Service Differential

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1. Remove Driveshaft

2. Remove Tires and wheels

3. Remove Rear Brakes to access the backer plates and undo those.

4. Pull the axels

5. Remove the 3rd member from the axel housing (it is very heavy) The gears and everything come out as one unit.

Any particular reason you want to do this other than curiosity as this job sucks? I may have missed something as it has been a while but once you get started it is pretty intuitive.

 
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I'm planning on pulling mine this winter and send it to a local rear end specialist nearby. Just looking for a basic service and new seals and bearings. Not a job I fancy doing myself. If the guy wants waaay tooo much money, then I may tackle it.

(while I'm at it, I may replace the almost new rear 4 1/2 leaf springs, Scott Drake garbage, for Eaton Springs custom 4 1/2 leaf to, a) get the ride height correct and most importantly, get the rear axle correctly centered )

Geoff.

 
Any particular reason you want to do this other than curiosity as this job sucks? I may have missed something as it has been a while but once you get started it is pretty intuitive.
I saw a youtube video on backlash in spider gears and contact patch for the main crown wheel 

I'd just be happy to know my spiders are ok considering age of car.

 
Not that I know of ... but not looking makes my OCD go off balance  ;) he's 48 years old - surely he's got gargantuan wear

 
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If no noise or leaks it is good to go. If you do pull be sure to change the axle seals and you might do the axle bearings while out also. They are cheap. I broke probably 6 axle bearings on 9" rear they are very weak. The usually split the outer ring. 

I could load my Ford van heavy and for sure would split the bearings had an N case 9" in it. Have also had the axles work out of the bearings even with the retainer rings present due to overloading.

 
If no noise or leaks it is good to go. If you do pull be sure to change the axle seals and you might do the axle bearings while out also. They are cheap. I broke probably 6 axle bearings on 9" rear they are very weak. The usually split the outer ring. 

I could load my Ford van heavy and for sure would split the bearings had an N case 9" in it. Have also had the axles work out of the bearings even with the retainer rings present due to overloading.
I have a tiny leak and slight overheat (not sure)  ...after 48 years of use, I'm unsure of condition.

 
Where is it leaking from? The pinion seal isn't hard to replace if you have the right tools, something to hold the yoke while loosening the pinion nut, something to pull the old seal out and fish out the old crush sleeve, a large enough torque wrench to tighten the pinion nut, and an inch-pound dial type torque wrench.

Why do you think it may have overheated, low on lube? It's not unusual for a 48 year-old seal to leak. However, a leaking pinion seal is often due to bad pinion bearings. Do you have any idea of the mileage on the differential?

What is the condition of the lube that is in the differential? Has it been changed?

Is your differential open or a posi-traction? If it's open you can get an idea of the condition of the bearings and spiders by preventing the driveshaft and one wheel from turning while turning the other wheel. If the free wheel turns 1/8, or more, of a revolution you likely have something worn. Due to the clearances in the spider and ring and pinion gears, and bearings, a slight amount of movement is OK.

 
As everyone is saying - if it isn't broke or causing problems I won't do anything other then change the gear oil.

You will need a siphon pump of some kind since there is no drain plug on the 9". Use a good quality gear oil and fill to bottom of filler plug. It will take about 2 1/2 quarts. Also, if you got trac loc / posi traction you will need to add a bottle of friction modifier additive. Can get from some of the parts stores or a Ford dealer.

If you do try to do a rebuild yourself "Bad Shoe Produtions" has an excellent video you can purchase on how to rebuild it and the tools you will need.

PS - the old gear lube stinks to high hell so try not to get it all over.

 
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You can also snake a magnet on a flexible shaft in there and see how much worn out iron and steel you can pull out of the bottom. You don't want a real strong magnet or it'll stick to everything on it's way in.

 
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