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'99 Outback/ '99 GSX 600f
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Discussion Starter · #1 ·
before you make first assumptions of what it could be, i have:


  • swapped both front cv axles ( not just reboot, new axles)
  • changed diff fluid
  • the tires have a fairly even wear to them. i have suspected it was the locking differential acting up because of tire pressure, wear ect. but the tires never lock up, and the car dosent jerk much during the noise, its just a violent *DUD* *DUD* *DUD* at a full turn at parking lot speeds.
  • the problem only occurs after the axles/ tranny have warmed up for 40 plus minutes. when its cold it feels very tit-s and turns on a dime.

so this is a problem i have been dealing with since shortly after i purchased my outback in 2010 with 186k. everyone i drive with cringes when it happens, i myself have become extremely comfortable with the problem and tell worried passengers that its a its a good noise", the truth is if it went away i would be more fearfull than i am now.

Its A sharp clang that sounds like metal catching metal, and then slipping of and catching metal again shortly after. it only happens when im in a full turn (both directions) and is coming from the tranny/ diff *not* the axles. the car has 209.5k and ha been making the noise for over 15k..... recently it has become more vicious than the past, so ill set my pride aside for a second and ask, what could it possibly be?
P.S no job is to big for the sake of my lego's, i have alot more info on the cars history if anyone thinks some more info would help

Cheers all,
-North
 

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This doesn't mean it can't be something else, but the symptoms, as you describe them, certainly suggest that the AWD center differential's viscous coupler is defective.

When the coupler malfunctions in a quasi-locked state, torque builds up in the drive train when turning. The torque is usually relieved by a wheel slipping or hopping, and this can happen repeatedly during a full turn. When it does, it sets up a slight shock in the drive train. Normally the effect of this is felt as hesitation and shudder (typical "torque bind" symptom), but if there's anything loose or worn (e.g., heat shield, propeller shaft U-joint) it could also result in a metallic clang.

It's not unusual for the viscous coupler to become quasi-locked only after it has being warmed due to the build-up of heat in the transmission. So everything can be fine when cold. (See: http://www.subaruoutback.org/forums/111-gen-1-1995-1999/47054-99-ob-mt-front-diff-issue.html, and http://www.subaruoutback.org/forums...1-clunking-noise-when-turning.html#post446854)

As the coupler is a sealed unit inside the transmission, changing the gear oil in the transmission or rear differential won't have any effect.

Tires are a factor. Tires should all be the same brand, model, size, and tread depth, and be properly inflated. The difference in circumference , if any, should be no more than 1/4-inch. See: http://www.subaruoutback.org/forums...umference-spec-confirmed-subaru-techtips.html.

The standard test for torque bind is find a paved, flat area, such as a shopping center parking lot, and run the car in a tight circle with the engine idling. When there's no problem, the car should move slowly but steadily around the circle. But if there's torque bind building up in the drive train, it will tend to slow down until the accelerator is pressed a bit, at which time a wheel will slip, relieving the torque, and the car will proceed again until the stress builds up again. In this case, because the car is going very slowly, and the engine is only idling, the same forces might not be developed in the drive train as when driving normally, and the "clang" might be far more muted or not apparent.
 

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Discussion Starter · #3 ·
sounds as if i should gear up for a tranny swap.
hmm, well no need for a parking lot test... its been doing it for 2 years now. thanks much for the speedy feedback. so this "torque bind" its only noticed at parking lot speeds, therefore i assume if it was going to go out/ cease on me it would happen at a relatively slow speed, not at 80 mph on highway I5. is my theory true or could it go at anytime? like i said the noise is only getting more vicious, and i wouldn't want to put anyone in danger.

i have a new name for my problem
"Vicious Viscous."
 

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so this "torque bind" its only noticed at parking lot speeds, therefore i assume if it was going to go out/ cease on me it would happen at a relatively slow speed, not at 80 mph on highway I5.
The slow parking lot test is only that, a way to confirm. If the viscous coupler is locking after it warms up, it will do so at all speeds. However, at 80 mph, it's not likely the car will be put into a full turn, which is when you notice the noise. On more moderate highway curves at high speed there will still be some torque build up, but the rapidly spinning tires will slip in tiny steps so that the full effect isn't noticed. At slow, parking lot or city turn speeds, the tires are less prone to slip, at least until the torque builds up to a higher degree and the release (when a wheel hops) is far more noticeable.

Again, I can't say for sure that this is your problem, but from the symptoms, and particularly the difference between cold start and after driving, it certainly fits the pattern.

Incidentally, does the clang appear even at slow, parking lot turning speeds (as in the idling speed test)? If so, have you tried having someone drive the car in a tight circle while you walk next to the car. This could help better identify the location of the clang. Then do some further inspection in the area. That might be a step worth taking.

A tranny swap could be problematic, as one with the identical final gear ratio (front differential) would have to be found. However, the center differential with the viscous coupler can be changed by removing the extension case at the back of the tranny. So if you're able and equipped to swap trannys, perhaps spoonfork's approach (see posts 8 and 10 in http://www.subaruoutback.org/forums...1-clunking-noise-when-turning.html#post371140) might be the way to go.
 

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before you make first assumptions of what it could be, i have:


  • swapped both front cv axles ( not just reboot, new axles)
  • changed diff fluid
  • the tires have a fairly even wear to them. i have suspected it was the locking differential acting up because of tire pressure, wear ect. but the tires never lock up, and the car dosent jerk much during the noise, its just a violent *DUD* *DUD* *DUD* at a full turn at parking lot speeds.
  • the problem only occurs after the axles/ tranny have warmed up for 40 plus minutes. when its cold it feels very tit-s and turns on a dime.

so this is a problem i have been dealing with since shortly after i purchased my outback in 2010 with 186k. everyone i drive with cringes when it happens, i myself have become extremely comfortable with the problem and tell worried passengers that its a its a good noise", the truth is if it went away i would be more fearfull than i am now.

Its A sharp clang that sounds like metal catching metal, and then slipping of and catching metal again shortly after. it only happens when im in a full turn (both directions) and is coming from the tranny/ diff *not* the axles. the car has 209.5k and ha been making the noise for over 15k..... recently it has become more vicious than the past, so ill set my pride aside for a second and ask, what could it possibly be?
P.S no job is to big for the sake of my lego's, i have alot more info on the cars history if anyone thinks some more info would help

Cheers all,
-North
Sounds like a worn out CV joint to me. I wouldn't go jumping to the worst case most expensive fix ie transmission locking up etc till you explore the CV issue. CV joints can get wicked loud and sound absolutely terrible when they have been run with out boots and suffered dirt and lack of lube for a long time. Any chance the prior owner drove on a blown boot for a few years had it rebooted and sold it to you? And yes turning hard in parking lots is where a badly worn CV will be really noisy
 

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Discussion Starter · #6 ·
Sounds like a worn out CV joint to me. I wouldn't go jumping to the worst case most expensive fix ie transmission locking up etc till you explore the CV issue. CV joints can get wicked loud and sound absolutely terrible when they have been run with out boots and suffered dirt and lack of lube for a long time. Any chance the prior owner drove on a blown boot for a few years had it rebooted and sold it to you? And yes turning hard in parking lots is where a badly worn CV will be really noisy
aah, you failed to read the "before you make first assumptions list"
butt i dont blame you, as this was my first suspect.

  • i have replaced both front constant velocity drive axles
  • i have replaced both front wheel bearings (which im positive is not the issue)
  • i've serviced all fluids
im leaning toward plain OM's "torque bind" suggestion, seeing as the noise is coming directly from within the tranny, and not in the axles (both brand new offline from world pac) although its hard to tell without my head under the car wile its driving. my brother had made the suggestion of a viscous coupling long ago butt i ignored him. I imagine i have an" i told you so" coming. anyhow, im not completely convinced. i have some research to do.

Thanks for the speedy feedback, much appreciated
this being my first post and all :29:

Cheers,
North
 

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Premium Member
(formerly) 03 H6 OBW , (presently) 06 WRX Sportwagon & 2021 Honda CR-V
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18,752 Posts
maybe a stub axle is pulling out of the diff?

but , yeah, torque bind seems quite likely
 
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