1971 Chevy Suburban - Transfer Case Rebuild

Simple and strong are two words we have grown to love, even when they're used separately. And when something is both simple and strong at the same time, well, that's even better.

Both those words can be used to describe the NP205 transfer case. Its all-gear construction and heavy cast-iron case make it both simple and one of the toughest transfer cases around. When it came time to figure out what to do with the NP205 found in our '71 Chevy Suburban, the decision was simple. We decided to keep the NP205 and bask in its simplicity and stoutness. However, our NP205 had been used hard over the last 33 years, so it was time to show it some love.

We carefully removed it from its home behind our swapped-in NV4500 five-speed and contacted National Drivetrain, which sent one of the company's rebuild kits for our 205. Then with parts and transfer case in hand, we headed over to the professionals at GM Truck Center in Burbank, California. If you can't tell from the name, GM Truck Center specializes in the restoration and also the modification of Chevy and GMC trucks of every year. The technicians there were happy to take apart our NP205 and rebuild it while we shot some photos.

If you plan to tackle rebuilding an NP205 at home, make sure to at least get an exploded diagram of the transfer case before you start. A service manual can also be of great aid and is a good place to find an exploded diagram. Also, make sure to carefully note how everything comes apart so it can be reassembled correctly. We have found that taking photos of parts as they come apart and then referring to the photos upon reassembly is very handy. The NP205 is not difficult to rebuild, but there are a couple of tricky spots; so if this chore seems over your head, take yours to a professional. Follow along as the folks at GM Truck Center show us what is involved in rebuilding the NP205.

The first step is to pull off the rear output yoke and then remove the five bolts that hold the rear output seal retainer.
The first step is to pull off the rear output yoke and then remove the five bolts that hol
The outer bearing on the rear output will slide out by using a screwdriver to gently pry on it. The bearing has a snap-ring on it, but it is to prevent the bearing from falling into the case, so it does not have to be removed to take the bearing out. At this time the speedo gear can also be removed.
The outer bearing on the rear output will slide out by using a screwdriver to gently pry o
Now the whole inner bearing retainer assembly can come off.

With the inner bearing retainer assembly out of the way, the rear output shaft, along with its gear, can come out. The main input gear and shaft will still be in the case at this time and should be left in place.
With the inner bearing retainer assembly out of the way, the rear output shaft, along with
The bearing that holds the main input shaft on the front of the transfer case can now be removed. Our bearing is of a sealed design because our NV4500 five-speed transmission uses synthetic oil that should not interchange with the gear oil of the transfer case. Your bearing will look a little different.
The bearing that holds the main input shaft on the front of the transfer case can now be r
Removing the bearing allows for the main input shaft to be moved so that the shift collar and gear assembly can be slid past the shift fork. This allows for the whole main input shaft and gear assembly to be removed.
Removing the bearing allows for the main input shaft to be moved so that the shift collar

Now it is time to turn our attention to the front output. The front yoke was removed so that the seal retainer could come off.
Now it is time to turn our attention to the front output. The front yoke was removed so th
The cover on the rear of the transfer case that holds the rear bearing for the front output shaft is next to come off. With it out of the way, the front output shaft, along with its gear and shift collar, can slide out. The bearing for the front output shaft, located on the front of the transfer case, can now be removed.
The cover on the rear of the transfer case that holds the rear bearing for the front outpu
Next, the two bolts at the top of the transfer case are removed. Be careful, as these have springs located on the backside of them. The ball bearing found in each bolt hole then needs to be removed with a magnet.
Next, the two bolts at the top of the transfer case are removed. Be careful, as these have

After that, a punch is used to carefully tap out the plugs located in the holes near where the two ball bearings were removed. Use caution, as these plugs will be used again unless you have new ones on hand. After the plugs are removed, access to the roll pins that hold the shift forks to the shift rails is possible. More than likely you will need a flashlight to see them, but once you do, you can carefully remove them with a small punch. This will allow for the shifter forks to be removed.
After that, a punch is used to carefully tap out the plugs located in the holes near where
The next step is to remove the shift rods and is a bit tricky. There are two smaller shift shafts inside of the transfer case that run perpendicular to the shift rods. These have to be positioned so that one is out from the center of the case and the other one is pushed in towards the center. This allows the detents of the shifter rod to clear the small shift shafts and come out. However, the shifter rods must be removed one at a time to accomplish this. As the shift rods slide out, the shift forks will come off.
The next step is to remove the shift rods and is a bit tricky. There are two smaller shift
The three bolts on the idler-shaft cover are next to come off. Then the big nut that holds the idler shaft on the front of the transfer case can be removed. Once that is accomplished, the whole idler shaft and gear assembly can be removed. We had to use an air hammer to drive the shaft out towards the front of the case.
The three bolts on the idler-shaft cover are next to come off. Then the big nut that holds