Auto tranny temps....

[TimAT]

That chart (IIRC) is really close to the one GM gave out when I went thru their 700-R4 school. Once it gets to the upper heat ranges, trans life (NOT fluid life) is measured in minutes.
And FWIW, again IMHO, no such thing as too cool for an auto trans. They work as well at -20F as they do at +200F.

Do you think the replacement seals have gotten any better over the years. I'm assuming heat kills the seals and other soft parts. I've never understood why everything didn't come with an air aftercooler. I understand that a liquid to liquid cooler is so much more efficient but if the rad is running 210-220 the tranny oil will never be able to get below that.

Technology improves over time- I've torn down several that were overheated to the point the fluid was black and stinking- and the seals were all still pretty soft and pliable- mostly the clutches come apart and the clutch material plugs the passages, gets into the seals and cuts them up. The cuts leak, won't hold apply pressure on the clutch packs, they slip, making more trash. Endless cycle until it gets so much clearance in the packs there's nothing to hold onto and drive the trans. The seals are pretty the only parts I'd call soft-
The liquid to liquid cooler is really the best- but I've seen engines that have overheated and cook the trans right along with it. An air to liquid cooler might not be the best, but it will keep the trans from getting off into the "fried" department.
Above 300F, the steel plates in the clutch packs start to warp, and that causes all sorts of wear and drag issues.

 

[mrvette]

That chart (IIRC) is really close to the one GM gave out when I went thru their 700-R4 school. Once it gets to the upper heat ranges, trans life (NOT fluid life) is measured in minutes.
And FWIW, again IMHO, no such thing as too cool for an auto trans. They work as well at -20F as they do at +200F.

Do you think the replacement seals have gotten any better over the years. I'm assuming heat kills the seals and other soft parts. I've never understood why everything didn't come with an air aftercooler. I understand that a liquid to liquid cooler is so much more efficient but if the rad is running 210-220 the tranny oil will never be able to get below that.

Technology improves over time- I've torn down several that were overheated to the point the fluid was black and stinking- and the seals were all still pretty soft and pliable- mostly the clutches come apart and the clutch material plugs the passages, gets into the seals and cuts them up. The cuts leak, won't hold apply pressure on the clutch packs, they slip, making more trash. Endless cycle until it gets so much clearance in the packs there's nothing to hold onto and drive the trans. The seals are pretty the only parts I'd call soft-
The liquid to liquid cooler is really the best- but I've seen engines that have overheated and cook the trans right along with it. An air to liquid cooler might not be the best, but it will keep the trans from getting off into the "fried" department.
Above 300F, the steel plates in the clutch packs start to warp, and that causes all sorts of wear and drag issues.

Did a trans pan gasket on a '94 Dodge ram 250 van, FI 318 and a 9.25 rear, the pan was full of metal shavings, a little steel, mucho other silver and even some brass....lovely.....I was scared of that, and have no clue WTF is rong, except to say the tranny is short for the world at this point....
belongs to wife's son, camping/fishing/backwoods hunting van, they always take two vehicles on those trips, but getting a tow truck back there will be an adventure....:hissyfit::bump: