Rear Diff replacement

[ernzo]

2003 mountaineer rear differential is going out, grinding. It’s a 3.55, open no stability control. I’m looking to have a used unit put in, but I’m concerned that a used unit may have bad bearings as well! I guess I could try to find a low mileage one and crack it to take a look before having it installed but is that going to give me anything? Could I grab the pinion and or axel stub outs and check for play? Thoughts?

 

[Fix4Dirt]

low mile= less chance of issues.
but usually the diffs are outside of the vehicle (already removed) and they aitn like engines where they can run on a stand, so dunno how to test them. maybe check around where the bearings are to make sure it isnt covered in oil. look for one from a yard w/warranty. companies like jasper also make remanned diffys for these, as do many other remanufacturers, so that may be someting to look into, as they are warrantied and garunteed, all new mostly, but they will cost more.

if its grinding that usually isnt the bearings, but probably the pinion gear... probably for the rear maybe 800 bucks to do max. and change sturf like seals etc when youre in there, make it 1000 then. thats what i think.. if its just the bearings see the below.

imo just redo the bearings. they aint that hard to do. looking at your sig, if you can built a b300, i think you can change the bearings in diff... imo similiar amoutn of work to changing it. and if you want put an LS carrier or locker in... nows the time!

 

[ernzo]

Thanks, I am not able at this point to do this myself, I can get the diff changed out for about $700 if I supply the part. Used seem to be around $300 +/- so about a grand out the door. If I can find a local (Denver) used unit I could crack the case and check. I understand that a “wiggle” test and visual check if the ring and pinion can be very effective.

 

[Josh P]

Usually it is the crush sleeve that lets go taking the preload off the pinion. I'd replace it on the one you get out of a junk yard.

 

[ernzo]

Usually it is the crush sleeve that lets go taking the preload off the pinion. I'd replace it on the one you get out of a junk yard.

Good idea, yes.

 

[Fix4Dirt]

how much are JY ones? i found a remanned one here Ford Explorer Rear Differential 8.8-Inch 1998-2002

wont fit the 3rd genm though, but gives you sme idea

 

[Josh P]

how much are JY ones? i found a remanned one here Ford Explorer Rear Differential 8.8-Inch 1998-2002

wont fit the 3rd genm though, but gives you sme idea

car-part.com has them listed starting at $100 and up. The $64k question is how long has the current one been driven on it its current state. If not long it could be opened up and reset if there is no visible damage.

 

[LMHmedchem]

Usually it is the crush sleeve that lets go taking the preload off the pinion. I'd replace it on the one you get out of a junk yard.

If you get a used one that has not been rebuilt I would try to replace as much as you reasonably can before having it reinstalled.

I would at least replace the carrier bearings/races, the pinion seal/bearing/race/crush sleeve, and ring gear bolts. All of this can be had for $125 or less for a good brand like Timkin, SKF, or National. I would also replace and the differential gasket, axle shaft seals (if you can get them), and the u-joint. These are not particularly expensive either.

Whenever you buy parts for a drivetrain you need to do some research since there can be multiple options. You need to confirm exactly which differential and axles you have. You need to do this before buying a used unit and also for replacement parts.

I would call around and let mechanics know that you have a used differential along with some parts that you want replaced before it's installed. Work with them to put together a part list, but let them know you will be buying the parts. A good shop will generally be ok with this as long as you are getting quality parts. There are probably more shops that will swap out a differential than will open it up and replace parts so you need to look into that. Transmission repair shops often do differential rebuilds as well so that's a place to look .

If it were me, I would also end up grinding off all of the rust from the case and repainting it before it went on, and I would replace all of the mounting bolts. I end up wasting more time than some as I want it to look nice for a while as well as work. I am always fighting rust up here so most things that come off get painted before they go back on.

LMHmedchem

 

[Josh P]

If it were me, I would also end up grinding off all of the rust from the case and repainting it before it went on, and I would replace all of the mounting bolts. I end up wasting more time than some as I want it to look nice for a while as well as work. I am always fighting rust up here so most things that come off get painted before they go back on.

LMHmedchem

My dad always cleaned and painted the parts before they went back on the car. It is a habit I picked up from him.

 

[ernzo]

If you get a used one that has not been rebuilt I would try to replace as much as you reasonably can before having it reinstalled.

I would at least replace the carrier bearings/races, the pinion seal/bearing/race/crush sleeve, and ring gear bolts. All of this can be had for $125 or less for a good brand like Timkin, SKF, or National. I would also replace and the differential gasket, axle shaft seals (if you can get them), and the u-joint. These are not particularly expensive either.

Whenever you buy parts for a drivetrain you need to do some research since there can be multiple options. You need to confirm exactly which differential and axles you have. You need to do this before buying a used unit and also for replacement parts.

I would call around and let mechanics know that you have a used differential along with some parts that you want replaced before it's installed. Work with them to put together a part list, but let them know you will be buying the parts. A good shop will generally be ok with this as long as you are getting quality parts. There are probably more shops that will swap out a differential than will open it up and replace parts so you need to look into that. Transmission repair shops often do differential rebuilds as well so that's a place to look .

If it were me, I would also end up grinding off all of the rust from the case and repainting it before it went on, and I would replace all of the mounting bolts. I end up wasting more time than some as I want it to look nice for a while as well as work. I am always fighting rust up here so most things that come off get painted before they go back on.

LMHmedchem

Thanks, I appreciate your comment

 

[ernzo]

So first I’m going to check the fill on the rear diff and add an additive. I know that the suggested fill level is slightly misleading and can result in under fill. I will fill it slightly above the fill hole. I am sourcing low miles replacement diffs, and if I can get one I will buy it, say under 140,000 and crack it open. I don’t think I can do the bearings but ill check it out, dono need a press?