Rear end repair

[adsm08]

Ok, so I do more driveability and streetability (suspension and alignment work) than anything else and rear ends aren't really my thing.

Anyway, I have an 04 Explorer about 210K on the clock, with the IRS 8.8, and the pinion bearing makes some pretty angry noises above 60 MPH.

Here's the issues, I have a pinion install kit already from my previous Explorer that I never got around to rebuilding the rear, it just had gear whine which wasn't a big deal. This pinion bearing will likely be fatal eventually, so I need to deal with it, but the gears have no hint of a whine to them.

At 210,000 miles, would anyone have any reservations about installing just new pinion bearings and using the existing gear set, or should I really spring for new gears. The old Explorer had 3.55s, and this one has 3.73s, so I can't use the set I have, and I'd really like to not spend the money on a gear set if I don't need it.

 

[Josh B]

Does a pinion bearing give one a roar/rumble type feeling under load condition?

 

[adsm08]

Does a pinion bearing give one a roar/rumble type feeling under load condition?

It can. It is usually a bearing type noise that happens only while driving and goes away when you let off the gas and start to coast.

I know for sure mine is the pinion bearing because I checked it under a stethoscope.

 

[Josh B]

Wow, a big part of my transmission problem could be a pinion then. It also rumbles sometimes in reverse under any torque above an idle.
Guess I'd better pull the pan and check it.
I've often gone from accelerating to a coast to minimize the growl, but attributed the ceasing roar under acceleration to the additional transmission pump pressure
(sorry to have interrupted your thread adsm :/ )

 

[sheep herder]

Unless the gears have visible wear, I wouldn't replace them. Properly set up, rear end gears will last just about forever.

 

[adsm08]

Wow, a big part of my transmission problem could be a pinion then. It also rumbles sometimes in reverse under any torque above an idle.
Guess I'd better pull the pan and check it.
I've often gone from accelerating to a coast to minimize the growl, but attributed the ceasing roar under acceleration to the additional transmission pump pressure
(sorry to have interrupted your thread adsm :/ )

It's all good. We are all here to learn, some of us are here to teach, I'm here for both.

I'd jack the rear end up, get someone driving it, and take a stethoscope around the diff to listen for the growl. Go just inside where the tubes meet the pumpkin, and right under the pinion, if you still haven't found it get out at the wheel ends of the axle.

Unless the gears have visible wear, I wouldn't replace them. Properly set up, rear end gears will last just about forever.

Unfortunately I won't know if there is a wear pattern until I open it up, and I won't have the down time to wait for gears once it is open.

 

[racsan]

any chance you could use a borescope through the diff fill plug to look at the gears?

 

[RonD]

If the pinion bearing has not failed, just making a noise before failing, then I would use the matched pinion ring set that is in there now, just replace the bearing

After pulling cover and driveshaft you will be able to feel if there is a wobble on pinion shaft, and see where that caused wear on ring and pinion teeth so then you may want to swap them out with new bearing

 

[4x4junkie]

I tend to agree, if the bearing hasn't gotten loose and shed significant amounts of metal into the diff oil, the gears themselves should be fine.

If you do end up finding a surprise when you open it, then I'd say the quickest remedy would be to find a 3.73:1 chunk at a wrecking yard to replace it entirely.

 

[91stranger]

Growl sound that comes and goes when letting off the gas is definitely a pinion bearing. That's what killed my last rear end. pinion seal failed 15 miles from home. Thought it was a wheel bearing so I limped home. Got home and jack the front up and both wheels spun nice and smooth, no sounds, no play.... Go to the back and see oil everywhere and a blown seal. Ended up only having a quarter of a quart of diff fluid when I drained it. I know those pinions are a PITA to set the back lash if you don't mark stuff properly like I failed to do. If you have an older I-beam style torque wrench then it helps. I would at least open the diff and change the fluid if you go that route.

 

[19Walt93]

The worst the gears will do is whine as long as they don't have chips or major damage, I'd definitely reuse them. Bearings that whine and growl will fail, gears that whine will keep on whining for a long time. If you have one failed bearing you should replace all of them that run in the same lube or you'll be doing the job again. I'd also take the differential apart and clean it out, too because any metal particles that remain will kill your new bearings.

 

[adsm08]

The worst the gears will do is whine as long as they don't have chips or major damage, I'd definitely reuse them. Bearings that whine and growl will fail, gears that whine will keep on whining for a long time. If you have one failed bearing you should replace all of them that run in the same lube or you'll be doing the job again. I'd also take the differential apart and clean it out, too because any metal particles that remain will kill your new bearings.

Yeah, if I'm doing the pinion bearings I'll do the carrier bearings too. Since it is the IRS 8.8 once the pinion is out there isn't a whole lot of disassembly left that can be done, and of course it will go to the parts washer before I put it back together.

Heck, the other day I was replacing a 4.0 valve cover because the little nubs that the PCV valve lock on to were busted off. I caught myself washing out the old valve cover after I got it off the engine.

 

[ericbphoto]

Yeah, if I'm doing the pinion bearings I'll do the carrier bearings too. Since it is the IRS 8.8 once the pinion is out there isn't a whole lot of disassembly left that can be done, and of course it will go to the parts washer before I put it back together.

Heck, the other day I was replacing a 4.0 valve cover because the little nubs that the PCV valve lock on to were busted off. I caught myself washing out the old valve cover after I got it off the engine.

Keep your trash clean.

 

[19Walt93]

I speak from experience, many years a go I replaced the bearings in the 9 inch on my 77 F150 one Saturday after getting out of work at noon. Being a long box truck I didn't worry about the gears, just replaced all the bearings. I also didn't take the time to thoroughly clean the old lube out of the axle tubes and there was apparently some residual shavings in there so I did it again a few weeks later. Wasting money pisses me off worse than doing a job over. Good work ain't quick and quick work ain't good.