Rear differential noises

[Chris'97exploder]

Hello,

I have a 97 ford explorer sport with a 8.8 LS with 410 gears. I was told there was an issue with the rear diff when I bought it. I have taken look at the ring, pinion and spyder gears but everything looks fine. The noise is a loud whining when ever power is to the drive train. When I let off the gas, the noise stops. Does anyone have any ideas?
Thank you, Chris

 

[imp]

Hello,

I have a 97 ford explorer sport with a 8.8 LS with 410 gears. I was told there was an issue with the rear diff when I bought it. I have taken look at the ring, pinion and spyder gears but everything looks fine. The noise is a loud whining when ever power is to the drive train. When I let off the gas, the noise stops. Does anyone have any ideas?
Thank you, Chris

@Chris'97exploder
Looks can be deceiving, as you found, apparently. How were these parts inspected? What appearance did the ring gear tooth surfaces have? Were they shiny and bright, especially the "drive" sides, or dull and grayish. Or worse yet, had a rough appearance?

The whining noise originates with the gears. Especially when audible mainly when the gears are working, as opposed to coasting. If the whine were constant, pinion bearings would become suspect. Did you rotate the gears by hand to determine if there was a roughness feel to them? To do that effectively, the driveshaft must be lowered off the pinion gear.

So, gear noise, but why? Either they have become misaligned slightly due to bad bearings, either pinion or differential carrier, or the gear teeth themselves are damaged, which could have resulted from bad bearings OR running low on gear oil. imp

 

[974X4BLACKSPORT]

Cheaper and easier to just find another good used matching LS 4:10 8.8 and swap it out.

 

[Chris'97exploder]

@Chris'97exploder
Looks can be deceiving, as you found, apparently. How were these parts inspected? What appearance did the ring gear tooth surfaces have? Were they shiny and bright, especially the "drive" sides, or dull and grayish. Or worse yet, had a rough appearance?

The whining noise originates with the gears. Especially when audible mainly when the gears are working, as opposed to coasting. If the whine were constant, pinion bearings would become suspect. Did you rotate the gears by hand to determine if there was a roughness feel to them? To do that effectively, the driveshaft must be lowered off the pinion gear.

So, gear noise, but why? Either they have become misaligned slightly due to bad bearings, either pinion or differential carrier, or the gear teeth themselves are damaged, which could have resulted from bad bearings OR running low on gear oil. imp

Imp, I dont remember if the gears where shiny, dual or scratched but will look tomorrow. The teeth where not chipped and I could rotate them from where the drive shaft connects to the pinion (I took the drive shaft off.) It seems like I should look at the pinion bearings nexy. I'll let you know about the gear conditon tomorrow. Thank you for your insight its greatly appreciated.

 

[Chris'97exploder]

Cheaper and easier to just find another good used matching LS 4:10 8.8 and swap it out.

I'll have to look into that. Thanks

 

[974X4BLACKSPORT]

If it was making noise when in use, chances are even after installing new bearings and races and re-setting the pinion depth, it will still make some noise or "whine", once worn, there is no going back.

 

[donalds]

Whine on acceleration = bad pinion bearing preload = loose pinion bearings because of wear
Or the pinion nut backed off a ill bit but that's unlikely

If I had to say change all your bearing s and crush sleeve
Take a look at your u joints as well

 

[Chris'97exploder]

Whine on acceleration = bad pinion bearing preload = loose pinion bearings because of wear
Or the pinion nut backed off a ill bit but that's unlikely

If I had to say change all your bearing s and crush sleeve
Take a look at your u joints as well

Thanks

 

[imp]

Imp, I dont remember if the gears where shiny, dual or scratched but will look tomorrow. The teeth where not chipped and I could rotate them from where the drive shaft connects to the pinion (I took the drive shaft off.) It seems like I should look at the pinion bearings nexy. I'll let you know about the gear conditon tomorrow. Thank you for your insight its greatly appreciated.

@Chris'97exploder
The "feel" of the gears meshing is best done by grasping the ring gear, not the pinion, and rotating back and forth in both directions. Hold the gear with gloves or a rag; sometimes a razor-sharp edge is built up. Doing it that way requires much more effort than turning the pinion. If any "raspiness" or roughness is felt, it's nearly a dead certainty the gears will make noise. Bad pinion bearings (or any others, for that matter, cannot always be felt by hand. For example, below is my left rear wheel bearing, one of it's outer races. That galled area made plenty of noise driving along, but COULD NOT BE FELT by hand! Look close to see why.


There was still a bit of good bearing surface left at the ends of the rollers travel, giving a smooth feel by hand, but carrying the weight of the Ex, contact included enough of the bad area to make noise like hell.

At this point it is important to know what your teeth look like, before doing anymore hypothesizing. imp

 

[imp]

If it was making noise when in use, chances are even after installing new bearings and races and re-setting the pinion depth, it will still make some noise or "whine", once worn, there is no going back.

@974X4BLACKSPORT
It really all depends on how long, how bad, and where the defect lies. I've replaced plenty of pinion bearings which howled like hell, gear teeth looked just fine, and you could fall asleep trying to hear the noise after that. imp

 

[donalds]

It's funny @imp I had bad pinion and carrier bearings looked just like that
quiet in till 30mph
Some new bearing s Inc axles fixed it
I had no marking compound for reassembly so I just took some of my kids driveway chalk ground it up add a ill bit of gear oil and mixed it up this worked great as a marking compound

Oh yea and never try to reuse a dam crush sleeve people it's just not worth it

 

[Chris'97exploder]

Imp, here are some pictures. There is a small dent in one of the teeth but that's all I found. Picture included

@Chris'97exploder
The "feel" of the gears meshing is best done by grasping the ring gear, not the pinion, and rotating back and forth in both directions. Hold the gear with gloves or a rag; sometimes a razor-sharp edge is built up. Doing it that way requires much more effort than turning the pinion. If any "raspiness" or roughness is felt, it's nearly a dead certainty the gears will make noise. Bad pinion bearings (or any others, for that matter, cannot always be felt by hand. For example, below is my left rear wheel bearing, one of it's outer races. That galled area made plenty of noise driving along, but COULD NOT BE FELT by hand! Look close to see why.


There was still a bit of good bearing surface left at the ends of the rollers travel, giving a smooth feel by hand, but carrying the weight of the Ex, contact included enough of the bad area to make noise like hell.

At this point it is important to know what your teeth look like, before doing anymore hypothesizing. imp

 

[fast_dave]

@Chris'97exploder,

I've been following this thread.

You've received a lot of good advice from competent Ex owners who've turned wrenches, skinned their knuckles, been there & done that

Based on where this thread is going I'd like to offer my .02 of recommendation.

Do you have a friend with a pick-up truck? Put him on stand by status.

Then, call these guys and ask them who they recommend to rebuild a 8.8

They might even be able to do it.

Link to Drive Line Service of Boulder, CO: Home

Your mileage may vary & hope that this recommendation helps!

 

[Mbrooks420]

If they do driveline work, they better be able to rebuild an axle and set up gears. Expect an 8.8 rebuild to be $$$, though.

 

[fast_dave]

If they do driveline work, they better be able to rebuild an axle and set up gears. Expect an 8.8 rebuild to be $$$, though.

Yes - I'd think they would be able to do the job, hence the recommendation.

I also think it would be pretty reasonable as a bench job - meaning that the OP bring it in the bed of a pick up/out of the Ex.

The rebuild parts are about $100 - 120 on Rock Auto + a couple of Quarts of 75/140 Synthetic Diff Oil.

Probably 2 hours labor max if they price it fairly to a person that approaches them with the right attitude...

Additionally, and most important; I believe that they'd be able to do the job correctly, the first time - AKA; Pay me now, or pay me later...

In closing, with all that said, I offer the following observation; having an improperly set-up rear end can lead to a very dangerous situation, for example, on a highway.

Our mileage/experience may greatly vary from the OP's - Just Sayin'

 

[Mbrooks420]

I’d expect 500-800 depending on what was needed.

 

[donalds]

Maybe even 1000$ at first glance the gears don't look to bad
If you can't do it yourself pay someone. Make sure you demand all of your old seals and bearings back. There are two axle bearings and seals by the wheels and there are four bearings inside the rear differential. If you get your ring and pinion changed get those gears back too. This will assure that the work you are paying for was done.

 

[imp]

Imp, here are some pictures. There is a small dent in one of the teeth but that's all I found. Picture includedView attachment 167428

@Chris'97exploder
In general, the teeth look pretty good, what we're seeing of them. but, if that "dent" is the kind of fuzzy-looking spot on the coast side to the left of the diff cross-shaft, looks like a piece of tooth missing, that alone would make noise, but only on coasting, not while applying power.

Keep in mind that if a piece of tooth breaks off at speed, it will likely wind up wedged between the next two teeth coming together. This happens very quickly of course, the result being that the enormous forces exerted on the teeth strip of a bunch in succession, something like shucking (sorry @shucker1 ) corn off the cob.

Keep in mind that until you determine that there is misalignment happening due to: faulty pinion or diff bearings, or faulty bearing preload of either of those, it's not possible to state the noise on acceleration is caused by the teeth condition. Actually, they look pretty good, overall. imp

 

[Chris'97exploder]

OK, I got it taken apart, attached are pictures. I think they look alright. I have to go get an impact from a buddy before I get the Pinion off.

 

[imp]

@Chris'97exploder For the most part, the ring gear looks good. The pinion appears to have a brown discolored spot on one tooth visible, localized overheating, on one tooth. There is a possibility that could "sing". I would get some 400 emery cloth strip, and polish that spot with a fingertip, as well as any other similar spots.

Please show the condition of the pinion bearings when you get them out. imp