By the way.. seeing that this thread was started 12/06, I'll give a little update...
Use it weekly during the summer moving heavy equipment trailers or hay trailers... Never skips a beat.. Only issue i have had is the light in the rocker switch gave up the ghost...

Great mod IMO.. especially for those with sticky clutches.. My DD is alot better, but I still use the 2LO

 

Just so people know... this can also be done mechanically with toggle valve (air switch).

 

How about a little more info?

 

Oooops... wrong picture. First pic is a 2-way toggle valve. That's not going to work.

This is the picture I meant to post... it's a 5-ported 4-way toggle valve.



You plumb it to reverse the input/output to the vacuum motor on the axle. I'll have to work up a sketch to show what I'm talking about.

 

Using a 2 position, 5 ported, 4-way toggle valve, the plumbing is as follows:

1. Plumb one of the vacuum lines from the t-case to the CAD vacuum motor to the "input" port on the toggle valve.
   
2. Plumb the other vacuum line from the t-case to the CAD vacuum motor to both of the "exhaust" ports using a T or Y fitting.
   
3. Plumb one of the "output" ports of the toggle valve to one port of the CAD vacuum motor.
   
4. Plumb the remaining "output" port of the toggle valve to the remaining port of the CAD vacuum motor.

Flipping the toggle valve from one position to the other simply reverses the vacuum and exhaust lines to the vacuum motor on the axle. When you shift into 4WD, the switch in the t-case engages the CAD vacuum motor. You then flip the toggle valve and reverse the normal function to disengage the CAD. If you shift back into 2WD with toggle valve in this position, the CAD will engage, but flipping the toggle valve back to it's original postion will disengage it.

You can also plumb the toggle valve to eliminate the vacuum switch in the t-case altogether. You simply plumb the vacuum source line to the "input" port, vent both "exhaust" ports to atmosphere, and plumb the "output" ports to the CAD vacuum motor. If you do this, the CAD will not "automatically" engage when you shift into 4WD, you will have to manually engage the axle by flipping the toggle valve. Likewise, the axle will not automatically disengage when you shift to 2WD, you will have to manually disengage the axle by flipping the toggle valve.

 

I've already picked up a Clippard MJTV-5 toggle valve to do this mod, but I haven't gotten around to it yet. Thought I'd pick up the rest of the connectors and some tubing to get it done, but I don't know what the size of the existing plastic tubing is. Weather isn't really conducive to motivating me to crawl under there and find out. So..... anyone who's been under there truck lately messing with the vacuum lines, do you happen do know the O.D. size the existing plastic tubing to CAD is?

 

I installed a 4 port 4 way solenoid in mine and I can shift in or out anytime at will.

 

Using a 4-way, 4-port, 2-position with spring return with 12 VDC solenoid allows you to install the unit inline and forget it. Two lines go in and two lines come out. When switched off, the two lines basically go straight through. When switched on, the lines reverse dropping the 4wd setting 2wd. Easy to install and when in 4low, you can switch in and out anytime.
Cost of solenoid was 43.84 from Numatics (AIROIL), P/N: L01SA459B000060. Might want to consider this. I have a switch mounted under the dash and have it wired to a switched breaker. I went one step further by installing a micro-switch, that the 4 wheel selector lever hits, under the boot so that the switch only functions when in 4low. It is wonderful when backing a trailer into a tight spot.

 

I just used a electric air interrupt switch from an old rx7 so I did not have to plumb the air lines into the truck. I like your way too...

 

exactly how do i do this???

 

Went to the pick a part, found a NO and a NC solenoids, put them in down by the transfer case, put a on-off-on switch in. should work will try it out tomorrow in the dirt.

 

Have you tried this out yet?

 

I ended up changing to both NO and then you have to shut off the truck, turn on the switch, then start and put into 4wd, then it works, 2low.

 

Mechanos and 01RAMer, sounds like both of your valves will keep vacuum on the motor holding the slip collar in the disengaged position when in 2-wheel lo. ......yes?

One problem I've considered is the possibility of the collar moving if you only disrupt vacuum rather than reversing it.

Thanks,

RR

 

moparguy, i've been thinking about that myself, just a matter of doing it right i suppose.