OK but how sure are you that it does go back to 2wd at WOT. Mind would not till I let off the gas completely.Originally Posted by fastlt1
Try driving around with more than 500 hp and pull into traffic in 2wd. Tires go quick. Then drive around on auto 4wd and when it kicks in it is rather violent.
Seems you missed the entire point of the swap.
99RCSB Broke because I wasted thousands and thousands of dollars on my truck.
Actually this isn't true of all AWD transfer cases. The 149 for instance has a viscous coupler that sends power to the gripping wheels not the slipping ones. In fact you can remove the front driveshaft with it and still drive the truck. I know it works because I did it moving mine around the shop when it was torn apart. Normally it has a 60rear/40 front split on the power and it adjusts the power according to the situation.
Even with the 4x4 in 2wd mode you have parasitic drag on the front axle. The left front wheel is always connected to the differential and turns it all the time. When the actuator isn't engaged the other 2 sides (right and input) of the differential are open and the one with less resistance will spin (usually a combination of the 2). This is why people who say you need to put the truck in 4x4 occasionally to lube the front diff are full of crap.
Anyway, yes the AWD will probably get slightly worse mileage, but not that big of a difference.
Really the answer is the xfer case used in the HUMMER line up. I think the H3 uses a Xfer case that will suffice for the 1500 series? And the H2 xfer case should work well in a 2500 series truck.
The Hummer xfer cases offer a TRUE AWD option. By using a center diff in the xfer case to split power 40/60. The center diff has a locker that will give you a 4-HI Locked option and also has a 4-Lo locked option.
Also the reason you could move your truck around with no front drive shaft with a AWD is because you were on flat ground. Had you been on a hill things would have changed.
Last march i was offroading a broke a my front right 1/2 shaft. Even in 4-HI Lock I still only had 2wd as all power beeing sent to the front was exiting via the broken shaft that was no longer connected to the wheel.
Also there is NO AWD System out there that sends power to the wheels that grip and not slip. This is a total load of crap. Power/Torque will always take the path of lest resistance. Its the TRACTION CONTROL system that reduces wheel spin. It does this by applying brakes to a tire that it rotating marginally faster than another causing more resistance the the spinning tire. This in turn sends more power/ torque to the other tire.
If you guys have ????? in regards to AWD im probubly the guy to ask lol.
THIS INFO IN RED ABOVE IS NOT CORRECT. Silverado SS transfer case will move the truck with front shaft removed. Many trucks have been dynoed by removing the front shaft. Some Denali and Escalade transfer cases rely on braking to the wheel that is slipping. So that transfer case will not move with out front shaft.
I disagree. If someone wants to know about the hummer transfer case I will give you that one.
What question are you answering? Did you read every post in this thread? My magic 8 ball says not likely.
Seems to me that you know about hummer and 4wd transfer case and very little about the transfer case for a Silverado SS. Really there isn't much to know about the SS transfer case however I think you missed it and the whole reason for this thread. THIS THREAD IS NOT ABOUT OFF ROADING. This thread is about street traction. You are putting information that will do nothing but confuse some one into thinking that all they have to do is bolt the hummer transfer case in a truck and drive. That would be cool if it were easy. Not gonna work that way. Body control module, Transfer case control module, switches and various wiring would have to be changed and or replaced.
The information you posted here should not have even been put into thread titled what the benefit of awd much less this one. Maybe reworded to describe the hummer transfer case maybe. So please if you are going to post information in my thread make it accurate.
Last edited by zeake; 11-02-2009 at 04:05 PM. Reason: this to there
99RCSB Broke because I wasted thousands and thousands of dollars on my truck.
My information is VERY accurate. I posted info that was relevant to a smart AWD swap. I never said and Hummer xfer case would be an easy swap. However I would assume anyone looking to do a mod of this type would understand its not just a plug'n play install.
I am really sorry if I offended you in some way. I just thought that some might really benefit from the information posted. That is why we are all here right? To learn from each other?
I dont see the point of awd, i saw your reasons but still i wouldn't do that, what wheels you got on your truck man that thing is freakin sweet
You information must not be too accurate if you don't know what type transfer case the SS has.
So my swap was not smart?
Previous posts in this thread described the SS transfer case. Viscous coupling. This link has some good info in it. http://www.denalitrucks.com/documents/TL_Jan03.pdf
The SS transfer case uses a viscous coupling that works by FM. You know Freakin magic. I can't accurately describe the mechanical functions of it so I won't try. It is really neat though.
Your post is informative about the hummer transfer case but not accurate at all about the SS transfer case, yet you say "ask me about all wheel drive transfer cases" like you are the expert when you are not totally accurate.
You did not offend me at all, and I hope I did not offend you. I just dont want someone to read my thread that I spent a ton of time researching and find information that will not help them, or worse, steer them into a tough direction. Why get some ones hopes up of having the hummer transfer case and then they find out how hard it would be. Some people that haven't a clue might think it is plug and play and waste some money and time trying to make it work when it has not even been proven to be possible. Several people had proven the SS swap before I did it. I am the only one that wrote a how to. I would love to see someone do it and write up a how to.
If I had known more about the Hummer transfer case I might have been the poor sap to try and make it work.Heck your info makes me reconsider owning a Hummer.
99RCSB Broke because I wasted thousands and thousands of dollars on my truck.
Crud
In my last reponse I was totally wrong about a good description of how the awd transfer case works. I even gave the Hummer dude an unnecessary hard time for it. Threads are currently running together in my brain. I will try and find the accurate info written by someone other than myself. Will post it soon.
SORRY
99RCSB Broke because I wasted thousands and thousands of dollars on my truck.
NVG 149 Transfer Case Description and Operation
The RPO NP3 is a single speed, single mode transfer case. The mode is full-time all wheel drive. It has a planetary differential gear set that splits the torque, normally 38 percent to the front wheels and 62 percent to the rear wheels.
The NVG 149 utilizes magnesium housings. Proper fasteners, brackets, and fill/drain plugs must be used to prevent galvanic corrosion. The planetary differential uses the carrier (6) as the input. The annulus gear (4) connects to the rear output shaft (5) and rear wheels. The sun gear (3) connects to the front output shaft (7) and front wheels through the chain (8) and sprockets. The viscous coupling (2) consists of a sealed housing filled with a high viscosity silicone fluid and thin steel plates alternately splined to the inner and outer drum. The inner drum is connected to the input shaft (1), and the outer drum to the sun gear (3). Whenever there is a speed difference between the front and rear wheels, the inner and outer plates of the viscous coupling spin relative to each other and the silicone fluid provides resistance. The resistance was tuned to be high enough to bias power quickly to the wheels with traction, and low enough to prevent binding in a tight turn on dry surfaces. This is the most common way the viscous coupling is activated, the shear mode. If the speed difference is high, the coupling can lock or hump. This "hump" occurs when the heat generated, expands the fluid inside the housing, changing the fluid dynamics between the plates. This results in pressure between the plates, forcing them into contact with each other, similar to a clutch pack. In the hump mode, the coupling can bias torque 100 percent to one axle, if required. Situations requiring this are extreme such as backing up a steep gravel grade or climbing over off-road obstacles. The viscous coupling is not serviceable; it must be replaced if defective. This is because each viscous coupling is calibrated for optimum vehicle performance for both the shear and hump modes. If the viscous coupling is in the "hump" mode too long, severe damage will occur. To prevent damage to the viscous coupling, DO NOT:
Tow with only two wheels down
Drive without one propshaft
Drive with a "donut" spare tire for an extended period of time
Power Flow - No Wheels Slip
During normal operation, 100 percent torque is delivered to the input shaft (1) from the transmission. The torque is split to 62 percent to the rear output shaft (2) and 38 percent to the front output shaft (3), by the planetary differential. Because there is not a loss in traction or slip in the front or rear wheels, the viscous coupling is locked in place and there is no "shear" mode or "hump" mode involved.
Power Flow - Front Wheels Slip
When traction is lost at the front wheels, the viscous coupling works in conjunction with the differential to bias the torque more to the rear wheels. The rear torque goes higher than the 62 percent, and up to 100 percent torque to the rear output shaft (2). The torque at the front output shaft (3) is lowered from the 38 percent, to as low as 0 percent torque.
Power Flow - Rear Wheels Slip
When traction is lost at the rear wheels, the torque is biased to the front wheels. The torque to the front output shaft (3) goes higher from the 38 percent, up to 100 percent torque. The torque at the rear output shaft (2) is lowered from the 62 percent, to as low as 0 percent torque.
Customers may have concern that the transfer case is not operating properly because one set of tires spun for a brief period. It is normal for one set of tires to spin until the viscous coupling engages.
Turning off the traction control switch, if equipped, enhances the function of the viscous coupling. The viscous coupling, as described above, engages by heat. Allowing one set of tires to spin or slip for a brief period will generate heat in the viscous coupling. The engine speed should be kept at a constant speed during the brief spin of the tires. Pulsating the engine speed or hard acceleration will not allow the viscous coupling to operate properly.
99RCSB Broke because I wasted thousands and thousands of dollars on my truck.
So sayeth someone with no traction problems on a daily driven 500+ horse power truck.
I never wanted a 4 wheel drive truck. I bought it because it was the right price and essentially the 4wd was free. Ever owned a 4 wheel drive vehicle?
The only non 4 wheel drive vehicle I own right now is an 05 GTO and it is for sale.
I absolutely love my awd/4wd vehicles.
99RCSB Broke because I wasted thousands and thousands of dollars on my truck.
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