Transmission Cooler Recommended?

<div class='quotetop'>QUOTE(NoMoShocks @ Apr 22 2007, 02:19 AM) [snapback]427687[/snapback]</div>

See Bob Wilsons analysis of the Classic Prius Transmission.

http://hiwaay.net/~bzwilson/prius/pri_T_cold.html

for an analysis of Prius transmission operation. I seem to remember that there are a few Prii running around with add-on transmission coolers.

Jeffd

 

Transmission coolers basically simply require some "plumbing"... A transmission guru is not necessary for the installation. Just make sure whatever you select comes with fittings and hoses and take your time with the install. I have tranny coolers on all my cars just for extra protection. Be very detail oriented and anal with the installation as blowing a cooler hose will shoot transmission fluid under your tires and that is never a good thing. I almost put my camaro into the right hand wall at the track one day when I blew a tranny line about 30 feet off the starting line and the right rear tie started spinning while the left hand tire had plenty of traction... I have never felt a car take such an abrupt turn without my using the steering wheel.

Of course, the 0-60 time in my Camaro is about three seconds flat so it is far more extreme than the Prius, but the message it sent me is very clear... transmission fluid is very slick stuff and if it sprayed the front wheel while decelerating it would not be a very pretty sight.

However, a good cooler will not hurt your car and properly installed will provide an extra measure of longevity for heat sensitive transmissions.

 

Strictly speaking, the Prius does not have a transmission. The PSD (power-split device) is basically a differential. (Frank thinks they actually took a stock differential from an existing model car.) The chances of a PSD failing are so extremely small that adding a cooling system to it is like putting sugar on a Hershey bar.

 

<div class='quotetop'>QUOTE(NoMoShocks @ Apr 21 2007, 11:19 PM) [snapback]427687[/snapback]</div>

A transmission cooler is generally indicated if you either tow a trailer or have modified the torque converter (in a traditional a/t). It (a transmission cooler) will not keep the fluid clean, only reduce heat-induced breakdown of the chemistry of the fluid. A more productive move for longevity of parts is to replace the transmission fluid at the first 5,000 mile point and then thereafter at every 30,000 miles.

 

<div class='quotetop'>QUOTE(jdenenberg @ Apr 22 2007, 04:04 AM) [snapback]427717[/snapback]</div>

Jeff, those are fluid filters, and IFixEm here put one on mine. I just took a peek at it after 12k miles and could not see any particles inside the (clear) filter case.

 

<div class='quotetop'>QUOTE(apriusfan @ Apr 22 2007, 01:21 PM) [snapback]427854[/snapback]</div>

Right, but this is required due primarily to the action of the torque converter itself (stock or otherwise), which creates lots of heat. Especially when it's under heavy load.

I don't believe that the mechanical design of the PSD is such that it creates any significant amount of heat. It does not use a torque converter (i.e., spinning vanes, which change pitch, in a bath of transmission fluid) for torque multiplication, and there is little other mechanical 'slippage' inherent to this design.

I would suggest that a PSD cooler is unnecessary for these cars, and will not extend the life of the PSD in this application.

But, it will provide additional possibilities for frying the PSD...due to fluid loss from a leak in the cooler or supporting hardware/hoses.

 

<div class='quotetop'>QUOTE(Pinto Girl @ Apr 23 2007, 10:55 PM) [snapback]428597[/snapback]</div>

Actually, the whole combination of PSD, battery, invertor, motors etc. could be classified as a torque converter. It does after all convert the low torque output of the ICE into high torque output via the electric motor. And like any torque converter, this contraption does generate heat, but in the electric path, not mechanically. So we have an inverter cooling system instead. The effect of it all is the same: engine running like it has a "slipping clutch", high torque at the wheels.

 

<div class='quotetop'>QUOTE(lowlander @ Apr 23 2007, 04:06 PM) [snapback]428604[/snapback]</div>

Thank you!! Nicely said, in my opinion.

 

Thinking about this a little further, I think our PSD's are already cooled by the bottom half of the radiator, If I remember correctly, the inverter cooling loop already runs through the motors/PSD, dosen't it? I haven't looked at that area in awhile, but I do seem to recall plumbing down there, not just for the inverter itself.

So... I think our vehicles already come with a cooler???
Of course, that is a WATER loop, not an ATF loop.

 

Yes, both inverters and both electrical motors are liquid-cooled (by SLLC in the new Prius model), along a common path. The transmission fluid is in the trans. also , but physically separate. It may also have a minor role in transferring heat away from the motors.