LS6427

iTrader: (2)

Do you think there's a temp for transmissions that is too cool.....like with and engine block/heads....?

100% street car........roll racer.

Is 150-160*F too cool if you could maintain that temp.....at least during normal driving periods...which is 99% of driving time...? Or is the coolest temps possible the best you can have with transmissions....?

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fleetmgr

TCI says between 180-225 is ideal. At 240, additives in the tranny fluid start to cook.

http://www.classictrucks.com/tech/08...smission_tips/

mrvedit

This current thread is similar:
https://ls1tech.com/forums/automatic...-stock-no.html

I'm confident most people would say that 225F is much too high for any extended period of time.
Having read all the trans threads here for several years, I think the consensus is in the 140-180 range as a good operating temperature.

This commonly referenced chart shows greatly reduced life expectancy at 225:

http://www.txchange.com/heatchrt.htm

01ssreda4

iTrader: (96)

Stock my trans ran about 190-200ish. In the off seasons now it runs 140, in the hot months I cant stop it from hitting 180-190. I'm pretty happy with this.

LS6427

iTrader: (2)

Well, the reason I bring this up is because any time Im in a rush to get somewhere and Im running late.....and I just jump into my car when its dead cold.....no real warm-up time at all. I start the engine and 2 seconds later Im moving. I pull out onto the road 30 seconds after the engine was started........and take off pretty quick but nothing crazy. The transmission is always at its best.....it shifts hard, very fast shifts and perfectly smooth. Rips second not even getting on the throttle that hard. The tranny, with that COLD fluid just bangs the gears and shifts fast. AFTER its warmed up, that all goes away. Its still obviously operates fine....but absolutely NOT as good as when the fluid was literally 80*F when I took off. That's the way I want it to shift all the time......
This has been with any car....modded or when it was bone stock. Cold fluid makes the tranny shift BETTER, without question.

The fluid is obviously thicker when its cold so I assume the pressure can build better.....but man, I want that fluid to be 90*F all the time if I could.

My stepfathers Dodge Ram 1500 does the same thing....so does my friends stock Mustang GT and so does my friends new Camaro. So COLDER the BETTER I guess........

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mjs1012

iTrader: (36)

My temps are anywhere between 165-180 if I'm driving for long periods of time and I think it's fine. As long as I'm not seeing 195+ I'll be happy with it. I'm one of the kind of people that likes cooler temps. I read my temps via the PCM so I'm not sure what the difference is exactly between that and the temps people read from the pan, but I'm sure my readings are a little higher.

mrvedit

LS6427: Some tuning of the trans shift tables should be able to get the firmer shifts you want. A full shift kit will give you even firmer shift potential.

quickvert1

140-145 makes a happy 4l60

senicalj4579

iTrader: (41)

Mine stays pretty cool up here in New England in the winter. Never saw any issues. If you are really able to keep those temps down 150-160 in FL I would take it no questions asked but I'm also curious how your reading those temps.

senicalj4579

iTrader: (41)

With my new cooler i'll see 150s 160s normal driving but there is no stopping it from going 190s after beating the daylights out of it. The highest coolant temp I see is 201 so I'm happy if trans temps stay below that. Highest i'v seen was 197 after driving 20miles unlocked stop and go in 85f weather.

Troy5061

iTrader: (19)

My 4L80e is 110-150 degrees cruising depending on the ambient temp outside. The hottest Ive ever had it was 210 degrees hot lapping at the track, this was read from the pressure port so the sensor in the trans was probably only 200.

LS6427

iTrader: (2)

My trannys have always shifted fine when warmed up.....its just that when everything is cold, it shifts WAY faster and with more bang into the next gear. As it warms up that brutal shifting subsides and then it just shifts normal.

Like I said.....this is true for bone stock cars too. Its also true for my girlfriends bone stock 2011 Grand Sport Vette....much more solid shifts when its dead cold.

So I guess we can at least say.....the cooler the better. No way to keep them at 85*F like a typical day in South Florida.......but as cool as possible is ideal I guess. Not like an engine, that really must be UP to a certain temp to run properly as far as emissions and fuel economy. Although, I would assume even an engine being dead cold will make more power than a warm/hot one. Cold equals more dense air.....that always means more power. When it gets heat soaked everything is just brutally hot even the cool air blasting through it.

I've felt the air coming out the exhaust pipe on my car...its literally cool air for the first few minutes till things start getting hot.

Little off topic I guess.....

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mrvedit

With a trans pressure gauge connected, I start up a cold engine/trans and at idle it reads 90 psi (I have a custom shift kit with .500 boost valve). As things warm up the pressure drops to 75 psi.

Higher pressure gives firmer shifts.

A stock trans (stock boost valve) will run lower pressure than I indicated above. So just install a .500 boost valve and you will likely have the desired shift firmness. The part you need is the Sonnax 4L60-LB1 boost valve, and with the pan and filter dropped, barely takes 3 minutes to install with a snap ring pliers.

Trying to keep your trans at 85F is unrealistic. First we had a recent thread on "minimum" operating temp. I suggested 100F might be enough, but a member claiming to be a knowledgeable automotive engineer said it was 140F.

Therefore, I suggest you install an aftermarket cooler (if not already) and a .500 boost valve from Sonnax or Transgo.

LS6427

iTrader: (2)

Oh no...I know trannys will never run at 85*F....Im just saying I guess as cool as possible is better. Id be glad with 140*F.

I will certainly have my tranny guy do those parts you mentioned......but for the money to build these 4L60Es, it only makes sense to build a mild 4L80E and have a MUCH stronger and reliable tranny, for much less money.

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mk2000

Not exactly like an engine, but temperature does affect the transmission's effiency. The losses to fluid shearing at colder temps 40C (104F) can be over 25% higher than when the fluid is at 90C (194F). All depending on which gear/ clutch clearances/ turbine speed and line pressure. So to get the power thru the box efficiently, "cool as possible" would not be ideal.