4HI conversion, it works!

[orion]

here's how it works, when you hit the switch it puts 12 volts to the clutch, giving you 50/50 split. as long as the switch is on, the clutch stays on. the TOD sees the two resisters and thinks all is well, no codes, no problems. the resisters act as a fake clutch, so if the TOD wants to add traction, like on hard acceleration, the voltage goes through the resisters to ground. TOD wont see wheel slip so you will only see the first bar light up. with the switch off the TOD works normally. this does not give you 2WD. if you read the last part of the article the author had no problems with the transfer case, remember he did this with a trooper that can switch to 2WD, so he has to be in TOD mode for it to work. I am thinking of swapping to the trooper transfer case, TOD computer and switches to get 2WD. from my research it looks to be the best way.

[ZEUS]

I am thinking of swapping to the trooper transfer case, TOD computer and switches to get 2WD. from my research it looks to be the best way.

Ah HA! BUSTED!! Now we know what you have planned next! I had that in mind too when I was considering the SAS but stopped short of the entire project... it is so much easier to SAY you are going to do things than it is to do them, ya know! At least for me, anyway... you might actually do it!

[Triathlete]

Orion, sounds like you may be doing some of my homework for me. Does the Tod send any signals to the anything other than the TOD system (the tranny, engine managment)? I ask because I want to swap my TOD for a manual T Case.

[Rogue]

here's how it works, when you hit the switch it puts 12 volts to the clutch, giving you 50/50 split. as long as the switch is on, the clutch stays on. the TOD sees the two resisters and thinks all is well, no codes, no problems. the resisters act as a fake clutch, so if the TOD wants to add traction, like on hard acceleration, the voltage goes through the resisters to ground. TOD wont see wheel slip so you will only see the first bar light up. with the switch off the TOD works normally. this does not give you 2WD. if you read the last part of the article the author had no problems with the transfer case, remember he did this with a trooper that can switch to 2WD, so he has to be in TOD mode for it to work. I am thinking of swapping to the trooper transfer case, TOD computer and switches to get 2WD. from my research it looks to be the best way.

Ok, two part question. What are the benefits to a 50/50 all time type of set-up? Meaning in real world driving situations, when would you feel the pleasures of 50/50? When would it be ideal? Where would you use it, on daily driven roads or in the dirt?
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?
Just a few questions that could motivate someone to do the switch over.
The reason for all this is really quite simple, I drive a 2002 LWB trooper at times and being in 2wd in regular driving conditions makes the vehicle very "drivable" and pleasant. It feels light and it is also QUICK!
There is also the pleasure of skidding into turns etc. then switch into 4wd and rockcrawling….
The motor in the VX is strong and powerful on a small truck like the VX yet we do not feed the pep it has in TOD mode.
Anyone driven an Infinity FX35? The motor has the same general specs as ours yet it would be a dream to keep up to one of those.

[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.

[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.

[ZEUS]

Ok, two part question. What are the benefits to a 50/50 all time type of set-up? More predictable driving experience in treacherous conditions. Meaning in real world driving situations, when would you feel the pleasures of 50/50? When would it be ideal? Where would you use it, on daily driven roads or in the dirt? Snow, icy streets, and soupy substances.
Second part of the question... What would unlock the hubs to make the front wheels spin freely? Aisin hubs, Superlift hubs, Warn hubs (discontinued?) all are manual locking hubs.

[Chopper]

Ok, two part question. What are the benefits to a 50/50 all time type of set-up? Meaning in real world driving situations, when would you feel the pleasures of 50/50? When would it be ideal? Where would you use it, on daily driven roads or in the dirt?
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?
Just a few questions that could motivate someone to do the switch over.
The reason for all this is really quite simple, I drive a 2002 LWB trooper at times and being in 2wd in regular driving conditions makes the vehicle very "drivable" and pleasant. It feels light and it is also QUICK!
There is also the pleasure of skidding into turns etc. then switch into 4wd and rockcrawling….
The motor in the VX is strong and powerful on a small truck like the VX yet we do not feed the pep it has in TOD mode.
Anyone driven an Infinity FX35? The motor has the same general specs as ours yet it would be a dream to keep up to one of those.

The only commonality between the VQ and this mill...is that they both have six cylinders