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AW4 Manual Shifting

jk333

NAXJA Forum User
Location
WA
so i read this write up and im wondering if converting the AW4 to manual shifting could help me in putting an AMC V8 in my Cherokee. If i follow this write up and do it, then will my AMC V8 work in my Jeep? would it be like putting a non electronic shifting transmission in, right. i know the bellhousing bolts right up. and ive got the flexlate thing covered. if anyone could clear this up for me i woul;d greatly appreciate it, thanks.

Parts Needed:


3 Pole Switch
Wire
Wire Tap

After taking out the Transmission Control Unit (TCU) and doing a few test, I figured out what wire did what. The TCU is located under the dash on the [COLOR=blue! important][FONT=Verdana, Arial][COLOR=blue! important][FONT=Verdana, Arial]passenger [/FONT][COLOR=blue! important][FONT=Verdana, Arial]side[/FONT][/COLOR][/FONT][/COLOR][/COLOR] under the glovebox. It's behind the plastic panel there. You'll only be using 2 out of the some 16/18 wires coming from it. First off you need to snip the yellow wire, this is the power wire for the TCU. You'll also need to locate the purple/white wire and tap into it. I used a wiretap that goes over the wire found from Radioshack. You than will send the TCU side of the yellow wire to position "A" on the 3 pole switch. The other half of the yellow wire will go in position "B". The purple wire that you tapped into will go to position "C" on the switch. I added wire to the ends of the yellow wire as I located my switch in a switch panel by the shifter.

Here is a diagram:

TCU1.jpg


Just remember where A, B, and C are in relation to the switch. This is how your switch will now work along with your shifter for the desired gear.

TCU3.jpg


When the switch is left in the position C, your transmission will act like it would stock. Also, if as long as the switch is NOT in the position C, the TCU will remain OFF and your torque converter will never lock up.

So now you want a switch to control the torque converter?

You can rig up another switch to control that.

Parts Needed:

2 Pole Switch
Wire
Wire Tap

You will now need to locate the white/black wire. You need to tap into it. I again used a wire tap from Radioshack. You will also use the yellow wire again. You need to tap into that wire again, but make sure you take power from the yellow wire BEFORE the splice for the first switch or it will not work.

Here is a diagram:

TCU2.jpg


Be careful not to stop with the converter locked up, or you may stall your engine. I don't think the converter locks up when the transmission is shifted in 1, but I havn't tried to stall it yet (need to go out and wheel and figure it out). Also, make sure if you're wiring up both switches (one above) that you take power from the yellow wire BEFORE the splice for the first switch (this is key!).

Now you can engage the lockup at redline and delay your shift! I LOVE IT!

EDIT: A bit more info on the AW4 and doing this.

Two things control AW4 shifting:

1) Shift lever (lever position controls tranny [COLOR=blue! important][FONT=Verdana, Arial][COLOR=blue! important][FONT=Verdana, Arial]valves[/FONT][/FONT][/COLOR][/COLOR] mechanically)
2) Transmission Control Unit (TCU)

The shift lever makes a very positive move in control, the only weak point being there is no separate position for 1-2, as they are combined. Position 1-2 holds in 1, provided there is no TCU connected. If you have the TCU connected, you'll get a 1-2 upshift at about 4800rpm. The shift lever does do one thing that the TCU cannot accomplish however - ENFORCING compression braking via transmission's internal overrunning clutches and sprags. But besides this, all other transmission controls are performed by the TCU.

The TCU monitors throttle position, ground speed, and shift lever position (switches in the console) to select the gears appropriately. It also monitors position of the POWER/COMFORT switch (for those of you who have it) to change upshift and downshift points and TCU lock parameters.

The TCU's outputs are very simple, only three wires. One for Tranny Solenoid 1, one for Tranny Solenoid 2, and one for Tranny Solenoid 3. Solenoids 1 and 2 perform ratio selection as follows:

TCU5.jpg


Solenoid 3 is very simple. Put power to it, and the torque converter will lock. (what we did above with the 2nd switch).

As far as the torque convertor Lock goes. Solenoid 3 is unique, in that it only controls torque converter lock functions. Being able to lock up a torque converter awards you with improvements in fuel mileage, a cooler-running transmission, less cabin noise from the tranny, AND MOST IMPORTANTLY, it has the ability to multiply torque from the engine.. It's in esance like having one more gear.

Although it's possible to lock the torque convertor in EVERY ratio, it really only works consistantly in 2nd, 3rd, and OD. Anyways, Locking it in 1st is pretty much worthless, and is not too good for the torque convertor.

When you come to a stop, either the torque convertor unlocks itself (by nature of how the hydraulic plumbing works) or it will bang a bit, and then stalls the motor. I'd just flip the switch and not worry about it.

NOW, giving it to much throttle with the torque convertor locked will give you a quick wake-up call. The torque convertor lock is not intended to handle full engine torque (remember where your peak torque occurs, fairly low) and it will give you a quick jolt if you forget to unlock before feeding too much throttle. Besides, the torque converter is your friend, it multiplies torque output in exchange for higher engine RPM, so only lock up when you know you don't need much "oomph".

Also, The TCU is programmed to force torque convertor lockup when engine RPMS's are above a certain point (not sure exactly what RPM though?), and you're at wide open throttle (WOT). Why? easy, top speed. The AW4's torque convertor has a very high stall speed (translates to high torque multiplication factor, and higher RPM off the line). If you allow 2500rpm of stall, that means the transmission's input shaft speed will be quite a few RPMs lower than crankshaft speed when you're under one "quick launch runs". At WOT, you're going down the highway at 75, and the torque multiplication factor really isn't required, thus you need more tranny RPMs.

And lastly, remember how I said the torque convertor lockup mechanism wouldn't handle full engine torque? Well, when you're screaming down the highway at WOT, engine RPMs are usually well above the engine's peak torque point (by nature) it's not developing peak torque output (although it may be generating peak HP). Locking the torque convertor here doesn't put it in jepoardy, but it does eliminate slippage that may be costing you MPH and/or MPG. (and we all know with big tires and a lift we need all the MPG we can get!).
 
How about this, for a simpler idea.

From rigging up a series of lights, I know that my AW4/4.0L combo never hits 2nd gear, unless I'm trying to go WOT from the holeshot. Under normal driving, I go from 1st -> 3rd -> 3rd w/TC lockup -> 4th (OD) w/TC lockup.

With this in mind, why don't you just unplug the TCU (full manual) or rig the power to a switch so you can toggle between manual tranny and auto.

TC Lockup is another story. You can use a 3 pole switch, which would allow for normal TC operation when the transmission is in "auto mode", and use the other two poles to lock/unlock the TC manually when driving in "manual mode"

I've unplugged the TCU and driven around without a problem, it's just that the Renix revs kinda high when there's no TC lockup. The switch for the TCU is the only thing I've got left to wire in.
 
Or even easier, just use the existing AW4 computer and wiring. It's seperate from the Engine Computer and only needs a TPS signal. Depending on the year, that signal either came from the engine computer or from a the second output on a dual output TPS. I imagine the V8 engine computer might have a suitable output?
 
I believe Brett mentions the ability to stall the engine when stopping with the t/c locked up. You still can't push start it even with the t/c locked up. The hydraulic pump is drive off the input shaft, so there would be no hydraulic pressure to engage anything in the tranny.
 
Just did this mod both switches works good........but I wanted to see if the convertor was really locked up so I put it in 1-2 and the other switch in B and no engine stall am I missing something? Also while in 1-2 it won' shift to 2nd even with the switch in the A position but if in 2nd while driving normal it will downshift to 1st when I flip switch to the B position
 
Anyone done the manual mod with the tc lockup please post up
 
Anyone done the manual mod with the tc lockup please post up
While I don't use that setup, I do run a manual mode setup. It seems from the feedback I have gotten from others is that some TC locked will kill the engine and some don't, not sure the reason. And one of mine did the other not. So not sure if that helps.
 
Okay thanks what about shifting to 2nd does it go right in????
 
I also run a manual set up (one that rory is familiar with:D) and my TC does not lock in 1 st gear. From what I have gathered the AW4 does not allow TC lockup in first gear even if manualy forced. TC lock up is 2nd, 3rd, and 4th. If Iam in 2nd low range with the TC locked mine will stuble and try and stall if I come to a stop but has not died totaly. Its a quick reminder to unlock the TC before you stop. :)
 
Okay cool but will yours shift from 1 to2 manually without hesitation????? Mine still don't like to go to 2nd
 
I also run a manual set up (one that rory is familiar with:D) and my TC does not lock in 1 st gear. From what I have gathered the AW4 does not allow TC lockup in first gear even if manualy forced. TC lock up is 2nd, 3rd, and 4th. If Iam in 2nd low range with the TC locked mine will stuble and try and stall if I come to a stop but has not died totaly. Its a quick reminder to unlock the TC before you stop. :)

Okay cool but will yours shift from 1 to2 manually without hesitation????? Mine still don't like to go to 2nd

Well I know that jeepme and mine shift just fine 1-2, but we are running a different setup than you. :D
 
wish I had money for the setup
Anyone else have my prob?
 
Well I know that jeepme and mine shift just fine 1-2, but we are running a different setup than you. :D

Yep mine shifts perfectly everytime. I wont even hit the trail without being in manual mode anymore.
 
Great writeup/mod...I haven't used it off road yet but I love having the control of gears.

Edit:
In my 2000 the wire colors were different but the post locations were the same. Also the TCU is located on the driver's side on the right side of the steering wheel down low. Harder to get to to splice wires but worth it.

This forum http://www.naxja.org/forum/showthread.php?t=996009&highlight=Baja+shifter&page=2 has wiring diagram with the post locations.
 
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