Is it possible to add 2WD lo-range on my Z71?

wsettle · October 3, 2005

I've got a 2004, z71 1500 and would like to add the capability of 2WD lo-range so I can maneuver a trailer at very low speed.

Is there a transfer case available or would lock outs be the ticket?

If you have any ideas I would appreciate it.

Thanks,

Bill

mmmikkke · October 3, 2005

I've got a 2004, z71 1500 and would like to add the capability of 2WD lo-range so I can maneuver a trailer at very low speed.

Is there a transfer case available or would lock outs be the ticket?

If you have any ideas I would appreciate it.

Thanks,

Bill

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You could probably put a switch on your front axle solenoid so that 4-LO would only be 4-LO if the switch is "on". When it's off, the xfr case would engage the front drive shaft, but the clutch in the differential would not engage, so you'd effectively have 2-LO.

redvett · October 3, 2005

Why not use 4 lo as it was intended for low speed.

wsettle · October 3, 2005

Why not use 4 lo as it was intended for low speed.

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4WD is intended for slow, straight line pulling since the left and right wheels are turning at the same rate. When making a sharp turn in 4WD, tires will have to skid or slip since each tire is turning in it's own radius path. Turning while in 4WD will prematurely wear and ultimately tear up the drive train... at least on my machine where I have to manually shift my transfer case.

On the full time (or is that all-time) 4WD machines this may be different.

I find it odd that 4WD trucks used to have a 2WD lo-range but not anymore. My transfer case shift cover even has a place for it so at some point in time they took that feature away.

asilverblazer · October 3, 2005

I've got a 2004, z71 1500 and would like to add the capability of 2WD lo-range so I can maneuver a trailer at very low speed.

Is there a transfer case available or would lock outs be the ticket?

If you have any ideas I would appreciate it.

Thanks,

Bill

<{POST_SNAPBACK}>

You could probably put a switch on your front axle solenoid so that 4-LO would only be 4-LO if the switch is "on". When it's off, the xfr case would engage the front drive shaft, but the clutch in the differential would not engage, so you'd effectively have 2-LO.

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I like the sound of doing this, but is it relly as simple as putting a switch to the solenoid, If so where would these wires be? (Besides by the front diff). Also, when placed in four wheel drive either high or low, the transfer case must be engaged as well as the front diff? I always thought the front was engaged much the same way as the rear, always on just not receiving power from the t-case. If one was to do this what problems could come up, would a code come up or something like that? Before this thread I figured the easy fix would be adding an aftermarket crawler box. But not as easy as this sounds.

wsettle · October 3, 2005

I've got a 2004, z71 1500 and would like to add the capability of 2WD lo-range so I can maneuver a trailer at very low speed.

Is there a transfer case available or would lock outs be the ticket?

If you have any ideas I would appreciate it.

Thanks,

Bill

<{POST_SNAPBACK}>

You could probably put a switch on your front axle solenoid so that 4-LO would only be 4-LO if the switch is "on". When it's off, the xfr case would engage the front drive shaft, but the clutch in the differential would not engage, so you'd effectively have 2-LO.

<{POST_SNAPBACK}>

Mike, that sounds like it would work so I started searching google and haven't found anything for my chevy but the concept is a mod done to Toyota's with electirically lockable hubs... http://www.wattora.com/mods/twolow/

You mentioned a 4-LO switch which sounds like the push button 4WD selector but I would think that my truck with a manual selector would use the same hubs as one with a push button selector.

I did find a 2003 Z71 for sale item that says it has 2LO built in. I wonder if that is factory? http://www.brettwho.com/tempfiles/forsale/...0Silverado.html

99-2door · October 3, 2005

I did this on my 95 and my Dad's 97.

When you are backing a gooseneck or 5th wheel trailer on pavement, the front wants to bind bad in 4LO. His truck is a 5 speed so it is easier to back in the low range.

Use a relay and interrupt the circuit for the front diff actuator. I wired so that the relay interrupts power when on, that way if there is a problem with the switch or wiring you still have 4x4 available.

It's as easy as that on the older ones but mid year 97 they switched to the newer actuator that has to have power to move in OR out. You ca neither interrupt the power supply and remember to hit the switch before you shift into 4x4 or interrupt the signal somehow.

silverado3500 · October 3, 2005

I do this frequently too. . . On my ford Its just a matter of not getting out and locking the hubs. Makes manuvering the gooseneck a snap.

I think even the manual transfercases on GM trucks, have automatic hubs?

99-2door · October 4, 2005

I do this frequently too. . . On my ford Its just a matter of not getting out and locking the hubs. Makes manuvering the gooseneck a snap.

I think even the manual transfercases on GM trucks, have automatic hubs?

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GM trucks post 88 don't have locking hubs at all. The hubs are direct driven by the axles which are then locked to the differential by the front diff actuator.

The left axle and the prop shaft are always locked to the diff, but the right axle is only locked to the diff when the actuator is engaged.

One advantage to that set-up, besides not having to get out to lock the hubs in, is the front diff is always turned by the left tire running on the ground. Thus you don't have to periodically engage the 4x4 to lube the diff.

wsettle · October 4, 2005

GM trucks post 88 don't have locking hubs at all. The hubs are direct driven by the axles which are then locked to the differential by the front diff actuator.
The left axle and the prop shaft are always locked to the diff, but the right axle is only locked to the diff when the actuator is engaged.

One advantage to that set-up, besides not having to get out to lock the hubs in, is the front diff is always turned by the left tire running on the ground. Thus you don't have to periodically engage the 4x4 to lube the diff.

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Sounds like you have researched this so do you know if the front diff actuator be disabled by inturrupting it's power to acheive 2LO?

Frozen001 · October 4, 2005

My interpretation of 99-2door's post is that by interupting the actuator's power you will be in 4-low, but the front letf axle will still turn... it will only effectively prevent the front right from spinning...

asilverblazer · October 4, 2005

So in 4lo, the front tires are locked together? I thought they were an open diff able to spin at different rates. By unlocking one tire from the other (which I thought was already the case) the front to back binding would still occur, so by doing this mod nothing is gained, in respect to preventing the binding between front and rear tires. For this to be effective BOTH front tires must be disengaged. Although unlocking one would minimize the problem, it would not eliminate it.

In short, would adding the switch prevent both front tires from receiving torque from the T-case?

WhiteyZ71 · October 4, 2005

Search for a product called "posi-lock" it allows 2Lo range

99-2door · October 5, 2005

My interpretation of 99-2door's post is that by interupting the actuator's power you will be in 4-low, but the front letf axle will still turn... it will only effectively prevent the front right from spinning...

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No, since the front is an open diff, when the actuator is not engaged the right side has basically no resistance. Thus all the driven power is transferred to the side of the diff that nothing is attached to.

Ever wonder why there are no aftermarket front diff lockers for the light duty IFS? Because the left wheel would be powering the drive shaft all the time if it had a locker in there.

When you are in 2HI the left axle and the prop shaft are locked to the diff, but no power is really transferred since one side of the diff is missing. You do get a little bleed through that makes the prop shaft turn, but no power on it.

99-2door · October 5, 2005

So in 4lo, the front tires are locked together? I thought they were an open diff able to spin at different rates. By unlocking one tire from the other (which I thought was already the case) the front to back binding would still occur, so by doing this mod nothing is gained, in respect to preventing the binding between front and rear tires. For this to be effective BOTH front tires must be disengaged. Although unlocking one would minimize the problem, it would not eliminate it.
In short, would adding the switch prevent both front tires from receiving torque from the T-case?

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Being locked to the diff and a LOCKED diff are not the same thing.

Imagine the front diff as being the same as an open rear diff. Don't worry about CV axles and all that, effectively it is the same. If either wheel loses traction the other one will not get power, right? Ok now imagine you take one of the axles and cut it in half. That's what the front diff actuator does basically. When you cut that axle that side of the diff loses all traction, so all torque is applied to that side and the other side is not driven.

So, if your actuator goes bad or you intentionally stop it from engaging neither front wheel is powered.