Freezing the Slushbox. Torque Converter on-demand lockup switch.

[orange4boy]

Lock up the TC and you cut the flow of ATF to the cooler. Heat builds up and expensive and often spectacular (a trail of parts and fluid scattered down the road) transmission failures follow.

Is this true on all automatics? Some of the newer ones must have fixed that issue because they now lock up the majority of the time. (obviously not mine)

I would imagine that since most of the heat generated by the transmission is generated by the inefficiency of the unlocked TC that over heating from a locked TC is a non issue. But since TCs normally lock at highway speeds, I guess all that wind does the trick, cooling it from the outside. Doesn't this essentially turn the auto into a manual (which cools passively) in terms of heat generation? Where is all this heat being generated?

Would it be prudent to install a temp gauge in the tranny to make sure? Most of my trips are too short to cause that much heating.

Face it: The automatic was never intended for hypermiling. The manual transmission is far superior.

I totally agree. I hate them. But since I'm stuck with slushbox, a ten minute mod to reduce the losses sure beats installing a manual transmission in my Previa IF I could even find one.

[2000mc]

Originally Posted by orange4boy

Is this true on all automatics? Some of the newer ones must have fixed that issue because they now lock up the majority of the time. (obviously not mine)

I would imagine that since most of the heat generated by the transmission is generated by the inefficiency of the unlocked TC that over heating from a locked TC is a non issue.

i dont know if all do it or not, but youre right on the money with your guess why. most of the heat generated is from the converter slipping, and why cooler flow isnt required during lockup

[orange4boy]

2nd run complete. Working great.

Observations:
TC lock does not engage in first gear. The safety there is still working even with the bypass switch. Not really a problem since I spend very little time in first. My driveway will have to be slushed. Fitting, really.

Second gear is pretty long so I have to start unlocked but I can get locked at about 40Kph / 25mph. A little below that on the flat and it needs to be going about 45kph / 30mph to do the hills here without bogging. (I'm not sure of the rpm shift points yet.)

Shifting into 3rd is not harsh at all under the conditions I tried it (slight up grade). There is a little "mount bounce" after the shift but it's very mild.

I believe OD is really just fourth gear so that has to be disengaged or it will shift into OD too soon after 3rd. The tree is really a pain for this type of driving so I'm dreaming of finding a suitable shift lever to replace the original.

OK, that's the last smiley.



You can see the lockup switch elegantly taped to the tree, my digital vac gauge (thanks Vtec-e) and my temporary, tacky low tech tach.
I like the washer fluid button in this pic. It's all "OH...OH...pick me...pick meeeee."



I need to figure out which of these wires is for solenoid one and two. I already know the green/yellow is #3
Anyone? ...... Anyone? ..... Bueller? ..... Bueller? .... Bueller?



This just shows how easy it is to find on the Egg. (Small mercy) The ECU is the ONLY thing engine-wise that's easy yo get to.

[Christ]

Originally Posted by Big Dave

Lock up the TC and you cut the flow of ATF to the cooler. Heat builds up and expensive and often spectacular (a trail of parts and fluid scattered down the road) transmission failures follow.

Face it: The automatic was never intended for hypermiling. The manual transmission is far superior.

I'm not sure about this... I try to get locked up as quickly as possible, and accelerate under as much load as I can put on it without unlocking... I've never had a problem w/ my transmission.

Why would locking the torque converter into 1:1 operation cut ATF flow when you're still turning the pump?

I'd think that if that was true, many people would have highway transaxle/transmission failures, no?

[2000mc]

#1 - BN-W pin#15@ecm conn.C pin#13@conn. IH1
#2 - BN-Y pin#14@ecm conn.C pin#12@conn. IH1
#3 - G-Y pin#1@ecm conn.C pin#11@conn. IH1 <---lockup

[Christ]

Just about any floor shifter that has a cable attachment can be made to work for you, as long as you have the guts to put a hole in your floor,and you can actually reach it once you're done.

[orange4boy]

Thank you 2000mc. You rawk!

Originally Posted by Big Dave:
Lock up the TC and you cut the flow of ATF to the cooler.

This is true in some transmissions although I haven't confirmed this in my particular one. Whether this would cause a transmission failure due to overheating, I also have not confirmed, but it seems illogical.

The following is not typical. You should check this out on your own transmission like I did but I highly doubt overheating from lock-up is an issue.

[2000mc]

i didnt see what sol. is on and off to get you each gear, but i suppose you could hook up a test light and drive it to figure that out. tricky part might be that one of the shifts require switching both sol. at the same time

[orange4boy]

There is a chart in the Toyota transmission course that shows the pattern of solenoids to gear selection. I just needed the #s

I guess we can put the overheating issue to rest:

Lockup?
All modern automatics (except for the continuously variable transmissions--CVTs--found on a few late-model cars) have locking torque converters to eliminate slip at cruising speeds, thus saving fuel. These are controlled by the powertrain control module (the engine and transmission management computer) on the basis of speed, temperature, throttle position, etc. If the engine is running at a higher rpm on the highway than usual--300 to 500 more--to maintain the same speed, it's possible that lockup isn't occurring. Besides reducing fuel economy, this can have the much more disastrous effect of causing the transmission to overheat.

From a very trusted source in the UK:

The lock up is based on a clutch that ensures that the rotation of the engine flywheel matches that rotation of the torque converter without slippage. It is completely independent of the oil flow which ALWAYS flows to the oil cooler. I happen to have the original Toyota workshop manual for the A46DE transmission and in fact I also own a 93 rear wheel drive Previa GL (or at least I will until Friday)

So there you have it. Not an issue on the Previa. I like to know these things for sure.

[orange4boy]

This is working so well. I can finally accelerate at low rpm with high load.

(In the voice of Bill Bailey) "I can now travel to the magic BSFC island of efficiency."

http://www.youtube.com/watch?v=O3F2e-x_EU8