Why are there so many rear diff bearing failures on the 2002-up Explorers? | Page 2 | Ford Explorer Forums - Serious Explorations

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Why are there so many rear diff bearing failures on the 2002-up Explorers?

31 splines is what you need.

I bought my bearings set on ebay (Motive) Couple Ks on them , howl didnt come back yet.

I did everything myself except for the preload/backlash , a specialized shop did this for me for 50$.
 



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Phoenix99-- Tnx for the info!!
Tom T.
 






Hey, I was just thinking, do the IRS expeditions exhibit the same problem with their differentials? The differentials between IRS explorers, and expeditions are not interchangeable are they?
 






I believe Expeditions has solid rear axle. But the internals might be the same (bearings/gears/clutches).
 






No, all ford Expeditions have had an independent rear suspension since 2003. Check it out.
 






It's neither here nor there, but the Expeditions also went to an IRS a while back... Unfortunately it's a Ford 9.75" unit. Much heavier-duty than the 8.8.

Please note that there are two different issues that you could be hearing. The high-pitch whine when cruising or accelerating at freeway speeds is likely a diff issue. However, some shops mis-diagnose a drone as being the diff too. A good shop (or dealer) with a vibration analyser can determine whether or not it's a first-order driveline imbalance from the rear driveshaft. It's very possible that the drone you're hearing isn't the diff at all.

-Joe
 






Do you suppose that the heavy duty differential from an Expedition could be installed into an Explorer? If not do you think the mounts for the differential could easily be modified to accommodate a differential from an Expedition?
 






Anything is possible with enough money.

But honestly, the 9.75" diff is usually 33 spline vs 8.8" being 31 spline.

In keeping with the higher spline count, the axle diameter will also be larger. Thus, you'd either have to swap over ALL of the Expy's rear end parts (wheel bearings, the knuckles they fit into, and of course the control arms and everything else)

Or you'd have to have custom axles made. You'd have to have them made anyways due to the difference in width between the Expy and Explorer.

You're better (cheaper) off just buying an Expedition if your Explorer isn't strong enough for you.

The real question is, would the iron diff 8.8" IRS from a 89-97 Tbird or Cougar mount up? I haven't really looked under the Explorer to see how different the mounts are.
 






If you seem to have an uncurable rear end problem, then maybe the problem isn't with the rear end at all. Wheel bearing drone can sure sound like a bad rear bearing. Try swerving back and forth at 55 mph and see if the noise gets better/worse as you swerve. If so, then you've got a wheel bearing problem.

Rear end problems will be consistent, get louder with vehicle speed, will not be rpm sensative, and may change volume with temperature of the rear end.

If you want to rebuild it right, I would suggest finding a speed shop that does Mustangs. The 03 Cobra had an IRS rear end in it, and in just about every young guys Mustang, they've changed the gears. That means that these Ford speed shops are going to be VERY familiar with setting up an 8.8 rear end.

Another great suggestions is to take it to a 4x4 performance shop. Those guys change gears really often too, so they should also be very good at it. The gears and bearings are available on Ebay cheap in both Ford Racing and Motive gears. Both are just fine. You can't change the gear ratio from stock though, without having your computer tuned for it. So don't go upgrading gear ratios without considering that.
 






My 2002 Eddie Bauer has the limited slip D4 rear end with 62,000 miles on it and so far (knock wood) no issues. I recently changed out the factory oil fill (synthetic 75W-140 according to the manual) to Amsoil Sever Gear 75W-140 synthetic with 4oz friction modifier and everything is smooth and pretty quiet.

The fill plug magnet had a fair layer of cruft on it when I did the change, but nothing too bad and nothing larger than fine particles.


Rumple
 






The Thunderbird/Cougar IRS looks very similar. The Tbirds never had a rear end problem, even with their 7.5 inch diff in the V6 models. All 8 of mine, including the two supercharged ones got over 100K with no real issues other than some faint whining. Its one of the reasons I loved the idea of IRS in the Explorers.
I have a parts Super Coupe with Iron 8.8 diff. I will do some photo comparison.
 






The Thunderbird/Cougar IRS looks very similar. The Tbirds never had a rear end problem, even with their 7.5 inch diff in the V6 models. All 8 of mine, including the two supercharged ones got over 100K with no real issues other than some faint whining. Its one of the reasons I loved the idea of IRS in the Explorers.
I have a parts Super Coupe with Iron 8.8 diff. I will do some photo comparison.

cool, :popcorn:
 






The Thunderbird/Cougar IRS looks very similar. The Tbirds never had a rear end problem, even with their 7.5 inch diff in the V6 models. All 8 of mine, including the two supercharged ones got over 100K with no real issues other than some faint whining. Its one of the reasons I loved the idea of IRS in the Explorers.
I have a parts Super Coupe with Iron 8.8 diff. I will do some photo comparison.

I wonder if the weight of the Gen 3 expos had anything to do with it.....whats a gen3 vs a Gen2 expo weigh?
 






The IRS 8.8 looks like it has a small fluid capacity to me. I wonder if it takes less gear lube than a Mustang 8.8? By the way, 03 Cobra IRS's aren't known for failure internally (except for strength issues in racing). Then again, most 03 Cobra owners have swapped gears out for a lower ratio within the first couple thousand miles. :D
 






Well I didn't take pics, but the MN12 Tbird housing is not the same at all. The side gears are 28 spline, the mount holes look different and the cover looks completely different, not to mention they don't have the hole for the sensor.
 






The 03 Cobra's got an IRS 8.8 with 31 spline axles, a traction-lok posi (same on as in the Ford trucks), but with carbon fiber clutches instead. That makes the 31 spline 03 Cobra posi unit an attractive upgrade to non-cobra Mustang racers who want to switch to 31 spline axles from the stock 28.
 






02 Explorer XLT V8.

I felt like an a-double-s for not changing my rear diff fluid. Rear diff was replaced at around 45k miles due to the infamous leak and it has not leaked since. Fast forward to 175000 miles, I heard howling noise coming from the rear after driving in heavy down pour (4x4 kicked in). Did not really pay much attention to it until the noise persisted for the next couple of days. Drained the fluid today and it's all black and burnt. Noise still exist after fluid replacement with synthetic fluid and friction mod, so I assumed it's been overheated and toasted.
Thing that got me upset was that in the past I checked the owner's manual for rear diff fluid change and nowhere it's listed under the scheduled service guide, and I foolishly believed the fluid was lifetime.
 






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