| | Tools needed: 12 , 14, and 30mm sockets, dead blow hammer (rubber mallet), magnet, 3/16" punch, snap ring pliers, 6mm allen socket , channel lock pliers, gasket scraper. |  | Step 1: Remove the transfer case from the vehicle. shift to hi-2wheel drive Unbolt drivelines from the transfer case (79-83 trucks will require a 12mm wrench, 84+ require a 14mm wrench). Place a floor jack under the transmission to support its weight before removing the transfer case crossmember. Once supported remove the 8-17mm bolts holding the crossmember to the frame. Remove the 4-12mm bolts that hold the crossmember to the rubber bushing between the crossmember and the transfer case. The crossmember should now be free and can be removed. Remove the 4-14mm bolts holding the transfer case mount to the transfer case. Drain oil from the transfer case, there is no need to drain the oil from the transmission although this might be a good time to do it. Unscrew the speedometer cable (or on 92-95 models, remove the electrical plug). Unplug the 4wd light electrical connector. 79-83 all, 85-88 efi: Shift transfer case to 4wd low and remove the shifter (4-12mm bolts) Remove the 6 14mm bolts holding the tcase to the transmission and slide it away from the transmission and remove it from the truck. 84-88 carb, 88-95 efi: shift transfer case to 4wd high. Using jack lower transmission, transfer case assembly, and either pull up small boot at base of shifter to remove retaining clip or unbolt shifter base, then pull upward on shifter to free from shift rods. Be sure to replace transmission output seal and lubricate its sealing surface (make sure the numbers on the face of the seal go towards the transfer case. Step Two: Install gears into case Remove the 30mm bolt holding the driveshaft flange for the rear driveline using an impact wrench (if you do not have an impact wrench you will want to use a punch to remove the indent on the nut and remove the nut with a breaker bar HINT: You may want to do this while the tcase is still in the vehicle). Pull flange off (do not lose the washer behind the nut) *troubleshooting If you can not remove the flange use a dead blow hammer on the backside of the flange Remove the 10-"6" grade 14mm bolts facing the back There are 3 tabs that are cast into the housing in order to tap the housing apart using the dead blow hammer, you do not need to remove the 7 double notch 14mm bolts on the tear drop rear cover but if you would like to there is a gasket provided that will not need to be used if the tear drop is not removed. A gasket is also provided for the front output and the seals for the front output however when we did our install we did not remove the front output so we did not use the seals Remove oil galleys (they will slide out easily, remember the orientation for putting it back together since it is possible to put them back upside down which would not allow oil to flow to the gears that need it) *note when removing oil galleys watch the orientation for when replacing them. |  | | Remove speedometer drive gear |  | | Remove .25 detent ball (use a magnet) |  | Remove oil sling gear (this moves oil to the front) | Remove rear mainshaft bearing |  | Knock out roll pin with 3/6" punch *note it is important that the tcase be in 2hi so the roll pin is exposed |  | slide off 2hi-4hi fork and hub remove shift hub slide off the next gear, the front wheel drive gear (there are two needle roller bearings and a thrust washer that will come off with the gear). Remove the ball bearing that is located under the thrust washer. Remove the 4 double notch bolts holding the cast retainer on. | Remove the snap ring |  | Use a 6mm allen socket to remove the shift interlock bolts, there is one on each side (these strip easily so be careful), tap the socket lightly to ensure the allen head is seated well, make sure you do not strip the bolts DO NOT USE AIR TOOLS FOR THIS!). Be careful not to loose the spring and ball located behind the interlock bolts, using the magnet remove the spring and bolt if they do not fall out. Note: shift rods will be loose without the interlock holding them in place, remove the 2wd/4wd shift rod (passenger side) twist it a quarter turn clockwise it will slide out. Use a magnet to remove the interlock pin Remove the 2 6 bolts on the casting Turn it around and remove the two on the front side of the case (one has the bracket on it) Remove the 4-12mm bolts holding the top cover on. Use a hammer to type near a bolt (so you do not bed the plate) Use the punch to remove the roll pin in the lo-high fork, don't worry if the pin falls into the case, we will be opening the case, just don't forget to get it. | Twist the shift rod a ¼ turn clockwise and remove it |  | | Remove snap rings (one on ea shaft) |  | To separate the two pieces tap lightly on the tabs to split the two pieces apart. If necessary. Tap on the main shaft with a dead blow while supporting the rear (gear side) Now that the case is apart you can get the roll pin that fell into the case with your magnet. Remove lo-hi-fork and the cage bearing. Now you can take both gears out, be careful not to damage the gears when they slide out. | Dissasemble factory gears |  | When removing clips it may help to tap the bearing to release pressure from it. Be careful not to loose the clips when removing them. Gears 1 and 2 can now be used for paperweights (no longer needed) | Note: be sure to remove the old snap rings, and not that there are 3 different sizes. The largest goes with the main shaft, the medium goes with the input and the smallest goes with the countershaft. |  | Remove the gears from your 4.7 box, they will have the bearings pressed on before shipped. Since you are re-using the snap rings you may want to use channel locks to tighten up the clips before using DO NOT BEND IN THE MIDDLE, tighen them up by tightening each side. Install c-clips on the preinstalled bearings. Once slipped over the shaft tap it into place. The c-clips should seal all the way around (not deformed). The main shaft gear will need to be pressed on, and the old one removed. The bearing on the main shaft will be reused so use caution when pressing it off (6308n bearing), also use caution not to loose the small detent ball located under the thrust washer. Before pressing on the new gear note that the tapered spline meats with the shifter hub of the main shaft. Once the gear is pressed on the thrust washer and detent ball need to be slid on before pressing on the bearing. Note: be careful to press the bearing on with the groove away from the large gear. DONE HEADING PREPARING GEARS PREPARE REDUCTION HOUSING We are working on a RF1A housing. Before any clearancing attempt to remove all oil. Clearance as necessare for the new larger gears. BE SURE TO CLEAN ALL SHAVINGS THOUROUGHLY! This includes any materail in the bolt hole threads. After cleaning look carefully for any cracks in the transfer case, a leaky tcase is a sign of a cracked tcase. See images for common crack locations. Now is also a good time to look for stripped threads, etc. before assembling the case. Now is also when you should clean off all gasket etc so when reinstalling no pieces fall into the case. Remove top plate gasket before putting the case back together and file the surface so you do not get shaving in ths the case. Also do the mating surfaces of the case. All parts should be cleaned before reassembly. All cases assembled at MC are cleaned thouroughly. You may have a clip if you have a mid 84+ case (run queit cases) Install pocket bearing (came off of the input gear) Grease all bearings before install CENTER SECTION Remove old gasket and clean up mating surface thoroughly. Place mainshaft into the middle section and insert snap ring. Next place the cast retainer on the main shaft and fasten with the 4-12mm bolts, do not use air tools as they are in aluminum and will break. Snug by hand. Use brake cleaner or other solvent to remove all oil off of all of the mating surfaces before placing gasket sealer. | The offset fork will need to be ground, when grinding be sure to grind the pin as well for clearancing. Check forks for excessive wear before using. |  | | Install shifter hub and grease it and the fork. (contact area) Long part of fork extends over the large gear (check clearance). |  | | Use gasket sealer on clean mating surface paying close attention to in between bolt holes for sealer. If using a gasket do not use silicone. Make sure the gasket is not dry when installing. |  | | Use matching gasket supplied with your gears |  | Put the middle and the outer case together, install the two outer bolts. If you do not install the bracket do not use the stock bolts as they are too long! Tighten the bolts before the sealer dries. Then install the back 2 bolts. (14mm also). Install hi-low fork (3 notch) and slide it though the fork, installing the roll pin (make sure it does not interfere with the gear when installed). | Roll gears to check for clearance. From the grinded fork and roll pin Push the fork all the way forward once the pin is in so that is shifted into hi-range. |  | | Place detent ball and spring and place teflon or hi-tack on the allen head bolt and tighten by hand. |  | Push interlock pin in though drivers side hole all the way in before (use something to push it all the way in to the middle) and then slide in passenger side shift rod (2 notch) in all the way making sure the ends of the forks are facing each other. Now install detent ball and spring like the other side, don't forget the tack or tape for the allen bolt. | Now place block off plate back on, be sure to clean all grease off before installing and use a lot of gasket sealer to ensure that it does not leak (lotsa goop ultra black reccomended, if it doesn't squish out when installing the plate you did not put enough on). |  | | Use caution when tighening (do not overtighten the 4 12mm bolts it is very easy to overtighten these!). |  | Flip to the other side | First install detent ball, thrust washer, and bearings, slide the gear over the bearings. Next slide the smaller gear (reverse of taking it apart). Next install 4wd/2wd shift hub and fork checking for wear on fork. (first assemble the hub to the fork) slide the assembly on watching for proper alignment, use light force or it will not line easily. |  | Install roll pin into fork and press the shifter all the way forward so the forks are alligned allowing easy shifter install (4hi). Next once again clean all surfaces from oil, burrs, etc. File all burrs etc so there are no rough edges, and scrape the gasket so the surface is clean. Also clean the rear side of the tcase for a clean mating surface. Now prepare surfaces, and install the gasket (long gasket), being sure to put the sealer on the gasket so that is not dry. Slide the bearing on to the main shaft followed by the oil slinger (has rubber gasket, smaller of the corkscrew type gears with the shiny side toward the tcase) be sure not to forget the detent ball when reinstalling. *note install new seal at flange before putting flange on. | Now slide the back of the transfer case on (all 3 gears and the seals need to slide on so use caution when lining it up). Now install the 4 long 6 bolts. Be careful not to overtighten these bolts. Next install the rest of the 6 bolts and tighten. |  | Place sylicone on the threads of the mainshaft (be sure to clean all of the old stuff first!) Before installing flange wrap the inside of it with sealant. Grease seal surface before sliding on flange as well. It is a good idea to rough up the seal mating surface first. Now push on the flange. Place sealant on the back side of the washer before putting it on to the main shaft. If you are reusing the nut make sure the indent has been beat back out, and tighten with an impact air gun (make it tight!). After tightening be sure to use a punch to stake the nut (do not use a chisel or it will just cut the nut). When installing the 4wd light be sure to use a gasket (aluminum and not steal). *this install is for an 84, for pre 84 you do not need to remove the back of the case Step Three: reinstall transfer case into vehicle When putting the transfer case back into the vehicle put sealant on the supplied transfer case to transmission gasket. Use 2 quarts of 79-90 wt. GL5 gear oil. Because you have just put gears into the case you simply reinstall the case as you took it out. No modifications needed! Marlin Crawler Contact Information: Web Page: http://www.marlincrawler.com Street Address: 1543-B N. Maple, Fresno,CA 93703 Phone Number: 1- (559) 25-crawl | 
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