Rear diff fluid change ?
Thread Starter
Instructor
Joined: Sep 2022
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Rear diff fluid change ?
Since I still have the gas tank out, I decided I’ll change out my rear differential fluid. I thoroughly cleaned the area and the red tag, it was gummed up what I could best describe as hard tar. Well after a thorough cleaning I drained all the fluid. I’m glad I decided to do this as it was black. I was surprised at how long this took between draining the oil and replacing it. Once I was done topping off the oil, I put the bolt back in and hand tightened it. Then I used a crescent wrench to tighten it the rest of the way.
Now my question, no matter how tight I try to make the bolt, I can still move the red plastic tag. Is that ok, or do I have a problem?
thanks,
BH
Now my question, no matter how tight I try to make the bolt, I can still move the red plastic tag. Is that ok, or do I have a problem?
thanks,
BH
Last edited by Bighog; Jul 23, 2023 at 06:04 PM.
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From: Sitting in his Nowhere land Hanover Pa
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You need to suck it out. There is no drain plug on a stock diff. Suck out what you can and put in 80/90 gear oil with a bottle of the additive
Tech Contributor
Joined: Aug 1999
Posts: 15,187
Likes: 4,008
From: Connecticut, USA
Since I still have the gas tank out, I decided I’ll change out my rear differential fluid. I thoroughly cleaned the area and the red tag, it was gunned up what I could best describe as hard tar. Well after a thorough cleaning I drained all the fluid. I’m glad I decided to do this as it was black. I was surprised at how long this took between draining the oil and replacing it. Once I was done topping off the oil, I put the bolt back in and hand tightened it. Then I used a crescent wrench to tighten it the rest of the way.
Now my question, no matter how tight I try to make the bolt, I can still move the red plastic tag. Is that ok, or do I have a problem?
thanks,
BH
Now my question, no matter how tight I try to make the bolt, I can still move the red plastic tag. Is that ok, or do I have a problem?
thanks,
BH
The red plastic posi tag fits in a groove under the plug head and will freely move, not a problem.
Thread Starter
Instructor
Joined: Sep 2022
Posts: 171
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I have a fluid extractor and I feel certain I got all the old fluid out. I used a little more than a quart and a half of ACDelco 10-4108 and a small bottle of the additive ACDelco 10-4003. Thanks on the red tag question
Tech Contributor
Joined: Aug 1999
Posts: 15,187
Likes: 4,008
From: Connecticut, USA
An empty diff will take the 8oz of additive and just under 2 qt's of oil before weeping out the fill hole. Sounds like you got most of it out, if it was full to start.
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Thread Starter
Instructor
Joined: Sep 2022
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Thanks, I believe this is the first time the fluid has ever been changed. My goal is to be driving her by the end of August. Once she has been driven, I’ll go back and check the fluid.
Tech Contributor
Joined: Aug 1999
Posts: 15,187
Likes: 4,008
From: Connecticut, USA
If the posi was replaced with a new out of the box one rebuilt with fiber clutches as mentioned by L88, then the oil will always be black and once the fiber wears off the posi will chatter. Of course, the answer to that from a supplier would be to replace the fiber clutches with new ones and start the process over again.