Re: De-electronify 42RE (was re:Signal light)

[farna@xxxxxxx]

I don't know specifically about the 42RE, but the AW-4 computer uses a speed sensor and a throttle position sensor for determining shifts. Of course the selector lever also came into play. The computer apparently computed what gear the trans should be in from demand (throttle position) and speed (in relation to throttle position and of course selector lever position). The GM electronic autos do pretty much the same, so the 42RE should. There are some hydraulic limits, but as far as I know just for down shifting. My AW-4 will attempt to start in fourth gear if I have the switch in that position. 

I was referring to a fully manual controller like I made. I simply have a four position rotary switch (well, six position from RS, that's all they carry) wired to power the correct solenoids. The AW-4 has two for shifting -- both on is one gear, #1 on #2 off, #2 on and #1 off, then both off (the only thing I recall from memory is both off is 4th, or OD). I used a couple diodes to prevent back feeding the lines when jumpering the switch. Only thee wires are needed -- +12V and the two for the solenoids. Just disconnect from the computer (or trans) and tap into the two solenoid lines. The AW-4 connector (87-95 stand alone computer) is more or less a doubel ro header connector, female on the harness. I just tinned the ends of the wires with solder and stuck them in the appropriate holes. I thought about a slide or for position toggle switch (if one's even made), but the rotary is safer. It's almost impossible to accidently bump it into another gear. 

I also used a fourth wire and a separate switch for the lock-up torque converter. If I want to start in second, or stop in second, I can switch the lock-up off. This comes in handy in traffic jams -- reduces shifting. The AW-4 locks up in all but first gear. For normal driving I leave the converter switch on and just remember to "turn down" to first gear when coming to a stop. If you forget the engine will remind you -- it will stall just like not pushing the clutch in when you brake in a stick shift car. 

The only problem is placement of the manual shifter. I have mine hanging on the side of the console I absconded from the same Eagle Premier I got the seats from. My right hand hangs right over the switch when I have my arm on the rest. Without a console it would be tough to mount it in a convenient place. I think you and I talked about an up-down push button arrangement, but unless it could be mounted on the steering wheel it wouldn't be much good. A little transmitter clamped to the steering wheel would be neat -- otherwise wires would wrap around the column. If the transmitter deal could be done and then zip tied under a steering wheel cover it would be great and I think marketable. Or even a foot operated switch. A foot switch could be made to coninuously cycle the gears -- 1-2-3-4-1-2-3-4-etc. No down shift at all, to go from 2 to 1 tap three times. Sort of like an old Lenco racing ratchet shifter for a four speed. Include a number display or line of LEDs and that would !
 work we
ll for a strip car and some customs, and be marketable as a manual shift. For street use you'd have to be able to shift at least from 4th (OD) down to third. 

There really should be some kind of safety to prevent accidental shifting from 4 to 1 though. Most transmissions have internal protections though -- the BWs all do. Even the AW-4 won't shift from 4 to 1 over 25 mph. At least it isn't supposed to -- I haven't tried it!! Shouldn't be hard to use something like a STAMP as the step controller (operating a relay board) and include a relay to prevent shifting over a certain speed though. IIRC the BW trans will down shift through the gears at the internal max speeds if you did happen to shift from 4 to 1 and leave it. I'm just not sure of using the simple cycling circuit for a street car and relying on the hydraulic safety in the trans. I don't think anyone else would like that idea either! 

--
Frank Swygert
Publisher, "American Independent 
Magazine" (AIM)
For all AMC enthusiasts
http://farna.home.att.net/AIM.html
(free download available!)

original message----------------------------------
Subject: Re: De-electronify 42RE (was re:Signal light)
From: Tom Jennings <tomj@xxxxxxx>
To: mail@xxxxxxxxxxxx
Date: Sun, 26 Mar 2006 18:47:42 -0800

On Sun, 2006-03-26 at 14:14, farna@xxxxxxx wrote:
> It's not hard to make a manual controller for any electronic auto trans like I 
did. The downside is you have to change the gears once it's in park. I don't 
mind -- I get better mileage by watching my vacuum gauge and tach, then shifting 
accordingly -- especially when towing. One of the GM stand alone TCMs could 
probably be re-wired to work, but that depends on how close the GM trans is to 
the Chrysler in function (meaning how the solenoids are arragned for shifting). 
They could surely be reprogrammed to work. Maybe one of the TCM companies would 
be interested if enough people wrote and suggested such? 


How big a "market" is there for a deelectronification controller? Whatsa
interface? I know nothing about this trans; are you talkign about making
it a "push-button manual valvebody" type thing? Did the original car
computer calc all shift changes?