The Stovebolt Site Forums The Shop Area Driveline Rear axle and differential 1/2 ton 1954 GMC

Hello,

I bought a 1954 GMC 3100. I took out every bolt there was and last week I received my rebuild chassis.
The first project is to paint the rear axle and to clean the differential and put new oil in it.
I have 2 questions:

- There is a hole in the rear axle. Is this normal? Will this be a problem?
- I opened up the rear of the differential. The oil is very thick and dirty.
How do I clean the inside of the differential before I put in new oil? I don't want to take the whole thing apart.
- I want to take off the front of the differential. I removed all 10 bolts. But I don't get it off.
Do I need to undo the bolt in the U-join?

Thank you very much!

The front of the differential does not come off, instead, the entire differential comes out through the front of the axle housing. You'll have to remove the axles first.

You need to first remove the rear cover and ther is some work in there that has to be done to remove the axles like twotone says. Here read up on it here.
Steve

http://chevy.oldcarmanualproject.com/shop/1954truck/index.html

I think you are talking about the ventilator hole on top of the axle.
When the gear lube heats up it greats pressure inside the axle housing, the ventilator releases the pressure.
Otherwise the pressure could push gear lube pass the axle seals into the brakes drums and out the pinion seal.
It should have a vent cap that screws into the threaded hole.

Group # 5.387 part # 3738462 ventilator

GMC axle exploded
Chevy axle exploded
GMC and Chevy 1/2 ton axles are virtually the same.

Venting the Differential Jim Carter Tech article

There usually is no problem unless you plan on submersing the axle in water, like living in a flood plane area.
That is probably what happened, the truck was driven in high water.

The cap might of been broke off and you will need a Easy Out to back out the threads that are still remaining in the axle housing.

Thank you very much for your answers!

The hole is indeed the ventilator hole, but it hasn't got the ventilator in it.I will fix this.

As I said I already removed all 10 bolts on the rear and all 10 bolts in the front.
I did this because I want to clean the inside of the differential. All axles and everything inside are looking good, so I don't want to remove any parts inside.
Can I just clean the inside, put new oil in it, and install front and back cover with new gasket?

Thanks (again)!

Rolf, there is no removable front cover. When you remove the front part, the entire differential comes out with it as one piece. It's very easy to do and makes it easier to clean everything. You'll want to pull the axles anyway to replace axle seals.

The way you are describing the axle, I'm starting to think you might not have an original axle.
Can you see any universal joints where the propeller shaft connects to the axle?
If the answer is no, then you have the original enclosed propeller shaft torque tube and the axle housing that goes with it.
If the answer is yes, then you have an open propeller shaft and the axle housing that goes with it. Which may not be original to the truck.

What you should do is take some pictures of your truck so we can properly identify what you have.
Once we know what you have, it will be a lot easier to walk you through your repairs.

You have to post 5 times before you can upload pictures, you are at 4 post right now, so one more post and you will be able to upload pictures.

There are a lot of knowledgeable people on the Stovebolt forums, that are willing to help with your restoration.
The hardest part is the terminology, knowing what the part is called, after awhile you will be helping other Stovebolters too.

Attached are 3 pictures of de differential, rear end and driveshaft.
I already found a guide to take out the axles. So that's probably I will end up doing.

Thank everyone for the help!

Rolf

Not a drive shaft/rear end from a 1954 3100. Later model. Also a GMC would not be a 3100 model.

Don't think '54 - 3100 series had a drain plug at the bottom of the diff either.