[mchell]

Update:
Yukon engineering contacted me today. Said they rarely see a failure like mine and if they do they attribute it to the carrier not having enough bearing preload. Stated that their 33 spline Posi is designed to hold much more power than I’m putting down. Also states that the bearing boss is not thin( even tho it measures thin). Yukon also provides a lifetime warranty for their diffs for an extra 50.00$ and lifetime warranty on gear set for an extra 45.00$....no questions asked, it breaks, they replace it.

Talked to Eaton again. They have not seen this type of failure on their diffs. They unequivocally state that their strongest limited slip diff is the TrueTrac without question.......

After deliberating, I bought a TrueTrac and new gear set from quick performance.

Thanks much for all your input

[Skip Fix]

Let us know how it works for you.

[AG]

I'm interested in seeing how it works, I was thinking about one for my 9".

[ponjohn]

Same axles?

[mchell]

yes

[HWYSTR455]

Just to say outloud, the 8.5 I built for the 442, if I recall correctly, was about $1900. Only thing I didn't do is weld the tubes, but the welds were checked. This was as I remember because the builder said it was not needed. (no need to go into this here)

So $1900 is roughly only about $600 less than doing a new Moser 12 bolt.

You will love the TruTrac. It is hands down the most even application of power of anything I've ever driven. No burps, hiccups, clunks, nothing, just smooth.

.

[65sport]

Looks like the bearing inner race had spun on the diff before it broke. What did the bearing look like?

[#1965GTO]

Looks like the case to ear surface was pretty thin.

[mchell]

Originally Posted by 65sport

Looks like the bearing inner race had spun on the diff before it broke. What did the bearing look like?

The bearing looks and works like new.......yes, it does look like the bearing spun.....not seeing signs of excess heat on the bearing boss or bearing race

Like Yukon said, maybe the side load wasn’t enough? Still studying cause and wonder if bearing did not have enough friction fit on boss or whatever reason?..........you would think the bearing would have to fail completely to spin on boss?.....bearing spins on boss and bang it snaps boss clean off.....

Could be bearing was spinning for a loooong time before boss broke?.....you would think it would leave signs of heat or bearing destroyed?

[mchell]

Originally Posted by #1965GTO

Looks like the case to ear surface was pretty thin.

Yes....

[mchell]

Note: when I put this thing together I do remember the diff going in very snug......needing dead blow to seat bearing cups .... without case spreader I’ve always tried to get the diff in as snug as I can

[mchell]

One thing I’ll definitely be doing this time is using permatex sleeve retainer for insurances.........

[mchell]

Everything’s back together.......motive 3.55 gear set and 33 spline Detroit truertrac.....two thumbs up for the Truetrac diff. So far....very nice piece

[AG]

Any time on the track? How is the hook? 33 spline axles must be pretty beefy.

[65sport]

Looks like the side bearing spun causing the carrier to snap. I'm thinking the bearing failure started this scenario. The way the inner race ate into the carrier, the gears became too far apart. So bearing failure first, then gears/carrier in short order. I did a gear swap on a truck 12 bolt once, the side bearing had spun but had not failed. Owner did not believe me when I told him his carrier was junk.

[mchell]

Originally Posted by AG

Any time on the track? How is the hook? 33 spline axles must be pretty beefy.

No track time yet. .....yeah the 33 spline axles are beasts.....probably overkill

[mchell]

Originally Posted by 65sport

Looks like the side bearing spun causing the carrier to snap. I'm thinking the bearing failure started this scenario. The way the inner race ate into the carrier, the gears became too far apart. So bearing failure first, then gears/carrier in short order. I did a gear swap on a truck 12 bolt once, the side bearing had spun but had not failed. Owner did not believe me when I told him his carrier was junk.

Yes, I’m leaning towards this scenario ......carrier bearings were still in perfect condition after diff broke....that’s what’s puzzling