You may have heard of axle shaft seals and wheel seals. If you’re here, you may be wondering what the difference is between both parts.
Some people use these terms interchangeably. These are actually different parts. It’s true that both parts are similar. Yet, they belong in different locations. If you’re shopping for a new seal for your axle, you want to make sure that you’re getting the right part.
Which seal(s) does your axle have? It depends on the type of axle you have. First, let’s talk a little bit more about each seal.
What Is An Axle Shaft Seal?
The axle shaft seal exists to prevent fluid from leaking out of the differential or transaxle. It also prevents contaminants from getting in. An axle shaft seal can be found in a few different places:
- On a vehicle with a semi-float live axle, the seal is at the outer end of the axle tube.
- On a truck or SUV with front CV axles, the axle seal is at the inboard end of the axle where it goes into the differential.
- On a front wheel drive vehicle, the axle seal is at the inboard end of the axle where it goes into the transaxle.
If you notice a leaking axle seal, replace it as soon as possible. If enough diff fluid or transaxle fluid leaks out, those components will be damaged.
What Is A Wheel Seal?
The wheel seal is often part of a wheel bearing assembly. It serves two important purposes:
- The wheel bearing uses grease as a lubricant. The bearings needs to be constantly lubricated as the wheel turns. The wheel seal keeps the grease inside the wheel bearing assembly.
- The wheel seal keeps all water, dirt, and other impurities out of the wheel bearing assembly.
The wheel seal plays a large role in your wheel bearing’s longevity. It’s a large rubber and metal seal that is sometimes located in the hub. Depending on the design of the wheel bearing and hub, the wheel seal is installed either:
- Directly into the hub
- Onto the spindle
It’s always smart to replace the wheel seal when replacing the rear axle wheel bearings. A seal is a cheap part that protects expensive parts. If you notice the wheel seal has gone bad, replace it as soon as possible, and you may not have to replace the bearing.
Full Float Axles Have A Wheel Seal
Most full float rear axles don’t have an axle shaft seal. The axle shaft is sealed with silicone RTV when it is bolted into the hub. The hub has a wheel seal to protect the bearings. The wheel seal is installed on the back side of the hub.
Semi-Float Axles Use An Axle Shaft Seal
Semi float axles have an axle shaft seal, but no wheel seal. That’s because on semi-float axles, the wheel hub and the axle shaft are one single part. The wheel hub doesn’t have bearings that need lubrication, therefore it doesn’t need a wheel seal. The axle shaft seal is pressed into the outboard end of the axle tube, just in front of the wheel bearing.
Most 8-Lug 4×4 Front Axles Come With Both Seals
Most 8-lug 4×4 front axles like the Dana 60 have both seals. These axles have:
- A seal at the axle shaft near the pumpkin (axle shaft seal)
- A seal in the wheel hub assembly (wheel seal)
Identifying The Replacement Seal You Need
It’s not hard to figure out which type of replacement seal your axle needs. You can figure it out by:
- Identifying the type of axle your truck has
- Identifying the location of the leak