Dana 70 rear differential overhaul

[DJP]

Has anyone ever had the pleasure of rebuilding the spicer 70 rear differential? I've purchased new carrier bearings, a shim kit and a limited slip clutch pack, and I'm ready to tear into it today. At 245,000 miles, I figure the bearings and clutch pack are about due for replacement. I've got a hydraulic press to press on the new bearings, and a dial indicator to check the gear back lash, however, my Chilton manual does not go into too much detail on setting one of these up.

Does anyone know what the ring to pinion gear backlash tolerance is? Also I don't know what the maximum allowable end play is for the carrier bearings.

 

[Philip]

here are a few spec's for you.





differential bearing

preload shim 0. 015



differential side

gear to case clearence 0. 007



ring gear backlash . 005-0. 008



drive pinion gear bearing

breakaway preload torque



orginal bearings 10-20in lbs

replacement bearings 20-40 in. lbs



I have rebuilt a few of these over the years. The break way torque is something to watch also. If you have it to tight your bearings will not last very long. This means you have to much preload on them.



If you don't want to take a chance of messing up a new bearing. When you install the carrier or pinion bearings. What I do is take a propane torch and heat the inner race for about 30 to 45 seconds. Then the bearing will drop right on with no force needed at all. Just make sure you have it straight when you go to drop it on. Wear gloves to.



I grew up about 25 miles southwest of where you live. To bad I am not on one of my yearly road trips. I would have given you a hand.

 

[Joseph Donnelly]

A lot of the info is in the factory service manual. You can take pretty much any year manual you find. Note since 1994 they use a lot less preload on the carrier bearings. Around . 003-. 005" would be good I think.



I strongly recommend against heating the bearings with a torch. They press on just fine with a big socket or a piece of tubing so the inner race gets all the force. I've "pressed" them on using a hammer on the socket with good results too. Make up trial bearings to get your shims right. Use a reasonably decent set of used bearings and hve a machine shop that rebuilds connecting rods hone the inside so it slips onto the carrier. After you determine the correct shimming, press the new bearings onto the carrier.



TDR Issue #24 has an article that might be useful.

 

[Paychk]

If you want to heat bearings to ease installation, a safer method is to use a double boiler with water in the outside pot and oil in the inside pot. The boiling point of water is well below the temperature that can pull the temper out of the bearing races.

 

[Philip]

I strongly recommend against heating the bearings with a torch

Your not the first one to say this. LOL





If you noticed I said a propane torch in my statement. For a 30 second heat applied to a bearing the size of a differential carrier bearing it won't go above 150 to 200 degrees in temp. When you use heat to apply a pressed on bearing you don't need to go anywhere near the draw temp. Around boiling like paychk suggested is the proper amount of heat to apply.



The double boiler works good. But unless you do a lot of bearings. The setup and clean up is a mess. The propane is the fastest way to do it. Just watch the time you are on the bearing.



If the bearing is going into a bore instead of on a shaft. You freeze the bearing to make install easier.



This is a way to do bearings fast and easy. Remember there are large forms of equipment out there that you can not take apart and use a press on. Just add this tip to your bag of tricks in case you have to replace bearing where you can't remove the offending part or it isn't practical.

 

[Case500D]

Deep Frier

We almost always use a deep frier to heat bearings to slip them on shafts. Works well and smell like lunch is almost ready.



Jeremy

 

[Joseph Donnelly]

I know, if you're really good and move the propane flame around, not concentrating heat in one spot. . . but a lot of guys may read your post and not have the talent or experience, or might pick up the acetylene torch. . .

Of course, nothing is foolproof. If you use a big socket and hammer the bearings on, you could hit the cage, or leave chrome flakes in the bearing.

 

[DJP]

Thanks for the help guys, especially Philip, who provided the specs I was looking for. To make a long story short, I checked the carrier bearing [ring gear] side clearance prior to taking it all apart last Saturday - 0. 020" - Not as bad as I was expecting. I pulled the carrier, and to my surprise, the bearings looked pretty good. All of the gears looked pretty good as well. When I drained the gear oil, I noticed a lot of brass or bronze metallic in the oil. I pulled the clutch pack, and found my problem. The clutch disks were grooved, and down to bare metal. I installed a new set of clutch disks, and decided to put it back together, partly because I could not find the 1/2"- 20 bolts to my bearing puller, and partly because it was getting hot outside, and there was cold beer in the fridge.

Anyway, its a lot quieter when turning sharp corners, and she no longer wants to wheel hop when I put it in reverse. Now that I have the specs, I can do it the right way, next time.

 

[Philip]

Glad to hear it was an easy fix.

 

[BushWakr - RIP]

Geeezzz Jeremy, no wonder your turkey's always look like they're sitting in an oil slick... ... .



Some guys...





bob.