TOD controller - knob, wheel, or buttons?

[blacksambo]

It would be nice if it would fit where the coin slot is on the dash. Or the JDM empty dummy button on the console.

[mbeach]

I'm glad that people seem to be leaning towards the 'rally VX' style torque splits. I've reconfigured the circuit to operate with even fewer components (less cost!) as long as we stick with discrete torque values.

I was thinking about an Isuzu 4WD button, ala Trooper, to activate the TOD controller. This switch would a.) turn off the AUTO display, and b.) turn on the controller.

The knob (maybe a junkyard fan control knob from a Rodeo) will be mounted anywhere there's space -I won't build it into the controller box, so You can pick where it goes. We can lower the cost even more by using this knob to turn the controller off and on -this'll eliminate the need for the separate dash-mounted button.

I've been running the prototype with a 5 ohm load on one of my benches for the last 22 hours -at 88% duty cycle, which should correspond to 4hi. It's in a sealed plastic project box, so there's no air movement. If it's going to fail, it'll do it on the bench and not under your seat.

I've taken to calling the TOD controller the "Torque Monkey," a name which I can't take credit for (this was a pet name for a similar device prototyped (but never completed) for controlling the torque split on a auto trans WRX).

[MustangO4]

I like the idea of the protected switch of some sort, but whatever you choose, put me down for one.-John

[VehiGAZ]

Go daddy go!! Whenever it's ready, mbeach, I'll take one, too.

Sorry to hear that you had to get rid of your Dragon. Good job on the trade-in deal, though!

[VR4-Quest]

This is awesome stuff mbeach, I've been wanting to come up with something like this (we should have had it from the start) but havent had the time. Whatever you come up with will be perfect Im sure, your the man calling the shots here!

[AREA 51]

When you said knob, I figured it was the same as a fixed position rotary switch. As far as the torque splits I'd like to see the following percentages to the front : 0%---15%---50%. Anything in between and you're just slipping the clutches in the tod, right? The 15 & 50 are factory figures and should be safe for the tod, although I'm curious about the tod clutch slippage at 15%.

I'll most likely buy one whatever the splits end up being.

Thanks

[LiquidVX]

I wish for buttons. But it seems I am out numbered.

[mbeach]

I wish for buttons. But it seems I am out numbered.

Buttons aren't a far jump from a knob. The knob just integrates all of the buttons into one fixture.

The TOD's e-clutch slips itself. It's kinda hard to explain without going full nerd. Each "cycle" or period lasts for 20 milliseconds. If the E-clutch were operating at a 50% duty cycle, the clutch would be engaged for 10 milliseconds, then disengaged for 10 milliseconds, then engaged, etc...

Since this is a coil, it takes a millisecond or so to really "load up" when current is applied. To operate at 100% duty cycle would burn out this coil over time. There would be no "rest period". In 4hi, the coil is working at @90% duty cycle, this is the same as 18 milliseconds on, 2 milliseconds off, 18 on, etc...
Even at idle, there is a brief surge of current every 20 milliseconds. So, in "2wd," there is a little bit of e-clutch engagement.

My first circuit went wild with the higher duty cycle. After 24 hours or so (this will never really happen in real life), the frequency shot up in relationship to the duty cycle. In short, at higher duty cycles, the 20 millisecond period went up to almost 10 milliseconds. This means that the clutch was being pulsed 2 times as fast as it was designed to be. This is bad. I'm bench testing another design that I found on the web. It'll probably work because a.) it's simpler, and b.) I didn't design it (I'm a mechanical engineer, I shouldn't be fooling around with electricity).

I have no intention of building these things "ready to install." Frankly, my time has a cost, and if I were to spend 2 hours putting it all together, we would suddenly crack the $$ barrier. Figure in the components (still less than $10-15) and shipping and it becomes unreasonable.

I'd like to provide the schematics, as well as a PCB (printed circuit board) layout. I could even burn the PCBs here if there's enough interest. Each person would be responsible for finding the components (if it can't be bought at Radio Shack, I'm not using it), and assembling the controller. There will be some soldering involved. I'll be able to provide some nice pictures of the finished board so component assembly will go smoothly.
This should be no more complicated than those electronic kits that you can buy for your kids (like the DIY lie-detector or the DIY burglar alarm).
The real difficult parts were getting the data together and determining what duty cycle corresponds to what torque split. Now that that's done, it's just a matter of putting all of the pieces together.