TOD and no rear driveshaft....

[Marlin]

Well, I promised I would try the VX with no drive shaft. 4Hi=no good. TOD is not fast enough, and it seems to constantly read the rear "slipping" and it momentarily sends power to the front and then starts over again. Its ends up being a jerky stop and go. This is why I am not a big fan of TOD, and this experiment proved that its not a great thing for snow/ice. That pulsing power transfer sounds like a recipe for disaster.

4low was fine, except I am locked, so it was a bit messy as far as steering and shifting. I would not drive it around town like that, but I would guess on the trail it would be fine, say for a busted drive shaft or universal or whatnot.

[Triathlete]

As punnie as the front drive shaft is, i would drive gingerly in that mode or you may be replacing that one also.:)

[atilla_the_fun]

If one had manual hubs in the front, could one disconnect one of the two wheels and drive in 4L, with the driveshaft disconnected as well? 1 wheel drive?

[blacksambo]

Not so quick, Mr. deep south. We have two '99's that out perform everything else in the snow and ice. I have never felt anything so sure footed in slippery surface conditions. We drive 'em everyday through you name it, and they operate flawlessly. If something else could do the job we'd be driving it, it doesn't exist. Move here and then try your experiment? You'll be whistling a different tune. Those Russian Vx'ers know what I'm talking about.

[Marlin]

If one had manual hubs in the front, could one disconnect one of the two wheels and drive in 4L, with the driveshaft disconnected as well? 1 wheel drive?

Only if you had a locker. With out OEMopen diff, you only get as much torque to the wheels as one needing the lowest amount to turn, which would be the disengaged hub. The diff would see that wheel as still spinning. Now with a front locker.....I don't even want to imagine how horrible that would be. It would be bad on the drivetrain, unbalanced stress on shafts and whatnot.

As for snow driving, I have read many complaints on here about TOD in the snow causing problems. Based on my experiment with the driveshaft. There was definitely surging and pulsing of power to the front, I could see it on the TOD display as well. That means, if I had a little traction in the front, then a surge in power, I just lost what little I had going for me in the form of spinning tires.

No worries, if it works for you, thats awesome, I just don't know that computers and technology in an Isuzu were really fast enough to make for seamless TOD ops in slippery conditions. I can tell you it sucks with no drive shaft and it sucks on gravel.

[Ebenezr]

I may be needing a transfer case soon and i have noticed some of the same time period troopers had a 4 hi option. I have found them in used parts locaters. I'm considering placing one in my vx. They are otherwise identical to our T-cases.

[Marlin]

I may be needing a transfer case soon and i have noticed some of the same time period troopers had a 4 hi option. I have found them in used parts locaters. I'm considering placing one in my vx. They are otherwise identical to our T-cases.

Well, they will fit, but they may be different. I believe the drive shaft flange may be different. I am not 100% for sure, but I would check first. If it is, should just be a matter of taking the fitting off of your case and swapping it over.

I do know the non-tod case will fit in ours, but definitely has a different prop shaft flange. I would personally go the non TOD route in order to gain a 2hi option. You would have to get the stick as well, but no biggie.

[Ebenezr]

I'm thinking its has all 3 TOD, 4hi, 4lo. Actually I just looked thru the manual and it appears this is wrong. If you want 4hi you give up TOD....:(

[Ldub]

I'm thinking its has all 3 TOD, 4hi, 4lo. Actually I just looked thru the manual and it appears this is wrong. If you want 4hi you give up TOD....:(

I'm reasonably sure, after a few conversations on the stoop in Moab, that you would also need the computer & frt axle from the donor Trooper.
The Troop frt axle is vacuum controlled, which would also need to be addressed...http://www.4x4wire.com/isuzu/tech/fwd_lockout/?

[Marlin]

I'm thinking its has all 3 TOD, 4hi, 4lo. Actually I just looked thru the manual and it appears this is wrong. If you want 4hi you give up TOD....:(

That is a bad thing? This would allow you to have 2hi, 4hi, 4low, like our JDM cousins. Less electronics is a good thing, especially as our vehicles get older. The less wires, the more reliable:)

[Triathlete]

After thinking a bit I have come to the conclusion that your front drive only experiment means moot. And here is why...
When in 4hi the front end was getting 20% power...obvouosly not enough to pull the VX. All wheels would have been turning equally at the same rate.
In 4lo there should not be any jerking since in 4lo the transfer case is mechanically split 50/50 and takes TOD out of the equation.

[Marlin]

After thinking a bit I have come to the conclusion that your front drive only experiment means moot. And here is why...
When in 4hi the front end was getting 20% power...obvouosly not enough to pull the VX. All wheels would have been turning equally at the same rate.
In 4lo there should not be any jerking since in 4lo the transfer case is mechanically split 50/50 and takes TOD out of the equation.

I agree, except that its not moot. TOD should sense the rear wheels slipping (no drive shaft, the puter thinks it is, so it senses slipping, no different than it would be on snow) and subsequently sends power to the front. That was the problem, it doesn't take the slipping input and then transfer power at a rate fast enough to make it doable,hence the jerky responses, then it seemed to reset and start the process over, giving it that bouncy jerky effect. Having said that, imagine the effects of the delay on snow or ice.

If I had to drive this way, it would be in 4low only, to remove TOD from the picture and have the straight mechanical drive engaged.

[Ebenezr]

I'm reasonably sure, after a few conversations on the stoop in Moab, that you would also need the computer & frt axle from the donor Trooper.
The Troop frt axle is vacuum controlled, which would also need to be addressed...http://www.4x4wire.com/isuzu/tech/fwd_lockout/?

I don't understand the vacuum actuator mechanism but I did look at the Trooper info in the manual and there is a 4 bolt flange coming out of the front pumpkin to connect to a more robust front drive shaft. If TOD is present on the Trooper then it has a round 6 bolt flange to connect to the limp wristed Front TOD shaft. At least the length of Trooper and VX front shafts are identical 22.7 inches. So I'm with Chris - the next move may be a 4 hi transfer case with no TOD wiring!!!

[Ebenezr]

I know my TOD works but I took my VX out to my local proving grounds - Florida sand - and as I hit the sand the VX began to sink and didn't go too far before bogging down and began to spin in place. I stopped immediately and threw it into 4 lo and took right off. Again I believe TOD is working. I tested it by lifting my rear end off the ground and hit the gas - the TOD kicked in and began drag the rear off the jack. Still however when it comes to the real rubber on the road and need for competent full power 4 wheel drive.....I am just not convinced the TOD is that great.?? :(

[Ldub]

I don't understand the vacuum actuator mechanism

I believe it's for the shift on the fly function.

[RickOKC]

Last year I felt my VX was pretty spooky on ice, but part of that was getting on roads with a good "dome". I was about to slide sideways into the curb so I had to stay centered on the crest. I don't have ABS and the rear end tried to swing around on me at the slightest touch of the brakes. It was bad enough that it made me reconsider my position on fixing my ABS. Acceleration seemed fine though.

On snow, I was simply amazed and never experienced anything that could be considered surging. I drive cautiously and the only time I pukered was when I tried to stop where some ice had formed. As I became more adventurous, I got to a point where I crawled through snow that was deep enough that I left two tire ruts with a perfectly flat snowplowed area in between. (That section was about 30' long.)

I'm looking forward to hearing what you think about TOD after you drive it on snow in WA. :) Since the VX is my first 4WD, I have nothing to compare it to other than FWD & RWD vehicles.

Oh yeah... and I found references that say the computer reads the sensors every 20 milliseconds.

[Marlin]

Oh yeah... and I found references that say the computer reads the sensors every 20 milliseconds.

I agree, but that does not mean it can analyze, react, actuate the electric clutch in the transfer case and send power to the front that fast. That would take much longer, even with a fast processor, needless to say I doubt early-mid 90s technology was up to the task on a passenger vehicle.

[Triathlete]

I agree, except that its not moot. TOD should sense the rear wheels slipping (no drive shaft, the puter thinks it is, so it senses slipping, no different than it would be on snow) and subsequently sends power to the front. That was the problem, it doesn't take the slipping input and then transfer power at a rate fast enough to make it doable,hence the jerky responses, then it seemed to reset and start the process over, giving it that bouncy jerky effect. Having said that, imagine the effects of the delay on snow or ice.

If I had to drive this way, it would be in 4low only, to remove TOD from the picture and have the straight mechanical drive engaged.
Where does the tod computer get its wheel speed input from? Maybe I am missing something but, if the VX is moving, with or without a driveshaft all four tires are spinning at the same rate so why would the tod send power to the front? Sounds like it is doing what it is supposed to.

[rowhard]

. That pulsing power transfer sounds like a recipe for disaster.

This is actually my first 4WD so I am no expert, but I did grow up in Michigan and learned how to drive in the stuff and I found the Vehicross to be EXCELLENT in the snow, even this wet crap they call snow here in western Washington

[blacksambo]

You guys really need to check out that new Ferrari FF Shooting Brake model, I mentioned earlier on. It takes it's power directly off the front and the back of the engine, itself. Both ends of the car are driven independently but guided by computer sensors. No transfer anything! I've driven everything from Blazers to Commandtrak Jeeps and M and G class Mercedes, and unless you go to the top of the line G class in multilock-up 4 Low they are not as good as VX "fulltime TOD" in my estimation on snow and ice, maybe this new Ferrari can out do it but it costs $300K. Also, you wheelers types are running larger than spec tires and that may throw off your TOD a bit, it's very tire size sensitive.

[Marlin]

Where does the tod computer get its wheel speed input from? Maybe I am missing something but, if the VX is moving, with or without a driveshaft all four tires are spinning at the same rate so why would the tod send power to the front? Sounds like it is doing what it is supposed to.
With no driveshaft,the vehicle is not moving at the calculated speed that it should be. I am not sure where all the sensors are, but I know there are front and rear. It basis the wheel speed off of the calculated speed based on RPM and gear. At 2000 RPMs, I was not moving, so it transferred power to the front, assuming the rear wheels were spinning out for some reason (rear tires on ice, spinning at 20mph, front tires only spinning at 5mph, therefore shifts power to front)? I don't know what it uses as a reference for the speed.
All I am saying, if the rear tires were on ice, as simulated by removing the drive shaft, I would think the power transfer to the front should be smooth.

I learned to drive in a 1978 volvo wagon, rwd, in Ohio. I prefer RWD cars in the snow, and anticipate the fish tale and prefer to drive based on my own predicted path, not a path that is determined by some computer.

[Marlin]

I got it! The TOD sensors are in the transfer case! When the drive shaft begins to spin faster than the prop shaft,that is considered wheel slip in the rear and power is transferred to the front. That is why TOD goes crazy. It sees the rear shaft spinning fast(even thought the shaft isn't there, the sensor is in the transfer case), the prop shaft isn't spinning at all. It then shifts power to the front, giving me the jerking as the clutch tries to engage at a few thousand RPMS and a higher gear, which gives the tranny a bitch of a workout.

One more experiment. Disengage my hubs, no wheels are connected to the driveline. Then I can watch the TOD lights disco it up on the dash without fear of hurting something.

[Ebenezr]

Without the fear of hurting something" Ah ah including yourself.....:bwgy:

sorry I couldn't resist. :happyface

[Ebenezr]

Hey I'm sorry but I'm thinking right now of a story I heard which emphasizes the great care and common sense that we all must use when fooling around under our vehicles. A man wanted to see where a problem was along his drivetrain so he slung a rope from side to side cross ways under the vehicle perpendicular to the drive shaft. Then he slung himself in the rope I guess kind of like a hammock in the rope and had his buddy take the vehicle for a spin. The buddy didn't get far and thump thump thump. The man's clothing got caught on the driveshaft and instantly spun his body around the shaft. He was history. Some of you may have heard this and this is my rendition of the story. I also know of a man killed when the car fell off a jack. And then there is the guy we all heard of that was working on his roof, tied a rope around himself then tied himself off to the bumper of his wifes car. :) The wife went shopping. but he survived to tell his story.

[RickOKC]

I agree, but that does not mean it can analyze, react, actuate the electric clutch in the transfer case and send power to the front that fast. That would take much longer, even with a fast processor, needless to say I doubt early-mid 90s technology was up to the task on a passenger vehicle.
Oh, sure enough... the number was just thrown out because it was the the only one I found that mentioned computer speed (Hopefully that was actually released by Isuzu and isn't some "friend of a friend who works for an Isuzu dealership" thing.) I was also thinking, "but what is the final reaction time?" the instant I saw it.

And, like I said, I'm very much looking forward to the opinion of first hand experience from someone who has lotsa more time on snow in various 4x4 vehicles. All I know is I was hoping I could get out of my driveway... then down the street... then up the hill to the main road... then to work... then it was 5 hours later and I'd had a blast! ;Dy; All the while, TOD seemed smooth to me. The only reason I went (rushed!) home is because the crazies came out en mass and I became afraid the probability of someone bouncing off my cladding had become very, very high. :(

Hey, I keep seeing references to "12 sensors" that control TOD - would all of them be within the transfer case? I wish I had bookmarked more items when I first started researching the VX. I could have sworn that also included the ABS sensors, but I've read messages here that make it sound like TOD is unaffected by a dead ABS sensor.

[Marlin]

Those 12 sensors would have to be somewhere in the transfer case. I cut the wires and pulled the fuse for my ABS, TOD works fine when I have my hubs locked in. Its not in the tranny, I did a tranny swap, JoeD did a tranny swap with a tranny from an OLD rodeo, it was old enough it still had the dipstick. No problems. I have had the front axle off, no plugs there.

My experience with TOD is limited to gravel. It would not let me drift, which made for slow going. Instead of allowing the rear end to kick out so you can power through a turn, it forced the front tires to spin, which in turn drove the front to slide as power was shifted to the front wheels, which of course is disaster in a corner.

[blacksambo]

The factory literature mentions the throttle and brakes as sensor spots, as well. Maybe it's just at the pedal itself??

[samneil2000]

I'm sure there are RPM sensors, TPS sensors etc.

[Greasemonkey]

I was under the impression that the ABS sensors are used too - as well as others within the transfer case and gear box -
My TOD is superbe - Mud , snow , ice never got stuck yet - maybe i haven't been trying but beleive me i have been
cheers
Steve

[nfpgasmask]

Well, out of all the vehicles I have ever owned, my VX is easily the best on snow and ice.

I knew someone who drove their 1st gen Trooper around with no rear drive shaft for several weeks, just using 4HI. Kinda funny.

Bart

[nfpgasmask]

All I am saying, if the rear tires were on ice, as simulated by removing the drive shaft, I would think the power transfer to the front should be smooth.

I see what you are saying here. However, in defense of the TOD, I think your "experiment" is only applicable in extreme situations, IE, rear end sitting in soup or on a perfect sheet of ice. Normally, the rear end is getting some traction, even if it is minimal, so that when the slipping begins in the rear, the TOD kicks on and send power to the front, making the TOD seem to operate smooth, more-or-less. Now, with the rear drive shaft out, you are going to experience a completely NON factory reaction to your experiment, so jerky stop and go action does not seem wrong to me, just natural for the TOD. Meaning, the TOD would rarely kick on from a DEAD STOP, as there is typically some forward momentum happening when it kicks on normally. Know what I mean?

All that aside, I see what you are saying about wanting a "normal" 4WD transfer case, but then I have no choice to go back and tell you that you bought the wrong vehicle to begin with. :)

I personally don't understand some folks extreme desire to turn the VX into something that it is not. The VX was not meant to be lifted 4"s, it was not meant to have a SAS, it was not meant to have a winch bumper up front, it was not meant to run 35"s, it was not meant to etc etc etc. However there are always people trying to make it do things it wasn't meant to do, and then they get discouraged or turned off or upset about it when these mods don't work out so much. And you know my answer to all of that (buy a Jeep, cough, cough). But again, all the power to ya. :)

On the contrary, got my VX front end back together, and removed the ABS speed sensors, tone rings, ABS fuse and the wiring, and she runs just fine!! ;)

Bart

[MSHardeman]

The VX wasn't meant to run without ABS.....:biggringr

Sorry Bart, had to do it.

Now, sort of, back on topic; from my understanding of the TOD system, it's not supposed to send sustained power to the front wheels. It's only supposed to throw power forward in little spurts to get everything moving again. It's not like an all wheel drive system in an Audi. I know the TOD has saved my butt many times in the Colorado snow and ice. I've tried to get her sideways before, but the little power blips to the front end just straighten her right back out.

[nfpgasmask]

The VX wasn't meant to run without ABS.....:biggringr

Sorry Bart, had to do it.

I know, I know, that's why I said, "On the contrary". My VX isn't 100% stock either, I just try to keep it clean and simple. :) And yeah, I have TRIED VERY HARD to do donuts in the snow and I can't. Now, the Trooper can spin like a merry-go-round in the snow.

Bart

[Ebenezr]

In this experiment the reason for "surging" to my thinking is this. You excellerate and the TOD senses slipping in the rear by comparing the rear and front driveshaft speeds. The TOD kicks in and moves the vehicle to a point where suddenly the drive shaft rotational speeds match and then the TOD kicks off. When it cuts off there is suddenly a mismatch in speeds so it cuts on. The speeds match again so the TOD cuts off. then on then off then on then off because of continuous mismatch in driveshaft RPM. IT is impossible to get smooth operation with TOD only because with smooth continuous operation the driveshaft speeds agree and the TOD must then kick off.

[Marlin]

All that aside, I see what you are saying about wanting a "normal" 4WD transfer case, but then I have no choice to go back and tell you that you bought the wrong vehicle to begin with. :)

I personally don't understand some folks extreme desire to turn the VX into something that it is not. The VX was not meant to be lifted 4"s, it was not meant to have a SAS, it was not meant to have a winch bumper up front, it was not meant to run 35"s, it was not meant to etc etc etc. However there are always people trying to make it do things it wasn't meant to do, and then they get discouraged or turned off or upset about it when these mods don't work out so much. And you know my answer to all of that (buy a Jeep, cough, cough). But again, all the power to ya. :)
Bart


By that logic, no one would ever have a modded street legal offroad vehicle as NO vehicle was meant to do these things.

Anyway, the next step in the experiment would be to do the TOD mod where I can adjust power manually via rheostat. I would think that the TOD software would have a feedback loop built into it to prevent the surging/thunking effect.

No worries, the shaft is back in, and she is back to normal.

On a side note, I figured out what my squeaking sound was!! The rear lower link mounts have the edges bent over just enough that the moving portion rubs on the fixed portion. It is always loudest in reverse, which generally means I am riding my brakes a bit when backing out of the driveway, which compresses the rear suspension backwards and at an angle, also the engine is quiet. That makes the squeak seem louder as the vehicle tends to bounce at an angle. Just need to bend that steel back a bit....:)

[nfpgasmask]

By that logic, no one would ever have a modded street legal offroad vehicle as NO vehicle was meant to do these things.

I dunno, I think Jeeps in general are built knowing that there is a huge offroad aftermarket for them. True, once you start modding in any way, you are doing something to a vehicle that was not originally intended, but that isn't my point. I'm not knocking anyone's attempt to turn their VX into something that it was not meant to be, I am just always confused when people do this and then get disappointed/discouraged/upset when the end result isn't so great or still doesn't do what they want it to. It's like taking a boat and turning it into a car. Sure, it can be done, but it might not look so good, and it might not handle so good, etc, etc, because after all, it's a boat. But, if you have the skill, drive and desire, by all means turn that boat into a car!

Bart

[Triathlete]

Bart, Bart, Bart...a jeep off the showroom floor is no more offroad capable than a VX off the showroom floor. You will rarely see a jeep on the trail that is not modded also...none of tem come with 35's :)
Of course all this "non-modded keep it simple" stuff coming from the giant spikes roof rack front.:D

[nfpgasmask]

Bart, Bart, Bart...a jeep off the showroom floor is no more offroad capable than a VX off the showroom floor. You will rarely see a jeep on the trail that is not modded also...none of tem come with 35's :)
Of course all this "non-modded keep it simple" stuff coming from the giant spikes roof rack front.:D
You guys are COMPLETELY missing my point. I'm not saying I have anything against modding (obviously). Look at my 1st gen, I am constantly trying to make it do things it was never meant to do. I did a freakin' engine swap!!!! I'm just saying that Jeeps, off the showroom floor, are more readily modded with lift kits, winch bumpers, etc. Afterwards they still look good and perform well when done because they were designed with this HUGE 4x4 aftermarket in mind. Our IFS VXes were never built with any of that in mind. And when people try to give a VX a Jeep like aftermarket treatment, things don't always play so nice. And if you think Jeep makes new Wranglers with modding not even part of the thought process, I think you are wrong. Jeep is the only company left making a vehicle that was MEANT to be driven offroad and not just to the grocery store. Know what I mean?

And the spikes come off with 3 little wingnuts, btw. ;)

Bart

[Ebenezr]

If your talking about ugly modified vehicles only 1 out of 20 or so pickups or jeeps actually look good afterward. Most in my opinion do not have a tire size-offset-lift configuration that looks good. That is what I like about my VX. It has all 3 in perfection. I like to just stand around looking at my own truck.

[Triathlete]

Bart, you were missing my point...I was just yanking your chain! :D