My friend has a 1988 Mustang GT with a 93 Cobra engine in it fully stripped for racing (rollcage and everything). He figures he's got about 300hp. He bought a quality racing grade auto tranny for it but is having problems with the tranny fluid overheating (reaches 300F on the track). The tranny was designed mainly for drag racing. He has a big cooler hooked to the tranny.

The shop where he gets his work done has been trying to figure this out for a long time. They heat gunned before and after the cooler and see a 50F drop after the cooler, so it looks like it is working. After looking at his setup, I'm guessing that the cooler is working fine, but that it's just not getting enough fluid through the cooler to cool the whole tranny. It's a 12 quart capacity tranny, and we're guestimating about 2quarts/min flows through the cooler (based on when he pulled the line off after the cooler, how much oil was coming out).

He's going to look into putting bigger lines up to the cooler (the lines are a bit smaller than the cooler ports it looks like. That should help some (less restrictive).

I'm also wondering if he could put an additional pump in the line to increase the flow? The current pump is built into the tranny. If you put another pump in the line, would that increase the flow or would the 2 pumps just fight each other?

Would it be better to close off those lines into the tranny (he thinks they're 1/4" or at best 3/8") and tap new holes at 1/2" and use a higher power external pump to get more oil flowing through the cooler?

Any other ideas?

Thanks guys.

(Oh yes, and the rest of us at work smack him on the head daily for not learning to drive a stick! poke beat_dow He's thinking if he blows this tranny, he'll probably do a manual swap )

[ April 17, 2003, 08:12 AM: Message edited by: Kevdog ]

 

using a auto tranny for road racing is retarded... but 2 each his own...

he should put a fan on the tranny cooler... use synthetic oil

 

What he should do is hook up temp props to his "inlet" and "outlet" on the cooler, and then do some driving. See how effective it is while he is driving.

he might have it in a bad location. At speed there might not be any air flow at that location, or it might pick up heat from the radiator or any other "hot" part near it's location.

Basically, PROVE it is working fine before trying to modify it or improve it's operation via pumps/hoses/etc..

My guess is, in it's current location, it cools fine in "stationary tests" but while driving it get's no airflow and so doesn't work.

 

Yes, using an auto is retarded, but right now he can't afford a swap (just bought a 65" Toshiba HDTV )

The oil cooler is mounted similar to an intercooler in front of the radiator and gets direct airflow from the front intakes. It also has a fan attached directly to it pulling air across it.

He uses synthetic oil in the tranny, though he just found out that the maker of the tranny urges people not to use synthetic oil as it eats away at the bands. Could be why he no longer has 4th gear!

He also heat wrapped the exhaust near the tranny to help prevent heat transfer to the tranny. That seemed to help a bit (it takes longer to get up to high temps), but still not fix it.

Hmmmm.... maybe two temp gauges before and after the cooler would be a good idea. Just to verify the temp drop while driving.

Based on watching the car and temp gauge while driving around I think the cooler is working, just not with enough capacity to cool the tranny under WOT most of the time. That's why I'm wondering about getting more oil through the cooler per minute... with bigger lines or an additional oil pump.

We'll see what happens smile.gif

[ April 17, 2003, 11:44 AM: Message edited by: Kevdog ]

 

Again, depending on how the tranny cooler is mounted in front of the radiator, it might get decent air flow at low speed, but at high speed the air might go "around" it rather than through it.

Also the heat from the radiator might "bake" the cooler and prevent it from being more efficent.

Just hook up some temporary temp gauges to the inlet and outlet lines, then have him do some "spirited" driving once the tranny is warmed up. That should show you how it behaves under the harsh conditions.

Also, if the tranny maker reccomends only normal tranny fluid, and this guy is using synthetic...and he lost 4th gear...that might cause the heat increase. The parts of 4th gear floating around inside the tranny/clogging the tranny fluid filter, getting inbetween gears. Also the synthetic fluid might have different thermal properties than the "normal" tranny fluid, meaning it doesn't cool as well.

First thing would be to do a tranny fluid change. Strain the fluid through a very fine metal mesh as it comes out of the tranny, before it hits your catch container. If there is a significant number of metalic particles in the fluid, flush the tranny with 2-3 quarts of fresh clean fluid. Keep doing this till the "rain" of metalic particles stop. Then repeat this procedure after 500 miles. Yes, it's expensive, tranny fluid isn't cheap, but a new or rebuilt tranny is quite a bit more expensive.


I would strongly urge him to have the tranny serviced. Metal bits floating around inside a tranny can kill the 3 remaining gears, clog bearings, clog the ATF shifter passages (the maze) and in general, cause havoc. A $250-$500 teardown and rebuilt might save him from having to buy a new $1000-$3500 tranny.

Oh, tell him to take the damn big screen back. The car is WAY more important!

 

I talked to him at lunch and he is going to hook up some temp gauges.... permanently smile.gif You're definitely right about the airflow possibly going around it at higher speeds... he's been thinking about ducting it. We'll get some temp gauges on there to see how it does.

He's definitely going to drain and replace the fluid. He just had the tranny cleaned out recently when 4th gear went out, so all the metal bits should be gone. He didn't want to replace 4th gear until he gets the cooling figured out, as he may just start saving for a manual (which I keep recommending ) The $600 to replace 4th gear might be better placed towards the $3500 for a manual swap smile.gif

Oh yeah... to make it a bit less retarded, his auto does have to be manually shifted.... he's got the stick set up for 1 2 D going to 1st 2nd and 3rd, with an extra switch to put it into 4th.

The playstation2 just looks waaaay too nice on a 65" screen bow_down And I'm stuck with just a lowly 54"

Thanks for your help Random.... as always smile.gif

 

A friend of mine has a Civic with a/t and turbocharged. He decided to mount the tranny cooler and oil cooler inside the wheel wells inset in the plastic covering, (behind the wheels). Not sure of how much air is actually getting to them but he is happy with his set up.

 

Best way is to get a cooler that is the right size and hook it inline with the cooler in the radiator. For racing applications, a larger cooler in front of the radiator and in line with the cooling fans will make it as efficient as possible.

On my truck, which has a 572 blown motor, the cooler in front of the radiator is the one of the larger coolers and it has a fan attached to it (a B&M cooler). On my Elantra, I have the cooler behind the grille and ahead of the A/C condenser.

Most racers will go for the automatic over a stick in drag racing. The auto can give you better times.

 

/\ maybe an AT built for racing, but a stock Auto is in no shape to race.

I was going to recomend your friend convert his cooler to water cooled, or use a cryo cooler shot on the cooler to cool it in between runs. but it sounds like his problems are deeper than just racing too hard to cool the oil. Get him swapped into a MT and problems will vanish.

 

A water cooled cooler can be warmer than using a air cooled cooler (the heat generated by the fluid warms the water and it will stay hotter). Having a cooler that is large enough works better, and coolers designed for racing are not the same as those found for street use. They are MUCH bigger.

The Ford auto, at least the new ones, can be reprogrammed so the line pressure is higher and the firmness of the shift is *feelable*. On the older C6's, they can have a shift kit installed.