Could the Shift Points of the Hydraulic A442F be Modified? (1 Viewer)

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For whatever reason the bigger 44x transmissions don't live behind turbo'd 1FZ's even with the expensive WAT VB's but the 343's do with the cheap shift kits. Probably just being able to easily increase clamping force.
 
Interesting. I guess you could mess with the throttle cable in order to change the relationship between those two valves, but you don't want to go too far with this as you need pressure going to both valves in order for the transmission to shift properly. So if you went too extreme on the TV cable adjustment such that the transmission was trying to shift when there wasn't much pressure going through the governor valve, I'm fairly certain you could damage something. It's impossible for me to say for sure without one of these valve bodies disassembled in front of me though.

Just keep in mind that an automatic transmission uses the fluid as hydraulic oil to actuate servos, apply pistons, etc. So if there is low pressure coming from one valve but the transmission tries to shift due to excess pressure in another valve, that could be a bad thing. It all depends on how the VB is designed though.
Yes sir, you make good points. I don't know how the valve body is designed. Also, I have a wholesale manual valve body on it. (I don't know if that makes a difference) I deliberately made small adjustments, attempting to prevent "overadjustment", if you will. When the trans went from shifting around 2000 rpm to 2500ish rpm under normal conditions (this also triggered a gear kickdown at approx 75 or 80% throttle, which allowed the trans to stay in lower gear all the way to redline) I stopped adjusting. I've run it for approximately 75,000 miles this way and it seems to be happy. I'm not sure where max torque is on a 4bt. But, 2000-2200 rpm seems to be a good shift point on my buddy's 6bt. I wonder if just putting 315s and leaving the trans alone would allow you to get what you need out of it.
 
For whatever reason the bigger 44x transmissions don't live behind turbo'd 1FZ's even with the expensive WAT VB's but the 343's do with the cheap shift kits. Probably just being able to easily increase clamping force.
Do you know the ways in which they fail?

it seems like the A4xx transmissions are much better suited to low RPM shifting so on a turbo 1FZ I could see why the A3xx is a better fit.

Also the ‘torque management’ on the 442 is much more rudimentary, so the more electronically complex 343 has the advantage with an electronic engine in that sense. But with a mechanical diesel obviously that doesn’t matter
Yes sir, you make good points. I don't know how the valve body is designed. Also, I have a wholesale manual valve body on it. (I don't know if that makes a difference) I deliberately made small adjustments, attempting to prevent "overadjustment", if you will. When the trans went from shifting around 2000 rpm to 2500ish rpm under normal conditions (this also triggered a gear kickdown at approx 75 or 80% throttle, which allowed the trans to stay in lower gear all the way to redline) I stopped adjusting. I've run it for approximately 75,000 miles this way and it seems to be happy. I'm not sure where max torque is on a 4bt. But, 2000-2200 rpm seems to be a good shift point on my buddy's 6bt. I wonder if just putting 315s and leaving the trans alone would allow you to get what you need out of it.
Sounds like you have it set pretty optimally then. WAT makes a full manual VB for the A442F? I thought they only had their ‘nomad’ and ‘extreme’ VB’s available.

The torque curve of a 4BT will be very close to that of a 6BT btw
 
Do you know the ways in which they fail?

it seems like the A4xx transmissions are much better suited to low RPM shifting so on a turbo 1FZ I could see why the A3xx is a better fit.

Also the ‘torque management’ on the 442 is much more rudimentary, so the more electronically complex 343 has the advantage with an electronic engine in that sense. But with a mechanical diesel obviously that doesn’t matter

Sounds like you have it set pretty optimally then. WAT makes a full manual VB for the A442F? I thought they only had their ‘nomad’ and ‘extreme’ VB’s available.

The torque curve of a 4BT will be very close to that of a 6BT btw
I do not, I just know on the turbo FB group they all have issues with their 44x transmissions and they spend big money trying to upgrade them. They did not get the 343 there, while I know many 343 transmissions behind turbo 1fz, and at least 3 6bt trucks and the 343 keeps kicking along. Could it be that if properly tuned/built the 44x could be a stronger transmission? Sure. But as I have seen it build with "Nomad" valve bodies and upgraded clutches and steels for whatever reason it does not seem to do the same job as the 343 does.
 
I do not, I just know on the turbo FB group they all have issues with their 44x transmissions and they spend big money trying to upgrade them. They did not get the 343 there, while I know many 343 transmissions behind turbo 1fz, and at least 3 6bt trucks and the 343 keeps kicking along. Could it be that if properly tuned/built the 44x could be a stronger transmission? Sure. But as I have seen it build with "Nomad" valve bodies and upgraded clutches and steels for whatever reason it does not seem to do the same job as the 343 does.
I know a good amount about transmission building & design, and while I'm certainly not an expert, based on what I have seen with Aisin A4xx transmission they do not really belong behind gasoline engines. At least not higher-revving OHC engines.

Those drums, planetaries etc. that are in the A4xx are beefy as hell. And while that makes them strong, it also makes them heavy. As they rotate faster, they have exponentially more rotational kinetic energy (E = I*w^2). And that means that every time a forward, direct, or brake clutch pack acts on one of these components to speed them up or slow them down, it puts a lot more wear and tear on the clutches and steels.

The A4xx transmissions are ideally suited for engines that seldom rev part 3000RPM, and very rarely rev past 3500RPM. Which is the vast majority of the applications in which they were used, with the 1FZ being the exception and not the rule. They are perfect for going behind a 4-banger diesel like I am looking to do.

The A3xx was designed with higher-revving DOHC engines in mind (just look at the applications it was put in), and while the 'hard parts' are certainly weaker, they are lighter, and therefore much more suited for higher-RPM applications. I haven't studied any dyno charts from turbo 1FZ's, but I imagine 3000RPM is where they really start picking up. Whereas that is the RPM where most 4-cylinder diesels are pretty much out of breath.

In my mind, putting an A442F behind an engine like a turbo 1FZ is misguided and shows a lack of understanding of automatic transmission engineering. It's a shame that so many people see automatics as a 'black box' function where you just hook it up to an engine and power comes out the back, when in reality they are like a matched pair that need to be tuned together.
 
I know a good amount about transmission building & design, and while I'm certainly not an expert, based on what I have seen with Aisin A4xx transmission they do not really belong behind gasoline engines. At least not higher-revving OHC engines.

Those drums, planetaries etc. that are in the A4xx are beefy as hell. And while that makes them strong, it also makes them heavy. As they rotate faster, they have exponentially more rotational kinetic energy (E = I*w^2). And that means that every time a forward, direct, or brake clutch pack acts on one of these components to speed them up or slow them down, it puts a lot more wear and tear on the clutches and steels.

The A4xx transmissions are ideally suited for engines that seldom rev part 3000RPM, and very rarely rev past 3500RPM. Which is the vast majority of the applications in which they were used, with the 1FZ being the exception and not the rule. They are perfect for going behind a 4-banger diesel like I am looking to do.

The A3xx was designed with higher-revving DOHC engines in mind (just look at the applications it was put in), and while the 'hard parts' are certainly weaker, they are lighter, and therefore much more suited for higher-RPM applications. I haven't studied any dyno charts from turbo 1FZ's, but I imagine 3000RPM is where they really start picking up. Whereas that is the RPM where most 4-cylinder diesels are pretty much out of breath.

In my mind, putting an A442F behind an engine like a turbo 1FZ is misguided and shows a lack of understanding of automatic transmission engineering. It's a shame that so many people see automatics as a 'black box' function where you just hook it up to an engine and power comes out the back, when in reality they are like a matched pair that need to be tuned together.
Sounds like you’ve got it all figured out! Good luck.
 
I think the WAT VB is a pretty substantial upgrade; at the very least it allows you to lock the TCC in 3rd which is a pretty nice feature by itself, especially for towing.

If you really think the A343F is better, here's a video of Gary Ferraro (one of the most underrated Transmission techs on YouTube btw, his videos are great) tearing down an A340E (basically the 2wd version of an A343F):



And here he is tearing down an AW450 (very similar to the A442, most of the parts interchange):



As you can see, the A4xx parts make the A3xx parts look like child's toys. The drums, clutches, planetaries, are all way beefier on the A4xx. The A4xx transmissions were used for many years in box trucks, medium duty trucks, buses, and even the military Megacruiser, whereas the A3xx was used in passenger trucks and SUVs. The A3xx is like the Aisin equivalent to a 4L80e, whereas the A4xx is the Aisin equivalent to an Allison. The A3xx is a great transmission no doubt but the A4xx is just on another level.

Seriously though I don't want this thread to turn into another 'A442F vs A343F' debate so if we could keep it on-topic from here on out I would appreciate it.

My point with the adapters is that it's not that difficult to machine a simple adapter to put the right flex plate on the chosen engine. Or you can just modify the stock flex plate that came with the engine to accept the converter from the chosen transmission. Or, like I said, you can graft the right TC backing plate onto the transmission's TC, although this solution is a little more redneck. But there are many ways to skin a cat here.

Anyway literally none of this has anything to do with the original discussion I started this thread for. So if anyone has any ideas pertaining to modifying shift points on hydraulically-actuated A4xx transmissions, please chime in.


So I have spoken to a could of knowledgeable transmission guys and they all say the same thing about the modified bodies they are nothing special , as for as just putting a modified flex plate well the first one's broke and just machining up an adapter, to get a diesel to the 442 tranny is not that easy there have been several different attempts, and the best way is a bell housing and using the stock dodge flex plate . JMHO
 
Ok I did not see the 442 shift kit I stand corrected ( there is one for the better transmission the A343F ), but have been told by some knowledgeable Ozzy who told me that valve body is nothing but a waste of time, and other transmission guys, because there are no huge changes, you think it is easy to just pop out a flex plate they dude you should be in business, spitting them out , and I have never seen any on the market for a long time .
Now just grab 2 TC and weld up something that may or may not work, probably won't . Now adjusting shift points go buy a stand alone and go to town, that is what you can do. Oh yeah done a few swaps and done some prototyping for them, no 4 bangers only 6 BT and I have over 85K on my swap 97 A343F Micro squirt stand alone

I've been reading the microsquirt trans controller firmware manual and it mentions the A341 but not the A343, but I suspected it was very similar to control. Could you shed any light on what went into controlling the A343F with the microsquirt? I know that there are 3 solenoids and what gear you have selected determines which is on/off
 
:popcorn:
 
I've been reading the microsquirt trans controller firmware manual and it mentions the A341 but not the A343, but I suspected it was very similar to control. Could you shed any light on what went into controlling the A343F with the microsquirt? I know that there are 3 solenoids and what gear you have selected determines which is on/off
So the 341 340 are all the same transmission used by several companies, I am not the guy to tell you, I have not the ability I wish I knew more but it, was done by someone for me I am pretty sure if you understand the information on wiring them and follow their instructions I believe you can get it to work
 

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