Need Advice: 4EAT Front Diff Bearing Failing

[carfreak85]

Background:  Struts are all newish, brakes recently serviced, new inner/outer tie rods, new ball joints, new FCAR bushings, wheels rebalanced, recent alignment.

 

Symptoms:  Faint clunking noise at low speeds while accelerating.  Shaking at 60 mph, felt like unbalanced wheel, except we just had them rebalanced.

 

Back story:  I've been chasing an issue with the passenger's front wheel on our 1999 Forester for a few months now.  The car is closing in on 200k miles and I had just finished replacing the ball joints and tie rod ends on the car when I noticed the passenger's side front control arm rear bushing was pretty badly torn.  I replaced that bushing, got an alignment, then my wife tells me that the car is shaking on the highway.

 

OK, wheels must be out of balance, so we get them rebalanced.  No change.  I do the wheel shake test and I felt some play, so let's take a look at the wheel bearing.  Wheel and brakes removed, I can feel some clunking as I turn the hub.  The driver's side feels smooth when rotated, but there is obviously something wrong with the passenger's side.

 

I get the passenger's side spindle assembly on the bench expecting to find some grumbling and play, but it feels pretty smooth in rotation, with no axial or radial play.

 

So I grab the halfshaft and rotate it.  The clunking is still present, but it doesn't feel like it's coming from the CV or DOJ.  I supposed it could be either of those parts, but I get the feeling that the passenger's side differential carrier bearing is going south.

 

Question:  I've read a lot about Subaru transmissions over the years and that if not reassembled properly with the correct backlash and bearing preload, they will fail again in pretty short order.  As I see it, we've got a few options on how to proceed:

 

1) Rebuild the original transmission - Has to go to a shop and could get expensive with labor and, "while we're in there" incidentals, rebuild could re-fail

2) Replace original transmission with a good used one - I can do this, no problem, but I worry about getting a bad used transmission

3) Sell the car and find the wife a new vehicle - Since our Forester is a the bottom of it's depreciation curve right now, does it really make sense to sink $600-3,000 into a vehicle that's only worth $4,000 tops?

 

Looking for opinions, experiences, etc.  If you've got a nice, used transmission, I'm all ears too!

[jmoss5723]

Just replace the trans. The 4EAT is a good transmission and I think your odds of finding a good one are WAY higher than finding a bad one. Just go to a junkyard with a 30-60 day guarantee. I don't know about where you live, but here I can get a transmission for less than $300 with a guarantee. Rebuilds are more expensive than just getting a replacement trans.

 

Keep it or not is up to you, but I'd replace the trans either way. If you do decide to sell the car, you'll get way more for it if it drives right and doesn't shake.

[1 Lucky Texan]

swap axles side to side, maybe it will help find a bad axle or prove the diff is the problem?

 

otherwise - what he said, you might find a lower miles trans from a wreck - chances are decent it was running well when the wreck happened. Fresh fluid and maybe a bottle of Trans-X.

 

reject any trans with a dent in the pan - be very careful with any torque converter that slips out of place - google it, must be seated properly.

Edited April 13, 2017 by 1 Lucky Texan

[Larsen Autoworks]

The clunking sound, do you hear it all the time while accelerating or just during shifts?

How do your trans mounts and pitch mount look? If somethings rocking it could cause the sound youre hearing.

[carfreak85]

The clunking is only audible at lower speeds in lower gears, while in gear, not during shifts.  I can't figure out how to make the clunk consistently while driving, but my wife claims to hear it often.  I heard it at least twice on a five minute test drive before I pulled it in for the repairs.

 

The trans mount looks great for the mileage on the chassis, haven't inspected the pitch mount yet.

[1 Lucky Texan]

any 'chunks' on the diff's drain plug magnet?

[carfreak85]

1 Lucky Texan - I haven't dug that deep yet, but I will find out tonight.

[carfreak85]

Update:  I drained the front differential and the fluid was caramel colored, not too smelly, perhaps a bit thin, but otherwise in great condition.  The magnet on the drain plug only had a light dusting of debris, nothing alarming at all.

[1 Lucky Texan]

Update:  I drained the front differential and the fluid was caramel colored, not too smelly, perhaps a bit thin, but otherwise in great condition.  The magnet on the drain plug only had a light dusting of debris, nothing alarming at all.

 

 

magnet sludge seems normal.....

[Fairtax4me]

Axle or rear driveshaft.

 

Diff bearings make a pretty obvious howl and grumbly sound when they start to fail and you'll have tons of glitter in the oil.

[carfreak85]

Update:  I pulled the halfshaft from the offending corner and it feels pretty smooth.  No binding as it goes through it's movement, DOJ extends and compresses ok.

 

I'll drop the driveline after work today to see how that feels.

Edited April 14, 2017 by carfreak85

[GeneralDisorder]

We just had a DOJ fail on an 03 forester with same symptoms. It felt ok and no torn boot, but one of the tripod bearings was wasted inside - 1/16" of play between the bearing and tripod/pivot. Shook on the freeway, etc. I found it by running the car on the lift and feeling the shafts as it rotates under brake load.... Swapped axle for Subaru reman. Problem solved. 

 

GD

Edited April 14, 2017 by GeneralDisorder

[CNY_Dave]

I had a really bad inner, didn't clunk at low speed but sometimes did shake like a unbalanced wheel at speed.

[idosubaru]

I like LTs statement if you want a free diagosis, symptoms should change because you're switching sides and the loading changes 180 degrees on the internal bearing parts.

 

Sounds like axle to me or a long shot of a bushing,captive nut failure.

 

If it's an aftermarket axle that's a "good" sign.

 

sounds too intermittent for diff failure.

 

Wheel bearings can fly sneakily under the radar...

[carfreak85]

Where do you folks source quality replacement axles?  I just looked them up on www.subarugenuineparts.com and they want $375 PER AXLE!!!

[1 Lucky Texan]

Where do you folks source quality replacement axles?  I just looked them up on www.subarugenuineparts.com and they want $375 PER AXLE!!!

 

 

it's a frustrating issue for all of us.

 

IMHO;

 

after new, 'best' is probably a regreased/rebooted used soob axle from a junkyard.

 

next and variable in quality is new aftermarket (FEQ, Raxles, Suretrak, EMPI, etc.)

 

most everyone agrees that the most unreliable are typical parts store rebuilds.

Edited April 14, 2017 by 1 Lucky Texan

[GeneralDisorder]

Subaru has a reman program. The axles are $193 each. 

 

GD

[idosubaru]

OEM axles that last the life of the car are like $15-$35 all day long.

 

www.car-part.com

 

In the past Ive called and found a yard that would send me a few OEMs for a deal (always the first place I called). Buy one more than you need as a spare. For $15-$33 who cares?

 

You can buy 3 or 5 OEM axles for $100. I have no need for $200 axles though that's a huge benefit having a one stop simple solution for many.

 

little extra work but considering all the front end and other work you mentioned it's basically nothing for what ends up being a permanent fix and something you'll never have to think about again.

 

When I worked on a lot I always got the 2000+ axles they have better outer boots. Knock the tone ring off and they work in any older 1990s Subarus and 00-04 legacy and outback and compatible Forester and Impreza.

 

2005+ outback/legacy starts the newer tripod style axles.

Edited April 15, 2017 by grossgary

[carfreak85]

More background:  Back end of the car is on the ground, front end on jackstands with the transmission in park.

 

Update:  We did some playing around with the halfshafts to see if it made a difference from side to side.  I pulled both, reinstalled the passenger's side axle on the driver's side (only one axle installed) and the clunking was very faint.  With only one axle out you couldn't really tell there was a problem.  I could feel something, but my dad said it felt like the ring and pinion meshing to him.

 

However, with both axles installed in their original positions you could feel the clunking, loud and clear.  We swapped the axles side-to-side to confirm, and the clunking was still there, unchanged.

 

I'm headed to the junkyard to try to find a spare axle.

[GeneralDisorder]

You can easily disassemble the inner joint of the axles and inspect them. In the case of the one I recently replaced, the tripod had one bearing that was obviously bad. It was rust colored from the fretting taking place - despite being covered in (rust colored) greasy goo. It just wasn't being lubricated. This was obvious upon disassembly. My theory is that if it's already broken - taking it apart can't hurt it. Also you'll learn something - even if that something is that there's nothing serviceable inside and you can't fix it. At least your can learn what and how it fails. Knowledge is power. Taking the time to associate a symptom with an exact, specific cause is knowledge.

 

GD

Edited April 15, 2017 by GeneralDisorder

[carfreak85]

More testing in progress...

Edited April 15, 2017 by carfreak85

[carfreak85]

I managed to find a pretty nice used axle in the junkyard over the weekend.  I installed it on both sides of the car, swapping the two original axles around at the same time to try a different axle in every position.  No luck, the clunking was still there.

At this point my wife is getting impatient and I think we will take it to the local shop today and let them diagnose the problem, then I'll perform whatever repairs they discover.

[1 Lucky Texan]

I completely understand on the impatient wife thing.

too bad, hoping for a cheap/easy solution.

Edited April 17, 2017 by 1 Lucky Texan

[Fairtax4me]

Did you drive it with the new axle installed?

 

You'll hear some clunking from the differential as you spin the axle anyway because of lash clearance in the ring and pinion set and the differential gears inside the carrier. You'll also have some noise as the pinion shaft turns and moves the output drum that's back in the trans. That will move a bit and you may hear a clunk from the parking pawl hitting the drum.

 

Tripod cv joint failure doesn't always result in noise but it can throw off the balance of the axle causing vibration especially when accelerating or decelerating.

Edited April 17, 2017 by Fairtax4me

[carfreak85]

Did not drive with the new axle installed, as the clunking had not changed.What has me concerned is that the clunking can only be clearly felt on the passenger's side.  Swapping axles side to side does not change this.

 

I understand that there will be lash built into the diff and can feel that when rotating the axle back and forth.  But the clunks are present while turning the axle through a continuous 400-or-so degrees of rotation, do I'm confident that I'm not feeling gear lash.

 

I should also note that the clunk I'm describing is more felt than heard.