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Discussion Starter · #1 ·
I'm just curious.


I had my truck off of the ground yesterday and in 2WD mode. I noticed when I spin one wheel only THAT wheel spins and if I spin the driveshaft from the front differential to the transfer case only the shaft spins.


I have a car with an LSD and if I did this both wheels would spin the same direction and I know that with an open diff that they would spin the opposite direction.


What I found out is that when you put these truck into 4WD it locks the transfer case and locks something in the front differential.


What I want to know is why does it need to lock anything in the front differential if the truck has an open differential in the front?


I hope this makes sense.....
 

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It locks the hubs. The axle shafts in the front when in 2wd are not connected to the wheel. When you engage 4wd, the hubs engage the axle and the transfer case powers the front axle.

https://en.wikipedia.org/wiki/Locking_hubs
 

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Discussion Starter · #3 ·
So this is simply to reduce wear and improve fuel economy?
 

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I'm not exactly sure how the Colorado Canyon works.... but most other 4WD trucks I've owned......

The actual 'drive' to the wheels is engaged via a 'collar' on one of the axle shafts. Toyota calls it ADD (Auto disconnecting differential).

If the Colly/Canny are similar - the front axle shafts spin 100% of the time. However - one side is attached to the front diff 100% of the time (one piece) and keeps the front diff spinning 100% of the time. Open diff function inside. However - when you engage 4WD - the other axle shaft is actually 2 pieces and is connected when you select 4WD. This connects the entire front diff to supply power to both wheels. The t-case......only engages the front propeller shaft.

We do not have manual hubs. If you jack up the truck and spin a front wheel - Look at the axle shaft itself. It's probably spinning (hence, the hubs are permanent). The engagement occurs at 'one side' between the diff /hub.
 

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Yep! Parasitic drag. If you were to lock the hubs manually (like on older trucks) and the transfer case was still in 2wd, you would be spinning the half shafts and then the front axle. That's a good 20lbs+ of metal and gears your having to spin around. While not harmful, it's just a waste in fuel being used, and added wear to all the gear and joints.

Back in the day, as well as current people who swap auto locking hubs to manual hubs need to get out and engage them manually at both front wheels to use 4wd.

When planning on running 4wd or in winter, folks will lock the hubs and run 2wd so they can engage 4wd on the fly without getting out. While it will add wear and reduce economy it is more convenient. Nothing will make you more miserable than getting stuck in a mud hole, and having to get out into the mud to lock the hubs.

Ahh, the joy of modern conveniences :)


Edit- if equipped, auto mode on the 4wd selector locks the hubs, but the clutch in the transfer case doesn't engage until wheel slip. Locking the hubs takes a second, but engagement of the clutch is almost instant. This is why they recommend auto mode only be used when 4wd is likely. It's not harmful to the drivetrain, but wasteful.
 

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Discussion Starter · #8 ·
I'm not exactly sure how the Colorado Canyon works.... but most other 4WD trucks I've owned......

The actual 'drive' to the wheels is engaged via a 'collar' on one of the axle shafts. Toyota calls it ADD (Auto disconnecting differential).

If the Colly/Canny are similar - the front axle shafts spin 100% of the time. However - one side is attached to the front diff 100% of the time (one piece) and keeps the front diff spinning 100% of the time. Open diff function inside. However - when you engage 4WD - the other axle shaft is actually 2 pieces and is connected when you select 4WD. This connects the entire front diff to supply power to both wheels. The t-case......only engages the front propeller shaft.

We do not have manual hubs. If you jack up the truck and spin a front wheel - Look at the axle shaft itself. It's probably spinning (hence, the hubs are permanent). The engagement occurs at 'one side' between the diff /hub.


I do know for a fact that on these trucks that the front axle does not spin 100% of the time.






So my roommate has a 2008 F-250 but it came with some aftermarket wheels that cover his hub lockers, if he were to take the wheels off and lock them and leave them that way would he be fine? and then use the electronic switch in the truck when he wanted 4wd?
 

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I do know for a fact that on these trucks that the front axle does not spin 100% of the time.






So my roommate has a 2008 F-250 but it came with some aftermarket wheels that cover his hub lockers, if he were to take the wheels off and lock them and leave them that way would he be fine? and then use the electronic switch in the truck when he wanted 4wd?
Are you referring to the front DRIVESHAFT? Or the front AXLE shafts?

I was referring to the axle shafts at the hubs - they would spin 100% of the time.

The front driveshaft (propeller shaft) will only turn when it is engaged via the transfer case.
 

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I thought the Colorado/Canyon had Automatic locking hubs.
A lot of confusion here.... Automatic Locking hubs on these trucks only means the hubs are engaged 100% of the time (permanent) and you do not have to manually engage them. That's it......

When you read the word 'automatic' - some folks might automatically assume they engage and disengage when you put the truck into 4WD. That's not the case...... If that were true - each wheel (at the hub) would have some sort of electric or vacuum operated actuator to engage mechanical gears together. Very costly and way too much mechanical parts to wear/tear and fail.
 

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A lot of confusion here.... Automatic Locking hubs on these trucks only means the hubs are engaged 100% of the time (permanent) and you do not have to manually engage them. That's it......

When you read the word 'automatic' - some folks might automatically assume they engage and disengage when you put the truck into 4WD. That's not the case...... If that were true - each wheel (at the hub) would have some sort of electric or vacuum operated actuator to engage mechanical gears together. Very costly and way too much mechanical parts to wear/tear and fail.

I've not heard of this. As its a part time system, the typical route is to have an actuator at the hubs, at least thats been the normal route for years. With all the fuel saving gizmos on the new twins, I wouldn't think its permanently engaged. I'm having a hard time finding more information on this. I'd like to know for sure how it all works. All the writeups I find says "Engages the front axle" its not very descriptive as far as what that process is.
 

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I've not heard of this. As its a part time system, the typical route is to have an actuator at the hubs, at least thats been the normal route for years. With all the fuel saving gizmos on the new twins, I wouldn't think its permanently engaged. I'm having a hard time finding more information on this. I'd like to know for sure how it all works. All the writeups I find says "Engages the front axle" its not very descriptive as far as what that process is.
Coming from a Toyota - it was referred to as ADD - Auto Disconnecting Differential.
The Automatic Disconnecting Differential system: Off-Road.com

If you search online and google images & such - "Chevrolet 4WD Actuator" - I'm pretty sure there's only ONE actuator near the diff that engages the diff (or at least couples something/shafts together). I haven't been able to find 2 different actuators (one at each hub).
 

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I believe the @Janster is correct. Maybe you folks are confusing what a hub is?? The hub is at the wheel. It looks like any front wheel drive in the front to me. No disconnecting is happening at the wheel, it is done inside the differential. The on/off is going on from the transfer case to the front driveshaft in the diff AND the front drive shaft to the transfer case in the transfer case.

all the above is describing the front stuff going on.
 

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I'm just curious.


I had my truck off of the ground yesterday and in 2WD mode. I noticed when I spin one wheel only THAT wheel spins and if I spin the driveshaft from the front differential to the transfer case only the shaft spins.


I have a car with an LSD and if I did this both wheels would spin the same direction and I know that with an open diff that they would spin the opposite direction.


What I found out is that when you put these truck into 4WD it locks the transfer case and locks something in the front differential.


What I want to know is why does it need to lock anything in the front differential if the truck has an open differential in the front?


I hope this makes sense.....
perfect sense, it is a normal diff in the front. Just like any rear diff without a limited slip of some kind. Limited slip connects the two axles together with a series of clutches. Our trucks do not have LS front or rear. They do have a type of auto locker in the rear but it is not LS, totally different. Sooo when you put it in 4wd it connect the shaft to the diff, making it the same as any rear diff. (connects it to the transfer case also)

to answer your question it needs to lock the driveshaft the the front ring gear so you have 4WD of coarse, even with an "open diff" like you called it, it does save from having to turn the drivshaft for no reason when in 2wd, saving wear and tear and MPGs.

The ZR2 has an electric locker front and rear which is totally different also, I'll let you google that one :)
 

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Thanks. Clearly I am outdated in how it all goes together. My previous 4x4's (Pathfinder, Tahoe, couple of F350's) have most all been hub actuated. It makes sense that its an internal shaft disconnect, as it doesn't have the typical bulky hubs sticking out the front wheels. To be honest, I thought they just replaced the hubs that stuck out, to one more internally mounted for better appearance. All my buddies are full size junkies with old school tech, so a little sheltered. :)
 

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A lot of confusion here.... Automatic Locking hubs on these trucks only means the hubs are engaged 100% of the time (permanent) and you do not have to manually engage them. That's it......

When you read the word 'automatic' - some folks might automatically assume they engage and disengage when you put the truck into 4WD. That's not the case...... If that were true - each wheel (at the hub) would have some sort of electric or vacuum operated actuator to engage mechanical gears together. Very costly and way too much mechanical parts to wear/tear and fail.
No. Automatic locking hubs means the hubs lock automatically when 4WD is selected. This was tradition on vehicles when people first started to get lazy and not want to get out and lock hubs. It is no more costly then your diff disconnect a lot of manufacturers still do it. You are incorrect about that. Now, maybe you are correct about the Canyon/Colorado in that there is a disconnect from the diff. That's really stupid though to have the truck in 2wheel drive spinning the front CV axles.
 

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No. Automatic locking hubs means the hubs lock automatically when 4WD is selected. This was tradition on vehicles when people first started to get lazy and not want to get out and lock hubs. It is no more costly then your diff disconnect a lot of manufacturers still do it. You are incorrect about that. Now, maybe you are correct about the Canyon/Colorado in that there is a disconnect from the diff. That's really stupid though to have the truck in 2wheel drive spinning the front CV axles.
I think we're speaking the same thing but in 2 different languages.

If you re-read what I posted and put "In Today's vehicles" in front.....
I wasn't referring to vehicles that were made 20 years ago. I was referring to today's systems.
 

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I think we're speaking the same thing but in 2 different languages.

If you re-read what I posted and put "In Today's vehicles" in front.....
I wasn't referring to vehicles that were made 20 years ago. I was referring to today's systems.
We'll in a lot of today's systems their is no disconnect at all for the front drivetrain save the transfer case. Look at the Jeep Wrangler. Even in 2wd, the stuff up front is always moving.
 
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