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

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I've been looking into using a hydraulic A442F behind a 4-banger diesel such as a Cummins 4BT, Toyota 15B, Mitsu 4D34, etc. There are provisions out there to physically mate up the transmissions, but I'm not sure about the shift points as the transmission originally came behind the 6-cylinder 1HD-T which is meant to rev higher than these engines.

My understanding is the hydraulic A442F shifts based on two parameters: throttle position (determined by the throttle valve cable) and the governor located in the rear of the transmission. Hooking up the throttle cable (often called the 'kickdown cable', although I don't think that's technically correct) wouldn't be too much of an issue. It's the governor I'm more worried about as that is what references engine speed.

Does anyone know if/how the shift points could be modified? If the governor is a centrifugal type, the weights in it could be modified. If that's not possible then the next place to look would be the governor valve in the valve body. Anyone have any experience or ideas with this?
 
No direct experience here, but it's a machine. It CAN be mod'd. The question lies with whether it makes sense to. I'll be interested to see where this goes.
 
The A442F was offered with fully hydraulic actuation on the 1990-1992 HDJ81's.

I swear there must be 1,000 threads explaining this at this point

Due to the lack of model differentiation I'd wonder if you could use a 440 valve body then cause almost nothing acknowledges that a fully hydro a442f exists, though I believe it.
 
Due to the lack of model differentiation I'd wonder if you could use a 440 valve body then cause almost nothing acknowledges that a fully hydro a442f exists, though I believe it.
The valve body is unique as there are passages in the case unique to the hydraulic A442F that neither the electronic A442F nor the older A440F have. But the hydraulic A442F is basically like a hybrid of the 440 and the electronic 442. Externally it is almost identical to the electronic 442 with the shift linkage on the driver's side and the PRN switch on the passenger side (this is flipped on the 440). Basically it uses the 442 case design and stronger internals, but uses a mechanical governor and throttle valve similar to the 440.
 
Looks like Wholesale Automatics in Austrailia are the only ones offering anything for this very specific oddball trans...


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Yep they are indeed the go-to guys for VB upgrades, although that goes for pretty much any model of A44x. I’m pretty sure the VB is the only significant unique part to the hydraulic A442F anyway, the rest of the parts should interchange with other A44x transmissions.
 
So I use a Mega squirt to run my A343F behind my 6bt, the swapping and using the Aisin transmissions you need a modified Torque converter and either a adapter plate or a custom bell housing also the TC had a special piece machined to be able to mount on the Cummins flex plate. So just trying to change the parameters/ shift points will not work very well due to the stall speed of the TC
 
So I use a Mega squirt to run my A343F behind my 6bt, the swapping and using the Aisin transmissions you need a modified Torque converter and either a adapter plate or a custom bell housing also the TC had a special piece machined to be able to mount on the Cummins flex plate. So just trying to change the parameters/ shift points will not work very well due to the stall speed of the TC
Yes I know all about TC stall speed. You can either have the stock converter cut open and modified to lower the stall or just buy a converter with a lower stall from WAT or other outlets as well. But, if you got a version of the A44x that was behind a 1HD, 15B, 4D34 etc. I imagine that the stall speed is already much lower than the gasser TC used with the 1FZ.
 
Yes I know all about TC stall speed. You can either have the stock converter cut open and modified to lower the stall or just buy a converter with a lower stall from WAT or other outlets as well. But, if you got a version of the A44x that was behind a 1HD, 15B, 4D34 etc. I imagine that the stall speed is already much lower than the gasser TC used with the 1FZ.
Well it sounds all peachy but you still need to mount it to the flex plate and I just read that the Toyota diesel revs at 3800 RPM which is 2K more than a happy Cummins, and it would not work the way you want .
 
Well it sounds all peachy but you still need to mount it to the flex plate and I just read that the Toyota diesel revs at 3800 RPM which is 2K more than a happy Cummins, and it would not work the way you want .
Flex plate adapters are not particularly difficult to manufacture if one cannot already be found. You can also cut the backing plate off of another converter and have it welded onto the A442F converter to make an adapter that way. This would only be applicable for the 4BT anyway, as all of the other engines I mentioned have some form of the A44X as their stock transmission so a flex plate/converter setup that works should exist.

The 1HD redline is 4200RPM, which is the same as the 4.1L 15B as far as I know. A stock 4BT can only safely rev into the low 3000's, but a 4BT that has been blueprinted/balanced and has proper valvetrain upgrades will have no problem revving to 4200RPM as well. Many competition 4BT's spin even faster than that.

But this really doesn't matter. My entire point is that the 1HD tends to make power at higher RPM's than the 4-banger diesels of similar displacement. So I am looking to lower the shift points of the stock hydraulic A442F. None of this has anything to do with redline, it's all about the power curves of each engine.
That there is a waste of money, you can just buy the shifter kit from Transgo and do the Mod's and get the same results, and you will have left over money to buy more gas :flipoff2:
Really? Please provide a link to a Transgo shift kit for any Aisin A44x transmission. Because as far as I know, it doesn't exist. So please do not spread misinformation.
 
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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
 
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 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.
 
My 80 is the first auto that I have owned and I don't know much about autos at all. I have the full hydraulic A442f from Wholesale Automatics. I am very happy with the trans. One thing I noticed was that it seemed like my shift points seemed be lower when I switched from stock tires to 315s. Could it be that easy? Where are you looking for your shift points to be roughly?
 
My 80 is the first auto that I have owned and I don't know much about autos at all. I have the full hydraulic A442f from Wholesale Automatics. I am very happy with the trans. One thing I noticed was that it seemed like my shift points seemed be lower when I switched from stock tires to 315s. Could it be that easy? Where are you looking for your shift points to be roughly?
Well the tires are basically the last gear in the drivetrain, so by going to bigger tires it could indirectly affect transmission shifting as you've changed the ratio. You've changed the relationship between engine RPM and forward speed slightly.

Honestly I'm not totally sure about the shift points, I would just ballpark a couple hundred RPM's lower than the stock 1HD points and tune from there. Keep in mind that the shift points are not linear as it is determined by two parameters (throttle position and output shaft speed). So the transmission will shift differently if you're at WOT and low RPM, compared to only a little throttle at a higher RPM. It's all about how the throttle cable & governor affect the throttle valve and governor valve in the VB.
 
Yes sir. I adjusted my throttle cable tighter to move my shift points back up. It seems to have basically worked. I want to say it was shifting at 2000 rpm (ish) when I went bigger tires.
 
Yes sir. I adjusted my throttle cable tighter to move my shift points back up. It seems to have basically worked. I want to say it was shifting at 2000 rpm (ish) when I went bigger tires.
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.
 
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.


If it's a hydraulic trans it has to have a rotating governor, I'd wager there are weights in there to change out. But given the rarity of the trans the science isn't as straight forward and figured out as say an old GM trans
 

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