Tranny cooling tech.

88Wrangles · #1 (**permalink**) 05-27-2005, 02:46 PM

So, I've got a '74 (at least the frame is :wink: ) Chevy with a TH400. I have a big 'ol aluminum radiator with an aluminum, auxiliary tranny cooler in front of it. On the engine side, I have two 18" electric fans).

Now the problem is that the tranny still likes to overheat quite a bit...especially out on the sand when I'm crawling up all the hills.

So the question is, what if I ran the tranny cooler lines through both the tranny cooler itself AND through the "built it" tranny cooler on the radiator (the spot that the factory usually uses)? I was thinking run the line from the tranny, through the cooler, through the radiator, then back out and to the tranny.

Would that work better, or would routing them a different way then that be better? Like maybe through the radiator first?

Thanks!

yjdave · #2 (**permalink**) 05-27-2005, 03:41 PM

2 IS BETTER THAN 1. Thats how i did my jeep was through the radiator then into the cooler...

Junkpile · #3 (**permalink**) 05-28-2005, 12:30 PM

While you do need a pretty heavy duty cooler with your setup, you really shouldn't have that much of a problem with everything right. That TH400 will handle what you're asking of it, so it's not being overworked if it's setup for your application. Speeding up the shift is a start. What is the stall speed of your torque converter? What diff gears you got? Do you manually shift it when offroad?

Wait, I just went and reread your post. Yeah, run it through the built-in too and see if you still have problems. Then look at the setup

Snitty · #4 (**permalink**) 05-29-2005, 06:33 AM

the aftermarket coolers can be used both ways. you can run them as a standalone or you can run it in series with the stock cooler. I figure if you're going to have 2 on the vehicle, you might as well use them.

88Wrangles · #5 (**permalink**) 05-29-2005, 10:52 PM

So is it better to go through the radiator first or the tranny cooler first?

Junkpile, it still has the stock 3.73 diff. gears (plenty of power, so I havn't gotten around to changing them yet), and for the torque converter....It's out of a diesel (and I don't know the specifics on it).

I don't ever really manually shift, but I will sometimes put it in "2" or "1" just so that it won't shift in situations where I need the rpm's....that's it though.

Like I said, the only times it will overheat are when I'm pushing the truck real hard and it's HOT out (which is a lot of the time!).

Thanks for the help!!

LBR · #6 (**permalink**) 05-30-2005, 12:07 PM

88 - Going thru the "built in" 1st, then the aftermart 2nd is my preferred method..... if your fluid is overheating, then it is well above the coolant temp, so the "built in" will act as the precooler, then the aftermart cooler will "finish the job." Other items to consider.....1) high capacity tranny pan - get the type that has the tubes running thru the middle of the pan sump - they work excellent 2) move the aftermart cooler away from the radiator and into another area of your truck with it's own electric fan - the tranny cooler won't get heat-soak from the radiator and the radiator won't get heat-soak from the tranny cooler, plus the radiator will catch more cool air. I know you have ample space to move that cooler after seeing your truck the other evening!!!

88Wrangles · #7 (**permalink**) 05-30-2005, 12:17 PM

Ok, thanks LBR!! Ya, there's definatly other places to put the tranny cooler where it could get some nice cold air.

So I guess I will now go run it through the "built in"...then through the cooler.

Thanks again guys!

Junkpile · #8 (**permalink**) 05-30-2005, 05:10 PM

Those 3.73s are certainly adding to your tranny cooling woes. While it's not unheard of for 3.73s to be run with 44s in the mud, it's hard on automatic transmissions and clutches. You already know they need to be changed, so that's all I'll say about it.

That converter should be plenty "tight". I know alot of guys run into problems when they try to putt around the trail with loose stall converters.
What about a shift kit? You need one.
The deep pan idea is a good one.

88Wrangles · #9 (**permalink**) 05-30-2005, 09:19 PM

Ya, I'll be putting in a shift kit sometime (soon hopefully)...along with a deeper pan.

The 3.73's definatly have both their advantages and disadvantages. They can definatly get the tires spinning really REALLY fast, but there's also times in more technical stuff where you want to just crawl along reall slow, with the tires spinning ever so slightly and is not possible with the low gears.