[mchell]

Anyone ever seen this happen?

Yukon Posi differential.( Eaton clone).... 6 years old?

Broke the ear off the diff carrier bearing and took the gears out as well....

[Chief of the 60's]

If you are going to play, you are going to pay. Unless you go to a 31 spline 9". Better hope it did not cause any internal tranny damage.

[mgarblik]

I have seen ring gear teeth break off like that many times. Generally, when the heel 1/3 of the ring gear teeth break off it is because the contact pattern was set up too far back toward the heel for high performance use. That set-up produces quiet operation but when you really run the car hard, the pattern moves up toward the gear face and back toward the heel and can break off the teeth. Even though it may run a little noisy, for performance use I set up the pattern in toward the toe a little. That way under maximum stress, the contact pattern never runs off the heel of the ring gear like it appears your's did.

[mchell]

The ring gear teeth broke due to the ear of the differential snapping clean off ...this wiped out the gear set

[mchell]

I run a built 12 bolt with 33 slime axles....and yes the trans was gone but not sure if it was because of the differential breaking....never seen a diff break like that...looking for cause and effect if it exists

Thanks

[mgarblik]

Originally Posted by Chief of the 60's

If you are going to play, you are going to pay. Unless you go to a 31 spline 9". Better hope it did not cause any internal tranny damage.

Based on the few pics I see, it really doesn't look like he was making too much power for the parts he has. If the ring gear teeth were broken off at the root of the gear, then yes, he needs a 9", or a 12 bolt with race gears. Of course a change to a 9" would eliminate these type of failures even with a lousy gear set-up because the ring gear is so much larger, there is more room for error.

[mchell]

Only thing holding the diff in were those monster axles....they survived ok

[mchell]

Look very closely at the first pic....the bearing ear is broken clean off at the diff

[mchell]

This caused gear failure I assume

[mchell]

Should help with these pics

[Scott65]

Do you have a girdle on the cover? Check the cap closely, and look at the bolts for signs of stretch.

[mchell]

Yes....have a cover with the pre-loads for the caps.......caps and bolts looked ok

[Scott65]

Almost looks like fret marks where the bearings inner race presses on? Or am I seeing things?

[JSPONT]

Is the car a street car or strip car? I run a strange spool even on the street, and drive it a whole bunch. I had a few issues when I had a posi unit, knock on wood since the spool was in no issue's.

[AG]

If the side bearing support broke first it must have happened under load. Tough to be certain what broke first, the teeth or the support. The area the collar is attached to the housing looks fairly small, could have broke from the pinion gear trying to push the ring gear out of the housing. Either way it sucks, and hopefully you were not going 111 mph. Must of made a good bang sound.

[mchell]

The side bearing support definately broke first.......the gears were broken randomly, looking more “chipped” off

The caps, bearings and races were in perfect shape......the one bearing was scuffed a bit from riding against the broken spot

It made no noise other than a strange howl.....happened on the street with street tires.....took it for a spin, layed into it in second gear around 45 spinning into third to around 85-90............... might have felt it wiggle a little strangely....... cruising home after the blast it started the howl

Kinda looks like garbage Posi housing where bearing side support is cast

[AG]

Originally Posted by mchell

The side bearing support definately broke first.......the gears were broken randomly, looking more “chipped” off

The caps, bearings and races were in perfect shape......the one bearing was scuffed a bit from riding against the broken spot

It made no noise other than a strange howl.....happened on the street with street tires.....took it for a spin, layed into it in second gear around 45 spinning into third to around 85-90............... might have felt it wiggle a little strangely....... cruising home after the blast it started the howl

Kinda looks like garbage Posi housing where bearing side support is cast

I'll take a look at my GM Eaton posi and my Moroso Brute Strength posi to try to get an idea of the amount of material there is of the bearing support where it attaches to the housing.

[johnta1]

I'd send the pics of the broken ear/dif to Yukon Posi and see what they say?


They may have an answer.

[Cliff R]

Not sure who is making the Yukon stuff but we've had ZERO issues with the Eaton carriers. A "clone" is just that, copy of the original but if it's offshore production who knows what old car bumpers they melted down that day to cast it from?

I broke two factory posi units WAY back when I installed my first 455 and started taking steps to hook it up. Installed an Eaton and it survives just fine nearly 20 years later. At about the same time I installed an Eaton posi in a friends car that is drag raced only. He's been beating on it all this time and the current engine is 505cid and close to 750hp. The car runs high 9's over 135mph and the Eaton is still taking the beating just fine. It's also a 12 bolt not a 10 bolt.......Cliff

[Chief of the 60's]

Originally Posted by mgarblik

Based on the few pics I see, it really doesn't look like he was making too much power for the parts he has. If the ring gear teeth were broken off at the root of the gear, then yes, he needs a 9", or a 12 bolt with race gears. Of course a change to a 9" would eliminate these type of failures even with a lousy gear set-up because the ring gear is so much larger, there is more room for error.

Although torque and power do play a role, putting any power sticky tires is what will break rear end parts every time.

That is why I say, you want to play you will pay. Especially without good parts. Everybody wants slicks but nobody ever considers the consequences of what that slick sticks. The weak link will always let go.