I recently needed to fix the transfer case on my 88 F-150.
1988 F-150 w/302, 5spd Man trans, BW1356 Man trfr, 4” Rough Country lift, 33x12.5 Micky Thompsons
I looked on the different forums and found a lot of good information and some good pictures. One of the write ups showed where he had welded a bolt on the oil pump retainer bracket. I thought that was a good idea, so I decided to take mine back out and do something similar.
I know there is an assortment of people out there. Some know a lot. Some don’t. I wrote this for the ones’ that don’t. If there is anything I missed please comment.
In my write up I wanted to try to explain how it works too.
I bought my parts from “National Drivetrain” in Chicago. 1-800-507-4327
Bearing and Seal kit $52.00
Range Fork $14.00
Mode Fork $11.00
Drive Chain $72.00
Pump Kit $35.00
Sub Total $184.00
Plus about $20.00 shipping.
As everyone knows to fix it you need to take it out.
Remove the main drive shaft. Take the nuts off the U bolts on the universal joint at the yoke on the rear end. Take the U bolts out. Push the drive shaft forward. Put some tape around the universal joint to keep the cups from falling off. Drop the drive shaft down and pull it towards the rear and off the tail shaft.
Remove the skid plate under the transfer case. On mine it was just 4 5/16ths bolts and nuts.
Drain the oil from the transfer case. Originally mine had aluminum pipe plugs with square holes. The square holes were messed up. Probably from other people removing them to change the oil. I used an easy out backwards that fit snuggly into the square hole. Then I used an adjustable wrench on the easy out to remove them. I replaced them with brass plugs that take a 3/8ths allen wrench.
Disconnect the front drive shaft at the yoke on the transfer case. Remove the nuts. Remove the U bolts. Put some tape around the universal joint to keep the cups from falling off. I was able to push it forward and then off to the side.
Disconnect any wiring and other things. Mine has a manual transmission. I disconnected the park neutral connector because it was in my way. Disconnect the 4wheel indicator connector on the front of the case. Disconnect the vehicle speed sensor on the tail housing. Disconnect the speedometer cable. Disconnect the case vent tube. Disconnect the shift linkage nut and pull the linkage arm off the case.
Remove the bolts that connect the transfer case to the transmission.
Now you can remove the case. It’s a little heavy. You might want to support the weight with a jack. Now put the case where you can work on it.
Remove the 4 T bolts that hold the tail housing on. Remove the tail housing.
Remove the black rubber washer. It just comes straight off the shaft. It’s snug. Pull harder.
Remove the spring clip from under the speedo gear.
Push the speedo gear down. Use a magnet to take the ball out. Take the speedo gear up and off the shaft.
Remove the snap ring. A good pair of snap ring pliers is a big help. Remove the T bolts that hold the case halves together. Split the case.
The inside will look something like this. There are a few parts already removed in the picture.
Remove the snap ring above the 4wheel drive lock sprocket. Remove the spring on the shift support shaft. Remove the 4wheel drive lock sprocket. Remove the 4wheel drive fork and lock by pulling straight up and off the shaft.
Remove the snap ring and spacer on the front drive sprocket. Remove the chain and both sprockets together.
This is what the pump assembly looks like when you’re done. When I opened mine up the pump was destroyed. The casting where the hose attaches had broken off. The sheet metal retainer had gotten all banged up. The pump had been spinning with the shaft. From what I have read, a pump failure is the beginning of most all problems.
Remove the hose clamp and hose. Remove the 4 bolts on the pump keeping one hand on the bottom of the pump. It may just drop apart. Remove the top plate. The pump is a small impulse pump. The pump housing is held stationary while the shaft rotates. There is a hole through the shaft. A spring goes through the shaft with a small plunger on each end. The hole in the pump body is eccentric. As the shaft rotates, the plungers go in and out because of the eccentric. This causes the pump to draw from the filter and reservoir and pump oil to the inside center of the shaft. The shaft is hollow with holes at the different lubrication points.
Remove the eccentric plate. Be careful not to loose the spring and plungers. Remove the spring and plungers. Remove the bottom plate. Remove the main output shaft. It just pulls straight out.
Remove the shift support shaft. Now you can rotate the range fork counter clockwise to remove it from the shift plate. Pull the range fork and range gear up and out of the carrier.
Inside the carrier there is a pilot bushing and a needle bearing. To remove the carrier, remove the seal on the input shaft on the front of the case. Remove the retaining spring that is under the seal. You can remove the carrier without removing the ring gear. To remove the ring gear, remove the large retaining spring on the inside.
I wanted to show the shift plate in the different positions. This position is 2wheel high range. The follower on the range and mode forks would be right above where the spring is on the plate. The follower on the range fork would to the extreme right in the center notch. The 4wheel follower would be resting on the top at the extreme right.
This is the 4wheel high range position. The 4wheel or mode fork would be resting on the hump pushing it up. The range fork would not have moved up.
This is the neutral position. The range fork would be half way up between high and low. The 4wheel fork would have dropped back down.
This is the 4wheel low position. Both forks would be up high. Putting it in low range and 4wheel.
This is the range fork and gear. Inside the carrier there is 2 different gear positions this mates up with. When the gear is towards the front of the carrier, it is in high range. Towards the back, low range.
At this point I replaced all of the bearings and seals. A roller bearing on the input shaft at the front of the case. A needle bearing inside the carrier. The pilot bearing was not included in the kit. I used the old one over. A roller bearing, seal and needle bearing on the front drive shaft. Taking the front yoke off was a bear. I had to hold it in a vise and use an impact wrench. A seal on the shift shaft where the shift linkage attaches. A roller bearing on the main output shaft in the back half case. A seal on the tail housing. I put the carrier back in and the spring retainer back on. Then I put the input shaft seal on. Now I started putting all of the internals back in.
Install the range gear into the range fork. Put both pieces together into the carrier. Rotate them clockwise until the follower engages the shift plate in the correct place and the shift support shaft lines up with the hole. Install the shift support shaft. This is what it looks like in high range.
This is what it looks like in low range.
Install the main output shaft.
Install the oil pump. Put the bottom plate on first. Drop it down right over the shaft. Put the spring and plungers together and through the hole in the shaft. Drop the eccentric plate down over the shaft. Squeeze the spring and plunger assembly together to get the eccentric over them. Look down through the boltholes on the eccentric to line up the bottom plate. Once they are lined up temporarily put one bolt part way up through the bottom at the 7 o’clock position. Drop the top plate on. Put a bolt at the 10 o’clock position. Remove the bolt at the bottom of the 7 o’clock position and reinstall it from the top.
The pump retainer attaches to the pump with bolts at the 1 o’clock and 4 o’clock positions. To prevent the pump from rotating, the retainer tip is trapped in the notch in the housing. When I put this retainer in the tip was just barely trapped. I could easily push it past the notch. Over time if the pump gets gummed up and starts to have some resistance, it may push past and spin with the shaft. If that happens there will be no lubrication. In one of the posting I looked at the other guy had welded a small shaft in the vertical on the end of the retainer. That would make sure it stayed in the notch. I liked that idea. I choose to do it a little different.
I welded a ½ 20 bolt to the underside of the retainer.
With the retainer in place and the hose and clamp on, the pump is done.
Install the filter and the magnet in the cutouts in the front casing.
Put the gears and chain together. Drop them down onto the shafts at the same time.
Put the spacer and the retainer on the front drive shaft.
Assemble the 4wheel lock and 4wheel fork together.
Install them by dropping them down over the main output shaft and shift support shaft. Install the 4wheel drive lock sprocket and retainer spring. Install shift support shaft spring.
Exercise everything to make sure it works. This is 2wheel high range.
This is 4wheel high range.
This is neutral.
This is 4wheel low range.
Make sure the mating surfaces on the case halves are clean. Put a thin bead of silicone on one case half and assemble the 2 halves. Don’t use to much silicone or it will squeeze out to the inside. The excess silicone may end up clogging the pump filter. You have to line up the main output shaft, the shift support shaft and the front drive shaft. Don’t bang on it. Just wiggle it until they all line up. Put all of the T bolts back in. Just snug them up. You want both halves to come in contact with the silicone without squeezing it out to much. After the silicone has completely cured tighten all of the T bolts. Install the retaining spring on the output shaft.
The speedo gear has a key that goes half way through it. Put the speedo gear on with the key pointing up. Put the ball in to the shaft indent.
Pull the speedo gear up on to the ball. Install the spring clip on the main output shaft under the speedo gear.
Install the rubber washer. Make sure the mating surfaces are clean and put a thin bead of silicone on the tail housing surface. Install the tail housing. Just snug the T bolts until the silicone cures. After the silicone cures tighten the T bolts.
That’s it. Put the transfer case back into the vehicle. Reconnect all the wires and other things. Put the drive shafts back on. Make sure all the bolts are tight. Put the skid plate back on. Make sure the drain plug is back in. Take the fill plug out. Fill it with oil up to the fill plug. Put the fill plug back in. Try it out.
I hope that’s helpful. It’s not rocket science, but it can be intimidating.