Axle & Diff Rebuild Time -

rklewis1005 · 2025-10-09T13:49:47-0500

Ok, so next up on my rebuild list is the rear axle and diff. 70 Charger SE, 383 HP, Auto, 8 3/4 Suregrip, 489 case (not sure of gear ratio until I remove the axles and pig). It was running/driving when parked in '83 (42 years ago) and everything spins. Based on the odometer, it has around 114k miles. I'm disassembling it so I can weld new brake line brackets in place and clean/paint the axle housing. I have the workbench book (specific to Chrysler differentials) and the service manual. I plan to clean and inspect the differential, but will rely on the book and suggestions here for what I should focus on or if I should rebuild it all.

- I'll need to replace the inner/outter axle seals and likely the axle bearings.

- What in the differential is "normally replaced" or should be checked closely?

- Any recommendations on how far to disassemble it or what NOT to disassemble/touch?

- Crush Sleeve eliminator - are they worth it/any good?

I'm sure I'll have more questions as I go - thanks in advance for any hints!

Jerry Hall · 2025-10-09T14:29:45-0500

Your saying it spins freely. Before taking it apart I would check the amount of play between forward motion and reverse motion. The results of that should tell you the overall condition of the chunk. A stock 489 sure grip will have a cone type sure grip. 114K miles is not necessarily a teardown and rebuild factor. If you have minimal slack between forward and reverse motion, I would clean it up and repaint it. I would also replace the inner and outer seals which will require pulling the chunk. Examine the gear lube by feel, and inspect the gears for wear. The same goes for the tapered bearings. If all looks good, reassemble with new gasket and seals and run it.
I just did the same thing to my project 67 Satellite with appropriately the same mileage. It hasn't been on the road since the early 80's. All was good, so I'm going to run it with all original parts, except for seals and gasket.

R413 · 2025-10-09T14:36:31-0500

The wheel bearings can be cleaned, inspected and repacked with grease. They don't run in gear oil.

Agree with post #2.

RemCharger · 2025-10-09T15:15:07-0500

Just watch for signs of orange in there. My concern would be if some tapered rollers got rust pitting. Other wise, probably good to go

451Mopar · 2025-10-09T15:18:20-0500

I think a big part depends on what tools you have. For replacing the bearings you are going to need a press to install them at a minimum.
If you are going to rebuild the diff, I would get a yoke holding / puller tool. The Raytech 18002 is affordable. Ratech 18002 Ratech Combination Pinion Yoke Holder and Puller Tools | Summit Racing
For pulling the differential and pinion bearings, the clamshell type puller is nice as you can remove the pinion bearing without destroying it if you have to replace shim spacers.
For tightening the yoke and checking pinion pre-load, you need a torque wrench that can goto 250 ft/lbs, and a in/lbs dial or beam type torque wrench. I have a CDI dial torque wrench that was around $300? I use it more than I thought I would, transmission band adjustments, valve cover and oil pan bolts and other smaller screws and such.

The Raytech 10007 Pinion depth setting tool is cheap and easy to use. The Pinion distance to the bottom of the diff bearing bore is just a bit over an inch, so i use a 1x2x3 block to square the pinion height under the diff bore centerline, and a machinist straight edge across the lowest point of the bearing bore, and the measure/check the clearance between the two. I have used stacked feeler gauges before, but I bought a gauge block set which makes it easier.
I forgot what the nominal distance is supposed to be, I have it in a spreadsheet somewhere, but the basics are the same for most pinion setting tools.
They use the diff bearing bore size and divide in half to find axle centerline to the outer bearing housing and use the bore of the bearing housing as the reference to the head of the pinion, then add them together to get pinion to axle centerline distance.

rklewis1005 · 2025-10-10T08:54:50-0500

451Mopar said:
I think a big part depends on what tools you have. For replacing the bearings you are going to need a press to install them at a minimum.
If you are going to rebuild the diff, I would get a yoke holding / puller tool. The Raytech 18002 is affordable. Ratech 18002 Ratech Combination Pinion Yoke Holder and Puller Tools | Summit Racing
For pulling the differential and pinion bearings, the clamshell type puller is nice as you can remove the pinion bearing without destroying it if you have to replace shim spacers.
For tightening the yoke and checking pinion pre-load, you need a torque wrench that can goto 250 ft/lbs, and a in/lbs dial or beam type torque wrench. I have a CDI dial torque wrench that was around $300? I use it more than I thought I would, transmission band adjustments, valve cover and oil pan bolts and other smaller screws and such.

The Raytech 10007 Pinion depth setting tool is cheap and easy to use. The Pinion distance to the bottom of the diff bearing bore is just a bit over an inch, so i use a 1x2x3 block to square the pinion height under the diff bore centerline, and a machinist straight edge across the lowest point of the bearing bore, and the measure/check the clearance between the two. I have used stacked feeler gauges before, but I bought a gauge block set which makes it easier.
I forgot what the nominal distance is supposed to be, I have it in a spreadsheet somewhere, but the basics are the same for most pinion setting tools.
They use the diff bearing bore size and divide in half to find axle centerline to the outer bearing housing and use the bore of the bearing housing as the reference to the head of the pinion, then add them together to get pinion to axle centerline distance.

Thanks! I have a press, but I will wait until I check them out before deciding if I need to rebuild the diff. My preference would be to clean and repack vs replace. But I'll see once I get in there.

If I don't rebuild the diff, does it save me from preload/backlash "stuff" during reassembly? Sorry for the newb question.

Axle & Diff Rebuild Time -

rklewis1005

FBBO Gold Member

Jerry Hall

Well-Known Member

R413

FBBO Gold Member

RemCharger

FBBO Gold Member

451Mopar

Well-Known Member

rklewis1005

FBBO Gold Member

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