1998 ford ranger 4x4 manual locking hubs

When the cylinder is then only halfway compressed and released pulsed it will unlock the hub. Ford decided to use vacuum to do this. So when 4wd is selected, a long, full vacuum pulse 45 seconds according to my factory service manual is put on the hub and released. This fully compresses and releases the white cylinder which unlocks the cylinder on itself, making it long, so it pushes on the ring gear and locks the hub.

The spring in the cylinder thing is stronger than the spring in the hub, so the hub stays locked. This is why constant vacuum is not needed to hold the hub in a locked condition. The hub will stay locked after the vacuum pulse. This low vacuum pulse is supposed to partially compress the cylinder and release it, causing it to latch on itself, becoming physically short, so it does not push on the ring gear and the hub disengages. I see two problems with this design- Ford uses vacuum to do it, so seals, O-rings, etc have to be good for this to work.

This stuff only gets worse with age. If this low vacuum pulse is too high or too long, the cylinder will compress too much, unlatch, and therefore keep the hub locked. I think the latter is what my truck does since my hubs hold a good vacuum, and I can always use a hand vacuum pump to engage and disengage them. This is easily done by a very simple modification to the hub cover allowing finger access to the cylinder. The hub cover modification is very easy.

Take a pair of dikes and cut out the piece of plastic in the middle that looks like a wagon wheel. Then using your fingers, push out the round piece of screen. This puts a finger-sized hole in the hub cover. Put the hub back together by putting the white cylinder back in, then the rubber piece, then put the modified cover back on. The vacuum operation or at least whatever vacuum operation you still have will still work, but you can now use your finger to engage and disengage the hub manually.

To engage the hub, push the cylinder in fully and release. You will feel the cylinder unlatch and fully push back out toward you and the hub will now be locked.

This guide is based upon my experience with my truck. Step 1: Jack up the front of the vehicle in a safe manner. You should be looking at the original vacuum hubs. I recommend constantly pulling on the hublock as you pry up on the retaining tabs using the flat head screwdrivers working in a circle until the tabs release the hublock.

Special Note: If your hublocks are rusted badly and will not release, it is possible that the inner hub gear has corroded itself to the end of the axleshaft.

If this is the case, you will need to be prepared for a different and frustrating repair. You will need to forcibly remove the hublock and possibly break and plastic housing, leaving the inner guts inside the wheel bearing hub assembly.

If this happens, you will need a new wheel bearing assembly, along with a new snap ring and a knuckle seal. All are available through Ford. Then, preferably with air tools, chisel out the hublock internals from the wheel bearing assembly.

Replace the wheel bearing assembly, knuckle seal, and snap ring as outlined in other guides in the Tech Library of TRS.

Continue to Step 3. Step 3: With the hublock removed, spray brake cleaner in the wheel bearing hub assembly where the axleshaft passes through. Make sure to get out all major dirt and grime to ensure a cleaner reassembly. Remember, cleanliness is key with this 4WD system. Step 4: Remove the old o-ring and install the new one supplied with your AVM hubs. Step 5: Look at our nice new hublock. Check to make sure the locking mechanism functions properly.

Step 6 Optional : This step is completely optional. I lightly covered the hub internals with Motor Oil to prevent corrosion and ensure proper hub to axle engagement. Step 7: With the hublock prepped and the new o-ring installed, we are ready to install the new AVMs. If the hublock does not slide onto the wheel bearing assembly, turn the axleshaft by hand until you feel the splines line up and the hublock will slide into place.

Make sure the hublock is fully seated and the retaining tabs are secured in place. Step 8: Our new hublock is on and ready to roll.

Repeat steps for the other side.