Disconnecting TOD

[Marlin]

I disconnected TOD today when I removed all of the interior. I marked the prop shaft with chalk. My thoughts, with TOD off, that gives me 2high, which means the front shaft should not spin at all. I drove it around the block. No TOD lights, which was a good sign, no vibration, no rumbling etc...I expected the prop shaft to be right where I left it. (I have manual front hubs). In my mind, it felt peppier and more responsive. May be a psychological thing. I checked the chalk mark, the prop shaft had rotated!
If TOD fails, does it automatically go to a 50/50 split? I will have to put the whole truck up on jack stands tomorrow and see what is going on under there.
Any thoughts?

[JoFotoz]

Do you have locking hubs....??

...'cause if not, I do believe that wheels will turn axles, axles will turn diff....

.....diff will turn shaft.

If you do have hubs...I'll be very interested to see what you think.

We had this discussion up at Dubs wedding......
.....and it was a split vote on shaft not moving/moving.

Then we had 'nother cocktail...... :jump:



Jo

[Marlin]

Do you have locking hubs....??

...'cause if not, I do believe that wheels will turn axles, axles will turn diff....

.....diff will turn shaft.

If you do have hubs...I'll be very interested to see what you think.

We had this discussion up at Dubs wedding......
.....and it was a split vote on shaft not moving/moving.

Then we had 'nother cocktail...... :jump:



Jo

I do have manual hubs, as I mentioned in my post, which why I was confused about the prop shaft turning. That means the transfer case sent power to the front somehow, hence the thought of a "fail on" condition for loss of power or signal to the tod system. I will put her on blocks and see tomorrow. Then its time to start removing cladding:(

[JoFotoz]

DOOHHH..my bad..I missed the manual hub bit :_brickwal

There was a school of thought up in Fargo...
... that says the clutch plates in the TOD will not disengage 100%

So..some front shaft rotation will take place.

I 'was' against this theory....
..but since comming back I believe its true.

Even with my hubs disengaged, I am noticing ( now I'm looking/listening for it!)...
..some clicking now and then from my front Aussie Lockers.

I'm pretty sure this would only happen if shaft was turning.

BTW..have a long/thin/sharp knife ready to cut the double sided tape when removing cladding :thumbup:
Start at the doors..move Fore & Aft from there.

jo

[Marlin]

I agree that there must be some front shaft rotation, but with the peppier feeling, it must not be much.
I have no definitive way to say how much power is actually being transferred, could just be a light friction amount, but I am not willing to try and find out with the rear axle on jack stands:)

[pbkid]

I agree that there must be some front shaft rotation, but with the peppier feeling, it must not be much.
I have no definitive way to say how much power is actually being transferred, could just be a light friction amount, but I am not willing to try and find out with the rear axle on jack stands:)

Put a Go Pro under there ;)

[blacksambo]

The internal ball ramp mechanism prevents TOD disengagement, by any means.

[Marlin]

I know it rotates Jack, I marked it with chalk. I just need to know how much torque is involved.

[blacksambo]

One aspect to know about is that a heavier Trooper 5 door gets only one 1 mpg more than the VX with its TOD turned off.

[Scott Larson]

I think what has been forgotten here is that the TOD relies on several clutches that distribute the torque. Inasmuch as they are clutches, they tend to drag regardless of torque applied. That said, the drag will rotate the shaft even though they exert no actual useable force. My two cents, please remit change...:_confused

[tom4bren]

I checked my trip odometer the first time that I towed the VX 4 down with locking hubs & quick disconnect on rear driveshaft. Nothing registered on the ODO after a 400 mile drive.
Not 'Xakly the same situation but though I'd throw that out there.

My personal guess is that you are probably getting some small amount of viscous coupling through the transfer case, or a minimal amount of clutch drag ... or maybe a little of both.
So you may get a bit of rotation on the drive shaft but I doubt that any torque is being applied.

You could make a small 'flag' out of duct tape on your drive shaft. If power is being applied, it'll spin fast & the sound of the flag slapping the snot out of your floor board will let you know (without damaging anything). If it's just a small amount of rotation caused by viscous coupling or clutch drag, I doubt the shaft will be turning fast enough to make the noise.

[samneil2000]

Just reach in there and try to stop the shaft from spinning. My guess is you'll be able to hold it back with your hand.
Try not to run over yourself again though!

[evillecutter]

im confused - if you have locking front hubs it does or does not disengage the tod? or is that what is being discussed here? locking hubs on an awd is different then typical 2wd/4hi/4lo like on my chevy truck? - i should be getting my proton back this week after a complete transfer case rebuild - they said "all the clutch plates were sheared off" - i dont want this to happen again and if i can prevent it by locking out my front hubs im all for it but i dont want to spend $275 on them if they wont really help - i was kind of under the assumption that the entire drivetrain would still be running just not affecting the wheels with tod active but the front hubs locked out... correct? after all the tod is a computer system that affects the drivetrain and the locking hubs have nothing to do with that computer so there is no way for the vehicle to know that it should not be turning the prop shaft...

[tom4bren]

Correct. The TOD has no way of knowing if the hubs are locked or not. If the TOD is still functional, then unlocking the hubs means that the front driveline is still being turned from the transfer case but the final connection to the wheel is missing.

Before I put the locking hubs on, I was very reluctant. I didn't like the driveline spinning unloaded. After installing them several years ago (for towing purposes), I've found that it doesn't bother the transfer case at all. Think of it this way, try running an engine with absolutely no load on it (not even a flywheel). The second you run up the rpms, nasty things can happen in the engine. All the mechanics are designed to drive a load & with none there, all the gears are not meshing as they are supposed to. Gear chatter & vibrations will eat the engine very quickly.

If you install the locking hubs, several members have discussed TOD cutoff switches that you could do as well (or just unplug the TOD computer under the passenger seat). Frankly, I'd just go for the locking hubs & be done with it. The TOD clutches were designed to last a long time. I don't think you'll have any issues after the re-build even if you don't put on the locking hubs.

BTW, you should be able to pick up a set of used hubs from a bone yard for $50-100. Marlin (not Merlin) may even be able to find you a set even cheaper (he seems to be pretty well connected for that stuff).

[Scott Larson]

It's amazing the problems we can create for ourselves when we start messing with what the engineers originally designed and spec'd-out...as gearheads, we just can't help ourselves! :slap:

[Marlin]

Not a bad idea Tom. I will use a zip tie. Then I will engineer a quick release function that allows me to disconnect the plastic retaining device. Then I can calculate the speed of rotation based on the distance the plastic retaining device travels from the rotating shaft assembly. I will of course take into consideration wind resistance/inertia and some amount of error in the timing of the release.

Or, I could just stomp on the gas, if the clicks don't speed up as fast the truck, that would be indicitive of slipping, meaning it is just some light amount of friction in the coupling portion.:smack: