Ok here is our SRT Transfer case.
Many thanks to Resume Speed for helping with links etc. on this thread!
Thanks also to Blown7 for the help on loading all the photos.
Below link is a basic parts list for our Transfer case:
http://www.wkjeeps.com/misc/Tcase_2008_Parts.pdf
Below is a write up from my Shop Manual:
The NV146 transfer case provides Full-Time Active Four-Wheel Drive for optimum traction in a wide range of conditions
and is used in the Grand Cherokee SRT8 vehicles. The transfer case center differential distributes torque 48
percent to the front axle and 52 percent to the rear axle along with an electronically controlled clutch pack that is
coupled to the center differential for torque biasing. The NV146 electronics provide an active system because it can
anticipate and prevent slip. The transfer case can redistribute 100 percent of torque to the front or rear axle,
depending on need.
The NV146 single-speed transfer case provides the following benefits:
² No shift lever or driver interaction required.
² Full-time four-wheel drive provides smooth operation and vehicle stability under all conditions because torque
is constantly being transferred.
² Even torque distribution provides traction to maintain forward motion under most conditions.
² The Brake Traction Control System (BTCS) works in tandem with full-time four-wheel drive. BTCS provides
resistance to any wheel that is slipping to allow additional torque transfer to wheels with traction.
² Robust design and improved sealing enhance reliability.
² No maintenance required.
Controls for the NV146 transfer case active clutch (torque biasing device) are located in the Final Drive Control
Module (FDCM) and communicated on the CAN C bus. The FDCM monitors wheel speeds at the front and rear
axles to detect wheel slippage. A complete vehicle dynamics model calculates slip at each tire for given vehicleoperating
conditions. The clutch pack in the transfer case is engaged to minimize the speed difference between the
front and rear axle, resulting in torque transfer to the axle with higher traction. The electronically controlled wet
clutch pack uses an electric motor to actuate a sector plate. The sector plate actuates a clutch lever that applies
normal force to the multi-disc wet clutch pack bridging the differential. The clutch discs are alternately splined to the
front and rear driveshafts. When normal force is applied to this clutch pack, torque is transferred to equalize speed
differences between front and rear axles.
Unfortunately, the shop manual just copied the text and illustrations from a similar transfer case so I was on my own as far as the dismantling and re-assembly of some components.
Basic operation as I see it:
All in all, a pretty straight forward design.
Enjoy these photos guys!
Many thanks to Resume Speed for helping with links etc. on this thread!
Thanks also to Blown7 for the help on loading all the photos.
Below link is a basic parts list for our Transfer case:
http://www.wkjeeps.com/misc/Tcase_2008_Parts.pdf
Below is a write up from my Shop Manual:
The NV146 transfer case provides Full-Time Active Four-Wheel Drive for optimum traction in a wide range of conditions
and is used in the Grand Cherokee SRT8 vehicles. The transfer case center differential distributes torque 48
percent to the front axle and 52 percent to the rear axle along with an electronically controlled clutch pack that is
coupled to the center differential for torque biasing. The NV146 electronics provide an active system because it can
anticipate and prevent slip. The transfer case can redistribute 100 percent of torque to the front or rear axle,
depending on need.
The NV146 single-speed transfer case provides the following benefits:
² No shift lever or driver interaction required.
² Full-time four-wheel drive provides smooth operation and vehicle stability under all conditions because torque
is constantly being transferred.
² Even torque distribution provides traction to maintain forward motion under most conditions.
² The Brake Traction Control System (BTCS) works in tandem with full-time four-wheel drive. BTCS provides
resistance to any wheel that is slipping to allow additional torque transfer to wheels with traction.
² Robust design and improved sealing enhance reliability.
² No maintenance required.
Controls for the NV146 transfer case active clutch (torque biasing device) are located in the Final Drive Control
Module (FDCM) and communicated on the CAN C bus. The FDCM monitors wheel speeds at the front and rear
axles to detect wheel slippage. A complete vehicle dynamics model calculates slip at each tire for given vehicleoperating
conditions. The clutch pack in the transfer case is engaged to minimize the speed difference between the
front and rear axle, resulting in torque transfer to the axle with higher traction. The electronically controlled wet
clutch pack uses an electric motor to actuate a sector plate. The sector plate actuates a clutch lever that applies
normal force to the multi-disc wet clutch pack bridging the differential. The clutch discs are alternately splined to the
front and rear driveshafts. When normal force is applied to this clutch pack, torque is transferred to equalize speed
differences between front and rear axles.
Unfortunately, the shop manual just copied the text and illustrations from a similar transfer case so I was on my own as far as the dismantling and re-assembly of some components.
Basic operation as I see it:
- The shift motor (which some of us unplug from time to time) rotates the shaft that has a cam attached to it. It appears that it can rotate clockwise and counter clockwise. I can see NO harm in unplugging it for the dyno etc. as the shift arm will not engage the clutch pack for the forward output shaft.
- The clutch pack is engaged when the cam is rotated...could be partially engaged or fully engaged, therefore increasing the torque to the front wheels. I did note that the clutches in this transfer case which had approximately 6,000 miles (per the junk yard) looked perfect. I did notice a shiny area on the output shaft where the clutches engage though.
- The chain and gears look substantial...time will tell!
- The one piece output shaft also looks substantial.
All in all, a pretty straight forward design.
Enjoy these photos guys!