Advance Adapters 50-6805 - Manual (Page 3)

GM 4WD TH350 AUTO TO JEEP NP231
TRANSFER CASE (27-SPLINES) 1995 & UP
ADVANCE ADAPTERS INC. P/N: 50-6805
P.O. Box 247, 4320 Aerotech Center Way New Item: (10/04)
Paso Robles, CA 93447 PAGE 3 OF 4
Telephone: (800) 350-2223 Fax: (805) 238-4201 Page Rev. Date: 06-01-04
SPECIAL NOTE: The components packaged in this kit have been assembled and machined for specific type of conversions. Modifications to any of the components will
void any possible warranty or return privileges. If you do not fully understand modifications or changes that will be required to complete your conversion, we strongly recommend
that you contact our sales department for more information. This instruction sheet is only to be used for the assembly of Advance Adapter components. We recommend that a
service manual pertaining to your vehicle be obtained for specific torque values, wiring diagrams and other related equipment. These manuals are normally available at automotive
dealerships and parts stores.
On the inside of the transfer case, you'll now be able to remove the planetary assembly. Set the assembly on a work bench and locate the
snap ring that retains the input gear into the planetary housing. Remove the snap ring and lift the input gear out of the planetary housing.
Once the input gear is removed, you'll find a thrust washer that must be reinstalled onto
the new 27 spline input. When comparing the two input gears, they should look the same
except for the internal splines. If you find a difference between the two. The NP231 transfer
case used two styles of front input bearings. The early transfer case used a wide bearing
and the later model used a narrow bearing. This new input gear is designed for only the
early style case. New Process changed the bearing and gear pitch design in 1995. The
center photo below show a later model input compared to a early.
Once you have verified that you have the same style
input gear, install the gear into the planetary, install the
snap ring. Re-install the planetary assembly into the case and secure the input to the bearing with the front snap ring. Note: The only part
you should have left out of the case is the old input gear. During reassembly, make sure the oil return hole matches the front retainer hole.
TH350 ASSEMBLY PROCEDURES:
1. Before assembling verify that the transmission has a 27 spline output shaft and the stickout is approximately 1" .
2. Trial fit the adapter on the transmission. Check to see that the casting seats flush to the transmission case.
3. Trial fit the transfer case to the adapter and transmission. Check for spline engagement, and shaft depth into the input coupler
of the transfer case.
4. If the transfer case does not mate flush against the casting, DO NOT DRAW IT TOGETHER WITH THE
FASTENERS. SEVERE DAMAGE WILL OCCUR.
5. Press the seal into the casting with the open side toward the transmission.
6. Install the rubber o-ring on the transmission side of the adapter. A thin bead of silicone should be applied as a sealant.
7. The four Socket Head Cap Screws are then used to secure the casting to the transmission.
8. Two rotations are provided on the casting. Choose the rotation that best suits your application.
9. The stock studs and nuts from the transfer case can be reused for securing the transfer case.
10. Two of the positions on the rotation will require removal of two studs from the transfer case and substitution by the two
3/8"-16 x 1-1/4" Socket Head Cap Screws. This is due to lack of wrench clearance around the casting.
11. Use silicone sealant on both sides of the transfer case gasket. Use Loctite on all bolts.