Torque Bind, TPS? VSS? Air Susp?...

[Mike W]

Hate to start another Torque Bind thread but I'm not finding answers searching the old stuff and I need to get this fixed during the holidays.

 

Car is a '93 LSi. A few thousand miles ago the AT failed due to pressure loss & slipping. I replaced the trans with a used out of a '97 and swapped the rear diff. to match the ratio. Worked fine for a couple thousand miles but started having torque bind. Interestingly, it didn't bind after sitting overnight, but after a driving a few blocks it starts binding.

Checked tire diameter...front and rear are pretty darn close.

Changed ATF four times...still binds.

Installing FWD fuse does nothing.

Power light blinks code for Duty Sol C.

After talking to some Subaru Master Techs, it sounded like Duty Solinoid C could be sticking or the clutch pack could be munched or the pinion shaft could be gnarled up. Cure... rebuild what's in the rear extension housing.

 

The old transmission did not have torque bind and it was still sitting here, so I tried putting that rear extension housing onto the trans in my car. Absolultely no difference. Still binds after I drive a half mile or so.

 

In the "Center Diff Lock" thread someone mentioned that problems with the Air Suspension system can be related to Torque Bind. How so?

It just happens that when my problems started, I had just removed the air suspension and swapped to KYBs.

 

I've also seen mention of Throttle Posistion Sensor faults causing Torque Bind. How so?

 

And I've seen that Vehicle Speed Sensors tell the TCU how to bias the AWD Torque. It just happens that my speedometer does bounce a little. Could VSS1 or VSS2 be the culpret? How to test VSS?

 

 

Sorry about the long post. I wanted to be clear on where I'm at with this.

Any help appreciated!

[Legacy777]

I would check the wiring of the duty C solenoid. Since it happened after swapping extension housing, I would look at the wiring going from the TCU to the transmission. You may have wiring that is failing, and as it heats up, resistance increases. If you don't want to test it, or if testing is a pain, try running a separate wire for the duty c solenoid.

 

Other thing I might recommend if you have a laptop is seeing what the ECU sees via a Vikash's scan tool.

http://www.graphics.cornell.edu/~v/bcbfscan/

 

I don't see how the TPS or air suspension could affect the torque bind. If your VSS's are acting up, that could attribute to some issues.

 

How "close" are your tire diameters?

[Mike W]

Just checked the tires again. Near as I can tell they're all within less than 1/16th of an inch and are at about 50% tread wear. Seems pretty close to me. I might go buy tires just because they're on sale at Costco.

 

No laptop and no code reader. That laptop homebrew method looks cool. I'm currently planning to take the car to Smart Service on Friday to scan for codes and see what they think.

 

I rechecked and cleaned the connectors. Running seperate wires for sol C looks like it'd be a pain and I'd rather not hack into the harness if I can help it. Ok well maybe I'd hack it to install a diff lock switch, but I need to sort this out first. I did check duty sol C with ohm meter at the connector. 12 ohms should be good, right? I checked sol C in my spare rear extension housing and it was also 12 ohms.

 

So just to be clear, the torque bind started a few months after I installed this '97 tranny into my '93 car. Then a few weeks ago I swapped out the rear extension housing hoping that'd fix the torque bind. No dice. The torque bind is exactly the same with either extension housing.

 

What I haven't swapped out yet is VSS2. When I swapped the rear extension I kept the old VSS2 because it appeared to be hard wired into the harness. So VSS2 might be the culpret. I wonder if VSS2 is the same part number for all final drive ratios? This is a 4:11 ratio tranny transplanted into a 3:9 car if that could matter.

 

I mentioned the TPS and air suspension because I'd swear I read on one of these threads that error codes or wierd signals from those systems can mess with the TCU. Maybe a shot in the dark but I did rip out the air suspension around the time I started having torque bind.

[1 Lucky Texan]

Just checked the tires again. Near as I can tell they're all within less than 1/16th of an inch and are at about 50% tread wear. Seems pretty close to me. I might go buy tires just because they're on sale at Costco.

 

No laptop and no code reader. That laptop homebrew method looks cool. I'm currently planning to take the car to Smart Service on Friday to scan for codes and see what they think.

 

I rechecked and cleaned the connectors. Running seperate wires for sol C looks like it'd be a pain and I'd rather not hack into the harness if I can help it. Ok well maybe I'd hack it to install a diff lock switch, but I need to sort this out first. I did check duty sol C with ohm meter at the connector. 12 ohms should be good, right? I checked sol C in my spare rear extension housing and it was also 12 ohms.

 

So just to be clear, the torque bind started a few months after I installed this '97 tranny into my '93 car. Then a few weeks ago I swapped out the rear extension housing hoping that'd fix the torque bind. No dice. The torque bind is exactly the same with either extension housing.

 

What I haven't swapped out yet is VSS2. When I swapped the rear extension I kept the old VSS2 because it appeared to be hard wired into the harness. So VSS2 might be the culpret. I wonder if VSS2 is the same part number for all final drive ratios? This is a 4:11 ratio tranny transplanted into a 3:9 car if that could matter.

 

I mentioned the TPS and air suspension because I'd swear I read on one of these threads that error codes or wierd signals from those systems can mess with the TCU. Maybe a shot in the dark but I did rip out the air suspension around the time I started having torque bind.

 

OK - I'm risking this question, How do you know its torque bind and not some other issue? Nipper often points out the possibilty some off feeling in the drivetrain can be a U joint or carrier bearing.

[Mike W]

OK - I'm risking this question, How do you know its torque bind and not some other issue? Nipper often points out the possibilty some off feeling in the drivetrain can be a U joint or carrier bearing.

 

Well I am often wrong and I like easier cheaper fixes. But both times I had the driveline off, I checked the u-joints and carrier bearing and they seemed fine. And the alleged torque bind feels like driving a car with a fully locked center diff on dry ground except that it stutters as the clutches chatter and slip. It's wierd that it doesn't bind at all when I first start driving but after a short distance seems like it's doing the 50/50 split thing.

[1 Lucky Texan]

Well I am often wrong and I like easier cheaper fixes. But both times I had the driveline off, I checked the u-joints and carrier bearing and they seemed fine. And the alleged torque bind feels like driving a car with a fully locked center diff on dry ground except that it stutters as the clutches chatter and slip. It's wierd that it doesn't bind at all when I first start driving but after a short distance seems like it's doing the 50/50 split thing.

 

Dang - that's a shame. If you could park it overnight in a large area, with the wheels cut hard to the lock, I wonder if you would feel the torque bind immediately doing a slow 'donut' after starting? I dunno what to think if the answer is; 'Its OK till you do 17 circles' - but it is weird the way its behaving. What about testing for the weird feeling with the rear shaft removed? Could it be a front diff problem (what?). I dunno.

[Legacy777]

Just checked the tires again. Near as I can tell they're all within less than 1/16th of an inch and are at about 50% tread wear. Seems pretty close to me. I might go buy tires just because they're on sale at Costco.

 

The 1/16" measurement is circumferance correct?

 

I rechecked and cleaned the connectors. Running seperate wires for sol C looks like it'd be a pain and I'd rather not hack into the harness if I can help it. Ok well maybe I'd hack it to install a diff lock switch, but I need to sort this out first. I did check duty sol C with ohm meter at the connector. 12 ohms should be good, right? I checked sol C in my spare rear extension housing and it was also 12 ohms.

 

I'll have to check my manuals regarding the 12ohms, but if they're both were that way, they're either both ok, or both bad.

 

So just to be clear, the torque bind started a few months after I installed this '97 tranny into my '93 car. Then a few weeks ago I swapped out the rear extension housing hoping that'd fix the torque bind. No dice. The torque bind is exactly the same with either extension housing.

 

What I haven't swapped out yet is VSS2. When I swapped the rear extension I kept the old VSS2 because it appeared to be hard wired into the harness. So VSS2 might be the culpret. I wonder if VSS2 is the same part number for all final drive ratios? This is a 4:11 ratio tranny transplanted into a 3:9 car if that could matter.

 

The speed sensor in the extension housing is VSS1. VSS2 is in the combination meter in the dash. It shouldn't matter about the ratio as long as the front and rear are the same.

 

The biggy that leads me to believe it's the wiring, the duty c solenoid, or something else is the fact that inserting a fuse in the FWD fuse holder does nothing to alleviate the problem. If the duty c solenoid is functioning correctly, when it receives 12v it stays open 100% of the time. This allows the line pressure to bleed off, and not go to the clutch packs, which in turn gives you 0% torque split to the rear wheels.

 

If something in the FWD fuse circuit, ie wiring, or duty c solenoid is not working, then the problem will still exist.

 

Just a shot out of the dark, but did you check to see that you had +12v at one side of the FWD fuse holder while the car is running? If not, you may have a problem there.

[Mike W]

Oh yeah VSS1 is the rear, VSS2 is the speedo.

Yeah the 1/16" on the tires is circumfence...all four are dang close in size and the master techs say that's close enough not to matter.

 

So I got 12point-something ohms for Duty Sol C on the two that I tested. Andyjo got 13 ohms on his in the diff lock thread. Maybe it's supposed to be exactly 13ohms? If you have time to check the FSM to confirm that'd be great.

 

I'll double check the FWD fuse.

 

Another weird thing it's started doing is that when I start it up, the trans feels like it's in gear even though it's definitely in park. So when the engine fires up it's immediately working rather hard as though it's trying to move the car even though the trans is in park. Not sure if that's due to bind in the AWD or if the trans is on it's way out. I'm starting to think a used trans from Japan might be in my future. But I still need to know what the heck is going on with this one.

 

Today I was going to have the gurus at Smart Service check it out but they're super busy until next week. Hopefully I can figure it out before then.

[nipper]

Checked tire diameter...front and rear are pretty darn close.

Changed ATF four times...still binds.

Installing FWD fuse does nothing.

Power light blinks code for Duty Sol C.

After talking to some Subaru Master Techs, it sounded like Duty Solinoid C could be sticking or the clutch pack could be munched or the pinion shaft could be gnarled up. Cure... rebuild what's in the rear extension housing.

 

 

 

If inserting the fuse has done nothing, i would Bet the duty c solenoid is shot. There is a long thread http://www.ultimatesubaru.org/forum/showthread.php?t=48865 Buried in there towards the end it telss you how to check that circuit and resistance of the solenoid. My gut feeling is the solenoid died and needs to be replaced.

 

 

nipper

[Legacy777]

The duty c solenoid is good according to the FSM and your readings.

 

http://www.main.experiencetherave.com:8080/subaru_manual_scans/FSM_Scans/duty_solenoid_c_diag1.jpg

http://www.main.experiencetherave.com:8080/subaru_manual_scans/FSM_Scans/duty_solenoid_c_diag2.jpg

 

I'd maybe check the sensor ground to the trans chassis. Also, I'd check the FWD fuse for voltage.

[nipper]

OK - I'm risking this question, How do you know its torque bind and not some other issue? Nipper often points out the possibilty some off feeling in the drivetrain can be a U joint or carrier bearing.

 

i dont mean to sound like a broken record .

 

Can you try starting the car in neutral (amuse me). YOU may have to go to a tranny shop and let them put pressuire gauges on the tranny and see exaclty whats happening..

Tires need ot have a circumfrence within 1/4" per subaru. im really at a loss for this unless you have a bearing going bad inside the tranny. Have you checked your front wheel alingmnet to make sure nothing is bent. the only other thing that will cause this feeling on the front is if you have lost your "toe in on turns".

The inside wheel should turn in father then the outside tire. If this doesnt happpen you will get tire scrub ...which will feel like torque bind.

Have you had any front end work done?

 

nipper