2013 STI Teeth on Front Diff Sheared

[TubsAlwaysWins]

Ive got a 2013 STI with just under 100k on it that I just replaced an engine in.
I had the car inspected after I did the engine and was told I needed to replace the sundial bearing retainer on the front diff. In the process i also replaced the axle seal. After doing this I test drove the car, and now the transmission sounds straight cut above 30 mph and leaks an immense amount of fluid out of the axle seal.
I took it to Subaru and was told that the axles are walking side to side and causing the seals to blow out, and that teeth were sheared off the front diff.

This post describes it pretty well: http://https://www.iwsti.com/threads...heared.316862/

Thoughts on what my options are? Anyone else had this happen?

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[Charlie-III]

So, you replaced a Sundial, how did you set bearing preload? The Sundial does the bearing preload and a new piece may not have the same dimensions as the old one so counting turns may not be viable.

Too tight, and you will likely roast the bearing.
Too loose and the diff moves around killing the bearings and tearing up the diff gears.

[arse_sidewards]

Originally Posted by Charlie-III

Too tight, and you will likely roast the bearing.
Too loose and the diff moves around killing the bearings and tearing up the diff gears.

That's a medium long thing though, not a "I slapped it together and **** was instantly ****ed" thing.


I think something else here is ****ed up. I'd want to see pics or something from the dealer.

[Charlie-III]

Originally Posted by arse_sidewards

That's a medium long thing though, not a "I slapped it together and **** was instantly ****ed" thing.


I think something else here is ****ed up. I'd want to see pics or something from the dealer.

True, but a consideration, especially clutch dumps on loose diff bearings.

[TubsAlwaysWins]

Originally Posted by Charlie-III

So, you replaced a Sundial, how did you set bearing preload? The Sundial does the bearing preload and a new piece may not have the same dimensions as the old one so counting turns may not be viable.

Too tight, and you will likely roast the bearing.
Too loose and the diff moves around killing the bearings and tearing up the diff gears.

So I have taken it apart twice. The first time i put it back together I just kinda put it back where it was roughly. The second time I tightened it basically all the way in and then backed it out a few turns. Im aware neither of those are very scientific... I could never find a guide or instructions or anything that told or even hinted at how to set the right preload.
I dont think the sundial is my issue at this point though, not sure what would be causing the axles to walk in and out. Wish I would have gotten pics from the dealership for what they saw.

[TubsAlwaysWins]

Originally Posted by arse_sidewards

That's a medium long thing though, not a "I slapped it together and **** was instantly ****ed" thing.


I think something else here is ****ed up. I'd want to see pics or something from the dealer.

Agreed I dont think the sundial is the cause of my issues...
I cant find a trans shop near me that will touch it unfortunately. Trying to see what my options are to replace. It looks like Rallispec offers a replacement program I might use.

[arse_sidewards]

Originally Posted by TubsAlwaysWins

The second time I tightened it basically all the way in and then backed it out a few turns.

It should pretty clearly go from "taking up slack" to preloading the whole case. Assuming you found that point and then put on some preload "backed it out a few turns" from that point is a ton. That would throw everything way off.

[TubsAlwaysWins]

Originally Posted by arse_sidewards

It should pretty clearly go from "taking up slack" to preloading the whole case. Assuming you found that point and then put on some preload "backed it out a few turns" from that point is a ton. That would throw everything way off.

Interesting.
Regardless subaru says the trans is trashed so wondering what my options are. Thoughts?

[arse_sidewards]

Quickest and easiest option is to install a used good trans.


You gotta open the trans to replace the ring and pinion so it's basically all the same work as a rebuild. It's not hard, just tedious and about a hundred bucks of tools.

I still wanna see proof that there's broken teeth on the ring gear.

[TubsAlwaysWins]

Originally Posted by arse_sidewards

Quickest and easiest option is to install a used good trans.


You gotta open the trans to replace the ring and pinion so it's basically all the same work as a rebuild. It's not hard, just tedious and about a hundred bucks of tools.

I still wanna see proof that there's broken teeth on the ring gear.

If I can get some pics I will. I think it might be the teeth that the CV Axle splines go into since Subaru was able to diagnose it without removing from the vehicle but I could be wrong.

From the invoice i recieved:

"INSPECTED TRANSMISSION ASSEMBLY, FOUND CASE LEAKING AS WELL AS BOTH AXLE SEALS. PASSEGER SIDE AXLE SEAL PUSHED OUT, FOUDN DAMAGE TO STUB SHAFT RETAINERS. FOUND CV AXLE PUSHING AXLE SEAL OUT DUE TO INTERNAL DAMAGE OF DIFF ALLOWING CV AXLE TO WOBBLE. FOUND INTERNAL TRANS NOISE WHILE DRIVING VEHICLE ON LIFT. RECCOMEND REPLACING TRANSMISSION ASSEBMLY. WOULD RECCOMEND NOT DRIVING VEHICLE."