[rfarrelly]

Well I was speaking to an old race guy. VERY VERY reputable. Hes been running the same auto tranny is his motorhome ( 12k ) pulling a 15K trailer. 282,000 miles on it and shifts perfect. After hearing all of this we were talking, hes got a chart on transmission tests, which compares temp v. life span.
300F- Tranny will run for approx 30 min
270F-1 hr
260 - 1.5

170F- roughly 70K-80K
130F- well hes never broken 130 and has almost 300K on his.

I don't have anything but what he told me about this, but like i said, this man is VERY reputable in this field. And his list of accolades is longer and spans more years than i've been alive. But I do know, i'm going to take my tranny cooler off, and put a larger one on.

FYI. Dont bypass the radiator with tranny lines, With a huge cooler it will run too cold. The radiator will warm the tranny fluid up...and I hope not to break 135F...

Just a thought.

 

[AutoJim]

{sigh}

This old thing keeps resurfacing like a bad penny. That chart was created more than 20 years ago (probably more like 30 years ago), and was of dubious relevance even then.

Here's the deal, folks: the sign-off specs for evaluating the performance of a transmission cooler circuit are quite simple: 221F max long-term ATF sump temp, with brief (30-45 minute) excursions to 248F max sump temp permitted under high-load circumstances (say, climbing a grade with a big trailer).

Are you below those numbers? Then you're okay. Above them? Something is weird -- you're overloaded, or something isn't working right. Simple.

 

[rfarrelly]

autojim, thanks for the info, like i said i don't know where he got it, or when he got it. I just thought it was pretty amazing hes got 280K pulling that kind of weight often on a trans. But after doing some research, It might be that 'old penny' youe talking about but the colder that transmission is ( to an extent ) the longer it will run. Correct? The chart may be older than I am, but I'm still going to try to keep that trans as cool as could be. I also work my truck pretty hard. so we'll see what happens.
thanks again
ryan

 

[AutoJim]

Ryan, for sure keep an eye on things, and do your PM as you should, and you should get a nice long life out of your truck. My 4R100 is at 167K with no performance issues at all, although it's maybe a smidge overdue for a fluid change. /ubbthreads/images/graemlins/wink.gif

 

[rfarrelly]

good to hear it will go that long. I'm ordering a tranny temp gauge as I type this, See what its running at now. And Ill go from there. But I'm expecting a nice long life from this thing.
thanks for the imput

 

[04crew]

slush boxes love running cool. the cooler the better. you cant "over-cool" them. all the race trans people say this.

 

[05superdutyTJ]

[ QUOTE ]
slush boxes love running cool. the cooler the better. you cant "over-cool" them. all the race trans people say this.

[/ QUOTE ]

That's because people that do race trans's usually have HIPO engines in front of them.

A stock trans can overcool (driving downhill for miles in -75 degree weather) /ubbthreads/images/graemlins/laugh.gif

 

[ghostbuster]

[ QUOTE ]
slush boxes love running cool. the cooler the better. you cant "over-cool" them. all the race trans people say this.

[/ QUOTE ]

In the 5-20 sec of staging waiting for the 'christmas tree' to go green the trans temp in my friends big block Camaro could go as high as 260 degrees, that is why HIPO trans builders are so big on cooling.

Minimum operating temp for trans fluid is around 140-150 degrees.

 

[AutoJim]

[ QUOTE ]
In the 5-20 sec of staging waiting for the 'christmas tree' to go green the trans temp in my friends big block Camaro could go as high as 260 degrees, that is why HIPO trans builders are so big on cooling.

[/ QUOTE ]

Yeah, and the C*m*r* (sorry, can't bring myself to write the complete word, see sig for reason /ubbthreads/images/graemlins/wink.gif) was probably running a 3000 or 3500 rpm stall speed converter, which makes TONS of heat because it slips so much, on top of running, in gear, with the brake (or trans brake) on, at some sort of elevated RPM so as to be ready for launch.

No wonder it hit 260F ATF temp.

 

[ghostbuster]

[ QUOTE ]
[ QUOTE ]
In the 5-20 sec of staging waiting for the 'christmas tree' to go green the trans temp in my friends big block Camaro could go as high as 260 degrees, that is why HIPO trans builders are so big on cooling.

[/ QUOTE ]

Yeah, and the C*m*r* (sorry, can't bring myself to write the complete word, see sig for reason /ubbthreads/images/graemlins/wink.gif) was probably running a 3000 or 3500 rpm stall speed converter, which makes TONS of heat because it slips so much, on top of running, in gear, with the brake (or trans brake) on, at some sort of elevated RPM so as to be ready for launch.

No wonder it hit 260F ATF temp.

[/ QUOTE ]

YOu got it, and man does that thing launch. Does run a cooler (a token attempt at cooling, more for cooling after the run). He changes the fluid after every show and is sponsered by a performance transmission and performance torque converter builders.

Back to the topic at hand, as you stated 240 for a short period of time is acceptable, and the trans temp must come up to at least 150 degrees operating temp. I feel the key to keeping a transmission alive is to flush it and change the filter every 20K miles-which is what I recommend to all of my customers that do stop and go driving or pull heavy loads. Personally I change mine every 10K (except on my Volvo beater car, it was not serviced very religiously in the first 150K miles so I am afraid to flush it now ((it is at 200K)) because I might take the 'glue' out of it) but then being an automotive tech it is cheap for me to do.

 

[AutoJim]

[ QUOTE ]
Back to the topic at hand, as you stated 240 for a short period of time is acceptable, and the trans temp must come up to at least 150 degrees operating temp. I feel the key to keeping a transmission alive is to flush it and change the filter every 20K miles-which is what I recommend to all of my customers that do stop and go driving or pull heavy loads. Personally I change mine every 10K (except on my Volvo beater car, it was not serviced very religiously in the first 150K miles so I am afraid to flush it now ((it is at 200K)) because I might take the 'glue' out of it) but then being an automotive tech it is cheap for me to do.

[/ QUOTE ]

Well, actually up to 248F for short durations is okay per Ford. I don't recall giving a minimum trans temp lately, but I might have at some point. Your maintenance schedule is maybe just a tick overkill, but in the right direction. I go about 30K between fluid changes myself, but I also don't tow full-time -- the truck is mostly my daily-driver and gets a mix of stop-n-go and highway miles every day.

 

[ghostbuster]

Minimum temp is from Honda and Toyota but I feel it applies to all vehicles. A tranny service and flush costs me about $50 plus my time, so doing it every 10K (since my truck sees only towing miles mostly over the Sierras) is not a financial hardship.