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Auto to Manual Hub Conversion Writeup


The first time I took my Bronco off-road I was by myself about 5 miles from pavement and busted the rear drive shaft. I couldn't move the bronco in front wheel drive. At the time I thought that it was the transfer case but later found out it was my automatic hubs that were not engaging. The easiest fix (and cheapest) is to convert the hubs to manual ones. It will also make them a lot more reliable. 

I hopped on the internet and ordered a set of Warn manual hubs with the conversion kit from Jeff's Bronco Graveyard I have since found out that the conversion kit was not necessary except for some 86/87 years (They have a 3 bolt pattern on the hub instead of 5). Since I was pulling it apart I also ordered new bearings with races since this Bronco has a lot of miles on it. I also went to Pep Boys and purchased a spanner socket for under $13. 

Tools used:
Safety Glasses
Ear Protection
Spanner Socket
3 ton Jack
3 ton Jack Stands
Large Hammer
Large Hex wrench (to remove the springs holding the brake pads)
Large Channel Locks (to squeeze in the caliper piston)
Metric & SAE socket set and wrenches
Needle Nose pliers Long straight and 90 degree bent
Torex wrench set
Allen wrench set
Retaining Ring pliers
Micro Screw Drivers
A large punch to knock out the old race and bearings.

Stuff to have on hand:
Rust Remover
Carb or Brake Cleaner
Wheel Bearing Grease

After I jacked up the Bronco, I placed jack stands under the frame and removed the tires. I then removed the brake calipers. There are two clips that are removed by squeezing them with a pair of pliers and tapping them with a hammer to get the ends of the clips in the caliper, then use a punch (in my case a large Allen wrench) to push them out. 

 Use a large pair of channel locks to slowly but firmly press the piston on the caliper in enough to take the pressure off the brake pads. 

 Remove the caliper and brake pads making sure to place it in such a way that the brake lines are not stressed. With the extended brake lines on my rig they sat nicely on the radius arms.

Then I began the process of changing out the hubs. First is to remove the five T25 Torex bolts on the Auto hub covers. There is a bearing and a spring that will come out with the hub covers. Place them aside. Then remove the small metal clip that is in a groove on the outside of the auto hub assembly.

Next use a pair of pliers to squeeze the retaining ring and pull the whole assembly out. 

 After removing the Auto hub assembly there is a c-clip that is similar to a retaining ring that you need to remove. I used two micro screw drivers to guide the clip to separate it enough to get another micro screwdriver under the opposite side and pull it out. After that is a washer that matches the splines on the spindle. Now use the spanner socket to remove the first spanner nut. you will then need to remove a washer that has holes in it to key to the inner spanner nut with a pin. I used two pair of needle nosed pliers at opposite sides to pull it out. Then I used the spanner socket to remove the inner spanner nut. 

Auto hub parts (top) Vs. Manual hub parts (below)

Now your hub is ready to be removed. When you pull it off the outside bearing will fall out. I then placed the hub on a bucket with a couple of wood strips to bang out the old bearing races. Using a large punch through the hub I was able to carefully hammer out the opposite bearing. the edges will be obvious. Make sure to move around the punch as you hammer to make it go evenly. when the outside race pops out flip the hub over and remove the inside race along with the bearing and grease seal.

To replace the races use the old ones as a buffer to knock the new ones in. Grease up the new ones and set them in place, then set the old one inverted to the new one and gently but firmly hammer it in place. You will know when it is seated by the sound of the hammering. It will go from a hollow sound to a heavy ring. 

When both races are inserted place the inner bearing (making sure you pre-greased it) in place and gently tap the new grease seal in place. Now place the hub back on the axle and push the outer bearing in place. Then screw in the spanner nut with the pin towards the outside. 

Torque it down to 50 Foot Pounds while turning the hub to set the bearings. This is a pain since the spanner socket wants to slip pretty easily but I found that using one hand to hold the socket in place and the other to torque it helps. Back the nut off by about a half turn then re-torque it to 40 foot pounds. Insert the washer with holes making sure the key aligns and the pin from the nut fits in one of the holes. If not flip it over. Then install the outer spanner nut torqueing it to 135 to 150 foot pounds. Now place the manual hub assembly into the hub. you will need to turn the hub as you push the assembly in to get it to seat. Once seated insert the outer retaining ring in place. If necessary use a micro screwdriver to fully seat it. Then insert the inner retaining clip with a pair of retaining ring pliers. 


Align the six hex bolts of the manual hub to get them started. then push the hub cover on and tighten the hex bolts down. The instructions say to turn the hub to the free position before-hand but I could not move them by hand. I pushed them on part way then was able to turn them to the free position before tightening the bolts down. Turn the hub and it should move free. Then set the hub to the lock position and make sure the drive train moves. Set it back to the free position and you are ready to start the other side. It should take about half the time the first side did since you are now familiar with the swap.

The job took me about 2 1/2 hours to complete. This is by taking my time and snapping a few pictures along the way.

Last Edited 5/14/2005