have three seals:

  1. One pinion seal located at the front of the differential
  2. Two rear axle seals

In this post, we’ll focus on the rear axle seals. Rear axle seals keep the differential fluid inside the axle. When the seals are doing their job:

  • Differential fluid can’t leak out the axle tube
  • Contaminants can’t enter the axle tube

There is one rear axle seal on each outboard end of an axle. The differential fluid needs to stay within the axle and differential. If a rear axle seal fails, differential fluid leaks out. That means the differential isn’t lubricated or cooled well. This can lead to a failed differential, which is an expensive repair. Replacing an axle seal is a very inexpensive repair.

How Can A Rear Axle Seal Fail?

Rear axle seals last a pretty long time. To be more specific, rear axle seals usually last between 50K and 100K miles. They’re simple parts, so how can they fail? It’s quite simple: wear and tear. Rubber seals dry out over time. This leads to cracks and leaks.

A rear axle seal failing while still new is unusual. If you’re in this situation, chances are something went wrong during installation. Maybe the seals were installed the wrong way. Or maybe the installer used the wrong size seals.

We’ll show you how to replace the rear axle seal on the following axles:

  • 14 bolt axle
  • Dana 60/70/80 axle
  • Sterling 10.25 axle

It is helpful to have the correct sized seal driver to install the new seal. If you don’t have one, use the old seal as a driver.¬†Even if only one seal was leaking, it’s a good idea to replace both of them. If one failed, the other is not far behind. If you’ve had a leaking axle seal for a while, it’s also a good idea to remove the differential cover and check the gears for wear. Keep in mind that you would need to replace the differential fluid after this.

Replacing The Rear Axle Seal On A 14 Bolt Axle

14 bolt axle

To replace the seal, take the following steps:

  1. Jack up one side of your truck to take the weight off the wheel.
  2. Remove the wheel.
  3. Remove the axle shaft.
  4. Remove the hub retaining hardware.
  5. Slide off the hub and drum as a unit. If you’ve got a 14 bolt with disc brakes, you’ll have to remove the caliper first. (Be careful not to drop the outside bearing.)
  6. Replace the seal behind the hub.
  7. Put everything back together in the reverse order of removal.
  8. Repeat on the other side.

Replacing The Rear Axle Seal On A Dana Axle

dana 70 axle
Image Credit: Pirate 4×4

For all Dana axles (60, 70, and 80) the seal replacement process is generally the same. Here’s how it goes:

  1. Lift the rear of the truck to take the weight off the wheels.
  2. Remove both rear wheels.
  3. Remove the 8 bolts to take the axle out. (Be sure to put an oil pan underneath. Some fluid might come out.)
  4. Remove the pin and retaining ring by hand.
  5. Remove the axle nut. (If you want to reuse the outer bearing, don’t let it fall out. Carefully remove it and then set it aside.)
  6. At this point, the hub/drum assembly should slide right out. Carefully slide it out.
  7. Now the axle seal is exposed. With a seal puller or pry bar, remove the seal.
  8. Clean the bore very well and then put the new seal in.
  9. Put everything back together in the reverse order of removal.

Do you have trouble putting the retaining seal into the outer hub assembly? Try this:

  • Put the retaining seal into a freezer. Let it get cold enough to shrink a little bit.
  • With a torch, heat up the outer hub assembly just enough to expand the metal.
  • Now the seal should go in smoothly.

Replacing The Rear Axle Seal On A Sterling 10.25 Axle

sterling axle
Image Credit: FullSizeBronco

To replace the rear axle seal on a Sterling 10.25 axle, take these steps:

  1. Lift the rear of the truck to take the weight off the wheels.
  2. Remove both rear wheels.
  3. Remove all 8 bolts holding the axle in place.
  4. Remove the hub retaining hardware.
  5. Slide off the hub/drum assembly.
  6. You’ll find the rear axle seal on the backside of the hub assembly. With a pry bar or special tool, pull out the seal.
  7. Clean the bore and then put the new seal in.
  8. Put everything back together in the reverse order of removal.