auto 4wd ?'s
#1
12-20-2013, 10:26 AM
auto 4wd ?'s
Hey guys I was hoping somebody could explain to me how the auto 4wd feature in my 99 ZR2 works.
It seems to be functioning properly, however I get some binding when turning sharp at low speeds, especially when on dry pavement or when I have really good traction.
any thoughts?
Thanks, for any help
It seems to be functioning properly, however I get some binding when turning sharp at low speeds, especially when on dry pavement or when I have really good traction.
any thoughts?
Thanks, for any help
#2
12-20-2013, 10:41 AM
Here ya go:
Take a read through the thread that quote came from (little arrow next to my name in the quote) as it discusses binding with an AWD Bravada. The NV136 transfer case found in the 98+ Bravada operates like the NV236 that is in your ZR2 when it is in Auto4wd mode.
AirRideFanatic,
If you are having problems with the NV136 transfer case, you likely have an issue with the fluid condition. If left in a degraded state long enough, it can burn out the clutch packs which can cause some very annoying drive-ability concerns.
The NV136 transfer case in my old '00 Bravada worked flawlessly year round in NY. And the same setup in my '04 Rainier works great as well.
The '1' in the NV136 nomenclature means that it is a single speed transfer case; differing from the NV236 transfer case which has a low range. Other than that, there are many similarities between the two. The NV136, like the NV236, has a viscous clutch in the transfer case that can bias torque from 0/100 Front/Rear all the way to a locked 50/50 F/R. You can definitely say that the Smarttrak arrangement is like driving an NV236 equiped truck around in Auto4wd all the time. About the only downside of this system, IMO, is that you cannot command it to be locked in.
It is true that the front axle is engaged all of the time which, IMHO, is a welcomed reprieve from the complicated and often problematic front axle engagement system that is used on all of the rest of the 4wd s-series trucks. While the constant turning of the front drivetrain does add a bit of parasitic loss to the vehicle, my old Bravada still maintain ~20MPG highway loaded down with +300# of tools most of the time. This dropped to ~16MPG combined with ~70% city/rural driving. So I wouldn't put a lot of concern into it if that was weighing on your mind.
Like the NV236, the NV136 requires GM AutoTrak II fluid. While it is about two to three times the cost of regular ATF, it's properties are essential to the health of the viscous clutch. And with a service requiring just shy of 2qts, it isn't something you should try to cut corners on to save a few dollars.
If you are having problems with the NV136 transfer case, you likely have an issue with the fluid condition. If left in a degraded state long enough, it can burn out the clutch packs which can cause some very annoying drive-ability concerns.
The NV136 transfer case in my old '00 Bravada worked flawlessly year round in NY. And the same setup in my '04 Rainier works great as well.
The '1' in the NV136 nomenclature means that it is a single speed transfer case; differing from the NV236 transfer case which has a low range. Other than that, there are many similarities between the two. The NV136, like the NV236, has a viscous clutch in the transfer case that can bias torque from 0/100 Front/Rear all the way to a locked 50/50 F/R. You can definitely say that the Smarttrak arrangement is like driving an NV236 equiped truck around in Auto4wd all the time. About the only downside of this system, IMO, is that you cannot command it to be locked in.
It is true that the front axle is engaged all of the time which, IMHO, is a welcomed reprieve from the complicated and often problematic front axle engagement system that is used on all of the rest of the 4wd s-series trucks. While the constant turning of the front drivetrain does add a bit of parasitic loss to the vehicle, my old Bravada still maintain ~20MPG highway loaded down with +300# of tools most of the time. This dropped to ~16MPG combined with ~70% city/rural driving. So I wouldn't put a lot of concern into it if that was weighing on your mind.
Like the NV236, the NV136 requires GM AutoTrak II fluid. While it is about two to three times the cost of regular ATF, it's properties are essential to the health of the viscous clutch. And with a service requiring just shy of 2qts, it isn't something you should try to cut corners on to save a few dollars.
#3
12-20-2013, 11:40 AM
swart thanks for the link and info there, that helped. So I think that this weekend I am going to try and service both differentials and the tcase, can the autotrak II fluid be purchased from napa or is that a dealer only item? And what do you recommend I run in the differentials?
I dont beleive that I am having any rear end issues like he was, I dont get any binding at all in 2wd, it only seems to be in auto or 4wd at low speeds when turning sharp, to the point where I will get some popping and can feel it try to "push" the front end through the corner. This only seems to happen in parking lots when pulling into a spot with auto 4wd engaged. I haven't done any other testing yet.
Do you think I will have any issues running in auto 4wd until sunday when I do the fluid swap, it is snowing here and is nice to have that engaged when driving around in it, I do also put it back into 2wd when cruising down the freeway.
My main concern is that if my wife drives it she doesnt have much experience driving in snow, I would like her to be able to leave it in auto 4wd and not have to worry about it.
Thanks again for any help, much appreciated, I haven't worked with a 4wd system like this before.
I dont beleive that I am having any rear end issues like he was, I dont get any binding at all in 2wd, it only seems to be in auto or 4wd at low speeds when turning sharp, to the point where I will get some popping and can feel it try to "push" the front end through the corner. This only seems to happen in parking lots when pulling into a spot with auto 4wd engaged. I haven't done any other testing yet.
Do you think I will have any issues running in auto 4wd until sunday when I do the fluid swap, it is snowing here and is nice to have that engaged when driving around in it, I do also put it back into 2wd when cruising down the freeway.
My main concern is that if my wife drives it she doesnt have much experience driving in snow, I would like her to be able to leave it in auto 4wd and not have to worry about it.
Thanks again for any help, much appreciated, I haven't worked with a 4wd system like this before.
#5
12-20-2013, 12:38 PM
Autotrak II is a dealer item most of the time if you want to walk in and walk out with it. You can order it online as well. But yeah, your link is to the right stuff.
As far as fluids for the differentials, any quality GL5 75w90 or 80w90 will do. I prefer synthetics, but have no real brand loyalty. I have used Pennzoil, Valvoline, Mobil 1, and Royal Purple 75w90 synthetics in various vehicles without a problem or noticeable difference.
As far as the rear end issues go, if it is fine in 2wd, then the rear axle probably isn't locked up, but a service will not hurt a thing and gives you a chance to look at everything to make sure there are no problems. Just be sure to remove the fill plug on the rear axle before you remove the cover. If you cannot get the fill plug out, do not go any further with the service until you can get it out.
As far as fluids for the differentials, any quality GL5 75w90 or 80w90 will do. I prefer synthetics, but have no real brand loyalty. I have used Pennzoil, Valvoline, Mobil 1, and Royal Purple 75w90 synthetics in various vehicles without a problem or noticeable difference.
As far as the rear end issues go, if it is fine in 2wd, then the rear axle probably isn't locked up, but a service will not hurt a thing and gives you a chance to look at everything to make sure there are no problems. Just be sure to remove the fill plug on the rear axle before you remove the cover. If you cannot get the fill plug out, do not go any further with the service until you can get it out.
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