Big transmission dilemma

[Gary Allan]

Automatic trans clutch

Manual trans clutch

The automatic trans you're talking about probably has no bands.

 

[Built_Well]

Kudos and credit to AzFireGuy, Gary Allan, and Tom Slick for clearing that up. There are clutches in an automatic tranz.

 

[friendly_jacek]

Originally Posted By: Built_Well
My goodness, you're not going to believe this. Toyota recommends T-IV *AND* ATF WS for the exact same automatic transmission, depending upon Camry model year.

The 4-cylinder 2005 and 2006 Camrys have the Aisin U250E transmission, whereas the V6 Camrys have the U151E.

One year later for 2007, the newly styled "next generation" Camry with 4 cylinders (same 2AZ-FE engine as the 2006) also uses the U250E transmission, but instead of T-IV, Toyota specifies ATF WS for the '07 model year!



Good find. I was doing similar digging and found the same story for U151E and U151F trannies matted to V6 engines. Switched from T-IV to WS sometime in 2006.

Toyota warns about incompatibility between T-IV and WS to comply with CAFE regulations. Identical to the engine oil specification that states than only 5W20 (or 5W30) is specified in USA while anything up to 20W50 is OK by Toyota outside North America.

 

[prax]

Maybe they're incompatible with each other, but if you do a flush and replace T-IV with WS fluid, the transmission could be fine. 100% T-IV or 100% WS, perhaps? Anything else and the transmission blows?

After all, people use non-OEM fluids in transmission all the time and it seems to work. I don't think anybody mixes Amsoil or Redline ATF with OEM fluid.

 

[crinkles]

Originally Posted By: prax
Maybe they're incompatible with each other, but if you do a flush and replace T-IV with WS fluid, the transmission could be fine. 100% T-IV or 100% WS, perhaps? Anything else and the transmission blows?

After all, people use non-OEM fluids in transmission all the time and it seems to work. I don't think anybody mixes Amsoil or Redline ATF with OEM fluid.


i do and i will... there is no issue with doing it...

 

[zrxkawboy]

Originally Posted By: artificialist
Sometimes the only difference is programming. Same transmission, different codes to control shifting.


Good idea. Sure makes sense to me.

 

[friendly_jacek]

Originally Posted By: prax
I don't think anybody mixes Amsoil or Redline ATF with OEM fluid.


Count me as nobody since I have a 50/50 mix of Redline/WS in one car and 50/50 mix of Mobil 1/T-IV in another. The trannies did not see a difference after a drain and fill.

 

[Kaboomba]

Built_Well:

If have not already checked out the part numbers for the clutch pack (aka clutch "frictions" or clutch "disks") you aught to do that before switching the type of ATF you use. If the numbers are different, I would say DO NOT change your fluid type. Here's why:

In an automatic transmission, the clutch pack makes up a critical part of what's called a "locking" torque converter. The locking torque converter is a major part of all modern automatic transmissions because it helps an automatic transmission almost mimic the fuel economy characteristics of a manual transmission. It does this by reducing the "slip RPM" or "% slip", which is comparing the RPM's of the "crankshaft side" of the torque converter to the RPM's of the "transmission side" of the torque converter.

Without the clutch pack, power would be transferred through the torque converter via fluid momentum acting on the vanes in the torque converter. This requires a certain % slip in order to work, and thus wastes gas by heating up the ATF.

With the clutch pack, the clutch can be pulsed (it is usually controlled via pulse-width-modulated signal to a solenoid valve that sends fluid pressure to engage the clutch) or fully engaged to reduce engine RPM's and heat in the ATF.

So you see, in normal operation the clutch pack is continually cycling on and off, and pulsing constantly; it is engaging and disengaging very rapidly (3-20Hz) all the time. In order for proper % slip to be maintained at all times under all load conditions with the fluid pressure that is available, the clutch friction compound and the friction modifiers, VI's/viscosity, film strength, and additive package must always sing in perfect harmony. The friction elements and fluid literally are designed for each other. Otherwise you will lug the engine or have rough clutch engagement due to agressive friction coefficient, or you will over-rev the engine because of weak friction coefficient preventing enough engagement to transfer engine power. In both cases the fluid and the transmission (starting with the clutch friction elements) will wear out much too fast.

So don't be too quick to swap fluid types!

Incidentally, IMO this is also why any and every modern AT should have fluid changes that are at least as frequent as specified in the owner's manual, even with synthetic fluid.

Sorry if I rambled too long!

K

 

[SteveSRT8]

X2 on that one^

Many modern cars have fully variable lockup, and it's really critical to have the proper fluids.

 

[AzFireGuy79]

I see you are running a non OEM ATF. So are you saying not to run a non OEM fluid in this or any application, or just one that might not be spec'd for use in this transmission?

Sounds like you are anti Universal ATF and using such a product would "wear out" both the transmission and the fluid. Am i misunderstanding your statement?

 

[mechtech2]

I don't believe Kabooma has a clue.


The torque converter locks up independent of the clutches in the trans. Sure, they have to work right, but so does any other part.
That is why it is called a LOCK UP CONVERTER.
And the clutches don't cycle insanely fast all the time. Mostly, they are on/off. They can move rapidly when needed, but they do not occilate when driving.

 

[JohnBrowning]

My Mom's Tundra came with Dex-III and a year or two latter they switched to T-IV with no mechanical switch at all in the transmission. SO my Mom's Tundra get's M1 ATF since new every 15K miles 4 quarts come out 4 quarts go in. I am thinking about use the latest Dex though due to price. On top of that the latest Dex in the Walmart brand lists both WS and T-IV and Dex-III along with a bunch of other's so with regard to Toyota I am confident you can run Dex-III,M1 ATF,RP,AMsoil,Redline D4 and a host of tohers with no problem at all! Almost no one use's T-IV or WS purchased from Toyota due to cost and poor performance. Toyota's ATF's have not been that pretty looking on UOA at all. IN fact Valvoline Maxlife is a better ATF then either T-IV or WS!

Many of us that have been servicing fleets of Toyota's for a while ahve said this all along and now we have plenty of people from Carolla owners to Lexus ownerson arious BBB borads chiming in with exactly what most of have been saying all along!

 

[JohnBrowning]

Many cares to day especially Toyota's have fuzy logic learning systems that account for the normal shearing of the fluid and the normal wear and tear of clutch plates. This means that a fluid only has to be close with regards to viscosity not exact. Few transmissions have propitiatory friction coefficients like the ATF+4 applications because too many companies do not build their own transmissions but buy any where from 1/3 on up from other.Chrysler could do that because no one else use's their transmission in their new vechiles. Toyota and GM both sell a lot of transmissions to other companies especialy in Europe.

 

[friendly_jacek]

Originally Posted By: Kaboomba

So you see, in normal operation the clutch pack is continually cycling on and off, and pulsing constantly; it is engaging and disengaging very rapidly (3-20Hz) all the time. In order for proper % slip to be maintained at all times under all load conditions with the fluid pressure that is available, the clutch friction compound and the friction modifiers, VI's/viscosity, film strength, and additive package must always sing in perfect harmony.


My friend, this how some AWD/4WD electronic/hydraulic transfer cases work (in subaru or GM) but NOT AUTOMATIC TRANNIES. Here we are talking about transaxles that are FWD or 4WD with electronic clutch.

Get a clue,

friendly

 

[SteveSRT8]

Originally Posted By: mechtech2
I don't believe Kabooma has a clue.
The torque converter locks up independent of the clutches in the trans. Sure, they have to work right, but so does any other part.
That is why it is called a LOCK UP CONVERTER.
And the clutches don't cycle insanely fast all the time. Mostly, they are on/off. They can move rapidly when needed, but they do not occilate when driving.



You may want to investigate that comment.

My car and many others use an infinitely variable lockup TC.

My particular car can go from 5% on up, and in any gear but first and reverse. It does that by regulating the duty cycle of the solenoid controlling that fluid passage.

It is indeed critical that the fluid be specifically approved by the Manufacturer or at least in conformance with the published specs to insure proper operation of all parts of the trans.

 

[SteveSRT8]

And just a note, perhaps a bit more tolerance of the fellow forum members would be a good idea, rather than rudeness.

 

[crinkles]

Originally Posted By: SteveSRT8
And just a note, perhaps a bit more tolerance of the fellow forum members would be a good idea, rather than rudeness.


+1

 

[Gary Allan]

Quote:
My particular car can go from 5% on up, and in any gear but first and reverse. It does that by regulating the duty cycle of the solenoid controlling that fluid passage.


Do you have a linkable overview for this process? I can't see that doing anything other than creating incredible wear and chatter/shudder ...but that's just my reasoning due to my acquaintance with the most common tcc's

 

[Gary Allan]

I've just read a few documents on this, one being HERE and they basically say nothing about clutch duty cycle. They talk of a pressure regulation modality using the duty cycle of solenoids.

This is to give all the sissies those "velvety smooth shifts" that you demanded.

 

[PT1]

Originally Posted By: Built_Well
You might be right, but the weight for both transmissions in the '06 and '07 Camry is shown to be the same 205 pounds. Wouldn't there be at least a one or two pound difference--maybe much more--if the composition of the internal clutches were changed, and the flow circuits were redesigned?


Not necessarily.