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2009 Forester lost [most of] the transmission & rolls in Park


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I've got a 2009 Forester with 150k miles, non-turbo, and automatic. After coming to a stop at a stop sign, I started to accelerate, heard a noise, the engine revved but the car wasn't accelerating anymore. Just enough power was getting to the wheels that I was able to limp the last mile home. On downhill slopes I could coax it up to 45, which helped get over the uphill slopes.

IIRC, the sound wasn't a BANG...more like dropping a hammer onto asphalt from 6" high. Maybe a 'thud'?

Once home, I jacked up one rear wheel with the parking brake off and the transmission in Park. I was able to rotate the wheel and could see that the driveshaft was turning. I don't think that should happen in Park. When I let the car back down, it started rolling forward despite being in Park.

I reset the parking brake and jacked up the front end. Both wheels rotate despite the transmission being in Park and the rear wheels on the ground. But rotating either wheel doesn't cause the opposite side wheel to rotate. CV joints appear fine. There's no slop in the axles or drive shaft, and there have never been clicking noises when backing while turning. Transmission fluid is up to the FULL mark.

I set the car down, started the engine and worked the gear lever. Drive and reverse gears feel like they engage normally, but the car barely accelerates regardless of throttle position/engine RPM. At idle it seems pretty much normal.

With the brakes on and the car not moving, I shifted to Park and there was a whirring or clicking sound for a second that then stopped, as if the parking pawl wasn't engaging. If I let off the brakes with the car in Park, it rolls as if it's in neutral.

I'm stumped. Thoughts on what might be wrong?

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Axles and CVs felt tight yesterday. After seeing your posts, I grabbed a light and checked out each joint while trying to shake the axles around. They were all still tight, but then I noticed the driver side front axle, where it goes into the diff didn't look right. Looks to me like the axle pulled out of the diff by ~1"!

I suppose it's good news my transmission didn't grenade itself. Any ideas on what might have caused this problem?

Cheers

Q

 

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6 hours ago, q240z said:

Axles and CVs felt tight yesterday. After seeing your posts, I grabbed a light and checked out each joint while trying to shake the axles around. They were all still tight, but then I noticed the driver side front axle, where it goes into the diff didn't look right. Looks to me like the axle pulled out of the diff by ~1"!

I suppose it's good news my transmission didn't grenade itself. Any ideas on what might have caused this problem?

Cheers

Q

has there been any kind of servicing of the axles recently? it may simply be that it was not pushed in far enough
or, it could be worn/broken snap ring..

i had an axle on my 02 forester pop out a short time after servicing - made a horrible racket, but then it was also sitting cock-eyed - popped out while making a turn into a local store. Luckily I was not on the road when it happened.. a couple of people helped me get it into a parking space and I called the garage that did the work.. they came & got it and fixed it for free.

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It's not hard to pop those out when replacing a ball joint or even strut. So if anything like that was done recently, that's likely the answer. I don't think I've seen one pop out on their own.

 

I would recommend replacing both the front differential gear oil (as it likely has some metal shavings from the slipping splines, and the spider gears likely got hot from spinning with only one axle connected), and ATF (as the transfer clutches got abused) after driving it like that.

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On 12/2/2022 at 5:07 PM, Daskuppler said:

How's the fluid level in the transmission?

From my first post: Transmission fluid is up to the FULL mark.

There's been no service to the axles in the 7 years we've owned the car. Boots are all in good shape, with no leaking grease. It popped out of position all on its own.

I removed the axle yesterday. That was a quick 20 minute job. I could have done it in 15, but for the life of me I couldn't get the shaft to reseat in the diff. The outer CV joint is tight, the inner one has just a tiny bit of play ~1/64". I can feel it but not see it. There was no clip on the shaft. But when I looked inside the diff through the shaft hole, there it was, blocking the hole in front of the splines. So that's why I couldn't push the shaft home. I pulled the clip out with a pair of pliers. It snapped back on the shaft good and tight, so the problem wasn't caused by a loose clip.

I've got new replacements on the way, and I'll be draining and refilling both the diff and tranny as suggested.

But I'm still stumped as to how such a small amount of play in the CV could have caused the shaft to jump 1" out of the diff.

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The new axles arrived just now, but they look different than the OEM one.

Specifically, the clip goes near the end of the shaft. There's a groove cut in the splines for the clip.

Mine didn't look like that. And I thought the end of the old stub axle didn't exactly look like it was machined to normal Subi standards.

Turns out the end of the stub axle snapped off clean at the clip groove. I put a magnet into the diff and extracted the shaft end.

This is the weirdest thing I've seen so far on this car.

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If you had tranny work done in the past I'll bet the axle was never fully installed in the socket and all this time it has wiggled further and further out until it finally put too much load on the very end section which cause a metal fatigue failure in the last few days before it happened. Very odd failure for sure.

Edited by azdave
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6 hours ago, azdave said:

If you had tranny work done in the past I'll bet the axle was never fully installed in the socket and all this time it has wiggled further and further out until it finally put too much load on the very end section which cause a metal fatigue failure in the last few days before it happened. Very odd failure for sure.

I've stated a few times that I haven't touched the OEM drive shafts before, and I've never hinted that I've had tranny work done before because there simply hasn't.

I agree it's an odd failure, but it has nothing to do with previous assumed work that had never happened. This driveshaft is stamped "Made in Japan", it's OEM Subaru.

On a brighter note, I topped up the diff with some throw-away Mobil gearbox oil and put a few miles on it. With the new axle, everything worked fine. I'll drain and replace the diff and tranny fluid after a few light miles.

I would have drained the diff fluid entirely, but Subaru decided to use an absurdly big star bolt for the diff drain plug, so now I'm awaiting the arrival of yet another custom tool so I can do an otherwise routine maintenance item.

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On 12/2/2022 at 2:53 PM, q240z said:

I suppose it's good news my transmission didn't grenade itself. 

RE: New transmission?

Sorry. I apparently misread your sentence quoted above. I thought it said you were glad the failure didn't grenade your new transmission.

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20 hours ago, q240z said:

There was no clip on the shaft. But when I looked inside the diff through the shaft hole, there it was, blocking the hole in front of the splines. So that's why I couldn't push the shaft home. I pulled the clip out with a pair of pliers.

Ha! i was right! Sort of, lol
had no idea about the end being broken off tho.. but your first pic just did not look quite right to me.

Excellent catch on that end piece being broken off.

The green cup on the old axle is definitely a Subaru OE axle - not sure what you put back on it, but I hope it does not give you any problems.

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