Small toothed gear behind ring gear in Ford 8.8 identification

[crazyramen]

I opened up my rear diff to see exactly how messed up it is. I already knew I was going to need new bearings+seals, so I have that on order.

When I cracked it the fluid came out all metallic, then I found this gear all chowdered up and throwing shards but I haven't found any info on what it is. My '01 has abs, so I was thinking it might be a speedo gear for the wheel position sensor on top of the diff?

The rest of the diff doesn't look too bad I don't think. The backlash is 55thou right now, but I was thinking that's probably from the bearing wear. The kit I ordered has the shims, too.

 

[Curious Hound]

That's not a gear. It's the tone ring for a speed sensor. On some trucks, used for rear abs system. On some trucks it is used for vehicle speed. That should be replaced. Nothing actually touches it. The sensor just magnetically reads those teeth. But the teeth need to be well defined and the sensor needs to be the right distance from it.

 

[crazyramen]

Thanks ericb!

That's what I figured. My abs light goes on driving at highway speeds for >10minutes, so this is probably the cause. I'll try to figure out what caused this when I pull out the carrier to replace the bearings

 

[RonD]

That tone ring is just a friction fit so just pry it away from ring gear to get it off

New one looks like this, assuming 8.8": https://www.yukongear.com/productdetails.aspx?ProdID=1889

 

[sickwilly]

What messed up the teeth? Just curious.

 

[19Walt93]

If the fluid is metallic replace the bearings now or you'll be in there again. Clean out the axle tubes and replace the wheel bearings. too. Those banged up teeth on the tone ring mean you should pull the speed sensor and look at it, I'll bet it looks thrashed, too.

 

[sgtsandman]

And find out what happened that caused the tone ring to wear down. Nothing should be in contact with it to cause it to wear like that.

 

[pjtoledo]

the pinion ring gear has marks that shouldn't be there, you have something in the axle that is seriously out of place.

edit: maybe

 

[Curious Hound]

the pinion ring gear has marks that shouldn't be there, you have something in the axle that is seriously out of place.

You've got some kind of crazy turkey vision to see the pinion gear in that photo.

 

[crazyramen]

Yeah I haven't taken out the carrier yet. I checked the speed sensor and that has no weird wear (though it did have about a pound of metal shavings attached). Already planning on doing all of the bearings. I just got my Yukon bearing kit in today, so I'll have to take the carrier out anyway and I'll check behind it then.

the pinion ring gear has marks that shouldn't be there, you have something in the axle that is seriously out of place.

Are you talking about the lines on the side of the gear? I'll try to get back to it today or tomorrow and inspect the teeth more closely, but the quick look I gave it the other day I didn't see an unreasonable amount of wear for a car with 200k miles on it.

 

[pjtoledo]

You've got some kind of crazy turkey vision to see the pinion gear in that photo.

I was trying to focus the attention on the ring gear, and away from the tone ring.
poorly worded perhaps, sorry 'bout that.

 

[pjtoledo]

Yeah I haven't taken out the carrier yet. I checked the speed sensor and that has no weird wear (though it did have about a pound of metal shavings attached). Already planning on doing all of the bearings. I just got my Yukon bearing kit in today, so I'll have to take the carrier out anyway and I'll check behind it then.



Are you talking about the lines on the side of the gear? I'll try to get back to it today or tomorrow and inspect the teeth more closely, but the quick look I gave it the other day I didn't see an unreasonable amount of wear for a car with 200k miles on it.

maybe it's just the camera angle or an aftermarket gear, the factory axles I've opened up didn't look like that.

 

[Curious Hound]

I think it looks like it got rubbed, too. But could be wrong.

 

[crazyramen]

Welp I should've taken the time to spin the gear the other day, that's all it would've took for me to find out what caused it! I believe all this is factory. I think at this point I'm just going to replace the whole carrier + ring gear + tone ring. The spider gears are well rounded. Maybe I'll find a junkyard unit, or maybe I'll go for yukon gears and a positraction carrier. -- on that note, can I just drop in a posi unit from a similar vintage mustang?

Along with that ring tooth being crunched off, the bolt holding the cross pin is also stripped out. I think the best course of action for me is going to be to drill out the pin itself. I think the bolt is too far recessed into the case for me to get a drill to it. I take it the pin is hardened steel? I'll have to invest in some good drill bits for this one.

Of course, I'm open to any other ideas or suggestions.

Edit: My buddy had an idea to cut a slot in the bolt and try to use a flathead to get it out. I guess it's time to buy a dremel!

 

[19Walt93]

Welp I should've taken the time to spin the gear the other day, that's all it would've took for me to find out what caused it! I believe all this is factory. I think at this point I'm just going to replace the whole carrier + ring gear + tone ring. The spider gears are well rounded. Maybe I'll find a junkyard unit, or maybe I'll go for yukon gears and a positraction carrier. -- on that note, can I just drop in a posi unit from a similar vintage mustang?

Along with that ring tooth being crunched off, the bolt holding the cross pin is also stripped out. I think the best course of action for me is going to be to drill out the pin itself. I think the bolt is too far recessed into the case for me to get a drill to it. I take it the pin is hardened steel? I'll have to invest in some good drill bits for this one.

Of course, I'm open to any other ideas or suggestions.

Edit: My buddy had an idea to cut a slot in the bolt and try to use a flathead to get it out. I guess it's time to buy a dremel!

View attachment 51124

The only way to put a positraction in is to use a chevy rear end. You often see Chevy performance cars with Ford rear ends after they get sick of breaking their posi over and over. Ford's limited slip is called a Traction Lok and some Torsen units were used, too. There's probably metal throughout the housing now so make sure to do a thorough cleaning if you rebuild it. It's apt to be cheaper to just buy a used rear end, especially if you need a differential along with gears, bearings, and seals.