Differential Rebuild or Used? 02 Explorer Limited

[jpoprock]

Hey guys... my diff is roaring like crazy. Sounds horrible. Replaced the hubs, so it's not those. My mechanic said he checked the diff oil and there was plenty, but there was metal present. He said it's hard to know what is wrong without taking it apart.

I need to spend as little as possible because I don't have it to spend at all to begin with.

I wish I could narrow down what could be making the sound. It's worse at low speeds. It's higher pitched at 60mph. It disappears for a second sometimes if you take your foot off the gas. It's present with or without OD on.

He thinks it could just be the side bearings. But if it's the Ring and Pinion, that is bad and costly. If it's just the bearings... then that isn't such a huge deal.

He suggested for my needs, I buy a used diff from LKQ. The labor charge won't be as bad as a rebuild, and they offer a 6 month warranty. I can get a used diff with a 100K miles on it and warranty for $550 shipped.

The question is, there really isn't a way to know if I can save money by buying a bearing rebuild kit vs putting in a used diff ... because the only way to know is to tear the thing apart anyway right? He said that's why he suggested the used diff. Because a diff can turn into a "while you're in there" part quickly.

I want to invest as little as possible as I only need about another 90K miles out of this vehicle. It's got 225K on it now, new hubs, rebuilt tranny, and runs like a top, doesn't use oil and it's in good shape. But I can't afford to have it start nickel and diming me to death now. I do need a new upper ball joint on the drivers side, and one other thing fixed and it would be structurally sound.

I need the best decision, for the least amount of money spent, and I need this vehicle to last me another year or two before it's retired to being a back up vehicle.

Thanks!

 

[Joe in NY]

Yep its the diff. Ford released a TSB saying rebuild the entire diff to rid of the noise. My 02 EB has the same problem. Its on acceleration and constant speed. When ever torque is being to applied to the diff it whines. Its a 7 hour job by the book.

If you buy a new diff or a used one, make sure you get the right one. There are a few diff options for the explorers.

 

[boominXplorer]

If you at least install new bearing in the diff it will quiet it up a bit. The carrier bearings wear really bad for some reason.

I have (2) 3.55 open diffs if your interested in a used one. One with 143k and one with no cover w/60k, send me a pm if interested.

 

[Joe in NY]

any idea how hard it is to do the bearing on a 3.73 limited slip?

 

[imp]

any idea how hard it is to do the bearing on a 3.73 limited slip?

Differential side bearings? Also called carrier bearings. They determine the correct relationship between the gear teeth: clearance as well as proper contact pattern.

How hard? Very, if one has never had any experience working with gears. This type of differential carrier has no means of adjusting bearing preload or location, other than by use of thin shims installed behind the cone and roller assembly. If done without pinion depth measurement tools, hit-and-miss methods might require pulling bearings off the carrier, changing shim(s), then pressing them back on, MANY times.

One reason for the failure of these center sections, if it indeed is that common, may be the fact they are aluminum (I believe, in 3rd. gen.), which allows more deflection between gears that cast iron units. imp

 

[Joe in NY]

They are Aluminum diffs.

 

[sfbayjay]

Your original post sounds exactly like what I experienced w/ my 2002 XLT a few years back. If I had it to do over again, I think I'd probably go for a re-built or 2nd hand rear diff. BTW: I have the 3.73 limited slip rear diff (axle code D4).

Issue for me began with rear end whine at around 60 mph, only if I had my foot on the gas - just like you describe. After research on this forum I found out this was common and not a big deal - a "feature" of the ring and pinion assembly in the diff getting a bit worn.

About 3 months after the whine started, though, I had horrible low-speed grind/roar starting to happen, along with the higher speed "whine". I had a couple of shops look at it. Long story short: I ended up having the carrier bearings and the pinion bearing replaced, and also the clutch pack. Bit I did NOT replace the ring and pinion gears. The shop convinced me that the gears looked good and that the new pinion bearing would hold everything nice and tight, eliminating the whine.

The carrier bearings, pinion bearing, and clutch pack install cost me about $1000. Ouch.

For about 1500 miles, everything was awesome - totally quiet like brand new.

Then, the high-speed whine came back. That was it - the low speed grinding has not returned. I've done nothing further to address it, except for one regularly scheduled change of rear diff gear oil and friction modifier.

When the whine first came back, I called around about having the ring and pinion gears replaced or tweaked - I checked with three Ford dealerships and a couple of reputable independent shops. Only one of the dealerships would even quote the gear replacement - the other two told me they would only replace the differential as a whole unit since doing just the gears had caused them problems (repeat work) in the past. Both of the independent shops advised that it would be better (cheaper) to install a whole new (or remanufactured) diff - less labor cost and possibly more reliable fix.

I decided to roll the dice and keep driving it until something broke, then maybe go with a remanufactured diff install. I've put on about 45,000 more miles since then and (knock wood) no real issues other than the persistent whine on the freeway. It's unpleasant at times, but I can live with it and I'm convinced there's no risk of catastrophic failure. I think having bad carrier and/or pinion bearings, which it sounds like you might, would be a larger risk.

The tech that did the bearings on mine told me that he didn't see any metal shavings when he took things apart, so you may have more going on than I did - maybe your ring/pinion gears are in worse shape.

With that in mind - and this is just my opinion - if you can get a re-built differential installed for less than $1000 perhaps it would be a good bet. Ford dealer won't do it with a used or remanufactured part, but a good independent shop will for sure. Just make sure you get a warranty on the differential assembly, and that the carrier and pinion bearings are new. If you just slap on a junkyard differential I bet there's a good chance you'll have the same issues soon enough.

And - be sure you get the right diff for your truck, as there are several even within the same model year. The 3.73 LS diff that I have was used on several different Ford vehicles, so if you get the specs right you can broaden your parts search. You can get your rear axle code from the door panel of your truck that will help you get started.

 

[jpoprock]

Guys... This is the kind of advice I was looking for!

I think my diff is the 3.73 LS diff. Can I switch to an open diff? If so, do I have to have matching F/R? Will I lose AWD? 4WD? AWD is nice, but horrible MPG.

Can I use a 3.73 diff from an 02-05 Mustang or F150? In other words, are all the diff's from Ford like mine prone to failure?

Rebuilt diff's on EBay are like $1300! Any other places to check?

 

[Joe in NY]

They made new parts to stop it wearing. I guess Ford does it once and then fixes it the second time lol.

 

[dablack]

Guys... This is the kind of advice I was looking for!

I think my diff is the 3.73 LS diff. Can I switch to an open diff? If so, do I have to have matching F/R? Will I lose AWD? 4WD? AWD is nice, but horrible MPG.

Can I use a 3.73 diff from an 02-05 Mustang or F150? In other words, are all the diff's from Ford like mine prone to failure?

Rebuilt diff's on EBay are like $1300! Any other places to check?

There is no "think". You need to be sure of what you have. Yes, you can switch to an open diff. The front differential (if you do actually have 4WD) doesn't care if you have traction lok or not in the rear. You do HAVE to have the same ratio front and back. If you have 3.73, you have to stay with 3.73.

No, you can't use a diff from something else. Only a 2002-2005 explorer/mountaineer.

If it were me, I would find someone in your area parting out an explorer. Get their diff and take it to a shop to have it rebuilt. Then put it in yourself.

Austin

 

[sfbayjay]

Guys... This is the kind of advice I was looking for!

I think my diff is the 3.73 LS diff. Can I switch to an open diff? If so, do I have to have matching F/R? Will I lose AWD? 4WD? AWD is nice, but horrible MPG.

I don't know if you can switch to an open diff or about answers to any of these other questions re. AWD/4WD. You should look in the "Transmission, Transfer Case, and Differential" section of the Explorer forums here: http://www.explorerforum.com/forums/forumdisplay.php?f=109

Can I use a 3.73 diff from an 02-05 Mustang or F150? In other words, are all the diff's from Ford like mine prone to failure?

Don't quote me on this, cause I could be wrong. My understanding is that you could use any limited slip Ford 8.8 differential (Dana 8.8) that is set up to work with 31-spline axles. I don't know exactly what that means as far as grabbing parts from another model. I think this rear diff was common, though, in many Rangers, Mountaineers, Expeditions, etc. I think the 8.8 rear diff from other Fords like Mustangs may be set-up for 28-spline axles - not what you need.

EDIT: Looks like the Ranger 8.8 was set up for 28-splines, too, so proceed with caution if you're hunting for a rear diff from another vehicle type.

Do some Googling about Dana 8.8 or Ford 8.8 and you will start to get some info.

I've heard (rumor) that the newer versions of the 31-spline 8.8" 3.73 LS diff were made with better materials - mostly the pinion and ring gears, so the whining issue may be better if you find a later model. Not sure how or if they improved the bearings, though - I think there was a new style of carrier bearing seal introduced at some point that may have improved that, too, but not sure.

 

[jpoprock]

If it were me, I would find someone in your area parting out an explorer. Get their diff and take it to a shop to have it rebuilt. Then put it in yourself.

Austin

That would be great, but I don't know how much time I have left on this diff, as it seems like it's getting worse by the week. It's getting to where i can't hear if talking on the phone and going 40mph because the roar is too loud. I don't have a spare vehicle, and I'm not a mechanic. I'm able to do certain things though, but I don't own any impact tools, etc. And I have to think that removing a differential might be a bit of job. I'd have to research it. I don't have time to research it.

I'd love to have the time to rebuild one though, but I don't. I think I'm going to buy a used diff with low mileage and have the guy I trust install it. I have no clue how many hours of labor that will amount to, but I have to do something and soon. If I buy a used one, maybe I could keep the old one and rebuild it myself later?

Jason

 

[sfbayjay]

Expect some significant labor, I think, even if swapping a used diff.

I may be wrong here, but if you're planning to re-use your existing rear axles, whoever does the install for you will have to pull them from the existing diff. Then re-install axles in new(used) diff along with new seals and circlips to hold the axles in place.

I think think the rest of the install is pretty much plug-and-play, since a re-built diff unit wouldn't need a new pinion seal and the bearings (installed from within the diff unit) should be OK.

I understand there can be some "complications" with removing the half-shafts, though, and basically the job means taking apart the the rear end on each side, so that takes some time.

I would probably expect something like 4 or 5 hours of labor, plus axle seals and clips, oh and rear diff fluid - in addition to the cost of the used/rebuilt diff. I may be wrong, but that seems about right to me.

 

[dablack]

I think we need to be a little more specific on what we are talking about. When it comes to 3rd members, rear ends, or differentials, lots of guys get confused (me one of them).

To sfbayjay's early point, can you use a "locker" or traction loc from another vehicle as long as the spline count is the same. I think so but I'm not 100% sure. Here is a new one:

http://www.americanmuscle.com/ford-31spline-88-carbondisc.html

Since most need to be rebuilt, I wouldn't use a used one unless you got it CHEAP!

Now, what I'm talking about is getting the whole pumpkin from a 2002-2005 explorer. Yes, you have to pull the axles to get it out. I don't have my haynes manual with me but it isn't a big deal. The pumpkin is what bolts to the frame and holds the gears and the axles go into that. The explorer pumpkin is unique to the explorer, mountaineer, and aviator.

I just want to make sure we are all talking about the same thing.

 

[jpoprock]

A fun new noise that I hear/feel seems to be something that is is fully rotation. Like a low vvvvrrrroooooommmmmm type of vibration or sound as I accellerate at low speeds. Like a tire rubbing, but that's not what it is. I can feel it. And my luck is that it's in the front. Feels like it. I have no clue what that could be.

I think i'm cursed.

 

[sfbayjay]

When my rear differential bearings and clutch pack went bad, I would have SWORN to you that there was also something going on in the front of the truck. I could feel grinding/vibration in the steering wheel and even the sound seemed to be coming from up front.

This "new" sound you're getting could just be the rear getting worse.

Having been through what you are, I know it's frustrating. Bummer.

 

[jpoprock]

Yes!! Exactly! But my hugs are new all around. And even though I have no experience with real trucks, I have worked on 1/8th scale 4x4 RC trucks. Many of the same principles apply really.

What I think the sounds is, because I can FEEL it, is the Pinion and Ring gear rubbing. That's exactly the right amount of "teeth" to correspond with the sound I'm hearing. Just like tread on a tire. It's constant. Unlike taking my truck out of gear and coasting. The sound I hear then is bearings I think.

The question I don't know the answer to is, when in neutral and coasting, is the drive shaft spinning? I say it's not... Because when I put it in gear, the horrible grinding roar comes back full force. My truck shifts great, so I don't have transmission on my mind.. but that doesn't mean that's not the problem.

The mechanic said "It's definitely your diff. What else is going on back there... I can't say until I'm in there". Which sadly is true.

Thanks!
J

 

[jpoprock]

Oh, and the only way to see what's going on is the take the diff pan off right? The oil will drain out, then I can just remove back plate and everything will be sitting there in front of me. I would then be able to see how bad the ring and gears are. But then since I can't fix it myself, I'd have to put the cover back on, fill it up up with oil and friction modifier, and take it for service. Correct?

Plus another little gem... is that my door plate is unreadable. This means I will have to get under the veh and read the numbers on the diff plate tag... then google it to translate the codes right?

 

[2Trux]

The question I don't know the answer to is, when in neutral and coasting, is the drive shaft spinning? I say it's not... Because when I put it in gear, the horrible grinding roar comes back full force. J

The rear driveshaft will spin whenever the truck is moving. There is a mechanical connection between the tire and the driveshaft.
The difference in sound you hear has to do with if the drivetrain is under load (power applied) or no load (coasting).

 

[jpoprock]

Thanks 2Trux.

So when under load, different things are engaged inside the differential, which means the ring and pinion are moving, the clutches, etc. And that is NOT the case if coasting in Neutral?

If this is true, then when I'm coasting in neutral and i hear a rotational "scraping" noise, and my hubs are BRAND new, then it's either in the stub axles, or the side bearings or drive shaft bearing.

But when I engage the vehicle into drive, it's a WHOLE different ball game of noise. That's because the ring and pinion are spinning, the clutches, etc.

Is this why it's worse at different speeds? Clutches engage and disengage depending on speed?