06 Sierra Denali
10-06-2010, 12:03 PM
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06 Sierra Denali
Does anyone know if on the all wheel drive, is there a way to install switch to disable? I assume that it has the same transfer case as a 4X4? Thanks Justin
10-06-2010, 12:24 PM
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like cody said no way to disengage... and unless u wanna blow ur transfercase, dont pull the front driveshaft...
i believe these cases split torque 60/40 or something like that...
i believe these cases split torque 60/40 or something like that...
10-06-2010, 12:45 PM
#4
From GM:
The NVG-149 has a rated 2203 ft/lbs Maximum Torque Capacity in an approx. vehicle weight of 6800 lbs.
The viscous coupling can transfer up to 300 lb-ft of torque during a standard loss of traction and up to 600 lb-ft at the extreme – far more than a driver should ever need – to ensure its responsiveness to any operating situation.
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 as the input. The annulus gear connects to the rear output shaft and rear wheels. The sun gear connects to the front output shaft and front wheels through the chain and sprockets. The viscous coupling 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, and the outer drum to the sun gear. 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% 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% torque is delivered to the input shaft from the transmission. The torque is split to 62% to the rear output shaft and 38% to the front output shaft, 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%, and up to 100% torque to the rear output shaft. The torque at the front output shaft is lowered from the 38%, to as low as 0% 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 goes higher from the 38%, up to 100% torque. The torque at the rear output shaft is lowered from the 62%, to as low as 0% 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.
© Copyright General Motors Corporation. All Rights Reserved.
Document ID # 873908
2003 Chevrolet/Geo Chevy K Silverado - 4WD
The NVG-149 has a rated 2203 ft/lbs Maximum Torque Capacity in an approx. vehicle weight of 6800 lbs.
The viscous coupling can transfer up to 300 lb-ft of torque during a standard loss of traction and up to 600 lb-ft at the extreme – far more than a driver should ever need – to ensure its responsiveness to any operating situation.
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 as the input. The annulus gear connects to the rear output shaft and rear wheels. The sun gear connects to the front output shaft and front wheels through the chain and sprockets. The viscous coupling 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, and the outer drum to the sun gear. 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% 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% torque is delivered to the input shaft from the transmission. The torque is split to 62% to the rear output shaft and 38% to the front output shaft, 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%, and up to 100% torque to the rear output shaft. The torque at the front output shaft is lowered from the 38%, to as low as 0% 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 goes higher from the 38%, up to 100% torque. The torque at the rear output shaft is lowered from the 62%, to as low as 0% 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.
© Copyright General Motors Corporation. All Rights Reserved.
Document ID # 873908
2003 Chevrolet/Geo Chevy K Silverado - 4WD
10-06-2010, 01:32 PM
#5
"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%, and up to 100% torque to the rear output shaft. The torque at the front output shaft is lowered from the 38%, to as low as 0% torque."
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10-06-2010, 06:23 PM
#8
Some have done exactly that in the past with no reported problems, but you have to remove the driveshaft on the dyno, as you can not drive it to and from the facility disconnected and it is also said that to do so, at the end of the pull you need to let out of the throttle, letting the rpm’s come back down on their own not using the brakes to slow it down. That’s just a brief portion of it, but never-the-less doing so is taking the viscous coupler’s life in your own hands.
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