Prepping an 8 3/4 Rear End...

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MuuMuu101

MuuMuu101

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So as I'm sitting at home most weekends going mad as all I do is surf the forums during the day instead of studying, I figured I might as well start working on the diff to prepare it for it's future installation in the Dart. It's an A-body 8 3/4 rear end with 10" drums and sbp. It has an open 489 case with 2.76 gears in it. I believe it came out of a 1970 Dart with a towing package out of a pick-a-part. All the brake lines seem to be intact. Anyways, the rear end is pretty greasy and I haven't touched it since I bought it almost a year ago. It's going to be swapped in when I start working on the suspension for the Dart and swapping the leafs. I just got a set of some shock plates I found on FABO and I believe the leaf springs I want to order come with the required U-bolts.

My question is, what are some simple things I can do to get this differential ready for it's swap. What's the best way to clean it? How do I change the lubricant? Should I tear it apart? Is this a fairly easy task? I think I'm going to keep the 2.76's for now as I don't mind the highway cruising. Thanks for all your help!

 
First thing I would do is take it to the car wash and blast as much gunk as you can off of it. Then wire brush it, rewash and paint it. Also I'd rebuild the brakes and have the drums turned.
 
Make sure the yoke has no side play and it turns smoothly with the drums off. If it checks out clean it, Replace wheel cylinders,brake shoes, spring kits, self adjuster kits mic and turn the drums if they are within specs. If not replace the drums. Also check your E-brake cables and make sure they work.
 
oven cleaner works great...but you'll need to wear gloves AND it tends to kill grass/plants...make sure its not the eco friendly type.

To drain the fluid, you'll either have to pull the chunk or just one of the axles and stand it upright. the axle only has a fill plug.

The e-brake cables and rubber brake line are interchangeable with the 7 1/4. Use whichever ones are in better shape. Same with the drums if the 7 1/4 has 10".

489's tend to have loose pinion bearings because of the crush sleeve getting loose over time. Check it for play.
 
goldduster318 said:
oven cleaner works great...but you'll need to wear gloves AND it tends to kill grass/plants...make sure its not the eco friendly type.

To drain the fluid, you'll either have to pull the chunk or just one of the axles and stand it upright. the axle only has a fill plug.

The e-brake cables and rubber brake line are interchangeable with the 7 1/4. Use whichever ones are in better shape. Same with the drums if the 7 1/4 has 10".

489's tend to have loose pinion bearings because of the crush sleeve getting loose over time. Check it for play.
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The 7 1/4 I have has the 10" drums as well. However, one of the drum hats is different than the other. I don't want to go too crazy with it right now. I'd basically just like to prep it so that I can drive it around for a year or so with little to no problems. After that I'd like to rebuild it with new bearings, bbp axles, disc brakes, and possibly a new pig if I decided I wanted/needed one. It kind of sucks that it seems you have to remove an axle or the pig to change the lubricant. I hear some people drill and tap a hole for ease.
 
Theres a drain plug on the side of the chuck but you prob won't get all the oil out. I guess you could try to pump it out. Unless you have seen it work I would pull the axles & diff, clean it out and inpect it. BCS you will only to replace a few gaskets. It will be alot easier with it out of the car than finding out theres something wrong after installing it. I bet theres a bunch of gunk you'll want to get out of there anyway.
 
MuuMuu101 said:
The 7 1/4 I have has the 10" drums as well. However, one of the drum hats is different than the other. I don't want to go too crazy with it right now. I'd basically just like to prep it so that I can drive it around for a year or so with little to no problems. After that I'd like to rebuild it with new bearings, bbp axles, disc brakes, and possibly a new pig if I decided I wanted/needed one. It kind of sucks that it seems you have to remove an axle or the pig to change the lubricant. I hear some people drill and tap a hole for ease.
Click to expand...

Someone put a pipe plug in the bottom of mine before I bought it. The plug leaks. I'm not real happy about it - I'll try putting some more teflon tape on it (am going to change the oil again anyway). If I pull the pig, I'd rather change it to a plug similar to the one on an oil pan - probably build a nice flat section with weld and then seal it with a copper crush washer. That would work a lot nicer.
 
MuuMuu101,

I picked up an axle as well. I put a while wheel on a HF "black" grinder and wire wheeled the crap out of it. It was so greasy and dirty that I got that gunk on the garage floor. Woops!

Anyway, I found a place in Lynwood that does powder coating and sandblasting. I'm thinking of having it blasted. They quoted me $50.00 bucks. There's this other place in Downey that quoted $80.00 bucks.

Like yours, mine also as a 489 case with 2.76 gears. I believe it came off a '69 Coronet. I'm in the same boat as trying to figure out what to do after that. I want to do the same thing, just throw it in the car and drive it!
 
JoesEdge said:
MuuMuu101,

I picked up an axle as well. I put a while wheel on a HF "black" grinder and wire wheeled the crap out of it. It was so greasy and dirty that I got that gunk on the garage floor. Woops!

Anyway, I found a place in Lynwood that does powder coating and sandblasting. I'm thinking of having it blasted. They quoted me $50.00 bucks. There's this other place in Downey that quoted $80.00 bucks.

Like yours, mine also as a 489 case with 2.76 gears. I believe it came off a '69 Coronet. I'm in the same boat as trying to figure out what to do after that. I want to do the same thing, just throw it in the car and drive it!
Click to expand...

I'm thinking, if it was a slant six car, that there may still be some meat on the shoes. If that's the case, I may just replace the wheel cylinders. I need to start looking into powder coating as well. When I redo my suspension, I'd like to at least get my K-frame and LCA's done.

Rear end carriers pop up quite frequently. I'll see if I stay with the 2.76 gears I have or buy something like a 3.55 in the future. However, if I go with turbos or boost in the future, I may just want the 2.76's. I'd sure like a sure grip though.
 
MuuMuu101 said:
I'm thinking, if it was a slant six car, that there may still be some meat on the shoes. If that's the case, I may just replace the wheel cylinders. I need to start looking into powder coating as well. When I redo my suspension, I'd like to at least get my K-frame and LCA's done.

Rear end carriers pop up quite frequently. I'll see if I stay with the 2.76 gears I have or buy something like a 3.55 in the future. However, if I go with turbos or boost in the future, I may just want the 2.76's. I'd sure like a sure grip though.
Click to expand...

Why reuse the old pads that are have been sitting for who knows how long and who knows how they were driven. Keep in mind the old springs could be rusted and prone to breakage. When you can get a drum brake rebuild kit from auto zone for less than 30 bucks, I'd do it. Why risk the car or your safety on old crappy brakes to save 30 bucks? The drums can be turned down and should be. AIT ozone again can do this for 10 bucks
 
goldduster318 said:
Someone put a pipe plug in the bottom of mine before I bought it. The plug leaks. I'm not real happy about it - I'll try putting some more teflon tape on it (am going to change the oil again anyway). If I pull the pig, I'd rather change it to a plug similar to the one on an oil pan - probably build a nice flat section with weld and then seal it with a copper crush washer. That would work a lot nicer.
Click to expand...

Gear oil can eat Teflon overtime. You might try a silicone designed for gear oil. I forget exactly what its called but auto parts stores sell it. Its called permablack or something to that effect. It'll say for gear oils on it.
 
dukeboy_318 said:
Why reuse the old pads that are have been sitting for who knows how long and who knows how they were driven. Keep in mind the old springs could be rusted and prone to breakage. When you can get a drum brake rebuild kit from auto zone for less than 30 bucks, I'd do it. Why risk the car or your safety on old crappy brakes to save 30 bucks? The drums can be turned down and should be. AIT ozone again can do this for 10 bucks
Click to expand...

O, I didn't know drum brakes were that cheap to do maintenance on. That's not bad at all. I have to remove all that stuff anyways if I'm going to change the wheel cylinders. Thanks for the heads up!
 
Yeah drum brakes are cheap. May check out rock auto.com too. They're even cheaper. I got my rebuild kit with wheel cylinder for 12.95 shipped
 
I'm going to start working on the rear end next week. It will be my spring break and I'll only be working about 16 hours at my new internship so I'm going to have some free days. I was thinking about redoing all the drum break components, changing the springs, wheel cylinders, and shoes. I've done this before with help from a friend but he had a bunch of drum brake tools I don't have. Where would be the best place to buy them? Do I need them? Also, I know I have 10" drums but how do I know the width I need for the shoes and hardware kit? I'm assuming the second number is the shoe width. The only 10' x 1-3/4" hardware kit from rockauto is part #F78541. I believe last time I got 15/16" wheel cylinders for my 7 1/4. I believe those are correct. I'm currently running a KH disc setup in front with a manual 1 1/32" bore MC.

Thanks for all your help!
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I bought the cheap drum brake tool kit from Harbor Freight, and while it's obviously made from cheap metal, it worked fine. Really it's mostly just to help install the springs and the little tool to push in the spring on the shoe peg thing is pretty handy. That's all you'll need.
 
You can do a brake job on drum brakes without the toolkit, but some of the little tools in the kit make the job a breeze.
 
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