Hi all. I've been through a lot of struggles getting my a340e to hold 420whp in my 89 Supra. I wanted to share what I've learned through trial and error, research, and experience. I wish I had known some of this from the beginning...even having done extensive research ahead of time. Disclaimer: The following information is based on what I've witnessed & learned. I'm not a mechanic. If something is technically incorrect, please correct me you transmission experts.
Lesson 1) If you have an a340e and are upgrading your power in any way, get a temp gauge for your tranny fluid. It's well worth the $100. Temp tells you almost everything you need to know about the condition/performance/health of your tranny.
Lesson 2) Get an external tranny cooler with temp activated pushfan and make sure it's in a well ventilated area. Under the driver's headlight is good for 1/4 passes, but not canyoning holding 2nd/3rd gear for 5 minutes or more; for long term pulls I'd recommend putting the cooler near or infront of the intercooler. If it's under the headlight, a tip I learned is to have the pushfan push air down, remove the bottom part of the headlight black shroud, and remove the dustshield under that area (there is a separate dust shield for that corner for some reason); then you can open your headlight to create ram-air down through the cooler. Drops 2 degrees a second when cruising after a heavy pull. Cooling seems to be more effective if the tranny fluid lines bypass the original cooler lines through the radiator.
Lesson 3) Upgrading the a340e is only viable if you really want to daily drive your supra and want to make 3-450whp. After 450whp, the maintenance on the tranny isn't really worth keeping an a340e. Better off going with an upgraded TH350 with OD if possible or some of the new higher-end transmissions (6-speed auto duel clutch etc). The 6 speeds (TCI/Summit) will run you around 6k...but are well worth it for a daily driver with 500whp...and you'll get better fuel economy.
Lesson 4) Can't use a standalone (most standalones) with the a340e. I made this mistake when I bought my AEM...I had to get a Suprastick auto tranny piggyback. The main reason for this is that the a340e has a separate computer that talks to the stock ecu; making it near inoperable if you bypass/remove the main ecu for a standalone. If you don't want to deal with buying and programming a piggyback tranny ecu, then stick with engine ecu piggybacks that still retain the use of the stock computers. See piggyback lessons 6 & 11 below.
Lesson 5) Go all or nothing. If you upgrade the a340e, you may as well do EVERYTHING and not most things. Replace EVERYTHING that is remaining oem as well. I burnt one of my $2k builds just on having a faulty lockup converter solenoid that would stick once the tranny got up to 160F (one of the few pieces left from stock). I was able to diagnose the cause of the tranny failure once I got a temp gauge and used the piggyback to watch lockup signal vs. lockup activation.
Lesson 6) If you get a tranny piggyback, learn how to use it before you let a shop/builder use it. My builder didn't program it correctly, and it took me months of troubleshooting to figure out how he set it up incorrectly.
Lesson 7) Learn everything about a tranny, it's computers, torque converters, before you start paying others to upgrade/build stuff. They need your knowledge to accurately troubleshoot & fix any issues that come up.
Lesson 8) Find an amazing shop that will give you a warranty with a specified Horsepower limit and stick to it until all troubleshooting is worked out (I'm glad I did this right the first time. It's saved me a lot of money). The cost for my build with the 500hp shop 3-year warranty (kit had a 1 year warranty for 800hp) was $3,000...this did not include the bolt-on cooler/filter/lines/piggyback (another $800).
Lesson 9) Get a shift kit (like transgo) instead of shimming accumulators under higher power. My shims started causing problems with how my car shifted after a while...and shift kits are more reliable.
Lesson 10) Get good fluids like Redline Synthetic...and use an aftermarket external Tranny Oil Filter to clear out any sediment.
Lesson 11) If you run a lot of power, avoid shifting into 4th gear (O/D) while under heavy boost/throttle. The 4th gear uses fewer clutches and is less durable. To avoid 4th, always shift out of O/D when anticipating a pull/spirited pass (push the O/D button). If you have a piggyback, some (like Suprastick) will allow you to program not to upshift while under a certain throttle percentage (I program anything over 35% throttle to hold to redline in 3rd). If you are doing a quarter mile run, you have the option of locking up the converter at the top end of 3rd as an alternative to hold the gear instead of shifting to 4th (I have not practiced this, but should work in theory).
As of now, my a340e transmission is safely holding 420whp and is very reliable and great to drive. If I were to do it all again, I probably would have saved up my money and done the newer 6 speed auto conversions...and may still do that in the future. I hope this helps.
Lesson 1) If you have an a340e and are upgrading your power in any way, get a temp gauge for your tranny fluid. It's well worth the $100. Temp tells you almost everything you need to know about the condition/performance/health of your tranny.
Lesson 2) Get an external tranny cooler with temp activated pushfan and make sure it's in a well ventilated area. Under the driver's headlight is good for 1/4 passes, but not canyoning holding 2nd/3rd gear for 5 minutes or more; for long term pulls I'd recommend putting the cooler near or infront of the intercooler. If it's under the headlight, a tip I learned is to have the pushfan push air down, remove the bottom part of the headlight black shroud, and remove the dustshield under that area (there is a separate dust shield for that corner for some reason); then you can open your headlight to create ram-air down through the cooler. Drops 2 degrees a second when cruising after a heavy pull. Cooling seems to be more effective if the tranny fluid lines bypass the original cooler lines through the radiator.
Lesson 3) Upgrading the a340e is only viable if you really want to daily drive your supra and want to make 3-450whp. After 450whp, the maintenance on the tranny isn't really worth keeping an a340e. Better off going with an upgraded TH350 with OD if possible or some of the new higher-end transmissions (6-speed auto duel clutch etc). The 6 speeds (TCI/Summit) will run you around 6k...but are well worth it for a daily driver with 500whp...and you'll get better fuel economy.
Lesson 4) Can't use a standalone (most standalones) with the a340e. I made this mistake when I bought my AEM...I had to get a Suprastick auto tranny piggyback. The main reason for this is that the a340e has a separate computer that talks to the stock ecu; making it near inoperable if you bypass/remove the main ecu for a standalone. If you don't want to deal with buying and programming a piggyback tranny ecu, then stick with engine ecu piggybacks that still retain the use of the stock computers. See piggyback lessons 6 & 11 below.
Lesson 5) Go all or nothing. If you upgrade the a340e, you may as well do EVERYTHING and not most things. Replace EVERYTHING that is remaining oem as well. I burnt one of my $2k builds just on having a faulty lockup converter solenoid that would stick once the tranny got up to 160F (one of the few pieces left from stock). I was able to diagnose the cause of the tranny failure once I got a temp gauge and used the piggyback to watch lockup signal vs. lockup activation.
Lesson 6) If you get a tranny piggyback, learn how to use it before you let a shop/builder use it. My builder didn't program it correctly, and it took me months of troubleshooting to figure out how he set it up incorrectly.
Lesson 7) Learn everything about a tranny, it's computers, torque converters, before you start paying others to upgrade/build stuff. They need your knowledge to accurately troubleshoot & fix any issues that come up.
Lesson 8) Find an amazing shop that will give you a warranty with a specified Horsepower limit and stick to it until all troubleshooting is worked out (I'm glad I did this right the first time. It's saved me a lot of money). The cost for my build with the 500hp shop 3-year warranty (kit had a 1 year warranty for 800hp) was $3,000...this did not include the bolt-on cooler/filter/lines/piggyback (another $800).
Lesson 9) Get a shift kit (like transgo) instead of shimming accumulators under higher power. My shims started causing problems with how my car shifted after a while...and shift kits are more reliable.
Lesson 10) Get good fluids like Redline Synthetic...and use an aftermarket external Tranny Oil Filter to clear out any sediment.
Lesson 11) If you run a lot of power, avoid shifting into 4th gear (O/D) while under heavy boost/throttle. The 4th gear uses fewer clutches and is less durable. To avoid 4th, always shift out of O/D when anticipating a pull/spirited pass (push the O/D button). If you have a piggyback, some (like Suprastick) will allow you to program not to upshift while under a certain throttle percentage (I program anything over 35% throttle to hold to redline in 3rd). If you are doing a quarter mile run, you have the option of locking up the converter at the top end of 3rd as an alternative to hold the gear instead of shifting to 4th (I have not practiced this, but should work in theory).
As of now, my a340e transmission is safely holding 420whp and is very reliable and great to drive. If I were to do it all again, I probably would have saved up my money and done the newer 6 speed auto conversions...and may still do that in the future. I hope this helps.
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