Fabricating a bearing race removal/installation tool
A few days ago, while replacing the inner tube on N977JT, my friend Nick (Velocity) noticed galling on one of the bearing races of my right wheel (outer half).
 |
| Jacking 7JT up the fast and EZ way |
 |
| Right wheel outer half |
 |
| Damaged wheel bearing race |
When galling occurs the very thin hardened outer surface starts flaking off, and the softer underlying steel is exposed. Once this process begins it progresses quickly, and destruction of the sliding parts is only a short time away. It’s imperative then that something be done about it quickly, and with this in mind I ordered a new bearing race from Aircraft Spruce (#214-00300).
 |
| New race |
That was the easy part, the hard part would be figuring out what to use to press the old one out, and the new one in.
In the past, I have used various size sockets as tools to press on the flat surface of various projects' races, but this one is quite large at over 2” (5 cm) inner diameter, and I don’t have any socket that size.
An extensive search uncovered the largest round stock in the shop. At slightly less than 2” it didn’t have quite enough purchase on the bearing race to press it out without damaging itself, or the race, but that’s all I had to work with.
Well, sort of…
You see, that tube was already tied up in another project, having been used during my TIG practice days, and was temporarily unavailable.
However, I thought I could still borrow some of it, and “press it into service” (pun intended).
 |
| Recycling |
 |
| When biggest is still not big enough |
To make the removal side of this tool better fit the race, I decided to increase its outer diameter slightly by welding an oversized rim to it, then put it the lathe and turn it down to proper dimensions and squareness.
 |
| TIG welded rim to increase the outer diameter |
 |
| Machining the rim to the proper size |
 |
| Not a looker, but good enough for our purposes. |
The newly machined tube end worked great, and pressing the race out was easier than I had anticipated.
 |
| Awesome fit |
 |
| Pressing action |
 |
| "Just like buttah!" |
 |
| Aluminum wheel and hardened steel bearing race |
With half my problem solved, I realized that my tool’s newly enlarged outer diameter was still too small to press the replacement race in without pushing on the tapered inner surfaces.
This was an obvious NO-NO as it would have damaged the surface of the race all over again.
What I needed was an even bigger outer diameter on what would become the installation end of this tool, and this could be achieved in a couple of different ways... I could build up an even bigger rim with my welder (time consuming and material intensive) then machine it back down... or perhaps I could weld the busted race to the end of my tube, and use that as an installation device. After welding it might have softened enough to be machined on the lathe, squared and slightly undersized.
 |
| Checking my options |
 |
| "I bet this would work!" |
 |
| Tacked in place |
 |
| Turning the damaged race turned into a new installation tool |
 |
| Machined the front flat and the shoulder square on the mini-lathe |
 |
| Removal/installation tool ready to go |
 |
| A quick fit check... slightly undersized... Perfect! |
With the installation end of the tool completed, it was time to retrieve the new race from the freezer, where it had been for a few days shrinking ever so slightly, and press it in.
 |
| Frozen race to aid in installation |
 |
| New race will be pressed in here |
 |
| Pressing the race. Clock is ticking.. race is defrosting. |
 |
| Race bottomed out. Easy peasy. |
 |
| First look at the race in position |
 |
| Perhaps a better shot |
 |
| Looking at the race from inside the wheel |
Pressing the race in with my new tool was a breeze.
As time and humidity work their worst to degrade more bearing surfaces, I am confident this tool will come in handy again.
 |
| Clear coated (poorly) and labeled |
For today though, all there’s left to do is putting the wheel back together, mount it on the plane, and go test fly it.
Sounds like an excellent plan to me! 😉
