TheTanSedan, I am rather critical of these setups so I expected a lot of heat!
I have seen these units fail so many times I just can not see useing them unless you have too. If you really have the need for one then fine but to add one just to add one????
The reason OEMs do it is because they already have the worthless one built into the radiator of just about everything with an automatic trans. It is much easier for them to plumb in an additional one as an aux. off of the worthless one already on in the rad. side tank. It would cost them more to design and valadate yet another radiator without it and then put an air only cooler up front. It would also complicate the dealershps ability to easily add the aux. cooler to any customers vechile easily and cheaply.
If the puny worthless heat exchanger/cooler in the rad. tank was worth haveing you would not have to add an additional aux. cooler. The more plumbing you have the more leak paths you have. A hydralic hose or fitting will always fail when it is going to cost you the most! The more plumbing you have on a truck the greater the chance of it getting snagged.
If a cop car breaks down he can call dispatch and he will be rideing home nice and warm in no time! If you are in the middle of death valley your aux. plumbing fails who is going to save you! If you are in Minasota and you spring a leak in the dead of winter on a back road who is going to save you.
Now on the other hand if your truck had no cooler at all and you were driveing through death valley with a trany full of Amsoil I am sure you will be ok. If you are in Minasota and you trans is full of Redline and has no aux plumping to fail again you are just fine!
A lot of the stuff on police cars is really of no practical value to the normal citizen. A lot of police cars have a little metal bracket that prevents downshift to L. This is to keep them from tearing up the trans by missed shift. Stab resistant seats with memory foam is another worthless featyre they have if you are not a cop. Courtey lamp defeat yet another. How about the ability to keep the engine idleing with the key out of the ignition etc........ Just because it is on a cop car does not really mean it is really going to make life better for the daily driver!
You can get most all of the benifits of a cooler by simply putting in a heavily ester based synthetic atf fluid. THe great thing about synthetic is that the benifitt is their if you have a cooler or not. You are not going to creat more potential leak paths buy chageing the fluid. You even add it to the ex-cop car if you like.
Thetansedan, When GM was testing an experimantal esterbased trany fluid at their Arizonia testing area they could not keep the standard fluids temps within limits at all. Under some conditions the fluids went well past 480F. This was useing a trailer towing dyno. It simulates various loads at each speed while being towed up a hill. The hill in this case was bakers pass if my memory is correct. Once they put the all synthetic ester based trany fluid in they could not get it to exceed 231F under the exact same conditions. THe ATF was custom made for this application and is not available to the public at all. So this ester based AT did what the cooler could not do!
It is an SAE paper but I no longer have copy of it at home. If ever I get a slow day at work I will try to look for it!
Note that I am not disagreeing that cooler work and can extend the life of a transmission. I am just pointing out that it is like cosmetic surger. Everytime you do unneeded surgery their is a chance that the complications latter on might out weight the potentialy rewards. The more like a Rube Goldberg device it becomes the likely the outcome will be the best!
[ June 12, 2004, 02:01 AM: Message edited by: JohnBrowning ]