Topic: Transmission cooler

So I'm building a 94 Dodge Dakota w/ the 3.9L Magnum to hopefully make a race or two in the 2020 season.  The obvious foolproof part of this plan is that it still has the stock 4 speed auto in it.  So knowing the sparkling reliability of this era Mopar transmission all too well it has become the #2 focal point of my build plan behind the complete lack of brakes the truck currently has.

So what I'm wondering is do you guys have any tips or ideas on what to do as far as transmission coolers?  This will be my first Lemons car so I am expecting a lot of growing pains, but you don't buy a $475 Dodge and expect perfection...I mean I do, but you probably don't.



Also any other tips or even theme ideas are greatly appreciated.  I haven't gotten to that part of the plan yet.

Re: Transmission cooler

I have seen teams use the AC condenser as a trans fluid cooler.  It makes sense as your most likely going to remove the AC system and the condenser can handle the pressure with no issues. The only problem may be that the tube size may be to small, but that will vary from condenser to condenser. I would also keep the radiator portion of the trans cooling system if you race in a part of the country that can get cold and where Lemons holds races.

I would try to see if there's an up grade for trans that firms up shifts, etc. That may cut down on slippage in the trans which will cut down the heat put into the trans fluid.

3 (edited by Spank 2019-11-17 11:29 AM)

Re: Transmission cooler

Look at ebay and type in Transmission Cooler.

For $28.50 and free shipping, it's no-brainer.

https://www.ebay.com/itm/Aluminum-15-1- … 3876393963

In general, the stock in-radiator cooler is a joke. I just took apart 2 radiators from modern cars and the stock trans cooler part for passenger cars is just a hollow-centered tube about a foot long in the bottom header tank.

Heat is your enemy. Add cooling to the trans. and like jimbbski says, if you can get a shift kit cheaply, then get it. or consider possibly just shifting it manually-- just don't over-rev it.

Re: Transmission cooler

can you convert it to a manual??    I think the oem trans coolers are actually trans heaters to warm up the fluid to operating temp quicker.  any picknpull has a yard full of coolers from trucks with towing packages.

Re: Transmission cooler

Ford Econoline vans, mostly the 3/4 and one tons, have a good quality transcooler.  In the Midwest, they rot before they break.  $12 or $6 on half-price weekends from a PnP.  All the ones I found when you unscrew the QD fittings it is a 3/8" or 1/2" NPT thread so about any barb fitting can be adapted.

Re: Transmission cooler

A car here, have campaigned w/autotragic for 10 years

A/C Condenser: As stated, some flow better then others, the best are older units that look like a big trans cooler with 3/8 tubes, avoid the more modern high efficiently units. Spanks mentioned cooler will work well, if you want to be extra cautious, buy 2 and string em in series.

Shift improver kit is highly recommended, if it shifts into 3rd with a slide,  @ WOT consider the kit mandatory.

Synthetic fluid, tried redline, tried other stuff ...have had the best luck with this, seriously, I use it at work all the time with ZERO issues even when flushing old units

https://www.amazon.com/Amalie-160-72866 … B00C7OQJFC

Cooler rubber line: use stuff made for it, have never had issue, if in doubt, double clamp

Homestead Chump 5th-Sebring 6th-PBIR Lemons 9th - Charlotte Chump  CrashnBurn 9th
Sebring 6th again -NOLA Chump 1st -PBIR Chump Trans Fail 16th
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Daytona 13th - Charlotte 9th - Sebring 2nd-Charlotte 25th broken brakes - Road Atlanta 14 10th-Daytona 14  58th- Humid TT 19th Judges' Choice!

Re: Transmission cooler

We raced a Camaro with an auto for years...had a few issues, but we managed to solve them, this is what we did.

Like many have said you NEED a bigger cooler.  Now for us, we stole one out of a box truck at the local pick and pull.  It was about the size and the width of a hotel Bible, we mounted it FRONT of the radiator, a lot of teams mess this up and try to cool things with warm air via putting it behind the radiator.  We also sealed up the front of the car to make sure all the air HAD to flow past the radiator and the the trans cooler.  A thick radiator and trans cooler will often make air flow AROUND and not into it. 

After melting a trans down in July we also installed a trans temp gauge, its not that expensive and it really showed us just how much heat built up in the car based on how we drove it.

Team Sucker Punch: Winner Class B Doing Time at Joliet 2023 Autobahn ,Winner Org Choice award Were the Elite Meet to Cheat 2015
Chevy Camaro (Tiger striped #38)  (1989-2017 RIP old friend)
Chevy Corvette 1984......and still racing!

Re: Transmission cooler

If you have you cooler directly in front of the radiator
(it should be sealed tight against it,)
it will heat the air intended for cooling your engine.
If your engine cooling is marginal, consider putting
the trans cooler in an alternate air flow pathway.

Redline does sell Racing ATF. It has fewer friction modifiers
and allows the clutches to slip less. It's like Type F fluid, but synthetic.
Anything you can do to lessen clutch slippage will help eliminate heat.

Capt. Delinquent Racing
RUST-TITE XR4Ti - '21 ARSE-FREEZE-APALOOZA  I Got Screwed
The One & Only Taurus V8 SHO #31(now moved on to another OG Delinquent)
'17 Vodden the Hell - (No) Hope for the Future Award, '08 AMP Survivor, '08 ARSE-FREEZE-APALOOZA Mega-Cheater

9 (edited by CarneroAsada 2019-11-19 08:36 PM)

Re: Transmission cooler

Spank wrote:

Look at ebay and type in Transmission Cooler.

For $28.50 and free shipping, it's no-brainer.

https://www.ebay.com/itm/Aluminum-15-1- … 3876393963

In general, the stock in-radiator cooler is a joke. I just took apart 2 radiators from modern cars and the stock trans cooler part for passenger cars is just a hollow-centered tube about a foot long in the bottom header tank.

Heat is your enemy. Add cooling to the trans. and like jimbbski says, if you can get a shift kit cheaply, then get it. or consider possibly just shifting it manually-- just don't over-rev it.

My man!


nimblemotorsports wrote:

can you convert it to a manual??    I think the oem trans coolers are actually trans heaters to warm up the fluid to operating temp quicker.  any picknpull has a yard full of coolers from trucks with towing packages.

That was the original idea when I started looking, however my long term goal is to take this baja racing after I get some lemon's races done and maybe a rally or two as well.  From what I was reading autos tend to last longer in the desert than manuals (when properly cared for/cooled) strictly because there is less to jostle/fewer weak points when you hit those bumps constantly.  So the lazy part of me basically decided to just start with auto instead of swapping and then swapping back.


Tiptoe the rat wrote:

We also sealed up the front of the car to make sure all the air HAD to flow past the radiator and the the trans cooler.  A thick radiator and trans cooler will often make air flow AROUND and not into it. 

After melting a trans down in July we also installed a trans temp gauge, its not that expensive and it really showed us just how much heat built up in the car based on how we drove it.

I just ordered a temp gauge the other day actually.  This truly is the one point on this old truck that worries me the most.

Thanks a lot for the help everyone, this really points me in the right direction.

Re: Transmission cooler

Theme idea:  the Dodge South Dakota “Meth: I’m on it” ad campaign. It’s worth googling.

Tri-Lamb Motorsports ‘87 528e

Re: Transmission cooler

You might also research the idea of swapping transmissions for a more robust unit (or, at least a cheaper one.)
If you can swap in a 727 or 904, you'd have many more options to increase reliability.

Capt. Delinquent Racing
RUST-TITE XR4Ti - '21 ARSE-FREEZE-APALOOZA  I Got Screwed
The One & Only Taurus V8 SHO #31(now moved on to another OG Delinquent)
'17 Vodden the Hell - (No) Hope for the Future Award, '08 AMP Survivor, '08 ARSE-FREEZE-APALOOZA Mega-Cheater

Re: Transmission cooler

DelinquentRacer wrote:

You might also research the idea of swapping transmissions for a more robust unit (or, at least a cheaper one.)
If you can swap in a 727 or 904, you'd have many more options to increase reliability.

From recent experience...the swap is something that can happen.  Biggest expense is the custom driveshaft which oddly, is cheaper than losing half a weekend of racing.  The main difference if an early truck is the length of the tailshaft housing (over-simplified).  Not even extended slip-yokes can make up the difference.

Re: Transmission cooler

Many 4WD SUVs have transmission coolers of various sizes. We used flex hose to adapt our Mercedes cooler fittings to a Toyota Sequoia trans cooler mounted in front of the radiator. The pick-n-pull is your friend.

Giubo Grabbers #190 - 91 Mercedes 190E
2016 CMP Fall South "Heroic Fix" Winner