Automotive automatic transmission temperature ?
Automotive automatic transmission temperature ?
(OP)
I am looking for typical and maximum allowable automatic transmission (oil) temperatures; specifically for a contemporary pick-up truck - 5 ratio + torque converter.





RE: Automotive automatic transmission temperature ?
I forgot what I was going to say
RE: Automotive automatic transmission temperature ?
RE: Automotive automatic transmission temperature ?
RE: Automotive automatic transmission temperature ?
As there is no normal way for blow by to deposit water in the transmission, there will be very little to be dispensed. I would be concerned for the ongoing health of my transmission if ATF temps regularly got around 250F.
Regards
Pat
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RE: Automotive automatic transmission temperature ?
I forgot what I was going to say
RE: Automotive automatic transmission temperature ?
I think Hemi has got things exactly right in his post.
Steve
RE: Automotive automatic transmission temperature ?
Also even though you might get a fluid to stand up at 250F, other components in the transmission might fail quickly if bathed in oil at those temperatures.
Regards
Pat
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RE: Automotive automatic transmission temperature ?
When I was a boy, I worked on transmissions from the 50's, before trans coolers :They usually had "burned" clutches and bands (phenolics ?). Apparently very high temps only developed during slippage at the contact surfaces.
I was wondering about changing trans oil in my Titan at 110,000 (it has 2 factory coolers). The oil looks and smells good (because of low temp ?)
RE: Automotive automatic transmission temperature ?
BTW, the early Hydro was engineered not to need anything but external convective air cooling. The power path in 3rd & 4th gears was 66% mechanical, and the fluid coupling was much more efficient than a torque converter.
I forgot what I was going to say
RE: Automotive automatic transmission temperature ?
Regards
Pat
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RE: Automotive automatic transmission temperature ?
RE: Automotive automatic transmission temperature ?
RE: Automotive automatic transmission temperature ?
RE: Automotive automatic transmission temperature ?
The traditional "beefed" hydro used Cad Eldorado clutch packs ( 9 and 13, regular Cad were 9 and 11- If I remember right), and a steel clutch piston instead of aluminum.
Old guy quiz- What was the first auto trans to "lock up" in direct drive ?
Ans; Packard Ultramatic (about 1955), It had about a 10" dry clutch in front of the torque converter. It looked very strange when you dropped the transmission.
RE: Automotive automatic transmission temperature ?
Therefore, the fluid coupling was reduced in diameter, which probably reduced efficiency, and a small, secondary coupling was added, which served the function of a clutch pack. Instead of engaging or disengaging a clutch pack, the secondary coupling was filled or emptied of fluid, resulting in extremely smooth, extremely slow shifts. I doubt anyone ever took one of these tranmissions racing. Sounds pretty inefficient, too. I don't recall if the second design retained the mostly mechanical power path in 3rd and 4th.
The first design Hydramatic, when prepped into a B&M "Hydrostick", was the first successful automatic transmission in drag racing, and actually dominated over all other manual and auto transmissions in gasser and probably other classes of drag racing in the early '60s, until superceded by the Torqueflite and Powerglide, I believe.
I forgot what I was going to say
RE: Automotive automatic transmission temperature ?
The guy I worked for in Chicago was one of the better Hydro builders. His story about the steel clutch piston was that the aluminum pistons would explode under a high RPM ( high pump pressure) shift with no accumulators. I had a '37 LaSalle trans- didn't believe in automatics.
Did you mean Powerflight?; I thought Powerglides were most useful as doorstops.
RE: Automotive automatic transmission temperature ?
I forgot what I was going to say
RE: Automotive automatic transmission temperature ?
Other popular choices are, the transmission the car came with and Lenco or similar with multiplate centrifugal clutches set to slip quite a lot at launch.
Regards
Pat
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