Fixing Axle Leak

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KOZ45

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1970 Duster project, rear axle is a 741 case 8-3/4"

It appears to be leaking diff fluid where the third member is bolted up to the axle housing

I have never messed around with fixing this type of leak

I assume I remove the driveshaft and then unbolt the third member?

The third member just "falls out" or will it be held in place?

Clean the housing the install a new gasket or RTV?

What type of fluid goes back in?

Thanks for any and all info
 
Yes, you will have to unbolt the drive line. You can let it hang out of the trans so you don’t leak oil or the trans.

As for the rear end; you will have to pull the rear tires, pull the brake shoes / hardware to get to the axel holding plate that has 5 nuts to pull the axels from diff.

Now check to see what style bearings you have. Cone style bearing are stock, and cased bearing are (green bearing) cone bearing have to be shimmed correctly (as they came out) to center the axels in the housing / diff. I’d recommend to get a set of “green bearing” from @Dr Diff. (He has diff gaskets also. Might be able to get from a local trans/diff supply shop) Cheaper and easier to deal with. Will need a press and bearing remover to remove/install the bearings. But worth the cheap insurance you don’t loose a wheel bearing. Can’t hurt the check the fronts also. I was working on a Chevy 2 last week and what do ya know the front passanger inner bearing was fucked.

For the diff, unbolt the 12 or so nuts ( I’d leave one on the top stud loose until the last moment before removing so it does not fall out. The diffs weight is about 60 pounds. Once removed, scrape the old gasket off of the housing and diff. Once clean, put a thin bead of black gasket maker on the housing, then the gasket face, reinstall the diff and put on 2 nuts to sung while putting the rest of the nuts on. (Think the torque is 35 ft pounds) slide the axels in, replace gasket, axel holding plate and the 5 nuts, again 35 ft pounds. Rebuild your brakes.( you might be able to not take the brake shoes hardware off)

As for diff oil. I used redline 75/90 gl5. But you could also use any 90w gear oil. If it is a sure grip you’ll want some friction motifier in there. Fill the diff until a little dribble is coming out of the fill hole.

As a side note, since your messing with the rear end, I’d had a diff repair shop check / rebuild the suregrip. So you know you have fresh clutch plates (as I assume it’s not a cone type diff) and bearings in your diff. That way you know the rear end is all good to go for the next 50k plus miles. Also, would be a good idea to replace the u joints in the drive line. Ask me how I know. Just blew out a u joint in my front drive line of my 4x4....
 
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I'm just going to throw this out and ask.
Have you tried to tighten the nuts at all?
They could need a little load on them.
Just a thought.
 
Assuming you don't want to do as scody21 outlined. You could try the following.

Buy a sufficient number of copper crush washers (used on ford 9" assuming ID is the same) and pull one nut at a time and Install them.

Might stop the leak, IF that is where it is comming from.
 
Stephen Mulkey said:
I'm just going to throw this out and ask.
Have you tried to tighten the nuts at all?
They could need a little load on them.
Just a thought.
Click to expand...

Yes ^^^^^ some of those "Pink" reusable pumpkin gaskets will weep oil over time. Best to spray down the pumpkin bolt pattern area with brake parts cleaner then blow dry with high pressure air at the gasket. Do it a couple of times to wash the oil out of the gasket material.

Then re-snug all the pumpkin bolts again so the gasket is seated well again.

May have to do this over time as normal maintenance when you are servicing and doing oil changes.

Nobody likes oil seeps and or leaks.

0806171541b.jpg
 
Suggestions are fine but it will be nice to refer to the Factory Service Manual.
No opinions and they are free if you download one. Complete with servicing directions , diagrams and torque specs.
 
MoparLeo your completely right if you are going to open it up, you should have that service manual and follow it. It's technically enough you can mess things up without it. But as George jets said I think he calls out something that can be done and wouldn't need to disassemble the rear end.
If it continues to drip you haven't lost anything.
If it stops, you could maybe check it periodically.
Just a thought.
 
Just makes sense to have a service manual any way. For anybody. They were good enough for the people who worked on these cars daily for a living. Why would anyone not want one for occasional servicing. And not everybody has the aptitude to even change their oil. You can't know too much and can't assume because you can do something that someone else can too.
We all had to learn sometime. Why does school take 12 years to learn to do the 3 R'S ? Have a senior tell a first grader how easy calculus is... Just throwing it out for anyone who might want to know... Their choice. But with an option...
 
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Stephen Mulkey said:
MoparLeo your completely right if you are going to open it up, you should have that service manual and follow it. It's technically enough you can mess things up without it. But as George jets said I think he calls out something that can be done and wouldn't need to disassemble the rear end.
If it continues to drip you haven't lost anything.
If it stops, you could maybe check it periodically.
Just a thought.
Click to expand...

I agree with what you and the other guys say also.

I stated what I did to the diff in my 72 duster and I’m glad I did. When I pulled the diff out and was inspecting the suregrip, I found out that the center pin was enlarging the holes in the diff and was going to be short lived with the 400hp 340 / 4 speed with sticky street tires that I put on the car. As for the U joint part I said, I learned my lesson that my father told me when I was a kid and did not heed, to do when getting a new to me ride. I’ll tell ya losing a u joint suck and totally messed up the under side of the floor boards of my 02 Ram. Just cheap insurance from the peanut gallery... to each there own...
 
You are completely correct. When I first seen the download service manuals I thought what a great thing they did for so many.
I have one for a variety of different cars I have.
I'm with you on the abilities of a lot of folks, including me. The manuals give you the insight to do your job correctly.
 
I hosed the housing down and scraped off alot of gunk

I was able to tighten each nut a decent amount, some seemed close to 1/8 of a turn, if not more

I dried it all off and will check the housing in the morning

Oh, and I did find a huge factory service manual used on eBay for cheap

Hope it stays dry over night

Thanks again
 
So far so good

Bottom of the housing is dry and no fresh oil spots on the cardboard on the ground
 
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