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More on Torque Bind


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#1 steamin53

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Posted 11 August 2007 - 08:32 PM

We're experiencing torque bind in our 96 Legacy Outback. 200K miles plus on this car. No question that torque bind is the problem.

I've put the appropriate fuse in the FWD fuse holder and am puzzled by the outcome. SOMETIMES the FWD light on the dash will illuminate and the rear drive-train disengages...but sometimes not. Sometimes when starting the day and the vehicle is cool the FWD illuminates as described but after a drive of 10-15 miles it goes out and the rear again locks up. Sometimes it doesn't disengage at all when initially started and stays that way through the day.

The intermittent nature of this makes me wonder if the transmission controller isn't malfunctioning as well as the duty solenoid C.


Does anyone have any experience with this intermittent symptom?

I'm not meaning to be rude in any way but PLEASE, I don't need speculation I need verified experience. This isn't the time for opinions. I'm really frustrated by this problem.

Steve

#2 Manarius

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Posted 11 August 2007 - 09:12 PM

Solenoid C is fried.

#3 2.5GL

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Posted 12 August 2007 - 12:49 AM

Quick fix: swap TCU for known good one... Get the part number off of yours, call dealer, get superceded part numbers, install any used ones that match the list, if you can find one... I choose this due to the intermittent FWD light, ect.

(BUT, chances are with 200k plus you'll be doing solenoid "C"-see below, and you just might need the TCU as well.)

IF no go, then R&R solenoid C, and remove "groves" on AWD clutch hub after removed from transmission, so the plates don't stick in the locked position. You could either grind 'em off with a small cut-off wheel or buy a new one. Sometimes the clutches are bad, about 1/100 in my experience.

You'll need a transfer clutch solenoid, two solenoid gaskets, a "transfer case" gasket for the back of the tranny, two exhaust gaskets for header, 1 gasket for back of "Y" pipe (maybe), a drain plug gasket, about 6-8 quarts of ATF, and about 4-6 hours.

ENJOY!

Lewis

#4 steamin53

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Posted 12 August 2007 - 11:41 AM

Quick fix: swap TCU for known good one... Get the part number off of yours, call dealer, get superceded part numbers, install any used ones that match the list, if you can find one... I choose this due to the intermittent FWD light, ect.

(BUT, chances are with 200k plus you'll be doing solenoid "C"-see below, and you just might need the TCU as well.)

IF no go, then R&R solenoid C, and remove "groves" on AWD clutch hub after removed from transmission, so the plates don't stick in the locked position. You could either grind 'em off with a small cut-off wheel or buy a new one. Sometimes the clutches are bad, about 1/100 in my experience.

You'll need a transfer clutch solenoid, two solenoid gaskets, a "transfer case" gasket for the back of the tranny, two exhaust gaskets for header, 1 gasket for back of "Y" pipe (maybe), a drain plug gasket, about 6-8 quarts of ATF, and about 4-6 hours.

ENJOY!

Lewis


Thanks for the comprehensive response.

A couple of more questions.

I've gathered from talking with others that I might be able to pull the tail-shaft extension to do the work without removing the transmission. I assume that would eliminate the need to remove the header pipes from the engine. Please confirm.

Also, my impression is that the grooves usually are found in the extension case. You mention the grooves being in the "clutch hub". Please advise.

Finally, where is the TCU located on this car. I have all data for it but the location diagram is not clear to me at all.

Steve

#5 nipper

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Posted 12 August 2007 - 12:44 PM

We're experiencing torque bind in our 96 Legacy Outback. 200K miles plus on this car. No question that torque bind is the problem.

I've put the appropriate fuse in the FWD fuse holder and am puzzled by the outcome. SOMETIMES the FWD light on the dash will illuminate and the rear drive-train disengages...but sometimes not. Sometimes when starting the day and the vehicle is cool the FWD illuminates as described but after a drive of 10-15 miles it goes out and the rear again locks up. Sometimes it doesn't disengage at all when initially started and stays that way through the day.

The intermittent nature of this makes me wonder if the transmission controller isn't malfunctioning as well as the duty solenoid C.


Does anyone have any experience with this intermittent symptom?

I'm not meaning to be rude in any way but PLEASE, I don't need speculation I need verified experience. This isn't the time for opinions. I'm really frustrated by this problem.

Steve


Its the begining of AWD failure. Not only are there electrical parts, but there also are mechanical parts. It sound slike the mechanical parts are sticking, and has nothing to do with the TCU. At over 200K this is not surprising.

If you dont have a flashing tranny temp light on startup electriclally its fine..

If you havent done it yet, change the tranny fluid. Sometimes that will cure it.

Make sure all the tires match and are equally inflated.

nipper

#6 steamin53

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Posted 12 August 2007 - 01:42 PM

Its the begining of AWD failure. Not only are there electrical parts, but there also are mechanical parts. It sound slike the mechanical parts are sticking, and has nothing to do with the TCU. At over 200K this is not surprising.

If you dont have a flashing tranny temp light on startup electriclally its fine..

If you havent done it yet, change the tranny fluid. Sometimes that will cure it.

Make sure all the tires match and are equally inflated.

nipper


Thanks for your input. I SHOULD have noted initially that the trans temp light does indeed flash on engine start-up indicating there is some electrical fault, but that it flashes 16 uniform time interval flashes and doesn't indicate a specific fault. No check engine or other fault indicator lights and my OBDII scanner finds no fault in the system.

As I understand it, the duty solenoid C (or the TCU) can cause the temp light to flash indicating a fault. Kind of ambiguous isn't it?

There is an alldata procedure for reading TCU generated codes on the AT temp light but as I understand it (from the instruction in the procedure to "turn the diagnosis selector switch to on" that the Subaru Select Monitor is required. Is that correct? It is also possible I suppose that "turn the diagonsis selector switch to on" could refer to the instruction on code retrieval regarding "grounding terminal # 5 of Diagnosis Connector B82, a 6 pole black connector located on right side of steering column, with one of the leads (either one) from the Diagnosis Terminal"?



Steve

#7 nipper

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Posted 12 August 2007 - 04:14 PM

Thanks for your input. I SHOULD have noted initially that the trans temp light does indeed flash on engine start-up indicating there is some electrical fault, but that it flashes 16 uniform time interval flashes and doesn't indicate a specific fault. No check engine or other fault indicator lights and my OBDII scanner finds no fault in the system.

As I understand it, the duty solenoid C (or the TCU) can cause the temp light to flash indicating a fault. Kind of ambiguous isn't it?





Steve


Do a search here. There is a procedure for finding out whats wrong. Its no more ambigous then a flashing CEL.

This is NOT a light that you can ignore. You may have already chewed up your clutches at this point. The light flashes to tell you that something failed the last time the car was operated. There are quite a few conditions that can cause that light to fail, but my money is on your c - solenoid.

nipper

#8 2.5GL

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Posted 12 August 2007 - 04:19 PM

Thanks for the comprehensive response.

A couple of more questions.

I've gathered from talking with others that I might be able to pull the tail-shaft extension to do the work without removing the transmission. I assume that would eliminate the need to remove the header pipes from the engine. Please confirm.

Also, my impression is that the grooves usually are found in the extension case. You mention the grooves being in the "clutch hub". Please advise.

Finally, where is the TCU located on this car. I have all data for it but the location diagram is not clear to me at all.

Steve


header comes off, rear drive line comes out, tail housing comes off, unplug connector for solenoid c, set asdie, pry out the drive hub on the top of the trans, inspect teeth on hub, remove grooves as needed.
R&R solenoid & gaskets, install.

remember, as nipper said: "Make sure all the tires match and are equally inflated."

TCU is under steering wheel to the left of the column.

I can get pics by tuesday night if needed.

Lewis

#9 steamin53

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Posted 12 August 2007 - 05:11 PM

header comes off, rear drive line comes out, tail housing comes off, unplug connector for solenoid c, set asdie, pry out the drive hub on the top of the trans, inspect teeth on hub, remove grooves as needed.
R&R solenoid & gaskets, install.

remember, as nipper said: "Make sure all the tires match and are equally inflated."

TCU is under steering wheel to the left of the column.

I can get pics by tuesday night if needed.

Lewis


Pics would be terrific for me as well I imagine for others.

About the tires. The Mrs. had failed to have the new tires rotated as instructed by me but at the origin of the symptoms the first thing we did was to rotate the tires front to rear without a change in the symptoms. I must assume that the tires were ever so slightly smaller on the front at that time but not by much as they were the high-end Michelin rain tires and only had ~15-20K miles on them. After that we put the FWD fuse in.... and it worked... for a shor time.

It does seems logical that the critical element would be a scenario where the front tire size is smaller than the rear which would indicate to the monitoring systems that the front was in a slippage condition and thus would engage the rear drive train. I have no idea what the system would do if the rear were slightly smaller than the front (I understand the rear should normally be in free wheel mode if not in a lock up condition). In other words front tires at greater RPM than rear triggers normal lock up of the rear drive train. I'm not sure the system would even monitor rear wheels turning at a greater RPM than the front.

Now all that said. I was able to retrieve the On Board Diagnostic tranny codes. We have Current Code 24 which is of course Duty Solenoid C fault and Historic Codes of 23 Engine Speed Signal, and 24 Duty Solenoid C.

Next step here is to check the wiring to Duty Solenoid C and ensure no faults there.

Any ideas about the Engine Speed Signal fault code? The fault code tables indicate that the symptom associated with this code is a lock up failure of the tranny. We have never experienced that problem. I'm tempted to clear all codes, drive, and then retest.

Steve

#10 nipper

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Posted 12 August 2007 - 05:17 PM

It does seems logical that the critical element would be a scenario where the front tire size is smaller than the rear which would indicate to the monitoring systems that the front was in a slippage condition and thus would engage the rear drive train. I have no idea what the system would do if the rear were slightly smaller than the front (I understand the rear should normally be in free wheel mode if not in a lock up condition). In other words front tires at greater RPM than rear triggers normal lock up of the rear drive train. I'm not sure the system would even monitor rear wheels turning at a greater RPM than the front.

Now all that said. I was able to retrieve the On Board Diagnostic tranny codes. We have Current Code 24 which is of course Duty Solenoid C fault and Historic Codes of 23 Engine Speed Signal, and 24 Duty Solenoid C.

Next step here is to check the wiring to Duty Solenoid C and ensure no faults there.

Any ideas about the Engine Speed Signal fault code? The fault code tables indicate that the symptom associated with this code is a lock up failure of the tranny. We have never experienced that problem. I'm tempted to clear all codes, drive, and then retest.

Steve


Clear the codes and re read them. There is never a zero split to the rear wheels. Its anywhere from 10/90 to 50/50.

nipper

#11 steamin53

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Posted 12 August 2007 - 06:33 PM

Clear the codes and re read them. There is never a zero split to the rear wheels. Its anywhere from 10/90 to 50/50.

nipper


What I would really appreciate if anyone has one is a pic of the infamous "grooves" in what ever assembly or part they are found. Does anyone have a good pic of that?

#12 2.5GL

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Posted 12 August 2007 - 11:23 PM

What I would really appreciate if anyone has one is a pic of the infamous "grooves" in what ever assembly or part they are found. Does anyone have a good pic of that?


I can't get to it until tuesday, sorry...

Lewis

#13 johnceggleston

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Posted 13 August 2007 - 09:29 AM

suggestion regarding the rear extention housing ans the clutch / duty c r&r.

beg borrow or steal a rear extention housing from another AWD trans. put in a new duty c and check the clutch hub etc. replace or repair as needed, then swap it onto yoiur trans. this will reduce your down time.

the duty c can be intermittent. and you may not have any problems with the clutch at all, but you won't know until you pull it.

i would think tyhere are lots oif bad trans with good rear extention housings.

good luck,

#14 eseiler

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Posted 13 August 2007 - 06:52 PM

I have the same problem with my 96 OBW. Replacing the TCU solved the problem...but only temporarily. Apparently, there is a piston which governs the amount of pressure applied to the rear clutch pack. This in turn controls the amount of torque transferred to the rear differential. The problem is in the system which controls the piston pressure. The current nature of the malfunction (at least in my transmission) is that there seems to be a 'bias' to apply a constant pressure. Under normal operating conditions, the pressure varies constantly depending on many different factors (acceleration, velocity, crankshaft torque, throttle aperture, wheel slip, turn radius, etc.) The malfunction results in torque bind and also a loud 'clunking' noise when shifting from D to Park after a drive (upon sudden release of pressure applied to clutch pack).

Eventually the clutch plates will wear down to nothing...but they are pretty tough...hardened steel. (The rear differential is supposed to be REALLY tough!)

I'm hoping to get another 30K miles out of my transmission (currently at 190K miles).

It is my belief that the problem is mostly electronic/electrical in nature.

I would guess the job would be $1.50 in electronic/electrical parts, hundreds in labor to get at it!

Could somebody explain how a solenoid could fail?

--Damien

#15 nipper

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Posted 13 August 2007 - 06:58 PM

I have the same problem with my 96 OBW. Replacing the TCU solved the problem...but only temporarily. Apparently, there is a piston which governs the amount of pressure applied to the rear clutch pack.


Could somebody explain how a solenoid could fail?

--Damien


I have been saying this all along :horse:


there is more to the AWD then just the solenoid.

AS far as to why the solenoid failed, why does a light bulb burn out. Why doea an ipod fail, or a refirgerator. These are electro-mechanical devices, they fail, it happens.

On a 1996, ask yourself why anything has failed in your car. The parts get old. Wires get brittle, insulation breaks down. Weall start failing with age.

Nothing lasts forever.


nipper

#16 eseiler

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Posted 13 August 2007 - 07:27 PM

Oh ok...so the insulation fails and results in a short.

From a consumer perspective, driving the vehicle until total transmission failure is probably more cost-effective than forking up the $800-1000 needed to fix the problem.


--Damien

#17 2.5GL

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Posted 13 August 2007 - 10:13 PM

No complete failure, just binding so bad that you can't stand your teeth rattling any more...

L

#18 nipper

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Posted 13 August 2007 - 10:51 PM

No complete failure, just binding so bad that you can't stand your teeth rattling any more...

L


Technically thats complete failure


nipper

#19 2.5GL

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Posted 14 August 2007 - 03:18 PM

Technically thats complete failure


nipper


It's still driving right? That means it hasn't reached complete failure.:lol:

Pics coming soon, they are in the camera, waiting for the right 'puter to upload while at work...

Lewis

#20 nipper

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Posted 14 August 2007 - 04:03 PM

It's still driving right? That means it hasn't reached complete failure.:lol:

Pics coming soon, they are in the camera, waiting for the right 'puter to upload while at work...

Lewis


The awd has completly failed. Brakes can fail but the car still drives. The trnasmission is only part of the drivetrain and thats fine.

Its a complete failure , as it is putting a high load on the driveline, including the carrier bearing and the universla joints. Also it can cause loss of control of the car in the rain.

Mr car meet Mr telephone pole.


nipper

#21 2.5GL

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Posted 14 August 2007 - 07:57 PM

Here's the pics...

The left one is the back of trans, drive hub on top.

2nd from left, close up of drive hub and grooves found on teeth that need to be removed.

middle is the drum the clutches live in without significant grooves.

#4 is the "transfer case" or "extension housing" with sol. C bottom right.

#5 is the rear out put shaft area showing light grooves in the aluminum, theese are minor, but may have an affect on operation.

Hope this helps...

Lewis

Attached Files



#22 ron917

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Posted 15 August 2007 - 10:57 AM

Regarding those grooves in the second pic above:

Are we talking about the 2 grooves on the tops of each tooth, or the 5 on the sides of each tooth? Or both?

And you just grind with a Dremel or similar?

Asking because I'm sure I'll need to deal with it at some point.

#23 eseiler

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Posted 15 August 2007 - 11:13 AM

Apparently the problem is with the control valve which governs the piston pressure used to regulate applied pressure to that clutch pack. I was told that part (with the wire hanging off it) in the lower right-hand side of pic #4 of previous post needs replacing.

I have some diagrams from Subaru outlining all the components and part numbers associated with the rear part of the transmission, if anybody wants a copy. You should be able to obtain them from a dealership.


Cheers!
Damien

#24 steamin53

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Posted 16 August 2007 - 12:33 AM

Excellent pics. Thanks much. I also pose the question regarding the grooves on the exterior of the "teeth"; are they to be removed in addition to those on the sides of the "teeth"?

Does anyone know about interchange information for the tailshaft housing as a separate part? i.e., what years and models will work on my 96 model with a 2.5 engine or are all the automatics the same?

Steve

#25 steamin53

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Posted 16 August 2007 - 12:34 AM

Apparently the problem is with the control valve which governs the piston pressure used to regulate applied pressure to that clutch pack. I was told that part (with the wire hanging off it) in the lower right-hand side of pic #4 of previous post needs replacing.

I have some diagrams from Subaru outlining all the components and part numbers associated with the rear part of the transmission, if anybody wants a copy. You should be able to obtain them from a dealership.


Cheers!
Damien


I'd be grateful for a look at the information you mention. Can you post it here or email it to me?

Steve




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