My transmission on my 07 GT 6sped Auto burned up a few weeks ago with 22k miles.

It had some slippage at 2k miles, fluid checked at 2 quarts over, and drained off.

Mazda and dealer immediately ordered a new one, and it was fixed in ten days.

So I'm at least good as new again, but the experience made me dig harder for the ATF temp codes which I found on a Miata site.

TXD:07E12217B3

RXF:0462051706B3

RXD:3008

MTH:001B0010FFC6

NAM:ATT

Running around while ago for about 15 miles in light town traffic with 73 deg f ambient gave about 180 - 200 deg on water, and the trans temp would follow slowly towards that up to about 195 deg.

When I'd caost out for a light the water might go back to 185 deg, but the trans temp would keep what it had longer than the water.

So my conclusion is that I'll watch and look toward the auxiliary trans cooler mod.

 

That's cool man, not sure what tranny temp fluid should be but 200F seems acceptable to me, assuming fluid levels are correct and changed on schedule.

 

There's some chart that show temps over 300 deg f killing the fluid in 5k miles, 220 deg lasting maybe 30k miles, and I'm pretty sure some of the seals om this AISIN trans are fragile under 250 deg.

That 200 deg was under a short burst to hear the new BHR ign roar from 20mph to about 60mph. A curvy road accelerating from 30mph to 90 mph might really put a heat load number on it.

BHR has a AT water rad for $550. that would probably work well, but the water only got to 215 to 220 max when the tranny went so I'm going to explore the DIY ATF cooler auxiliary rad mod. for under $100.

Would you be up to the install? It's a small rad clipped to the mesh in from of the water rad, and some small hose bypass.

Also, could you ask Jose what kind of fluid they used in the trans, and any temp recomendations.

 

Adding an additional inline ATF cooler would be pretty simple. I have done similar things on my dads various Jeeps. I am always down, I am planning to add an extra radiator in one of the empty slots where my factory oil coolers used to be.

You could even go crazy and install one with a fan and thermo switch for pretty cheap. when looking into adding a second radiator I found a ton of options on Ebay and from some race part sites.

This is made by Derale and runs about $25.00.





something a little bigger like this is about $45.00

 

A good operating temperature of an automatic transmission is 160º
to 200º F as the fluid exits the cooler. If you can
maintain fluid temperature below 175º F the fluid
should last for as much as 100,000 miles. At 195º
F the fluid life should be 50,000 miles. At 240º the
fluid life is only 5,000 miles. Higher fluid
temperature drastically reduces the life of the
fluid. Cooler temperature equals longer fluid life.

 

Yeah, like that!

I'll keep watching the temps when spring comes, then do something with you.

I looked up Aisin transmissions, and found a six speed for a VW where they talked about counter measures to lower temps at 250 degs and 300degs so that clues me in that it should live at the max water temp I've ever seen : 229 deg f.

Or Invasion08's idea is even better that I definitely need to do it to keep temps under 200 deg f.

 

All this said, I've noticed VERY few (almost none) reports of A/T failures in the RX-8, and there are plenty of them out there. Unless the car is being tracked regularly, I'm wondering if there is really any cause for concern, other than regular fluid changes...

 

Yeah, I don't think there is an issue overall with the tranny. REDRX3RX8 does track his car but he noticed issues with the tranny from day one and discovered it was overfilled so likely that had something to do with it.

 

I get my transmission flushed every 15k

 

I notice you've got a Level 10 trans, so I guess draining at 15k is a real good idea.

Why did you change, and does it perform better or different.

I assumed the stock Aisin 6spd auto was good enough to shift around while running down curvy roads, and that the hard use would be stop and go traffic, which I only get when I go to the cities.

I'm leaning toward a Mishimoto cooler kit, which'll cost less than $100.