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73-87 Chevy _ GMC Trucks => Engine/Drivetrain => Rear Drivelines, Drive Axles and Gearing => Topic started by: Sprinkler-Man on May 27, 2019, 02:48:03 PM

Title: What differential do I have?
Post by: Sprinkler-Man on May 27, 2019, 02:48:03 PM
1980 GMC K10 4wd, 12 bolt corporate. Need to replace the drivers side axle wheel seal.  Axle code tells me it’s a open differential with 3.08 gears. Opened up the differential cover and this is what I found.  I can’t push the axle in far enough to get the c-clip off. Any ideas? (https://uploads.tapatalk-cdn.com/20190527/9bd9656c90d884c2614204d1cdcdc83b.jpg)(https://uploads.tapatalk-cdn.com/20190527/b8ee9fc62cefbd40d0c7525089aaffba.jpg)(https://uploads.tapatalk-cdn.com/20190527/44ee21e9e5c1356fd03605a26882c700.jpg)


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Title: Re: What differential do I have?
Post by: Rapid Roy on May 27, 2019, 04:56:26 PM
Looks to me water has gotten inside somehow. I haven't seen cream colored gear oil. All I have seen is dark colored.
Title: Re: What differential do I have?
Post by: VileZambonie on May 27, 2019, 05:17:22 PM
Not an open differential. You need to change that fluid a few times. To remove the axles you need to remove the pinion shaft for the differential gears by removing the pin bolt and sliding the pinion shaft out. Push the axle in, remove the c clip and pull the axle out. try not to rotate the axles while it is apart.
Title: Re: What differential do I have?
Post by: Sprinkler-Man on May 27, 2019, 05:24:57 PM
I removed the pinion shaft but still can’t get the axles in far enough to remove the c-clip. I have the rear end up in the air and when I spin one tire forward the other spins backwards. Doesn’t this mean it’s a non limited slip unit?


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Title: Re: What differential do I have?
Post by: Sprinkler-Man on May 27, 2019, 05:57:55 PM
It appears that I have what is called a GM gov loc posi unit.


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Title: Re: What differential do I have?
Post by: 1967KaiserM715 on May 28, 2019, 05:39:15 AM
Gov-loc differential

Definitely want to change fluid at least 2 times to make sure all water contamination is gone.

Might be a stupid question, but tires and drums are off?

Sometimes due to brake dust, rust and oil, you may need to scrape the visible portion of the axle to get it to slide past the seal.

Once you do get it apart, don't spin anything, as it is possible to spin the gears out of the carrier, and then the Gov-loc assembly will find new homes all over the ground.

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Title: Re: What differential do I have?
Post by: Sprinkler-Man on May 28, 2019, 05:43:20 AM
Tires and brake drums are off. I have spun it a few times and nothing has dropped yet but I will try not to do it anymore. I plan on replacing the seal and bearing on both sides. I saw some people gave it a nudge with a hammer so maybe I will try that.


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Title: Re: What differential do I have?
Post by: bd on May 28, 2019, 09:37:07 AM
(https://uploads.tapatalk-cdn.com/20190527/b8ee9fc62cefbd40d0c7525089aaffba.jpg)

Looks like someone experienced a catastrophic gear failure at some point.  Once you get it cleaned up, inspect everything closely.
Title: Re: What differential do I have?
Post by: Sprinkler-Man on May 28, 2019, 09:41:54 AM
I saw all the teeth marks and was wondering the same thing.  Now that I know I have a limited slip, what gear oil should I run? 


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Title: Re: What differential do I have?
Post by: 1967KaiserM715 on May 28, 2019, 04:00:16 PM
I saw all the teeth marks and was wondering the same thing.  Now that I know I have a limited slip, what gear oil should I run? 


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It's not a limited slip, run regular oil, no additives of any kind.

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Title: Re: What differential do I have?
Post by: 1967KaiserM715 on May 28, 2019, 04:02:46 PM
Tires and brake drums are off. I have spun it a few times and nothing has dropped yet but I will try not to do it anymore. I plan on replacing the seal and bearing on both sides. I saw some people gave it a nudge with a hammer so maybe I will try that.


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It's really only after the axles come out you shouldn't spin it, once the axles are out, they spider gears have a chance to walk out of the carrier.

I would gently tap the axle ends, might just be a small burr hanging up on the spider gears.

Also get a new center pin bolt, too many times I've seen them reused and they fail. They are supposed to only be used once, at least that's how it is described in some of my service manuals.

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Title: Re: What differential do I have?
Post by: Sprinkler-Man on May 28, 2019, 10:30:41 PM
Tapping with the hammer worked on getting the clips out.  The axles are all pitted up where they ride on the bearings. Now I know why the seals are shot. Looks like new rear axles to go with the bearings and seals.


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Title: Re: What differential do I have?
Post by: JohnnyPopper on May 29, 2019, 05:57:27 PM
Can someone post what a gov loc posi is, and why something that looks so cool isn't in every truck?
Title: Re: What differential do I have?
Post by: Sprinkler-Man on May 29, 2019, 06:24:17 PM
Do these look salvageable?(https://uploads.tapatalk-cdn.com/20190529/e3d128657e6bc19dea493e3d552fc024.jpg)


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Title: Re: What differential do I have?
Post by: bd on May 29, 2019, 07:10:09 PM
No.  Replace them.  They will tear up new bearings.
Title: Re: What differential do I have?
Post by: Sprinkler-Man on May 29, 2019, 07:52:42 PM
That’s what I thought....thanks


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Title: Re: What differential do I have?
Post by: VileZambonie on May 30, 2019, 04:01:33 PM
Can someone post what a gov loc posi is, and why something that looks so cool isn't in every truck?

https://www.youtube.com/watch?v=KbMZ9vcYVSg
Title: Re: What differential do I have?
Post by: JohnnyPopper on May 31, 2019, 09:00:32 PM
Wow! Thanks Vile, had not seen one before!

Title: Re: What differential do I have?
Post by: rayjos_1 on June 04, 2019, 11:20:22 AM
https://www.youtube.com/watch?v=CGq15JBBUQw