3.7L V6 QT1 to QT2 Conversion.

[Matt]

That would also mean you have no brake traction control when in Low since the computer will never know if a wheel is slipping...... And it may even set off codes if the programming expects to see different wheel speeds when turning (I believe there's an encoder on the steering wheel.... would have to double check)

[cmdr jim]

That would also mean you have no brake traction control when in Low since the computer will never know if a wheel is slipping...... And it may even set off codes if the programming expects to see different wheel speeds when turning (I believe there's an encoder on the steering wheel.... would have to double check)

I think I see what you're trying to do.... but that would only work if the gear reduction in the tcase is the same as the gear reduction in the axle (in other words the axle RPM out of the tcase in Low is equal to the wheel RPM when not in Low)..... or did I misunderstand the concept?

Under normal running in High and High Lock, the Jeep would look at the 4 wheel sensors at each corner. The rear wheel sensors run on a tone ring with 48 teeth. I assume the front is 48 teeth too, but I need to confirm this before going farther. What I plan on doing is tricking the Jeep into thinking it is seeing the 48 pulses per rev when the transfercase is running the wheels 2.72 times faster. So when I run in Low or Low Lock, the Jeep sees 131 pulses per rev on the wheels, and the Jeep thinks there is something wrong in the transmission because of the low rpms of the engine and transmission and it throws an error code.
My plan is to go to 3.73 gears, so I'll use this as an example of how I'm going to trick the Jeep to think all is correct. However the speedometer with be off in low and Low Lock. I need the Jeep to see 48 pulses, to do this my plan is to make the rear drive shaft upper flange into a tone ring with 5 teeth. Only 5 teeth? Yes, remember I'm on the other side of the differential so that 48 has to be divided by 3.73 (12.87 teeth) and it also has to be divied by the 2.72 ratio of the transfercase 4.73 teeth, round this up to 5 teeth. If the differential was 3.07 the number would be 6 teeth.

Now I will lose the electronic traction control since the way I'm doing this all wheels will appear to be running at the same speed looking at that one tone ring and sensor. Not sure what the steering encoder will do. But keep in mind, I'm adding a manually controlled front ELSD (QD2 differential) and a ARB locker in the rear. In Low Lock I can manually lock up fully. In high and High Lock, the traction control would work normally as it is back to monitoring all 4 wheels and wheel spin. But with the manual lockers I can still elect to be fully locked up.

I think for most people this last option of speed sensor is not needed. You would have Low and Low Lock with traction control and as long as you don't shut off and restart the Jeep, or place it into Park, the limp mode does not affect transmission gears as long as you don't shut off and restart in Low or put the Jeep in Park. And even if you do get into an error code after using Low and Low Lock, once you go back to High and High Lock, shut off and restart the Jeep, the transmission shifts and works correctly. The Engine Error Light will stay on for 3 trips in the Jeep and then disappears.

[Matt]

Got ya... i thought you were going to use the same rings as the ABS and therefore have the same number of pulses, not accounting for the difference in gearing (should have known you already thought of that lol).

And yeah, with lockers the traction control isn't an issue.... for anyone not installing lockers, id live with the check engine light and maintain the traction control otherwise your 4-low will be almost useless with 2 open diffs.

[cmdr jim]

The days of buying the cheap low end model Jeep and upgrading it as you want at are pretty much gone. I bought the XK to be different than the JK crowd, it's becoming very apparent the JK is really the only model left that you can modify the drivetrain. It's unfortunate that's the case. And if it wasn't for AEV, the 2012 JK's equipped with automatic transmission would be stuck with stock gear ratio's. All of these electronics sound good upfront, but without Jeep and Jeep dealer support for modifications (the old days) we are limited.....Don't get me wrong, our Jeeps are very capable, but some of us want more.

[cmdr jim]

Update on some more testing. I start up the Jeep this morning and once the Jeep is running, I shift the transfercase to Low, back out of the driveway and shift the transmission to 1st gear. I drive away and Low feels really good. I get up to about 10 or 12 mph and I feel a shift to 2nd. Yet I still have the Jeep in 1st. The Jeep just went into "Limp Mode" for what I can tell. So I can continue to drive in 2nd gear in Low and all is fine. I stop, but leave the Jeep running and shift the transmission into Neutral. Then shift the transfercase back to Hi. Put the transmission back into drive and I'm in Neutral, I shut the Jeep off and restart it in Park, remember the transfercase is in Hi position, and it now has all transmission gears and drives and shifts correctly, with no "Check Engine Light". I do this again to test it all out and it reacts the exact same way in Park as well. Obviously the Jeep is going into "Temporary Limp Mode" when I'm in Low and once I stop and shift the transmission into Neutral or Park, it goes into "Loss of Drive Mode" shifting the transmission into Neutral to protect the drivetrain because of the miss-matching output speed. Once I shift the transfercase back to HI, shut off and restart the Jeep the "problem" goes away and it releases "Loss of Drive Mode" and never do I receive a "Check Engine Light".

So where this all leads? We can't have fully functioning Low or Low Loc in 1st gear.....This also means if you were to swap in another Jeep or Atlas transfercase, you would still have the issue of no 1st gear in Low or Low Loc. Adds another degree of difficultly to all of this. Do I have fully fuctioning Hi Loc, yes. Could I live with Low Loc and 2nd gear possibly?

To make this work correctly for everyone, what really needs to happen is to have an additional tone ring and wheel sensor at all 4 corners that can be switch to when in Low or Low Lock. Then Traction Control, and Low Loc would work correctly. I know how to switch between the wheel sensors, but where to mount the tone rings and sensors? The tone ring count at each wheel is 48 stock, I confirmed that last night, the front and back are the same count, the additional tone ring would need to be 18.

[Sal-XK]

Have you reprogrammed the computer? The super chips allows you to program TC gear ratios as well as the axel gear ratios.

[Matt]

.....Don't get me wrong, our Jeeps are very capable, but some of us want more.

I would like the ability to manually control my front/rear lockers so I can put them in full-lock at the push of a button

[cmdr jim]

Have you reprogrammed the computer? The super chips allows you to program TC gear ratios as well as the axel gear ratios.

I had the same thought, just hook up the programmer to change the gear ratio lower when in Low Lock and when finished program it back.
I have a HyperTech Max Energy programmer, I thought that was the only Programmer for 3.7L V6's. It goes down to 5.13 ratio, I need much lower:
For 3.07 in Low it would need to be 8.35
For 3.55 in Low 9.66
For 3.73 in Low 10.15
Anticipating a possible gear ratio issue in Low, I emailed HyperTech a while back to see if they would add these ratios to my Programmer and problem solved right? Nope, no custom programs is what I heard back. This would have been the simplest solution to it all......

[Matt]

Changing the ratio would be a bit of a pita every time you switch back and forth anyway (well unless you leave it in the whole time).

I wonder if you could add some sensors to the CVs up front near the diff..... the rear would be a bit more challenging

[cmdr jim]

Changing the ratio would be a bit of a pita every time you switch back and forth anyway (well unless you leave it in the whole time).

I wonder if you could add some sensors to the CVs up front near the diff..... the rear would be a bit more challenging

I agree, any ideas on location and mounting would be greatly appreciated.

I know how to switch between the wheel sensors, but where to mount the tone rings and sensors? The tone ring count at each wheel is 48 stock, I confirmed that last night, the front and back are the same count, the additional tone ring would need to be 18.