Rear axle painted from the inside?

[Yennes]

Hi experts,

I am about to restore my 8 3/4 rear axle and I wanted to sand blast the outside and degrease the inside. I do this with high temperature chemical tanks in a plating shop, I would destroy the whole liquid with the paint that would loose. If it is painted, I would just clean it from the inside by hand. Here are some pictures I made.

Thanks in advance
Yannik

 

[steve340]

I believe the axle housing will not be painted on the inside.

 

[R413]

I don't know what the black coating is inside but I have seen it on them. Solvent and brake cleaner doesn't remove it.

 

[gkent]

mill scale !!

 

[steve340]

Definitely could be something to do with the heat used to form or while welding the housing together.
I wonder if it is some component that "bakes" out of the gear oil after years of use.

 

[Yennes]

Definitely could be something to do with the heat used to form or while welding the housing together.
I wonder if it is some component that "bakes" out of the gear oil after years of use.

I thought about that too.

 

[moparsaver]

mill scale !!

Yep. Start with soaking in vinegar.

 

[R413]

I don't see a need to remove it. We have come 6 decades from manufacture with it inside there with no harm. Whatever it is it keeps rust away. It doesn't come off in flakes and contaminate the oil. It stays on the surface very well.

 

[Yennes]

I don't see a need to remove it. We have come 6 decades from manufacture with it inside there with no harm. Whatever it is it keeps rust away. It doesn't come off in flakes and contaminate the oil. It stays on the surface very well.

I do not want to remove it. I worried about it because I do not want to destroy the tank with the paint.

 

[33 IMP]

Make a plate to cover the center section area, and the axle tube ends, gasket them, blast it and paint it.

 

[steve340]

I agree make up cover plates or wood.
You do not want any sand from the blasting inside the axle housing. Absolute nightmare to get it all out.
I wouldn't bother with tanking the axle housing.
Blast it and wash it out with a good quality parts wash.