4HI conversion, it works!

[MrCrowley]

I may be mistaken on some of my recollections, but I think the difference with the T-cases has to do with an added function or unit between the tranny and T-case for the TOD on/off. However, if mods are going to be done, you might as well try to do something else. Plus, old Troopers for years had automatic hubs for front axle disengage/engage. Drive forward in 4wd they engaged. go to 2wd back up several feet and they disengaged. They werent the stoutest hubs, but also one of the aftermarket companies warn?, superwinch?, etc. had an auto hub that also you could get out and manually engage for "rougher" use. For what its worth to ya.

[orion]

Triathlete, the TOD only receives input, from the engine it's throttle position, and the tranny it's speed and gear selection. with the TOD gone the other computers wont care. now I'm not 100% on this but i can't find any instance were the other computers need input from TOD. but I'm still researching this.

[orion]

posted By Rouge

Second part of the question, let’s say one was to do the intelligent thing and switch to a TROOPER Transfer case. Would it be a simple plug-N-play type situation, where you have a switch to go from 4wd to 2wd? What would unlock the hubs to make the front wheels spin freely? Would the TOD display on the dash work?

you would have to swap the trooper front Axel as well as all related wiring harnesses, the trooper disengages the front wheels in the axle not at the hubs.

[ZEUS]

Orion, the t-case does have a gear selection for 2wd, doesn't it? If so, then you wouldn't need to swap the Trooper axle components unless you just did not want the manual hubs, correct? If you were to swap in the axle components instead of selectable hubs then you would still be turning the CV shafts, causing wear on the boots, and re-creating that bit of parasistic drag, even when in 2wd. With disengaged hubs though, (assuming the t-case does have a 2wd option) nothing would be turning in regards to the front drive components. I am assuming the axle disconnect in the Trooper is vaccuum-actuated like on some GM models. Select 2wd by lever or button and the t-case disconnects the front driveline from the gears, and the front axle disconnect device is actuated at the same time. In any case, I don't think that actuator would have any effect on the TOD, if it did, couldn't you just run another wire to trick the computer into thinking it was engaged?

[mbeach]

This one has been beat to death, and sadly, I never got to finish my work on it before I sold 0723. Now the test mule (complete with my custom made TOD eavesdrop harness) is laying dead behind a BMW dealership in Anchorage...

The E-clutch that engages the TOD is activated by a modulated voltage -NOT direct current. While DC will lock up the clutch, engaging the front driveshaft, it will also burn out the e-clutch over time.
You might be able to search my gallery for photos of the TOD computer in operation (look for the o-scope pics).

In order to have reliable 4hi, you need to generate the 88% (iirc) PWM signal that simulates the TOD computer's signal, and send that to the blue wire.
Google "DC Speed Controller" to get an idea of how PWM is used to control inductive devices like motors and clutches.

A few of us got a long way into figuring this out, and we pretty much had the solution on paper. Picture a knob, that allowed you to dial in the exact amount of torque you wanted to go to the front axles. Pretty cool.
However, no one really managed the jump from paper to reality for whatever reason.
Mine was a lethal combination of laziness and wife.

There are also two huge reasons that this knob solution never took a priority:
1. The Ball Ramp Mechanism. The original purpose of the TOD controller was 2hi, not just 4 hi. Two-wheel-drive has all kinds of practical daily benefits, not just the occasional mud run. Unfortunately, even with the blue wire disconnected (toggled), there is a mechanism within the Borg-Warner T-case that still transfers rotation to the front driveshaft. The e-clutch simply modulates this rotation to create torque. Tone discovered this phenomenon on a 2wd dyno, with disasterous results. So, unless your front wheels are suspended in the air (no friction at all), 2hi is unobtainable.
2. TOD is awesome. There was an army of engineers behind this one, and us lowly mortals could never improve its function. The truth is, that with a mechanical T-case, there is no way to reliably control it's doings from the driver's seat. The DCCD in the Subaru STI is on a viscous center diff, like the Evo -this is not a mechanical transfer case. I know that the Baja VXs have a torque controller (at least you can see the knob from the pics), but they also have a warehouse full of spare parts...

So, Tad's solution on PI is great, but use it with care (just like the owners of Air Lockers do). If you leave it on for an extended period, you will break something -it's about the size of a hockey puck and it's buried deep within your transfer case.

Not finishing the TOD speed controller has been one of the greatest automotive letdowns of my life. I really wanted to finish this one up, if only to say it was done.
I still have all of the files though...

[orion]

ZEUS, the Trooper t-case has the 4LO lever only just like us, 2WD is just the TOD turned off and the front axle disengaged. if your looking for minimal parasitic loss I'd go with a fully mechanical t-case, and ditch the TOD. getting the Trooper TOD system to work with manual huds just seem like a lot of work. I don't like the idea of having to get out and locking the hubs when i have the sudden urge to get the old girl all dirty.

[ZEUS]

ZEUS, the Trooper t-case has the 4LO lever only just like us, 2WD is just the TOD turned off and the front axle disengaged. if your looking for minimal parasitic loss I'd go with a fully mechanical t-case, and ditch the TOD. getting the Trooper TOD system to work with manual hubs just seem like a lot of work. I don't like the idea of having to get out and locking the hubs when i have the sudden urge to get the old girl all dirty.

It's not a lot of work... all you have to do is take the axle disconnect components from the Trooper axle and have a machinist fab up some mounts, driveshaft housing, driveshaft, and then rig the driveshaft to disconnect like the CV shaft normally would! It should only cost you around $3000! See, nothing to it!

[MrCrowley]

Lololol! Heres one even better.

Go buy a good trooper, take the body off, have the VX body shell limo-stretched, and voila! Just dont forget to put the VX suspension goodies on the new ride!

[twistedsymphony]

...
In order to have reliable 4hi, you need to generate the 88% (iirc) PWM signal that simulates the TOD computer's signal, and send that to the blue wire.
Google "DC Speed Controller" to get an idea of how PWM is used to control inductive devices like motors and clutches.

A few of us got a long way into figuring this out, and we pretty much had the solution on paper. Picture a knob, that allowed you to dial in the exact amount of torque you wanted to go to the front axles. Pretty cool.
However, no one really managed the jump from paper to reality for whatever reason.
...
Not finishing the TOD speed controller has been one of the greatest automotive letdowns of my life. I really wanted to finish this one up, if only to say it was done.
I still have all of the files though...

I don't mean to bump a long dead thread but I was just perusing through the archives and came across this.

I don't have my VX yet (put a deposit down, should only be another week or so) but I'm very interested in what you discovered here... I do LOTS with electronics in my spare time (I can show you some of my projects if you're interested). Creating a PWM signal is easy peasy... and you could probably even take it further than that with a little display to tell you the % rate you're sending or whatever...

I'd probably use an MCU to get the job done but there are other cheaper/easier methods if one were so inclined.

[Knigh7s]

I don't mean to bump a long dead thread but I was just perusing through the archives and came across this.

I don't have my VX yet (put a deposit down, should only be another week or so) but I'm very interested in what you discovered here... I do LOTS with electronics in my spare time (I can show you some of my projects if you're interested). Creating a PWM signal is easy peasy... and you could probably even take it further than that with a little display to tell you the % rate you're sending or whatever...

I'd probably use an MCU to get the job done but there are other cheaper/easier methods if one were so inclined.

you should check out this thread: http://vehicross.info/forums/showthr...ght=tod+switch .

The project died awhile back and then was revived again by Orion... We are all waiting for the results of his tests, but it looks pretty good so far...

Oh, welcome to the VX Fam! Looks like you are awaiting the addiction! LoL

[Greasemonkey]

True 4hi can only be obtained mechanically like the Trooper , Rodeo etc without TOD , even a VX with TOD has to have a mechanical lock to put it into 4lo this also locks the gearbox and non of the electronic clutches are working while you are in 4lo its all locked in place - and you will create transmission wind up if you are not on soft or slippery surfaces - unlike TOD which doesn't wind up - so the easiest way to obtain 50/50 drive is to fool the transfer case into telling the transmission its in low box then the TOD locks itself to 50/50 - surely this has been thought of but i just have not read it - everyone seems intent on rewiring the TOD - to achieve something which it does already - all it needs it the lo box lever sensor rewiring
cheers
Steve

[VehiGAZ]

Creating a PWM signal is easy peasy...

DO IT BROTHER!!! I'm dying for this mod. It'll be perfect for winter driving!

[taylorRichie]

DO IT BROTHER!!! I'm dying for this mod. It'll be perfect for winter driving!

I've already done it ...

I'm just wrapping another project before I can get the boards shot. I'll try to get a deadline set, and let you guys know.

We've already got the legwork done (THANKS MBEACH!!) and have done a proof of concept. We're even planning on controlling the TOD Christmas tree so you can see where you're at.

We'll all have this mod soon enough.