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AMC20 leaking gear oil

AMC20 leaking gear oil
C

Chipw

Jeeper
Posts
71
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0
Location
North Georgia
Vehicle(s)
1980 CJ7. Iron Duke 4cyl., SR4, Dana300, Dana 30 with aussie locker, AMC 20 with detroit locker and 4.88 gearing, welded and trussed axle housing, one piece axles. 33x12.5 tires
Hello,
New CJ owner here with a couple questions. My rear differential is leaking oil. Picture attached shows amount of oil after two days of sitting. Im going to remove the cover to drain the oil and to also see what type of locker i have in there. My concern is resealing the differential. Im assuming a gasket is needed, any suggestions on which one?

also, would it be worth adding a stronger differential cover while i have the stock one off? The previous owner thought there is an aussie locker in there and it spins both wheels same direction when the rear is jacked up.

one more question. are those welded on supports above the axle housing stock or added later? thanks
IMG_0239_zpsargo8td4.webp
 
Chipw said:
Hello,
New CJ owner here with a couple questions. My rear differential is leaking oil. Picture attached shows amount of oil after two days of sitting. Im going to remove the cover to drain the oil and to also see what type of locker i have in there. My concern is resealing the differential. Im assuming a gasket is needed, any suggestions on which one?

also, would it be worth adding a stronger differential cover while i have the stock one off? The previous owner thought there is an aussie locker in there and it spins both wheels same direction when the rear is jacked up.

one more question. are those welded on supports above the axle housing stock or added later? thanks
IMG_0239_zpsargo8td4.webp
Click to expand...

The welded things are axle trusses and they were added by a previous owner. The axle tubes are also probably welded and the next logical step he probably took was to replace the two place axles with one piece. You can check this by looking at the axle ends at the center of the rear wheels. If there is a cap then the axles are two piece and if they are flat they are one piece. I wouldn't worry about the diff cover. Replacing it is not necessary for strength.
 
Check to be sure the cover bolts are tight.
When I have rebuild any mod 20 rear. I use RTV silicon sealer and no gasket. Never any issue. Let it sit for 24 hrs before adding oil.
LG
 
For a stronger rear diff cover, I would suggest something made from a stamped steel and not a cast material as they can break. I like the plan for a stronger diff cover as it can give a bit more protection in the rocks. Lumpy's way of not using a rear gasket has worked fine for me also.
 
It's not leaking, just marking it's territory😁
I've used black rtv on mine and customers vehicles for nearly 2 decades, no need to waste money on a gasket that can't be reused.

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Thanks for all the replies. You guys have already been a big help.
I did indeed have some sort of locker in my rear differential, not sure what kind.

Can anyone identify what this is?
IMG_0245_zpsi3zmh0aw.webp


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That looks like a Detroit Locker. Can you find any ID numbers etc. Is it closed up all the way around?
DL's are the K.I.S.S. of lockers. I run'em front and rear in mine.
Sure hope you have 1 piece axles. Can you post a picture of your rear axle flange?
Do you know the R&P ratio?

LG
 
Lumpy Grits said:
That looks like a Detroit Locker. Can you find any ID numbers etc. Is it closed up all the way around?

DL's are the K.I.S.S. of lockers. I run'em front and rear in mine.

Sure hope you have 1 piece axles. Can you post a picture of your rear axle flange?

Do you know the R&P ratio?



LG
Click to expand...


I had to order a special lug key to get my wheels off so I can't see if I have one piece axles until it shows up. I bet they are one piece though. One of the PO's welded the axle housing, reinforced them and put this locker in so I bet he put one piece axles In Too. Never know though.

It is solid all the way around. I'll see if I can get some ID numbers off it tomorrow before I try and make my first gasket :-)

Thanks for the help


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If you don't have a center cap on the wheel. Post the picture. We can see if it's 1 piece or not.
What about the ratio?
There should be markings on the outside of your ring gear. Get a picture of those and we can tell you what you have.
LG
 
Looks like a Detroit from here. The kind you don't want , the kind you ship to a guy in Pa. Nice find.
 
:laugh::laugh:
You'll just drop it on your foot-:poke:

LG
 
4.88
I'm sure you have 1 piece shafts to go with the DL and truss.
 
:agree:
YUP-4:88. I run that with my 5 speed.
What size tires are you running?
LG
 
Same size I run in tires.
You should be fine. That 4 popper likes some RPMs to run.
What type of diff do you have in the front?
That gearing takes a lot of torque load off the tranny and t'case.
Do you know the ownership history of your CJ?
LG
 
Pretty sure it's the stock Dana 30 up front but with what I think is an Aussie locker in there. I didn't pull the cover because it's not leaking but I could see what looks like an Aussie in there through the fill hole.

I bought the jeep from a guy in Chattanooga Tn. He got it from a shop in Dalton Ga., which happens to be where I live. Not sure where they got it from but my Tennessee title says previous title Arizona.
I stopped by the shop, which is closing down but the mechanic came out and said he remembered the jeep, used to be reddish brown and was pretty much rust free when they had it.

He didn't mention who did all the gear work.
The Chattanooga guy didn't know either, he just said he was pretty sure it had a locker in it when he got it.
Chattanooga guy put the lift, big tires , paint, and got all the lights, and gauges working, new soft top etc.
it's really nice and I'm excited I got it. I really didn't know what I was getting, I just wanted an older jeep I could learn to work on and do some light wheeling. I'm biased but I think I really found a gem

Here the gearing peaking through the fill hole of the front differential
http://i56.photobucket.com/albums/g175/mightydog/IMG_0251_zpsdpgvzidn.jpg

Here she is topless in all her glory
http://i56.photobucket.com/albums/g175/mightydog/IMG_0218_zpst4dft6uv.png
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Last edited:
Good picture. :notworthy:
Could be either an 'Aussie' or a Lock-Right.
The weakness is in the carrier.
Looks like you have a very good setup. :chug:
LG
 
^thanks!


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Can you tell if that's a 4 or 2 inch lift?


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