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-   -   3.4L (5VZ) Automatic Transmissions (http://www.risingsun4x4club.org/forum2/showthread.php?t=20329)

AxleIke 10-08-2013 02:48 PM

3.4L (5VZ) Automatic Transmissions
Decisions Decisions....

For various reasons, I am considering an automatic for my 4Runner. Not seriously yet, just in the research stage. May not keep the truck at all, we'll see.

Anyway, the one downside of the A340 seems to be its affect on the power of the engine, whether it is high gearing, or possibly the power gets sucked away during shifts.

IPT will turn around a valve body in a few days providing crisper, and what I would assume, less power sapping, shifting, as well as a decent strength upgrade. They also sell a nice rebuild kit, and automatics look to be really simple to rebuild (hell, they always have guys on the car shows do autos with blindfolds on, never see that with a manual).

Essentially, I am looking to avoid a gutless wonder, but don't need the thing to be capable of jackrabbit stars off the line. As long as there is plenty of power for climbing the mountains (which it currently has), I'm good.

Is there anything else I should consider in the performance department? I'm not that familiar with the operation of autos', so I'd like to learn.

The second set of issues is making the swap work. I assume that while the A340 does seem to still use a hard, manual throttle connection, there is also a control module that talks to the main computer. Is this a separate unit, universal to the A340 and the 3.4, or is it integrated in the ECU, and therefore fairly year and model specific?

I have thought of cooling lines, cooler, pedal assembly and shifter pieces that are needed. I also assume the flywheel is different, but are the starters the same? Am I overlooking a major piece (I'm not worried about crossmembers or any thing requiring some fab, for obvious reasons).

I know UB is uber plugged into this but I didn't want to bend his ear forever as he is crazy busy at the moment. Thanks all!

thefatkid 10-08-2013 10:19 PM

The engine ecu is also the transmission control ecu. You will need the harness and ecu for the model/year vehicle. Some of the body harnesses have different plugs when switching from manual to automatic. This could create the need for a custom harness/cut and splice. If you have a wiring diagram for your model year, look at the engine ecu and see if there is a difference in connector name from auto to manual.

I can rebuild a manual faster then an automatic. I don't think either one is easier though. The auto will require less press work but more difficult clearance measurements. If you can do one, you should be able to do the other. A quality automatic build requires a cleaner person/workspace. A manual can live through a dirty technician but not an auto. So many seals, o-rings and small passages can't handle any dirt

I didn't like having an auto behind my 3.4 supercharged. It felt way slower/weak. The torque converter loss just seems to be too much. Overdrive is way too tall. When running loaded, I could slip the converter before it would come out of lockup. I was able to up the line pressure and change brands of fluid to stop that.

I'm not a 100% sure what IPT does, but shift points will still remain the same as they are ECU controlled. I'm sure they just raise the line pressure and change the accumulator springs to make it shift more firm. Remove some designed restrictions in the valve body plate so the clutches apply faster/firmer. Will it make up for the drag of an automatic, I don't know. I'd like to try/drive one though.

Uncle Ben 10-09-2013 04:47 PM

For an e-auto to auto shift it needs a computer as it has no way to sense engine load. You can do an econo set up and manually shift it up and down but if it's street driven that would be a PITA. Optimally, a stand alone trans computer would be the ticket as you could program it how you want it. The a340 auto's are very similar to each other so start snooping through Supra forums for tranny controllers. Older auto's did eat up a lot of available power but modern auto tranny's are much more friendly on the engine power robbing. Of course direct drive of a clutch/manual trans transfers the most power from engine to drive-train. An unexpected issue I ran into by having a full built auto is the fact that it holds too well! In 5:1 transfer case gears the brakes cannot stop the rig if the engine RPM is up. Idle or just off idle is no problem. 3:1 doesn't have as much of that effect but due to the aggressive clutches more effort is still required to hold the beast when dropping down steep rocks. I am now used to it so I can slide it in and out of neutral without really having to think about it. If and when I do it again I would run stock clutches and a enhanced valve body. It is much easier to put an auto in a manual equipped vehicle than the other way around! In a rock rig (or snow) you cant beat an auto for climbing. Brakes are a huge part of wheeling with an auto, so keep that in mind too. The guys at IPT are awesome and really know their craft! Tell them exactly what you want and they will build exactly what you ask for.....just make sure what you ask for is exactly what you want! :rolleyes:

AxleIke 10-10-2013 02:08 PM

Well, exactly what I was looking for, but bummer. This sounds to be as much work as an engine swap from a wiring standpoint, so if I were to go this route, I'd certainly consider a 4.7 or something similar to compliment the transmission! :D

Thanks Gents!

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