Originally Posted By: Colt45ws
If the ATF is cold that will effect clutch fill times since viscosity and pressure effect flow through the various orifices and valves. In theory you could run into issues because of this especially on multi clutch shifts where you have to dump one clutch and engage another.
I don't think its a problem on modern vehicles since the pressure tables are adjusted for transmission temperature in the computer. So a correction is just applied to ask for more pressure on a cold shift than the base shift pressure table would be calling for on a trans at ex 200F.
Both engines and transmissions are designed to operate best over a predetermined temperature range . On a cold start up , I am guessing , the sooner each reaches that temp range , the better .
Dad used his car to pull a camping trailer . He had a full size Ford 302 V-8 with a 3 speed automatic and a tall / high gear ratio rear end , some where around 1978 , 1979 .
One summer , he & Mom were pulling the camper to the lake and the tranny blew the front seal and started puking fluid . They limpe into a little town & found either a transmission shop or general mechanic . The mechanic pulled the tranny , replaced the seal and re-installed the tranny for Dad & Mom . Dad asked what he could do to prevent this from happening . The mechanic told Dad to install a transmission cooler .
When he got back , the came to our house & Dad asked me to help him find one &m install it . I told Dad I did not know much about such , but suggested we go to Checker Auto Supply ( long gone now ) . It was near the house & I had purchased a few parts there .
We asked where the tranny coolers were , were pointed to the correct aisle . There were several . Dad asked which one I thought he should buy . I said I did not know , but it sounded like he had a pretty good size problem , blowing the front seal . So I suggested the biggest one they had . Dad thought that sounded like a good idea .
I told Dad we might be able to go other places and find a better price ( normally both Dad and I were cheap ) . But he said no , he was good with what Checker had & did not want to mess around the remainder of the afternoon shopping . I suspect the cost of the cooler was cheaper , by far , than transmission repair .
We ashed the parts guy , which of the 2 lines going to the cooler in the radiator to tie into ? He said to tie into the line coming from the transmission ( not the one going back from the radiator to the transmission . He said in winter , as the engine coolant warmed up , it would help warm up the ATF .
Did he know what he was talking about ? I do not know , but it sounded plausible . He never had any more transmission problems .
When Dad traded the Ford off & purchased the 1991 Chevy Caprice ( which I now have ) , one of the first things he did was to ask me to help him install a transmission cooler on it . He towed with it & never had any transmission problems with it . It has 4 speed automatic , with 4th an overdrive . And a high speed rear end , also .
So , if you tow , I guess the tranny cooler works .
Best of luck to you ,