8 3/4 gasket replacement

Beekeeper

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Can someone give me some instruction on replacing the
differential to housing gasket? I've never done any work on the
rear, can the pinion seal be replaced without replacing the crush sleeve? I'm aware that I will have to remove the brake hardware and axles but have never removed the axles before.
This is a 489 case diff
Thanks
 

71airgrabberRR

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Gear case change 101

First thing is to properly secure the vehicle either on a lift or using jack stands on level ground. I always chock the front wheels too as an additional safety precaution.

Break the u joint bolts loose and then place the car in Neutral so you can turn the drive shaft around to remove the u joint bolts. They should be a 7/16 head size and I normally use a long box end wrench.

Remove the rear u joint from the rear yoke. If you remove the drive shaft from the transmission you may end up losing some transmission fluid or gear oil depending on which transmission you have. So get a drip pan ready................

Remove the rear wheels and brake drums.

If you have the stock factory axles there will be a series of holes in between the wheel studs. You will notice one is larger than the others. This one is the one you use to gain access to the 5 nuts that are holding the axle in place on the housing. You can use a 1/2" deep well socket through this hole and remove the nuts that secure the axle flange to the housing. One of these nuts will hold a retainer clip that sets the end play adjustment on a stock type factory axle bearing.

You should not have to touch your brakes. They will remain in place as you pull the axle out. The only thing you will have to pay close attention to is the equalizer bar that goes in between the rear shoes. Sometimes it may drop down just enough to catch on the upper part of the axle flange retainer as you pull the axle out. The axles only need to slide out a few inches. You will feel the end of them drop a little as they exit the spider gears.

Then it's a matter or removing the 10 nuts that secure the rear 489 gear case to the axle housing. If your lucky you may find an axle ratio or "sure grip" tag under one of the nuts. These should also be 1/2 physical size and you can use the same socket that you used to remove the 5 axle nuts from each side.

If your housing has never been apart, it will take some considerable "persuasion" to get it to break free from the axle housing. Sometimes it is necessary to use a floor jack and put just a little pressure under the nose of the housing. This should break the seal where the gasket is. Again get ready for an oil bath since most of the gear oil will be spilled out when the seal is broken.

Then it's a matter of pulling the gear case out from the front.

Be ready because the gear case is pretty heavy and very awkward. It is best to try and set it down on the swivel part of a floor jack and lower it while someone steadies it from dropping off the jack.

Clean the housing off very good and scrape off all of the old gasket.

Installation is just the opposite. It's actually pretty easy.

Back in the day when I used to drag race, I could do a gear swap in about 15 minutes.

Hope this helps.

- - - Updated - - -

PS sometimes the U joint bolts will be 3/8 "

- - - Updated - - -

IMG_0104.jpg

- - - Updated - - -

IMG_2823.jpg

- - - Updated - - -

Now is a good time to replace the rear axle seals if needed..................
 

Beekeeper

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Thanks that's a great write up! Seems pretty straight forward. For the pinion seal I guess I need to check rotational torque before removing the yoke for seal replacement? Do I need to replace the crush sleeve or just reuse the old one and set the preload to the amount found before yoke removal?
 

themechanic

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Auto parts stores have tools for loan like the axle seal puller and seal installation tool kit.

I used the Permatex Gear Oil RTV around the axle housing flange with no paper gasket and no leaks.


41869461_081413_sm.jpg
 

mopar 3 B

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Thanks that's a great write up! Seems pretty straight forward. For the pinion seal I guess I need to check rotational torque before removing the yoke for seal replacement? Do I need to replace the crush sleeve or just reuse the old one and set the preload to the amount found before yoke removal?

Yes you will have to replace the crush sleeve anytime the pinion yoke is removed. You will need a spanner wrench or a large pipe wrench to hold the pinion yoke and a good torque wrench to compress the sleeve to proper bearing preload.
 

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I have all the needed tools to get it done just have to get to it
thanks for all the help
 

rscurtis

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There is no need to replace the sleeve unless you accidentally over-tighten the pinion nut on reassembly. If the rear end was operating quietly, mark the nut on the pinion shaft and return it to the exact same location when you're done.
 

Beekeeper

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Thanks rscurtis,
The rear isn't quite but isn't very loud but does roar. I don't believe that can be cured without a new gear set.
 
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Robert Bart

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Gear case change 101

First thing is to properly secure the vehicle either on a lift or using jack stands on level ground. I always chock the front wheels too as an additional safety precaution.

Break the u joint bolts loose and then place the car in Neutral so you can turn the drive shaft around to remove the u joint bolts. They should be a 7/16 head size and I normally use a long box end wrench.

Remove the rear u joint from the rear yoke. If you remove the drive shaft from the transmission you may end up losing some transmission fluid or gear oil depending on which transmission you have. So get a drip pan ready................

Remove the rear wheels and brake drums.

If you have the stock factory axles there will be a series of holes in between the wheel studs. You will notice one is larger than the others. This one is the one you use to gain access to the 5 nuts that are holding the axle in place on the housing. You can use a 1/2" deep well socket through this hole and remove the nuts that secure the axle flange to the housing. One of these nuts will hold a retainer clip that sets the end play adjustment on a stock type factory axle bearing.

You should not have to touch your brakes. They will remain in place as you pull the axle out. The only thing you will have to pay close attention to is the equalizer bar that goes in between the rear shoes. Sometimes it may drop down just enough to catch on the upper part of the axle flange retainer as you pull the axle out. The axles only need to slide out a few inches. You will feel the end of them drop a little as they exit the spider gears.

Then it's a matter or removing the 10 nuts that secure the rear 489 gear case to the axle housing. If your lucky you may find an axle ratio or "sure grip" tag under one of the nuts. These should also be 1/2 physical size and you can use the same socket that you used to remove the 5 axle nuts from each side.

If your housing has never been apart, it will take some considerable "persuasion" to get it to break free from the axle housing. Sometimes it is necessary to use a floor jack and put just a little pressure under the nose of the housing. This should break the seal where the gasket is. Again get ready for an oil bath since most of the gear oil will be spilled out when the seal is broken.

Then it's a matter of pulling the gear case out from the front.

Be ready because the gear case is pretty heavy and very awkward. It is best to try and set it down on the swivel part of a floor jack and lower it while someone steadies it from dropping off the jack.

Clean the housing off very good and scrape off all of the old gasket.

Installation is just the opposite. It's actually pretty easy.

Back in the day when I used to drag race, I could do a gear swap in about 15 minutes.

Hope this helps.

- - - Updated - - -

PS sometimes the U joint bolts will be 3/8 "

- - - Updated - - -

View attachment 245848

- - - Updated - - -

View attachment 245849

- - - Updated - - -

Now is a good time to replace the rear axle seals if needed..................
Old post I know but this was the best explanation on how to do this on the internet. Thank!!!!
 

Gus chiggins

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Can someone give me some instruction on replacing the
differential to housing gasket? I've never done any work on the
rear, can the pinion seal be replaced without replacing the crush sleeve? I'm aware that I will have to remove the brake hardware and axles but have never removed the axles before.
This is a 489 case diff
Thanks
If you have to replace the crush sleeve Dr. Diff has a crush sleeve eliminator kit. Making it like the 741/742 3rd members where a crush sleeve is not needed. Other vendors may have those kits.
 
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