AT Fluid Change?

[AJPG]

Originally Posted by finch1750

I am not sure how we could. OBD scanners just give the coolant temp under the ATF temp heading.

Yup! With the bigger rad (koyo) coolant temp are well controlled, but I want to increase the heat dissipation capacity of the trany, my mechanic said that currently "he thinks" is not necessary... But think about it, heat is the enemy or at least an independent risk factor for shorter engine/trany life and currently with FI...
Also we don't have oil pressure readings from the engine and IMHO we should.
I have the VIDI, it plugs to the OBD2 and have 2 aux that could be use for this things, but won't be log as they are parallel to the engine comp. currently one of the aux is been use for wide band and working fine... If I'm the first to measure the trany oil temp will post if not the first will post anyway

[finch1750]

Originally Posted by AJPG

Yup! With the bigger rad (koyo) coolant temp are well controlled, but I want to increase the heat dissipation capacity of the trany, my mechanic said that currently "he thinks" is not necessary... But think about it, heat is the enemy or at least an independent risk factor for shorter engine/trany life and currently with FI...
Also we don't have oil pressure readings from the engine and IMHO we should.
I have the VIDI, it plugs to the OBD2 and have 2 aux that could be use for this things, but won't be log as they are parallel to the engine comp. currently one of the aux is been use for wide band and working fine... If I'm the first to measure the trany oil temp will post if not the first will post anyway

Yeah. I have been really interested in figuring out what the temps really are and what they should be. If you could get an aux temp probe for the ATF im sure a bunch of people would appreciate it for sure.

[Sithspawn]

Originally Posted by AJPG

Anyone out there reading AT oil temps?

I just picked up some gauges to monitor temps and will be publishing the results of my testing pretty soon.

[Estey]

Originally Posted by Sithspawn

I just picked up some gauges to monitor temps and will be publishing the results of my testing pretty soon.

sounds awesome! Will you go into detail about your setup as well?

[Sithspawn]

Originally Posted by Estey

sounds awesome! Will you go into detail about your setup as well?

Other than some paddle shifter extensions, my car is otherwise stock. Since this car is known for having really high engine oil temps, I figured I would look into how hot the ATF fluid gets as well. Another member had mentioned changing the ATF after 3 track days so I am genuinely concerned about how hot the fluid gets. I mean, if temps are high enough to break down a synthetic ATF, imagine what that is doing to the clutches and seals long term.

As for the gauge setup that I am doing, I have an end game for it so my setup is overkill for the average enthusiast. I am going to be running a pair of Innovate MTX Oil Temp/Pressure gauges to monitor the temp and pressure of the fluid from the transmission to the factory cooler and the temp and pressure from the cooler back to the transmission. Since the Innovate gauges can do data logging, I can measure how quickly the fluid comes up to operating temperature and what the deltas are.

The reason I will be monitoring pressure as well is to establish whether or not a transmission cooler can be tied into the circuit without undue pressure drop.

I should have the necessary fittings tomorrow and get the gauges installed in the next day or two. Then I can start data logging and hopefully have results and analysis published around the middle to end of next week.

[aegisdrgn]

Originally Posted by Sithspawn

Other than some paddle shifter extensions, my car is otherwise stock. Since this car is known for having really high engine oil temps, I figured I would look into how hot the ATF fluid gets as well. Another member had mentioned changing the ATF after 3 track days so I am genuinely concerned about how hot the fluid gets. I mean, if temps are high enough to break down a synthetic ATF, imagine what that is doing to the clutches and seals long term.

As for the gauge setup that I am doing, I have an end game for it so my setup is overkill for the average enthusiast. I am going to be running a pair of Innovate MTX Oil Temp/Pressure gauges to monitor the temp and pressure of the fluid from the transmission to the factory cooler and the temp and pressure from the cooler back to the transmission. Since the Innovate gauges can do data logging, I can measure how quickly the fluid comes up to operating temperature and what the deltas are.

The reason I will be monitoring pressure as well is to establish whether or not a transmission cooler can be tied into the circuit without undue pressure drop.

I should have the necessary fittings tomorrow and get the gauges installed in the next day or two. Then I can start data logging and hopefully have results and analysis published around the middle to end of next week.

Subscribing for this!

[Sithspawn]

Update: I got the Innovate gauges installed and got everything to steady state at idle last night. Here's what I've discovered so far. The factory lines running to and from the factory cooler are low pressure lines. Cold start showed 12psi from the transmission to the cooler and 9 - 10psi from the cooler back to the transmission. This is good news since it doesn't look like you have to go crazy with high pressure lines and fittings: push lock hose and band clamps appear to be sufficient.

Steady state at idle showed the temperature coming out of the transmission to the factory cooler is 189 degrees and the temperature going from the cooler to the transmission is 192 degrees with coolant temperatures at 199 degrees. At these temperatures, the pressures were at 9psi out of the transmission and 8psi going back to the transmission.

Traditional ATF has been mineral based and these temperatures would be considered rather high as a mineral based ATF starts breaking down above 180 degrees. The Toyota WS fluid used in our transmissions is a synthetic fluid and can take a lot more heat before breaking down. Also, the WS fluid is relatively thin compared to other synthetics and has great thermal stability. Toyota uses this fluid in a number of other vehicles as well to help improve fuel economy.

While the fluid can take a good bit of heat, there are other components in the automatic that can't: seals and clutches. Generally, seals start to harden up around 260 degrees Fahrenheit and clutches will start to slip and degrade quickly at temperatures above 290 degrees. Therefore, we don't really want to be seeing temperatures above 240 - 250 degrees to ensure longevity of the transmission.

One other note is that while installing the gauge sensors, I captured some of the ATF that came out of the factory lines. With only 11k on the odometer, the fluid is starting to darken and there is a little bit of particulates in suspension. The fluid does not smell burnt, but it is getting a little wear. I have done a little spirited driving and I have noticed that the 1 -2 shift with the paddles is rougher than when the car was new.

I'm going to be doing some data logging today with a mix of normal (for me) street driving, highway cruising, spirited driving up and down a mountain pass as well as some light track driving at Adams Motorsport Park in Riverside, CA. Adams is a short technical track that comprises 3 laps per run with about 3 runs in a 1 hour session. The laps are 53 - 57 seconds long and back when I had my manual FR-S, I would top out 3rd gear on the main straight.

Stay tuned for more information as I acquire it.

[tonystewart]

Had much pressure loss would you anticipate running a set of lines to a cooler mounted to the condenser core ?

[aegisdrgn]

Excellent. Thanks for the update. Wish someone would do a UOA on the ATF, so we can have an idea if we need to change it.

[Sithspawn]

Update: I did not get a chance to do the mountain run, but I did take the car to the track as well as some street driving and highway cruise. Also, the highest pressures logged were 13psi. It seems the valve body regulates the line pressure to the cooler circuit and the pressure is typically 8 - 10psi.

Highway cruising at steady state came back with 194 degrees going out of the transmission and back in. Generally, it was very stable and only occasionally varying by a couple degrees.

City driving, however, had a lot more variation in temperatures (as to be expected), but they had a tendency to run a bit higher at 205 degrees coming out of the transmission and 201 degrees returning from the factory cooler. Here you can see the factory cooler actually bringing temps down compared to steady state at idle where the "cooler" was actually keeping the temperature elevated.

For the most part, the factory transmission cooler works great and does exactly what it needs to do when driving Miss Daisy, getting groceries and normal day to day driving.

When you take the FT86 to the track, however, we found that the factory transmission cooler just cannot keep up. At Adams Motorsport Park we ran the 3rd session of the night and it was 80 degrees Fahrenheit ambient temperature. A session consists of 3 runs (3 laps each) with approximately 10 minutes between each run. Each lap took between 51 and 55 seconds.

During the first session, the transmission outlet temperature started at 205 degrees and climbed up to 216 degrees. The return temperature from the factory cooler started out at 199 degrees and climbed up to 214 degrees. OK, no big deal the temperature isn't out of control and there is a 10 minute cool down before the next run.

The second session, however, showed that in 10 minutes, the transmission hadn't dumped the heat accumulated from the previous session and was still fairly warm with temperatures starting out at 214 degrees from the transmission and 212 degrees on the return. By the end of the session, temps had climbed to 228 degrees coming out of the transmission and 223 on the return. Notice that the cooler is only pulling 5 degrees of temperature from the fluid at this point.

Now for the 3rd session, the transmission has really started retaining heat as the outlet temperature remained at 228 degrees and the cooler is not doing so well now that the car is heat soaked with temperatures coming out of the cooler at 225 (only a 3 degree delta). By the end of the run, the temperature had climbed up to 244 degrees coming out of the transmission and 235 degrees going back to the transmission. My gauges were in the red by the end of the last lap and my co-driver called out over 240 as we were pulling into the pits.

Keep in mind that this is just a total of 8 minutes of track time with two 10 minute breaks on a stock car with stock power levels. Most HPDE's at a full size road course are 20 minute sessions. While I would be interested in seeing how high the temps go during a 20 minute session, I'm not really inclined to subject my transmission to that kind of abuse without proper thermal management.

The bottom line here is that if you track your FT86 and you have an automatic, you need a transmission cooler to keep the temps in check.

I'm still going to do a mountain run and log the temps to see how much sustained driving it takes to get the temps to 240 degrees. After that, it'll be time to hook up the cooler and see how it does.

Stay tuned for more.

[Estey]

geez, looks like a transmission cooler is a necessity. It freaks me out that you had temps like that in such a short amount of time. Ive put my transmission through a lot of abuse and i still havent even swapped out the fluids at 40k. Im sure spirited driving will end up with the same results.
I appreciate all the work you put into this, and Im sure that everyone else does too. I applaud you sir

[Sithspawn]

Update: I got a chance to do a mountain run today, but there were quite a few people going up the mountain so I didn't really get much of a chance to do a lot of spirited driving. For the short amount of time that I did have an opportunity to get on it, the temps did shoot up quite quickly.

According to my logs, I got 2 minutes and 15 seconds to open it up and drive at 7 tenths on a 5 - 6% grade uphill section with a few good turns. In that time, the transmission outlet temps went from 217 degrees up to 235 degrees. The temps from the factory cooler started at 212 and ended up at 223.

The interesting thing is that it took 38 minutes going an average of 40mph in traffic for the temps to get down to a more reasonable temperature of 212 degrees. Basically, once I got to the top of the mountain and had been driving for about 10 minutes, the temps came back down to normal.

Now I will say that "spirited driving" is rather vague and depends heavily on the terrain and the road you are driving on. Obviously, an uphill section is going to put more heat into the transmission than a downhill section where you are beating up your brakes more. Also, a relatively flat section that is full of tight hairpins where you aren't really going that fast and have very short sections where you are on the throttle isn't going to beat things up too badly even though you are having a great time.

Ambient temperatures also play a factor in the transmission temps. Down in the valley, temps were up at 106 degrees and up in the mountain, temps were 78 degrees. Remember, the transmission is an aluminum case and aluminum is great at conducting heat. The steel plates, drums, shafts and whatnot do store a bit more heat so it takes them a little longer to dump any heat they absorb.

The conclusion of this testing shows that even at stock power, an ft86 driven on the track really ought to have a transmission cooler. If you just use your car as a daily driver, never do track days or spirited driving, don't worry about it. If you do spirited driving, I highly recommend a transmission fluid temperature gauge, preferably one with a warning feature you can set for 250 degrees Fahrenheit (120 degrees Celsius). If you find that you are consistently hitting that warning on canyon runs or whatever, it's time to invest in a transmission cooler. Ultimately, this is a lot cheaper than replacing/rebuilding the transmission.

One last thing I'm going to do before installing the transmission cooler is get a UOA on the transmission fluid. I only have 11k on the clock, but with a track day and a few hard runs, I want to know how it is holding up.

Stay tuned for more updates after installing and testing a transmission cooler.

[Tye300]

@Sithspawn, do you encounter the AT shifting by itself at redline during manual mode when the temps are hot? I usually get it during the last couple of laps on the track. It seems to protect the tranny by shifting up at redline.

[Sithspawn]

Originally Posted by Tye300

@Sithspawn, do you encounter the AT shifting by itself at redline during manual mode when the temps are hot? I usually get it during the last couple of laps on the track. It seems to protect the tranny by shifting up at redline.

I have not encountered that issue. I had a customer with a G37 and 7AT that experienced it, but this is the first I've heard of it happening with our cars.

Edit: I just noticed you are supercharged. Your transmission could be getting very hot indeed. I'm going to be testing the transmission cooler with the airflow modifications tonight, so we'll see how it does. I won't be able to get the thermostat this week, so we'll be testing that at a later date.