Dirty Howie

Are you guys that run your tranny coolers bypassing the radiator getting good results. Please post your temps ..... especially in hot weather and if you run hard (canyons or track)

I'm thinking that once you are running hard in hot weather and your radiator (coolant) is up around 230 that having the tranny fluid running thru it is not giving much cooling effect. I think better cooling would be obtained bypassing the radiator and just letting the cooler do the heat exchange even though it may be 100 ambient.

Any real life experience or thoughts would be appreciated.


DH

tiojames

I have the cooler on my vert running thru the radiator. I had a deisel suburban with a built turbo 400 and hi-stall convertor that did not go thru the radiator. The engine was over 600 HP and the vehicle weighed over 7,000 lbs. and never had any heating problems with the tranny. You would probably be okay to bypass the radiator as long as you are not in really cold weather as the radiator is used to warm up the tranny fluid in cold conditions.

Dirty Howie

Thanks for that info.

It seems like the cooler inside the radiator would be good if its freezing outside. And maybe benificial if your coolant is running at 180. But at some point the coolant is going to be too hot to be as benificial as a straight heat exchanger with ambient temps 100+ degrees cooler than the radiator temps.


DH

16Again

PM sent

hotwheels57

I've always ran my external a/t coolers (B&M RACING stacked plate design) independent of the coolant radiator. This is contrary to what is recommended by the cooler manufacturers for the most efficient systems. I had the same thought process with the radiator contributing to the heat of the transmission, especially in AZ summer temperatures or rush hour traffic. I never had any "issues" with the transmission, either.
But, how do you know what your transmission temperatures are (aka "issues") w/o a temperature gauge in the plan?

MattB

The A4's have a temp gauge stock. Do you drive at HPDE events? or just around town. I don't have a problem around town, but at HPDE events the trans temp goes up a lot.

Dirty Howie

Glad to hear that it works for you .... I will probably have to try it.


DH

Dirty Howie

Matt

What kind of temps are you seeing on the track.....


DH

Dirty Howie

Talked to Tom Dewitt today. He was very gracious with his time

We discussed my plan ( as others have successfully done ) to bypass the internal cooler due to exessive tranny heat at the track....and just run thru the external cooler.

He said I could quote him here on the forum......

For applications where high tranny temps are concerned it is best to bypass the radiator!!! He feels that internal EOC is only benificial to HEAT up the tranny fluid....not to cool it down. That GM has it so that in cool climates the fluid is not too viscous.

He further noted that opposed to common belief it would be better to run tranny fluid first thru the external cooler and then back thru the radiator. This would give a more constant tempature to the returning fluid. This he says was proven by the people who make overdrive transmissions for the C1/C2 vettes.

Just thought I would update this post for those interested.....


DH

frank dupuy

Howie! I know you push your A4 tranny quite hard at the track. The only way to keep that A4 cool under extreme conditions is to use a large external cooler with or without running through the radiator. I find the placement of the cooler to be critical for maximum cooling. The C5 is very limited in this way. What I did recently on my SC C5 was to mount my tranny cooler behind the front license plate area. I then opened up the lower half of the front license plate cover and fabricate a ram air tube direct shot to my tranny cooler. This design channels the air at speed directly through the cooler. So far I have had good results with my design, just can't mount my license plate up front without cutting of ram air to the cooler.

Mr. Lucky

Interesting... so even though the total volume of fluid is less doing it this way, he still feels it will lower temps. Well, I guess he should know.

Dirty Howie

Bob

There isn't that much extra fluid ..... anyways I put on a B&M large tranny pan.

Tom told me that the ONLY reason he has internal coolers is because his compitition was doing it and his customers wanted it. He says REAL cooling is best accomplished with air cooled heat exchangers.


DH

16Again

I run my cooler as a stand alone and rarely see temps higher than 163* I think I saw 167* once this summer.

LeMansBlue04

DH sent me a PM today telling me I might like to take a look at what you guys are discussing here. (Thanks for the heads up Howie) He and I have been chasing the same problem and sometimes communicate privately.

I have a 402 with a Gear Star built A4, an SS3600 Yank and 3.73 gears, 470 RWHP and 461 RWTQ. I installed a Doug Dewitt's direct replacement radiator about two years ago. I was (yes was) originally running my A4 fluid through the radiator. When I got my original 346 CI motor up to 442 RWHP I had two transmission failures about a month apart. At the time I was using another transmission builder but when I put in the 402 I changed to Gear Star as a transmission builder. (They did a fantastic job by the way)

During this time my tuner and I decided to bypass the radiator cooler and use my B&M stacked plate cooler as the only method of cooling the A4. I have been running this way for over a year and it allowed the A4 to run cooler. For example, during street use I stay at around 169F even when the ambient temperature is 101F outside. However, I live in the Deep South and down here we rarely get below freezing. This means I have no need to pre-heat my A4 fluid with the engine coolant.

During a drag racing event this all works extremely well but a HPDE is another story. The process of getting off and on the throttle causes the SS3600 converter to generate an enormous amount of heat. This is because it slips so much and the resulting friction generates the extra heat.. This slip works wonders for drag racing but not for an HPDE. I know I need to change the converter to road race but that will impact my drag racing. Of course, I want a car that does it all but unless I can come up with a creative way to dump all that extra heat I can't do that.

I have been trying to find a place to add a second cooler with a fan on it. I could then tap into the A4 oil pan and use an electric pump to circulate oil from the pan, to the second cooler, and back again. I simply have not been able to find a good spot to install a second cooler in clean air.

Frank's suggestion offers me a possible option. I could install my second cooler behind the front plate if it will fit between my VaraRam ducts that are attached to the front screens. I would only need to turn this secondary system on during a HPDE, the rest of the time I could cover the plate area and turn off the secondary system. It sounds like it might work.

Dirty Howie

I want it all too My converter is smaller and my new cooler is bigger(7.5 x 22 inches) and I got the bigger pan. So we will see ..... next track day is Sept 9.

If necessary I will add a second cooler too. Maybe the B&M with fan so it can be placed out of direct air flow.

Frank is convinced that he gets better tranny cooling NOT bypassing the radiator. But putting a secondary cooler in this spot and opening the front licence area just for track days could be a good way to go.

Then again a new tranny every 1-2 years might be inevitable


DH

Dr. Pham

Andy,

I just wanted to follow up on what you said above.

Are you saying that the yank SS3600 is good for drag racing, but not good for HPDE?

And if so, are you saying it is not good for HPDE because the stall rating does not match the braking and accelerating nature of HPDE. Or is the stall rating fine, but it's the additional heat due to the slippage the real problem?

Thanks.

AU N EGL

Howie looks and reads like you should be getting a handle on your trans cooling issues.

Good to hear

LeMansBlue04

I like the converter, it's the heat it produces during an HPDE that's a problem. Because the event requires that you get on and off the throttle so much it causes the converter to build up heat.

AU N EGL

20 to 40 min sessions of WOT to 150 mph stomp on the brakes down to 30 mph, WOT back up to 100 mph slow to 50 mph WOT back up to 120 mph then stomp hard on the brakes down to 20 mph and WOT up to 150 again doing this every 2 min / lap for 20 to 40 min at atime is a bit hard on the car not to mention all the heat that is generated thoughout the drive train.

usd2sing

boy oh boy....does anybody else see this statement as being a total blast. fun. rush.