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

Be careful when removing the idler gear, as its front bearing has shims underneath it. The same shims need to be reused upon reassembly, so make sure not to lose them. You'll need them all.
Be careful when removing the idler gear, as its front bearing has shims underneath it. The
Now it was time to open up the NP205 rebuild kit from National Drivetrain. It included all the seals and gaskets we needed, along with high-quality Timken bearings to replace our tired ones.
Now it was time to open up the NP205 rebuild kit from National Drivetrain. It included all
The next step was to install new races and bearings from the rebuild kit into the idler gear.
The next step was to install new races and bearings from the rebuild kit into the idler ge

There are also bearings underneath the gear on the rear output shaft that have to be replaced. To get to them, a snap-ring, along with a washer, must be removed. This tiny pin must also come out-be careful not to lose it. Once that is out, the gear can be slid off the shaft, but make sure to note how everything came off the shaft, as the parts need to be reassembled in the correct order. Also, be careful as the needle bearings will fall out when removing the gear, but it is OK since they are being replaced.
There are also bearings underneath the gear on the rear output shaft that have to be repla
With the rear output shaft stripped, the bearings can be replaced with the new ones supplied in the rebuild kit from National Drivetrain. The trick is to grease the shaft so that the bearings will stick to it. Once the bearings are in place, the gear, along with its washers and snap-rings, can go back into place. Also make sure to remember to install the tiny pin.
With the rear output shaft stripped, the bearings can be replaced with the new ones suppli
There are also bearings on the inside of the front of the rear output shaft that need to be replaced. These are difficult because they are down in the shaft. We used plenty of grease, a magnet and lots of patience to get ours into place. After they are in place, the ring and washer must also be put back into position.
There are also bearings on the inside of the front of the rear output shaft that need to b

The front output shaft is similar to the rear, as there are bearings also under the gear that need to be replaced. To remove the gear, remove the snap-ring and washer first. The bearings can then be replaced by greasing the shaft and sticking the bearings on just as we did with the rear output shaft.
The front output shaft is similar to the rear, as there are bearings also under the gear t
After thoroughly cleaning the case and all of the parts, it was time to put the idler gear assembly back in. It takes a bit of patience, as you have to support the gear, hold the bearing and make sure the shims don't fall out while you slide the shaft into position. Once the shaft is in, the nut on the front of the shaft located on the front of the transfer case can be tightened. After that is accomplished there should be no front-to-rear play in the idler-gear assembly. The end of our shaft (seen here) was below flush with the case after being slid in all the way. If it is not, there may be some play in the gear assembly, so make sure the shaft is all the way in.
After thoroughly cleaning the case and all of the parts, it was time to put the idler gear
Next, the new seals for the shift rods can be put into place and then the shift rods themselves can slide into position. Make sure the detents on the rods are pointed toward the center of the case as they go in.
Next, the new seals for the shift rods can be put into place and then the shift rods thems

As the shift rods are sliding into position, the smaller shift shafts (seen here) on the inside of the transfer case also need to be installed. Remember to slide one shift shaft out and the other in a bit to get the shift rod to clear. Then repeat the process with the other rod.
As the shift rods are sliding into position, the smaller shift shafts (seen here) on the i
As the shift rods are being installed, the shift forks on both rods should be put on the rods. The hole on the back of each shift fork needs to line up with the hole on the rod and then the roll pins can be reinstalled to attach the shift fork with the shift rod. Also, remember to install the plugs over these pins, otherwise the case will leak oil. The two ball bearings that were removed before can also be installed at this time in the holes on the top of the transfer case. Make sure they drop into the detents on the shift rods, and then install their retainer bolts with their springs.
As the shift rods are being installed, the shift forks on both rods should be put on the r
Now the front output shaft and its gears can be put into position. Make sure that the shift collar lines up with the shift fork so that the case will shift. Then install a new bearing on the front of the shaft, along with a new bearing in the rear cover. With the bearings in place, the rear cover can be put on.
Now the front output shaft and its gears can be put into position. Make sure that the shif

The main input gear along with its smaller shaft can now be installed. Make sure that the shift collar lines up with the shift fork, as seen here.
The main input gear along with its smaller shaft can now be installed. Make sure that the
Next, the rear output shaft can slide onto the main input gear. The front of the rear output shaft has needle bearings in it, so care must be taken so that these do not fall out, or come out of position, while putting the shaft into place.
Next, the rear output shaft can slide onto the main input gear. The front of the rear outp
With the rear output shaft and gears in place, the rear output bearing retainer assembly can go back on. Then the speedo-gear assembly can go back in. Make sure that its gears mesh correctly before installing a new bearing from the rebuild kit. After that, the rear output shaft seal retainer with a new seal can go back on.
With the rear output shaft and gears in place, the rear output bearing retainer assembly c

1971 Chevrolet Suburban Transfer Case Yoke Reinstall0

The final step is to install a new seal into the front output seal retainer and then bolt it into position. Then install both yokes. Your transfer case is now rebuilt.

Project SuperBurb - Part 1
Project SuperBurb- Part 2
Project SuperBurb- Part 3
Project SuperBurb- Part 4
Project SuperBurb- Part 5