Torque Bind Solved $10

[Guest D1Driver]

I read somewhere about this and tried it. Worked perfectly.

 

Go to NAPA and buy limited slip differential additive. Put in trans. Run it.

 

My torque bind on my 98 Legacy Outback Wagon was totally gone within 20 miles.

 

Not sure the long term effects, but I haven't had any problems within the last 250 miles.

[outback_97]

More history please... this was after trying other things like changing ATF, checking tire PSI, etc. I assume? My wife's car had slight TB, went away after changing ATF, that's my only experience with it.

 

Steve

[porcupine73]

Cool idea. Well that's basically a friction modifier, which Dexron flavour ATF already has some/certain kinds, not sure this would actually do anything to correct the cause of the torque bind, it might just mask the symptoms? Would be interested to know how it works out over the long term.

[fnlyfnd]

I thought the diff and trans were seperate in autos. Hence, if you put something in the tranny, you aren't effecting the diff.

[kimokalihi]

Yeah I thought so as well. My 90 legacy has seperate sticks for the front diff and the tranny.

[Guest D1Driver]

Not sure the years, but I know my 98 Legacy Outback Wagon had the EJ25 with an auto tranny. The center diff, which typically causes torque bind, is the last 14 inches or so of the transmission. And it gets fluid from the tranny. The front diff, as well as the rear diff, are seperate, but not the center diff.

 

History:

 

Prior owner had spare on front left for a few days at highway speeds.

New tires got installed

Torque bind obvious, diagnosed by dealer and told needs new clutch pack in center diff

Changed tranny fluid 3 times, but no help

Put LSD additive in after reading post somewhere, fixed problem almost immediately

 

Sorry guys. Won't be able to give you extended history after all. Just sold the car for $750 more than I paid a month ago. Wife said I was limited to one car, and I decided to keep Land Rover!

[fnlyfnd]

No, the diff does not get fluid from your auto tranny. How could a diff run off ATF. That makes no sense. If your poured the diff fluid in the tranny you just ************ed someone really bad. Now not only is the center diff screwed, but you messed up the tranny itself.

[Guest D1Driver]

This is an automatic with an EJ25 engine. Before doing this, I searched for days on posts from all kinds of forums. I didn't know anything about them prior. The center diff on this setup is the back section of the trans, and it does use trans fluid.

 

Get facts straight!

[fnlyfnd]

Yea I guess you're right. I still don't like the idea of having diff. fluid in an auto tranny though. Are you sure this isn't just a cleaning process, and should be flushed out in a couple K miles. From what I read (quickly) it cleans out the gummy stuff. Which I would imagine means, don't run for a long time. I have a manual tranny, I usually dont pay attention to this auto stuff.

[Guest D1Driver]

I haven't delivered the car to the new owner yet. I thought about going ahead and changing the fluid before delivery anyways. It is so damn easy!!! Only car I know that has a drain plug in the tranny!

[avk]

I thought the diff and trans were seperate in autos. Hence, if you put something in the tranny, you aren't effecting the diff.

The limited-slip additive in AT affects the transfer clutch located in the extension housing. It is a solution recommended in a factory TSB.

[nipper]

the friction modifier is only a stopgap. If you tried everything else, and had to use an additive, its only a matter of time. I am not sure what the stuff does, but you need friction to make the AWD work.

I am assuming you added it to the tranny fluid. If you added it to the diff fluid i dont have a clue

 

nipper

[GLCraig]

This is an automatic with an EJ25 engine. Before doing this, I searched for days on posts from all kinds of forums. I didn't know anything about them prior. The center diff on this setup is the back section of the trans, and it does use trans fluid.

 

Get facts straight!

 

The Automatics do not use a center diff, instead they have a transfer clutch. Only a manual transmission will have a center diff.

[avk]

the friction modifier is only a stopgap. If you tried everything else, and had to use an additive, its only a matter of time.

It just might be a permanent, or at least semi-permanent fix. My suspicion is that Dexron-spec. fluid is simply not always adequate for this type of constantly engaged clutch. Kind of like Chrysler transmission, controlled entirely through solenoids, that may shudder if filled with Dexron but works good on ATF+3 or +4. Last time, I used Valvoline "high mileage" ATF which meets both Dexron and Mopar specifications, for better peace of mind re. torque bind.

[xrturbo]

i almost bet the problem will be back. one major problem is that the rings on the output shaft wear a grove into the rear journal causing it to hold full pressure. i just did one in an impreza the other day that was the worst one i have ever seen. i still have it on the bench at work.

 

just an idea, and i know nipper can probably contribute some to this, maybe we should get some photos up of what the assembly looks like dismantled and problem areas. then people who haven't actually gotten into one of these setups can see the problems and what they are all about.

[1 Lucky Texan]

I'd like to know the exact product or link to a pic of the container, etc.

 

Is this a 'gear oil' type additive for, say, rear differentials that is being put into the autotran fluid?

 

color me confused

 

lol!

 

Carl

[avk]

The groove worn by the seal (into the aluminum housing, per TSB), as well as failed solenoid, are two known "hard" causes for the bind. But a 1998 trans. should already have a steel sleeve in the housing, and a solenoid would set a code.

[1 Lucky Texan]

The groove worn by the seal (into the aluminum housing, per TSB), as well as failed solenoid, are two known "hard" causes for the bind. But a 1998 trans. should already have a steel sleeve in the housing, and a solenoid would set a code.

 

good point on the sleeve - IIRC those were pre-mid 90s (I'm sure someone will know)

 

But a solenoid that is bad from 'gummy' builup or a worn/leaking valve seat might not throw any codes.

 

Carl

[porcupine73]

OK, he did not put diff fluid in with the ATF. He put what I'm guessing is a few ounces at most of a friction modifier (which is not necessarily a friction reducer) of a type often added to gear oil in limited slip differentials. Dexron type ATF's already have friction modifiers in them anyway (unlike type F), so adding a little more probably isn't going to kill anything (hopefully ) You're right, putting gear oil into an AT is bad for many reasons including that it has a lot of sulfur in it which may eat things up, but he didn't put gear oil into the ATF - just that additive.

[1 Lucky Texan]

OK, he did not put diff fluid in with the ATF. He put what I'm guessing is a few ounces at most of a friction modifier (which is not necessarily a friction reducer) of a type often added to gear oil in limited slip differentials. Dexron type ATF's already have friction modifiers in them anyway (unlike type F), so adding a little more probably isn't going to kill anything (hopefully ) You're right, putting gear oil into an AT is bad for many reasons including that it has a lot of sulfur in it which may eat things up, but he didn't put gear oil into the ATF - just that additive.

 

this what he said;

 

***Go to NAPA and buy limited slip differential additive***

 

so - what is that? Doesn't seem like the correct term for a substance designed for a transmission - unless its a limited slip front automatic transaxle or ???

 

sorry I'm so dense.

 

Carl

[cookie]

Actually there is no reason this would not work, as stated it is just a friction modifier. With a clutch type limited slip you cannot use standard gear oil either. There are trasfer cases with this type of clutch, motorcycles, LSD rear ends, and the ever popular subaru automatics.

It's not going to work if the clutches or seals are really wasted, but if it is just chattering a bit this should be great. You would have to be sure it is a modifier that mixes well with ATF and does not do seal damage, but rear ends have seals too.

[avk]

Carl: the old TSB calls for GM additive, don't remember if it says how much. I'm guessing it's a full "small" bottle. Someone with a current techinfo subscription may be able to look it up, I didn't save that one.

[newsance]

For many years, GM "positraction" rearends used a limited slip differential that engaged via clutch packs, much in the same manner as the differentials work in AWD subarus.

 

However, the diff fluid would cause the clutch to be grabby, leading to shudders and differential chatter when going around corners as the clutch packs wouldn't release.

 

The solution is limited slip additive. This is not a gear oil, it is exactly what it says it is- a friction modifier.

[nipper]

For many years, GM "positraction" rearends used a limited slip differential that engaged via clutch packs, much in the same manner as the differentials work in AWD subarus.

 

However, the diff fluid would cause the clutch to be grabby, leading to shudders and differential chatter when going around corners as the clutch packs wouldn't release.

 

The solution is limited slip additive. This is not a gear oil, it is exactly what it says it is- a friction modifier.

 

excpet for one detail, subaru clutches are designed to slip when they are engaged in the awd unit. The Gms would engege and disengage rappidly causing the shudder, so the friction modifier would smothe them out. The modifier would be the same as slipping the clutch.

 

nipper

[newsance]

I'm sorry, what? There is no rapid disengagement, or really any engage/disengage action in a posi rearend.

 

Clutch packs are given constant spring pressure to keep both axles rotating at the same speed. If the difference in traction is enough to overcome the holding force of the clutch packs, the diff will slip. If there is not enough force, it won't. The spring pressure doesn't change or release.

 

Perhaps you are thinking of a locking rearend? Those would function like you are describing. But locking rearends don't need limited slip additive. Nor do Torsen rearends, which function with a worm gear. The additive is only needed in limited slip rearends that employ clutch packs.

 

The chatter happens because the clutch binds, then gives and then binds again instead of having a smooth action, not unlike what happens with torque bind.