Drive Axles

[Lee Davis]

I would like to talk with someone who is knowledgeable about drive axles in terms of , what components are normally considered part of that "system", what the components do (like what does a "carrier" do?), how does it all work together, are air bags part of that system, etc.

This may be too long and complicated for a typed response, so if anyone can help with that, please give me a call. I will be happy to add a concise version of what I learn to the forum afterward.

Thanks

[Don Meyer]

Hello Lee,

The term carrier, refers to the center section of the drive axle that houses the gears. The ring gear, pinion gear and spider gears, as well as the carrier bearings and the pinion bearings. The carrier is removable from the axle housing to facilitate repairs or rebuilding. The gear ratios will varies from application to application, but they all serve the same purpose. That is, to move the vehicle forward (or backward). The drive shaft comes from the transmission to the drive axle and attaches to the pinion gear. The pinion gear then rotates and turns the ring gear that is attached to the axles.
The spider gears are what allows one wheel to turn faster or slower than the other while cornering.

The air bags, while attached to the axle, is not really part of the drive mechanism. The air bags are the suspension system, along with the shock absorbers, and are used instead of conventional springs to give a better ride.

Hopefully this is some help.

Don

[birds_first]

Lee I hope you don't mind me jumping in here on your post but I have an issue with my right rear axle seal. It is leaking about 1/2 pint every 4 - 5K miles. Last fall when I had tires replaced on the rear I noticed it, but the shop I go to does not recommend a new seal. They added 1/2 pint last fall and again I checked it in early March and it took about 6 ounces. The Peterbilt Dealer said it is not a serious issue at this time and it's not getting into the brake drum. My question is this, is it one of those things which I should have done now or could/should I wait until I need new brakes if it is not getting into the brake drum? I really don't want to have to pull the brakes now and take a chance on busting one, if it ain't broke don't fix it. What do ya think?

[Don Meyer]

Hi John,

I'm not sure why in the world a shop would recommend you not replace a leaking wheel seal! It will most likely only get worse. Plus the fact that if it's the inner wheel seal and not simply the outer gasket, it's probably leaking all over your brakes and now. And if it is, you effectivly have NO brakes at that wheel. You will probably need to replace the brake shoes (I would) when you do the seal. Fortunately brakes are not expensive.

I just replaced both drive axle seals simply because I had to pull the hub to repair the 'S" cam bushings. And I had the right rear tag axle leaking, (wasn't on the brakes yet), but I replace it any way.

Plus there's nothing worse that having 85-140 gear oil all over everything around that wheel. I'd say go ahead and replace it now, it's not a big job and then you have peace of mind when you're on the road this summer.

Don