Yet Another Torque Bind Case

[slowner44]

I have a 1993 Subaru SVX with a 4.44 4eat from a 98 Legacy GT and it is suffering from the infamous torque bind issue.

 

So I've been doing reading on this for a while and fortunately there seems to be a lot out there on this issue so I already have a bit of an idea on what the causes of my issue might be.

 

1) Duty Solenoid C

2) Bad Transfer Clutches

3) Tire Inconsistencies

4) Rear Diff

 

More Background Info:

-The car had no TB before the 4.44 trans and rear diff swap

-Torque Bind Disappears when put in FWD mode

-There is 16 Flashes at startup but gives no codes when doing procedure or hooked up to a Subaru Select Monitor

-Ive tried a different TCU and nothing changed

-Adding 10oz of Lubegard Red seemed to help a bit at first when doing some figure 8's but now 100miles later it almost seems like it reverted back to how it was

(maybe just placebo) 

 

So I'd say the solenoid is not the issue since FWD cures the TB. Is it safe to assume that this also indicates that the tires are not the issue?

 

I guess that leaves the transfer clutches and the rear differential (which was rebuilt by my mechanic with 4.44 gear but SVX LSD carrier)

 

I read somewhere that flushing the trans 3 times cured their torque bind, but I've also heard horror stories about how flushes destroy the 4eat.

 

What should my next step be?

[Olnick]

I'm no tranny expert but--I don't think people are saying flush 3 times.  They say to drain-and-fill 3 times.  Draining only removes about half of the old fluid, so doing it 3 times in a row gives you a reasonable change of ATF.

[wtdash]

^+1

So, the SVX tran plugs (under the hood on top of the trans bellhousing) plugged in perfectly to the GT's? Have you grabbed an SVX and GT FSM to compare TCU/TCM pinouts?

 

TCU's you've tried for the GT or SVX?

 

I've read the SVX trans is the same as the '91-'94 Legacy turbo - just different FD ratio....and the Legacy/Impreza trans are all interchangeable (including turbo) from '90ish-'98 (w/the matching rear diff), so if A=B and B=C, does A=C? :-)

 

Anyway, I'd look @ the pinouts b4 swapping any 'hard'ware.

 

Might be worth browing the http://www.subaru-svx.net/forum/ or similar for info?

 

GL,

TD

Edited July 19, 2016 by wtdash

[1 Lucky Texan]

some people have had bad u-joints mimic TB - but you'd expect to feel that with/without FWD fuse in place I guess?

 

if there's any suspicion about final drives, you could put the FWD fuse in, go to a large flat parking lot, mark the tires with chalk at the bottom, then drive X number of rotations forward and have a helper pace you and you when to stop with a chalk mark on the bottom. Compare all 4 tires. Subaru want you to be within 1/4" in circumference so - 40 revolutions is 10" or less difference from any chalk mark to any other chalk mark?

 

w'ever - you do the math lol!

Edited July 20, 2016 by 1 Lucky Texan

[slowner44]

So I just referenced an online FSM of a 98 Legacy to the SVX FSM I have at home and the pins from the transmission harness all seem to correspond to the same TCU functionality for both. The car shifts and drives fine with the swap other than the Binding. Also the other TCU I tried was from another SVX. 

 

While I was digging in the manuals, however, I found something saying that the Vehicle Speed Sensor 1 (on the transfer case) can cause excessive braking in tight turns. A diagram seemed to suggest that the signal the VSS1 gets is from the transfer clutch pack, so I'm not sure if this could be the problem.

[Caboobaroo]

Remove the tailshaft of the transmission, replace the duty C solenoid, check the hub for grooving and reinstall. If the hub has grooving from the AWD clutch pack, it will cause it to stick and bind.

 

The 16 flashes of the AT Temp light is an indicator that there is an electeical issue. Usually its the duty C solenoid failing.

[slowner44]

Remove the tailshaft of the transmission, replace the duty C solenoid, check the hub for grooving and reinstall. If the hub has grooving from the AWD clutch pack, it will cause it to stick and bind.

 

The 16 flashes of the AT Temp light is an indicator that there is an electeical issue. Usually its the duty C solenoid failing.

 

Wouldnt the fact that putting the FWD fuse in alleviates the binding indicate that the duty C is functioning properly?

[mikec03]

Im not sure that he OP has read the trans code.  For my 95, I had to get under the driver dash and connect two wires.  These were extremely difficult to find.  Fortunately someone mentioned the color which helped a lot.  They are not the green ones but I forget what the color was.  The method of reading the trans code was changed shortly after the 95 model so don't be confused.

 

And isn't the FWD option disabled when the 16 flashes are present?  So putting i the fuse should have had no effect on the torque bind.

[wtdash]

Clear this up a bit:

 

As the OP stated, he can NOT get the codes to show up using the normal diagnostic methods...this is strange.

 

The FWD fuse works regardless as it's directly connected to the Duty C ( I believe). 16 flashes or not.

 

The FWD fuse DID work as stated by the OP and it STOPPED the TB, so YES the Duty C is working (but I'd personally still replace it while i was in there if the tailshaft is removed).

 

There should be Black and Green connectors under the dash. The black were used on the '90-'94 models for CEL codes. Green for diagnostics...albeit, I'm not sure about the SVX use of these;

 

FYI:1995 has turned out be something of a transistion year.

 

 

SLOWNER44: What is the Maintenance history of the trans? Mileage? 

 

TD

Edited July 20, 2016 by wtdash

[mikec03]

I happened to find some of the literature on the diagnostics for the 96 model subaru.  This also applies to the 95, and I wouldn't be surprised earlier models.

 

The first step, after driving a little, is to turn off the car and put it in Drive .  Then connect the "plug diagnosis terminal to the diagnosis connector number. 5 under the instrument panel."  It's basically two plugs that are tapped up so they are not obvious.  

 

Then there is a few steps that need to be made and the trouble codes will then show up on the indicator light.  The duty C is 2 flashes followed by 4 flashes for example.  This is all on page 3-2 of the automatic trans and dis of the 96 service manual.

 

It's important for the OP to understand that if there are no code, which seems impossible if the light is flashing, then the indicator continuously blinks at 2 hz intervals [1/4 sec].  If you don't see the continuous blinking, then you haven't varified that there is no codes.  .    

[idosubaru]

my guess:

1.  wrong rear diff ratio - mis-identified parts, previously swapped and assumed the wrong ratio...etc...

2.  the transmission is not a 4.44 - it was mis-identified, or previously swapped...etc.  there are 98 legacy's with 4.11's and they have been swapped in place of 4.44's before - i've done it. 

 

I would verify the diff ratios.

 

Check rear diff ratio by rotating and comparing number of wheel revolutions to the number of driveshaft revolutions. 

See what you get. 

Then check front diff of the trans - i think the only way is to pull plug and paint mark the gear teeth and rotate that way I think. 

I think you could probably put it in FWD and compare the speedo to a GPS unit speed and see if it's accurate - that would suggest it's the correct 4.44, or it'll read off 10% if it's different?  probably not ideal but might be an easy check. 

 

Yes - Duty C should be operating fine if FWD mode works. 

[wtdash]

What's the TZ- code on the trans bellhousing? That's an easy way to verify the trans.

[slowner44]

What's the TZ- code on the trans bellhousing? That's an easy way to verify the trans.

Trans code is TZ102Z2DCA. Has about 106k miles on it, and the extent of the maintenance history that I'm aware of is that it was filled with fresh fluid when the swap was first done, since then, the pan has been dropped and it has been refilled. Ive driven it less than 1000 miles since the swap.

 

Also my understanding was that if the rear diff and trans FD did not match, there would be binding in a straight line. This was the case when I originally swapped it so I had the rear diff rebuilt by my mechanic to correct this.

Edited July 20, 2016 by slowner44

[wtdash]

^ TZ = 1998  GT - see attached.

 

 

[idosubaru]

Clutch plates / grooved basket. Running with mismatched gear probably hosed them or the straw that broke the camels back.

 

In some cases I install a switch to the FWD fuse and switch between FWD and locked 4WD as needed and call it an upgrade/mod!

[slowner44]

Clutch plates / grooved basket. Running with mismatched gear probably hosed them or the straw that broke the camels back.

 

In some cases I install a switch to the FWD fuse and switch between FWD and locked 4WD as needed and call it an upgrade/mod!

Im starting to think this might be the most likely cause. I know it was driven for 2 miles with mismatched gears plus however much my mechanic drove it like that to test it out.

 

It seems inevitable that I will need to open up the transfer case. Assuming I find that the basket is grooved, would I be able to use the basket from my stock SVX transmission?

I'd need new clutches and a gasket and maybe a new C solenoid. Anything else I'm forgetting?

[msmithmmx]

Did the donar car have this problem before the swap?

[slowner44]

Did the donar car have this problem before the swap?

I wish I knew. It was a junk yard car.

[msmithmmx]

So I understand this.  You have the 16 flashes but unable to read codes?  If that is the case follow this procedure in the link below.  You will need to find the two black test wires that are wrapped in the wiring harness under the driver side dash.  If you can't find it I can send you a pic of the connectors.  This is my theory....  Years ago people complained of the head gasket issue.  Now as we hit 20 years transmissions are wearing out.  20 Years or 200K miles take your pick on what is worse.

 

http://www.ultimatesubaru.org/forum/topic/121116-at-light-flashes-16-times-what-to-do/?hl=msmithmmx&do=findComment&comment=1021625

[rustfarmer]

Just because the FWD fuse works to activate the transfer clutch solenoid, does not mean it operates correctly when the fuse is not installed.  I was having torque bind and installed the FWD fuse but at first nothing changed.  After two start/stop cycles the FWD light came on and torque bind was gone.  It was easy to confirm FWD mode was working as front tires now spin coming up driveway.  Note that solenoid may be sticking when fuse is not used, such that torque bind comes and goes.

[slowner44]

UPDATE:

So this past weekend I finally got around to opening up the transfer case and replacing the reduction drive gear/basket combo and the transfer clutches. I took it for its first spin since being put back together and the very first shift from 1st to 2nd didn't happen until about 3k, maybe 4k rpm. After that, it would shift from 1st to 2nd at 2.5k consistently but this is about 500 rpm higher than i'm used to. I didn't think much off it since its got new parts and new fluid and it probably needed to get the fluid flowing to the new parts.

 

 Next day, I drive it into town and again that FIRST shift after pulling out of my driveway was delayed to close to 4k rpm, then down to 2.5k. Get to my destination, the car sits for about 3-4 hours and does the same delayed initial shift and then its fine.

 

Whats going on here? I cant help but think it has to be something with the reduction gear/shaft, but I don't know what exactly would cause it.

[msmithmmx]

I thought that was normal. You described how my car shifts when cold.

[slowner44]

I thought that was normal. You described how my car shifts when cold.

 

I just cant help but feel its abnormal since it never did that before and its been like 80 degrees out lol. Also, it only does it in AWD, with the FWD fuse in it shifts normal (to me).

 

I noticed that after putting the trans back together and putting the driveshaft back in, that the driveshaft did not rotate nearly as easily as it did before (trans in neutral, all 4 wheels off the ground both times). Perhaps something causing it to drag is raising the shift points?

[slowner44]

So I was finally able to remedy all the problems that have been plaguing my car since the swap. I figured I would return and document what I found in hopes it will help someone else in the future.

 

First off, what made this fix most difficult was not being able to pull fault codes stored in the TCU.

After going though inhibitor switches and tcus and individual wires, the issue was finally narrowed down to the Throttle Positioning Sensor. It turns out that the TPS was so far out of wack that the final step of the 'secret handshake' (pressing the accelerator) didn't register which is why codes couldn't be pulled.

The only code that was making the light flash 16x at startup was for the TPS (Go figure).

 

The torque bind issue also seemed to be remedied by re-calibrating the TPS.

I learned the sensor was not set properly AFTER I went in to the transfer case and replaced clutches and the reduction drive gear so I cant be 100% sure if that had anything to do with the fix, but what I can tell you is that after replacing those parts, the car still had TB symptoms until readjusting the throttle sensor.

 

Finally, the most recent issue I ran into upon putting the transmission back together was that the car now revved to about 4k rpm before shifting after start up, and then shifted about 500 rpm higher than usual for the rest of the ride.

After the TPS was set within spec, I was able to pull codes and I was intermittently getting one for Vehicle Speed Sensor 1. Upon inspection, I had squashed the wire to that sensor when tightening the transfer case bolts. A simple re-solder fixed this and now it seems my baby is finally driving like she's supposed to.

 

Sorry about the lengthy post, and thank you to everyone who gave their input!

[wtdash]

Awesome update and results. Good job!