Assemble the wheels

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(Click images for larger version)

Assembling a wheel should not be that difficult but it always seems to give newcomers a lot of trouble. I even noticed George Orndorff struggling in his video series, and it was not his first aircraft. So I decided to make a little photo essay and show how to easily assemble a wheel with the tire and tube. You will need the wheel, tire, and tube, of course, plus an air compressor, air gauge, flat blade screwdriver, sockets, torque wrench, and talcum powder. Regarding the sockets, I prefer a deep socket to fit over the nut for the torque wrench, and an extension for the socket on the bolt head to reach past the brake disk, if needed. For talcum powder, you can still use baby powder but check the ingredients. Cornstarch powder can rot in the tire, affecting both tube and tire. Use only talcum.

The wheels usually come assembled so the first task is to disassemble them. Use the screwdriver to pry the retaining ring from the bearing assemblies. Once you have them started you can easily remove them the rest of the way by hand. Pull them toward the center of the wheel axis so you do not twist and distort them. Remove the bearing assemblies as a unit (they should be already greased so you do not want to pull them apart and possibly contaminate them) and place them in a clean, protected location along with their retaining rings. Note which side of the wheel they came from as they are not always identical and you want to put them back the way you found them. By the way, if your bearings are not greased or you are replacing or repacking them, I will describe how to grease them farther along where we reassemble them to the wheel.

Now you can use your sockets to split the wheel halves. For main wheels, there will be, in addition to the halves, a brake disk. Set aside the hardware neatly as you remove it so you do not lose washers or nuts and can replace them as you found them. The picture below shows an RV-10 wheel disassembled.

The wheel parts disassembled

Now we turn to the tire and tube. Use a generous amount of talcum inside the tire to lubricate it. I find a couple of squeezes of a container of baby powder delivers enough to flow as you rotate the wheel to get it everywhere (and it will get everywhere; do this away from the bearings or wheel halves). Dump the excess onto a piece of cardboard and use it to rub all over the tube. If the tube is fully deflated, it is easy to fold (in the fashion that a new tube arrives) and insert into the center of the tire, where it can be unfolded into the tire itself.

Be sure the valve stem is aligned with the red (not pink) dot on the tire. It does not matter if it is on the same side of the tire as the dot, which is handy when you turn the tire around to even the wear on it at a later date. Now, inflate the tire partially. You want it to achieve a donut shape but still be squishy and loose inside the tire. Below is a picture of the tube partially inflated in a tire.

The tube is partially inflated but still loose.

Now insert the wheel half with the opening for the valve stem into the tire, inserting the valve stem as you do. This is your last chance to align the stem with the red dot. Press the wheel as far into the tire as you can but the bead will not fully seat just yet. That is normal, so flip the assembly over so the tire is on top of the wheel. It will look like the photo below. Notice that the partially inflated tube has plenty of clearance around the wheel half; there should be no chance of pinching it when you insert the other half.

The tube has plenty of clearance around the wheel at this point.

Now insert the other wheel half. The tire should be able to compress enough that the halves will meet. One of the reasons we removed the bearings, aside from protecting them from contamination, was so we could look inside and align the halves so the bolts will go through - notice the cast lug in the photo below which is where the bolt passes. With the lugs on both halves aligned, add the brake disk (assuming there is one) and pass a bolt through the assembly. It should protrude enough for you to start a nut. Then proceed to the next bolt and repeat until all the bolts are started. If you have somehow managed to pinch the tube between the halves, you will not be able to get all the bolts in, so remove them and try again. If you are having problems, try deflating the tube a little more so there is more clearance for the wheel.

Aligning the wheel halves and inserting the bolts.

Now tighten all the bolts. I like to go around until all the nuts have only part of a thread showing or just barely snug, whichever is first. Then set the torque wrench for the recommendation by the manufacturer - the bolts in the photo are called out as 150 in-lbs (not ft-lbs!). Torque all the nuts and then go around and check them again. When working by myself I find it easiest to tighten with the wheel oriented so the nut is on my left and across the wheel from me. Then, as I tighten, the wrench moves down with the floor or surface I am working on to resist me; otherwise the wheel tends to move. If you have a helper to hold the wheel, orientation does not matter.

Torquing the wheel bolts.

Now we can inflate the tube. It is already in position but we want to be sure that it inflates properly so there are no wrinkles or misalignment that will cause problems later. Rather than inflating it to full pressure, use about half the pressure called for. We just want enough to stretch the tube and allow us to seat the tire beads. In the example, the final pressure will be 42 psi and I used an initial setting of 25 psi. So, fill the tube to your initial setting and bounce the wheel on the tire, rotating it. The pressure should be enough that the bead seats on the rim as you bounce it, if it did not while you inflated the tube. By the way, as you fill the tube, it will push air trapped in the tire and wheel out and you will see a little smoke-like talcum dust expelled. That is normal and perfectly fine; it will probably stop after the first couple of times you inflate the tube if you dumped the excess talcum out.

Now, deflate the tube. There are some clever tools for this or you can remove the valve stem but I like to use a drill bit a little smaller than the stem body, as you see in the picture below. It is small enough to allow air to pass but large enough to easily depress the stem core. Let as much air out as you can without squeezing the tire and unseating the bead, then re-inflate it. Do this a couple of times to give the tube a chance to position itself. Then, if everything has gone well, go ahead and inflate the tube to full pressure. Now when you bounce the tire, it will really have some bounce! Be careful not to allow the wheel to fall over and damage the rim or brake disk.

Deflating the wheel using a drill bit.

Now the final step is to replace the bearings. For a new wheel with the bearings already greased, simply inspect the races for contamination and wipe them with a clean rag if necessary and then replace the bearings as you found them. The retaining ring can be replaced by hand, inserting one end in the slot and pushing the other end toward the wheel axis as you guide the ring into the slot; it should easily slide into place. If not, check that the bearing is seated correctly and the ring is not deformed and try again.

If the bearings need grease or you are replacing or repacking them, then you will definitely want to clean the races and also the bearings themselves and then pack them with fresh grease before following the above procedure. I prefer hand packing bearings; the packing tools tend to be more trouble than they are worth and can over-pack the bearings. Hand packing is easy but words and pictures don't explain it well enough. Fortunately, the EAA has a nice [|video of the process].

When you are done, wipe off any excess grease or talcum - that stuff gets everywhere! If you are not going to mount the wheel right away, cap the bearings with the plastic caps that came with the wheel. You did save those, right? Otherwise, you are ready to mount the wheel.

Assembled wheel capped and ready for storage.

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