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Grinding/buzzing sound in tight turns


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19 replies to this topic

#1 liquidnonsense

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Posted 15 August 2013 - 02:02 AM

Hi all, I've just registered to help identify a few quirks with my new 2003 Outback.

 

When making tight, low-speed turns (such as pulling into a parking space, or pulling out onto the street) in either direction, there is a low grinding/buzzing/vibrating sound from under the floor, much like the vibration a subwoofer makes with very bass-y song.  The vibration is strong and seems to be coming through the whole floorpan.  A friend said it could just be low transfer case fluid - any other ideas?  Is it dangerous, or can I live with it and ignore it?



#2 1 Lucky Texan

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Posted 15 August 2013 - 08:12 AM

most likely torque bind.

confirm that all 4 tires are the same brand and wear level.

if you have an automatic, try the FWD fuse in the box under the hood on the left side.

do a search for 'torque bind' here and read.

your car's AWD system either IS damaged or will be soon.

get back to us.

Edited by 1 Lucky Texan, 15 August 2013 - 08:13 AM.


#3 NorthWet

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Posted 15 August 2013 - 10:13 AM

Does the sound only occur when the wheels are rolling, or does it also occur if you stop in the middle of turning?



#4 liquidnonsense

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Posted 15 August 2013 - 10:58 AM

most likely torque bind.

confirm that all 4 tires are the same brand and wear level.

if you have an automatic, try the FWD fuse in the box under the hood on the left side.

do a search for 'torque bind' here and read.

your car's AWD system either IS damaged or will be soon.

 

I put the FWD fuse in, and the sound is gone.  So it's definitely an AWD thing and not a caliper or bearing or something.  All four tires are the same brand and wear level, although the rear tires are slightly underinflated, I'll fix that soon.

 

Does the sound only occur when the wheels are rolling, or does it also occur if you stop in the middle of turning?

 

It only occurs when the wheels are rolling.



#5 1 Lucky Texan

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Posted 15 August 2013 - 11:05 AM

you could try doing 2-3 drain/fill cycles in the transmission with new fluid. Drive for a day or few days in between. Then, try some Lucas or CRC (Trans-max ?) additive. If no help witht he binding, you need internals repaired.

at least you could drive the car with the fuse in place and you know the Duty C solenoid works.

#6 NorthWet

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Posted 15 August 2013 - 12:47 PM

Some technical background:

 

There is no "transfer case fluid" with your drivetrain.  The AWD is provided for by another clutch-pack in your automatic transmission, one that connects the transmission-section's output shaft to the tailshaft/rear-driveshaft.  This clutch-pack is controlled by hydraulic pressure controlled by the "Duty-C solenoid"; putting the "FWD fuse" in causes the Duty-C solenoid to always be activated, which dumps the pressure.  All of this stuff is housed in the very back, removable section of your automatic transmission.



#7 liquidnonsense

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Posted 15 August 2013 - 11:07 PM

Some technical background:

 

There is no "transfer case fluid" with your drivetrain.  The AWD is provided for by another clutch-pack in your automatic transmission, one that connects the transmission-section's output shaft to the tailshaft/rear-driveshaft.  This clutch-pack is controlled by hydraulic pressure controlled by the "Duty-C solenoid"; putting the "FWD fuse" in causes the Duty-C solenoid to always be activated, which dumps the pressure.  All of this stuff is housed in the very back, removable section of your automatic transmission.

 

Interesting, I did not know any of that.  What does that mean in terms of fixing the problem?  If I can't drain/refill the transfer case, what can I do?

 

Just in case I hadn't mentioned it, the vibration continues in a tight turn even if I am not on the accelerator and am just coasting through the turn/into the parking space.  Also tried the FWD fuse again with the same results: silent when in FWD mode, harsh buzzing/vibrating in AWD mode.  Can't tell where it's coming from because it seems to be vibrating the entire floorpan.

 

Also, a friend told me today that leaving the FWD fuse in can be bad for the computer - is this true?  I was thinking of keeping it in FWD mode until the problem is fixed, to avoid damaging it more.


Edited by liquidnonsense, 15 August 2013 - 11:08 PM.


#8 NorthWet

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Posted 16 August 2013 - 02:02 AM

IIRC, the usual causes of "torque bind" (common name for it on USMB and elsewhere) in the automatic (commonly referred to as a 4EAT, though really an R4AX-EL when looking for parts) are:

 

issues with the clutch-pack friction plates (gummed/glazed/worn),

 

issues with notches being worn in the clutch basket (not allowing the plates to slide smoothly while engaging/disengaging)

 

and failure of the Duty-C solenoid.

 

The latter 2 causes would not be helped by using the  FWD fuse.  Likely that your plates are gooky.  This is why "1 Lucky Texan" recommended changing your ATF and using additives.  To speed the process, I think others have suggested going to a parking lot, or similar open space, and make several tight circles going both left and right:  This will hopefully rub some of the contamination off of the plates.  First things first:  Change that ATF.

 

Oh, the FWD fuse is unlikely to hurt the TCU "tranny's computer", but can shorten the life of the (pricey) Duty-C solenoid.


Edited by NorthWet, 16 August 2013 - 02:03 AM.


#9 liquidnonsense

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Posted 16 August 2013 - 09:15 AM

IIRC, the usual causes of "torque bind" (common name for it on USMB and elsewhere) in the automatic (commonly referred to as a 4EAT, though really an R4AX-EL when looking for parts) are:

 

issues with the clutch-pack friction plates (gummed/glazed/worn),

 

issues with notches being worn in the clutch basket (not allowing the plates to slide smoothly while engaging/disengaging)

 

and failure of the Duty-C solenoid.

 

The latter 2 causes would not be helped by using the  FWD fuse.  Likely that your plates are gooky.  This is why "1 Lucky Texan" recommended changing your ATF and using additives.  To speed the process, I think others have suggested going to a parking lot, or similar open space, and make several tight circles going both left and right:  This will hopefully rub some of the contamination off of the plates.  First things first:  Change that ATF.

 

Oh, the FWD fuse is unlikely to hurt the TCU "tranny's computer", but can shorten the life of the (pricey) Duty-C solenoid.

 

Thank you.  I am still confused about how the clutch pack works - does it share a sump with anything else?  Does it use transmission fluid or its own fluid? Is the front differential attached to it?  I'm new to Subaru's version of AWD.



#10 1 Lucky Texan

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Posted 16 August 2013 - 09:30 AM

the wet clutchpack that transfers torque to the rear wheels based on slippage detected by the wheel sensors shares the same fluid as the rest of the auto tran. The Front diff has its own GL-5 gear oil and its dipstick is on the right side, maybe a little lower and further back than the auto's dipstick on the left.

 

try the valvoline maxlife Dex/Merc fluid for the drain/fill (other similar fluids probably just as good), check carefully while idling. Take out the dipstick and lay it aside,start the car and idle it, best to wait for it to be at normal operating temp., move the shifter through each gear, then back to park. Maybe wait another coupla minutes, take a measurement while idling. If the fluid level is between the HOT marks, then, when you drain the fluid (you might wait a coupla hrs for it to cool off) drain it into a clean container or otherwise make note of how much you drained (mark the bottles/w'ever) and you'll know exactly how much to pour back in. You should consider getting a new filter too - it's special and should come from the dealer, it's on the side of the tranny OR above the wheel liner under the battery- this is where it should be on an 03 I think) The marks on the dipstick are about a pint apart - not a quart like engine oil so, top-off auto-tran fluid half-pint at a time. Move thru the gears and wait a minute to measure - the dipstick is crazy if you measure too fast. After 3 drain/fill cycles, you will have maybe 80-90% new fluid. On the 3 rd fill, put in the Trans-max. I've seen people refer to a GM additive too.

one of these helped me (pour slowly though)(DISCLAIMER: I have not had torque bind, just sharing what I've read and how I changed my trans fluid - other folks here have more experience than me so, try searching and reading about these issues);

 

mGnUdAVFd6TxYBb-PsId89A.jpg


Edited by 1 Lucky Texan, 16 August 2013 - 11:29 AM.


#11 NorthWet

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Posted 16 August 2013 - 10:52 AM

Thank you.  I am still confused about how the clutch pack works - does it share a sump with anything else?  Does it use transmission fluid or its own fluid? Is the front differential attached to it?  I'm new to Subaru's version of AWD.

"Clutch packs" and "bands" are standard automatic transmission parts, usually used to control what gear you are in; this is done by locking together (clutch) or stopping rotation (band) of sections of the planetary gear set.  They are main components of every traditional automatic transmission. No wiz-bang, space-age engineering here; just an inspired application of an everyday part.

 

A "clutch pack" is simply a clutch (a steel disk and a friction-material covered disk pushed together to transmit power), except that there are a stack of alternating steel/friction disks packed together.

 

The AWD parts are just standard automatic transmission components, and they are housed inside the tranny like the rest of the automatic's components.  Lubricated by ATF, controlled by ATF from the tranny's pump just like the rest of the parts, and suffers similar to other AT parts (slipping, dragging, harsh engagement, too-soft engagement).  You seem to be experiencing dragging/sticking.

 

The front differential is directly connected via gear to the tranny's output shaft:  It is always driven.  The AWD's clutch pack is mounted to the end of the tranny's output shaft (after that gear), and only powers the rear differential when told to do so by the TCU.  (Technically, the control works backwards, but that is harder to grasp.)

 

Bottom line:  The AT's innards are probably gummed up (very common with 4EATs), and the best course of action is similar to what "1 Lucky Texan" has suggested.  Listen to him (or others with practical advice) and don't sweat the technical stuff too much.

 

Cheers!


Edited by NorthWet, 16 August 2013 - 10:54 AM.


#12 1 Lucky Texan

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Posted 16 August 2013 - 11:27 AM

another issue comes to mind, you say the car is new to you. Do you know if either the rear diff or the transmission was replaced? If someone didn't get the correct final drive ratio unit, you'd get torque bind.



#13 liquidnonsense

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Posted 16 August 2013 - 11:44 AM

another issue comes to mind, you say the car is new to you. Do you know if either the rear diff or the transmission was replaced? If someone didn't get the correct final drive ratio unit, you'd get torque bind.

 

I'm not sure.  I have to go back to the used car lot tomorrow anyway to sign a few more things, and he said he'd take a look at a few of the issues I'm experiencing (there's also a squealing sound when I put my foot to the floor at highway speeds, and probably needs new rear struts).  And even then, it's a used car dealer, so who knows if he'd be honest with me?



#14 1 Lucky Texan

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Posted 16 August 2013 - 01:08 PM

If it comes down to the last and they aren't willing to help you out, just say; "look, I know I'm stuck with the car, just be honest with me and let me know where to start working on it so it will be safe and reliable." Offer the salesman your email and ask him if he could forward that to the previous owner to contact you. if it doesn't help, you're just back to where you are now.
 
or, take it to a good mechanic and pay them $80-$120 to go thru it and locate the stuff you can live with, the stuff you need to save up to fix, and the stuff you need to do NOW.
 
if someone reading here knows a good mechanic in Vermont, maybe they'll respond. If not, start a thread asking for a recommendation for a shop near your city.

#15 liquidnonsense

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Posted 19 August 2013 - 08:03 AM

UPDATE:  Took it to the auto place near the dealer I got it from, they drove it around for a while, did some tight turns in parking lots, and said they had absolutely no idea what it was.  I replaced the front and rear differential fluids as well as the transmission fluid, and the noise still persists just as loud as ever.  I also discovered that if you drive fast enough - pretty much as fast as you can with full steering lock - the noise starts to go away.  It gets louder the slower you turn.



#16 Downbound

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Posted 19 August 2013 - 09:47 AM

I had a 99 Forester with similar problem (it may not have been as bad as yours) and could not afford the suggested repair. It was suggested by my mechanic to find an empty parking lot and do figure 8's in reverse. It seemed to clear up the problem. I am not sure why, something to do with reverse flow. Al I know is that it worked.



#17 Fairtax4me

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Posted 19 August 2013 - 11:27 AM

This the earliest stage of torque bind. Drain and refill the trans fluid 3 times and use an additive that will act as a conditioner for the clutches. The reason for changing it three times is because the transmission and torque converter will hold about 11 quarts of fluid, but the transmission pan only holds about 4 quarts. When the pan is drained, there are still about 7 quarts of fluid in the transmission housing and torque converter. Draining and refilling multiple times, with short drives in between, is the easiest way to remove the majority of the fluid in the transmission without having to use a flush machine.

Doing tight turns in reverse can help because it causes the clutch plates to slip in the opposite direction of what they normally would when going forward. This can help to scrub away some of the material and debris that is causing the plates to bind. Do this in between fluid changes so the debris from the clutch plates can be drained out wih the old fluid.

#18 Gloyale

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Posted 19 August 2013 - 12:21 PM

You reffer to a buzzing?  More of a sound than a clunking or binding?  Do you ever hear the tires dragging/chirping as you pull into parking spaces?

 

 

What I'm getting at is that certainly his noise is from the Duty-C solenoid........But I haven't heard anything that makes me think he has ACTUAL torque bind....

 

 

What he's hearing and feeling could be a very noisy and buzzy Duty-C solenoid doing it's job......Which would make sense, the slower and tighter you turn, the more the solenoid has to pulse to keep the AWD slipping, but close enough to engaged to actually still be AWD.

 

I've heard solenoids and relays and electronic valves make loud buzzing before....Anybody think it could be?

 

Liquidnonsense.....can you confirm the symtom as just a noise/buzz/vibration?  Or does it actually "bind" acting as if the brakes are on pulling tight turns into a parking space?

 

If you don't have actual torque bind it could be just a very noisy solenoid. (perhaps not solidly grounding in to the trans case)



#19 darsdoug

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Posted 19 August 2013 - 01:10 PM

Some technical background:

 

There is no "transfer case fluid" with your drivetrain.  The AWD is provided for by another clutch-pack in your automatic transmission, one that connects the transmission-section's output shaft to the tailshaft/rear-driveshaft.  This clutch-pack is controlled by hydraulic pressure controlled by the "Duty-C solenoid"; putting the "FWD fuse" in causes the Duty-C solenoid to always be activated, which dumps the pressure.  All of this stuff is housed in the very back, removable section of your automatic transmission.

Excuse me for crashing your thread but when I insert a FWD fuse in my 96 Legacy wagon it has no effect on the torque bind at all. Does that mean my duty-C is junk and not working at all? I know I need to get this torque bind gone. All of the OEM alloy wheel's and tire's are of identical brand names and size.  If you know anyone who will do the work for a reasonable price here in the PNW please feel free to contact me. It's driving me bonker's. 

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#20 1 Lucky Texan

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Posted 19 August 2013 - 02:04 PM

scrub away some of the material and debris that is causing the plates to bind. Do this in between fluid changes so the debris from the clutch plates can be drained out wih the old fluid.

I was also concerned about debris which is why I recommended a filter change.




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