In some wheelchairs fork bearings are found in the frame, which is referred to as Fork Mount or in the forks themselves. This step by step guide will walk you through to how to remove and replace the wheelchair fork bearings when the bearings are in the forks themselves. Quickie (Sunrise Medical) and TiLite (Permobil) are two wheelchair manufacturers for which some of their wheelchairs have bearings in their forks. TiLite Lightspeed Forks are the forks we get the most questions about, so the pictures in this “How To” are of the TiLite Lightspeed Mono Fork.
Tools that you will need:
- Socket Set (Metric or SAE depending on manufacturer)
- Hex keys
- 2 wrenches, usually adjustable
- Bearing extractor, or screw driver for the more courageous of us, to remove the bearings
- Snap Ring pliers to remove the snap ring between the two bearinsg
- Bearing Press or large diameter dowel rod to install the new bearings
- Cleaning items
- Swear Jar, if you are honest you will be making a few deposits.
How hard is the process?
This is a harder project than changing the front caster bearings, but if you have the right tools and are patient, then it is a very reasonable job even for the most novice of users.
Caution - Force is not your friend:
- Many of the parts are precision aluminum, DO NOT whack at things without knowing what you are whacking at. Force is not your friend, it will just lead to damaged parts.
- Bearings are best removed using the inside diameter ring (inside bearing race) of the bearing. If you try to remove them by the using the space between the outside and inside ring the bearing will often break apart and it all goes down hill from there.
- Bearings are best installed by the outside ring. Installing them using the inside ring or the space between the two rings may cause the bearing to come apart and it all goes down hill from there.
These instructions will be broken into three parts. Part 1 will be getting the fork off the wheelchair. Part 2 will be removing the old bearings. Part 3 will be installing the new bearings.
Part 1: Removing the fork from the Wheelchair
Remove the Caster:
- Remove the caster wheel so that you can access the fork axle nut. Using 1 or two hex keys remove the caster axle bolt by turning it so that it starts to unscrew. Unscrew all the way.
- Remove the caster axle. This can be done by pulling on the axle or by gently tapping the axle out.
- Caster should now be disconnected from the fork.
- Use this opportunity to clean all that hair out from around the caster bearings.
Swear Jar Tally: Add $0.25 for smashing your finger while tapping out the axle
Remove the Fork:
Let me explain how the fork is mounted to the wheelchair. Basically a bolt extends from the wheelchair downward, through the bearings in the fork to what is the underside of the fork. There is a lock nut and a washer that holds the fork onto the wheelchair.
TiLite Mono Fork Diagram:
TiLite Standard Fork Diagram:
Using a Socket Wrench to Remove TiLite Mono Fork:
- Find the right socket for the lock nut.
- While holding the wheelchair, use a socket wrench and socket to remove the locknut and washer. I find it best to turn the wheelchair upside down. Some like to turn the wheelchair on its side. The key is that you are removing the nut from the wheelchair itself so make sure the wheelchair is braced.
- Put the nut and bolt to the side. (No, not on the white carpet because now there is grease on the carpet)
- Remove the fork by hand slipping it down off the axle bolt.
Swear Jar Tally: Add $1 for grease on the living room carpet.
Part 2: Removing the Fork Bearings
Picture of TiLite Mono Fork with Bearing Extractor:
With the fork upright the bearing stack, from bottom up, is bottom bearing, then snap ring, then top bearing. Bearings are removed and installed from the top only. This process is much easier done with a bearing extractor vs the old screwdriver method. First the screwdriver method is tricky because you are only knocking one side of the bearing out at a time. Uneven removal will deform the fork. So you really need to tap lightly and move the screw driver frequently. Second, the two bearings are only has far apart as the snap ring, so it is very hard to get a screwdriver blade between them. Not impossible, just very hard. You can very easily damage your fork beyond usable. A bearing extractor on the other hand will grab the bearing from the inside diameter (ID) of the bearing. Then when you knock it out, use a pin punch and strike the bearing extractor. This removes the bearing evenly from the bearing seat. We created this line of tools because we could not find any tools that worked for wheelchairs.
- Remove the top bearing. Insert the bearing extractor into the inside diameter (ID) of the top bearing. Using two wrenches tighten the nut in the bearing extractor. When asked how tight the nut should be, I say this, “tighten until is it hard to tighten, then just a little more.” DO NOT use a power tool otherwise you will shear the bolt.
- Tap the bearing out. Turn the fork upside down, using a pin punch, tap the bearing out by tapping the bolt head on the extractor.
- To remove the bearing from the extractor, loosen the nut and tap out of the bearing. Sometimes it can stick, so you can tap the bolt from the nut side to loosen the nut in the tool and then tap out from the front.
- Remove the snap ring. Using a snap ring pilers, remove the snap ring (retaining ring) between both bearings from the top of the fork. This is done by squeezing the ring with the pliers to reduce the size of the ring and then feeding it through the hole left by the top bearing.
- Use the same procedure to remove the bottom bearing.
Swear Jar Tally: Add $1.25 because you smashed your fingers with the hammer AND you put the greasy snap ring on the carpet.
Part 3: Installing new bearings:
- Clean the fork bearing seats thoroughly. You want get rid of all that old dirty grease. Do a good job like your momma is watching.
- Put a very light coating of grease in the bearing seats. This acts like an anti-seize agent so that next time the bearing will come out more easily.
- Install the bottom bearing first. Side the bearing through the top. The bearing sides easily into the bottom bearing seat, then use a pin punch and tap gently around the outside of the bearing to make sure the bearing is fully seated. Most likely, you will need a little force. This is where the bearing press comes into play. Remove one handle, extraction spacer and 1 of the two bearing spacers (drifts) from the bearing press. Run the rod through the bearing and reassemble the press. Generally turn one of the two handles until the bearing fully seats in the bearing seat. The press works by gently squeezing the bearing to the bottom of the fork bearing seat.
- Install the Snap Ring. Using the snap ring pilers, squeeze the snap ring to reduce its diameter. Feed the snap ring through the top of the fork and place in the snap ring groove between the two bearings
- Install top bearing. Using the press, install the top bearing the same way as you did the bottom bearing.
- Install the fork. Using a socket wrench, stand fork on wheelchair.
- Install caster. Using hex keys install caster (hairless).
Swear Jar Tally: Add $2, why you ask, becuase you just realized have to do it all over again with the other fork.
If you have any questions, even if you are not using our tools or bearings, please feel fee to contact us.