The NP gear driven transfer case is considered by many to be the king of at the photos provided then you will be ready to do this rebuild on your NP From Jeep History to Tech Specs and Projects. The NP transfer case is a heavy duty gear driven transfer case in a cast iron case. Pertersons 4Wheel & Off-Road details how to rebuild the full-time four-wheel-drive NP transfer case . NP Transfer Case Rebuild Kits and Parts for 4wd pickup trucks, also free We offer quality professional New Process model NP transfer case parts and .
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Rebuilding your GM NP Transfer Case is not all that difficult IF you have the right service information and at least the QT Dummy Idler Shaft Tool. Does anyone have a pdf (or similar resource) for rebuilding an NP transfer case? i ordered my kit and want some info before i get into it. NP Rebuild and Info All 4x4 Tech & Off Roading. Suburban 4X4 build thread · 95 Yukon Daily Driver · Rebuilding an NP .. I did not find any specs on depth of the seal so I installed it flush. I'm showing this picture.
The and older versions used a fixed rear-output yoke, while some later versions often used a slip-style yoke at the tail. Front output shafts were typically spline early or spline late pieces, with the crossover occurring around Some Ford and Dodge diesel NP cases were optioned with a spline front output.
The NP was often found in heavy-duty pickups with ratings up to 1-ton. The transfer case is a good match in fullsize trucks running a healthy engine and big rubber, but in stock form is limited to a 1.
We spoke with Stephen Watson, an NP expert from Offroad Design who mentioned a few items to watch for when looking over an NP for use or during a rebuild. Check the condition of this surface. You'll often find this wear on trucks with substantial road mileage, but they were seldom or never put in low range.
High-mileage transfer cases may have the problem of popping out of low range. Cases that have been forcibly shifted into gear may show wear issues on the sliding collar teeth and corresponding teeth on the gears themselves. Note also that drive sleeves on male-input NP versions can wear and exhibit a sloppy fit.
Eventually, the splines can strip out and fail if used under this condition. Upgrades to the NP are readily available today. They include stronger shafts and yokes, shifter enhancements, and lower gearing options. Another big benefit of the NP is the fact that it can now be fitted to many more powertrains. There are the OEM adapter components, but aftermarket vendors have added new adapter components to put the transfer case behind an even wider range of transmissions.
The NP was manufactured as a stout drivetrain component and, with aftermarket support, can handle most anything an off-roader can throw at it. Many of the later versions of the NP came with a slip-yoke-style rear output as shown here. In other words, the rear driveshaft has its splines on the end where they mate into the transfer case. This configuration adds transfer case length and is generally weaker than a standard fixed-output yoke.
Aftermarket kits can eliminate the added length and convert to a standard fixed-yoke output. The divorced versions typically used series input and front output yokes, and a series rear output yoke.
This one has been upgraded to accept CV driveshafts front and rear. The NP has an identification tag on the rear of the housing confirming the model number, low-range gear ratio, and date of manufacture, but these tags are frequently missing. The helical gears inside are huge, and one can quickly see why this transfer case is so robust. Here's the rear output shaft assembly. The shaft rides in the housing on a large ball bearing and a set of roller needle bearings.
A rubber seal sits behind the yoke to seal oil inside. All NP transfer cases were built with a spline rear output shaft.
The front output shaft has a splined end which mates to a front driveshaft yoke or flange. This one is a GM spline front shaft with limited mating yoke variety.
The GM spline with Saginaw 3R flange is a bit beefier. Large aluminum plate. Remove retainer plate from case. Using a rubber mallet, tap the front output shaft assembly from the case. Remove the snap ring from the front output shaft bearing and remove bearing from case. Remove the 4 bolts from the input shaft seal retainer, and remove retainer from case. Remove the 8 bolts from the rear drive output shaft assembly.
Remove assembly from case. There are 15 roller bearings in the assembly, put them in a small ziplock bag. Remove the snap ring from the input shaft bearing. From inside the case, grab the input shaft assembly and pull the assembly out.
Tapping on the input shaft with a small hammer will ease removal. Remove the two shift rail poppet nuts and springs from the case. There is a ball bearing in each hole that can be removed using a slim magnet. If no magnet is available, you can tilt the case over and the ball bearings will fall out.
Position both shift rails in neutral to line up the shift fork retaining pins.
Using a narrow punch, tap the shift fork retaining pins out. Pins will fall to the bottom of the case. Remove the range shift rail short one first, then the 4 wheel drive rail long one.
When you remove the rails hold the shifter forks with the other hand and remove them from the case. Keep them together. Slide the rail pins out. Remove the idler shaft lock nut. An impact wrench can be used for this. Remove the washer behind the lock nut.
Remove the idler shaft rear cover. Use a punch and mallet to drive the idler shaft out. Roll the idler shaft assembly to the right and pull it out of the large hole. Remove the PTO access cover. At this point you are finished with tear down. If you are going to paint your case, this is the time to do that.
Pull the shift rail seals. During tear down, it is a good idea to keep the parts from each assembly together in bags. Assembly begins with a freshly painted case. If you need new bearings in the idler shaft assembly, drive out the old races and put new ones in. It will cost substantially less to rebuild if you don't have to replace all your bearings.
Here is all the parts for the idler shaft assembly. Start with one of the bearings on a piece of cardboard. There are 4 shims in the assembly. Two of them go on top of this bearing.
Place the idler gear on top of the bearing. Place the spacer on the bearing and shims. The NP gear driven transfer case is considered by many to be the king of bulletproof.
NP Transfer case Data Sheet. Converting Your NP from a single stick to a twin stick Twin stick conversion for the NP is simple and can be done at your home if you manage to get your t-case out of your truck without getting crushed by it.
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