|The Trials and Tribulations of riding a
CJ750 in China Part 3 by Dave Vella
Building a Wheel Truing Stand
Receiving that big crate holding my new CJ750 is probably one of the more exciting events that occurred since my arrival here in China. Everyone in the warehouse came out to help and watch.
I had put off the purchase for two years because I wanted to get my driving license first. I know some guys who ride without a license, but if you are caught riding illegally here; the police are not shy about confiscating your wheels. I dont find the thought of losing my bike very appealing; and having a bike I couldnt ride just didnt make much sense.
Getting a license in a big city like Shanghai or Beijing isnt too difficult; but here in the countryside things are a bit different. I could have traveled to one of the larger cities in my province and taken the car drivers license, they are prepared for that and have the test copies translated into English, but no foreigner had ever wanted to get a motorcycle license before and the folks down at the police station did not seem to want to go through all that trouble just for one crazy laowŗi.
Eventually we worked things out; I was now licensed and the proud Papa of a shiny new sidecar motorcycle. I wasted no time in getting out and hitting the road.
At about 500Km I lost one of the bearings on the sidecar wheel
This did not really surprise me much. I had read a couple of items on the internet that talked about the poor quality of the bearings manufactured here. Someone actually wrote they only expected to get 500Km out of a set of wheel bearings; so I imagined I would be changing them periodically too.
I made a bearing puller based on the design I found in Bart Sanders Toolbox, (It works great, Thanks Bart!). But as I was cleaning the old grease out, I noticed that the hub on my nice new aluminum wheel had a big ugly crack right through the center of the bearing pocket.
The bike still being under warrantee; the shop informed me they would ship a new hub right away. Unfortunately I did not have any of the tools I knew would be required to reassemble the wheel.
I knew from past dealings with this shop that it would take a while to get everything settled. I had my only spare tire on the sidecar now, and I did not want to be out riding any distance with an empty spare tire rack. I figured the quickest way to get the spare replaced would be to just buy a complete wheel and tire assembly and worry about fixing the old hub later. I made arrangements to have my newly purchased wheel assembly delivered, and I would return the broken wheel assembly in the same box and let the guys at the shop replace the hub.
When I finally received my repaired wheel, the first thing I noticed was the axle spacers in the wheel hub were askew.
I was curious why this was, so I pulled the bearings and spacers out of the new hub. It was fortunate that I had saved the inner assembly out of the old broken hub because when I compared the two I realized that the new middle spacer installed at the shop was narrower than the one that came in the hub originally. Not only that, but one of the sealed bearings I removed was only half sealed. The little cover had fallen off one side and the guys just went ahead and installed it anyway. Of course there wasnt a dab of grease to be found anywhere inside the new hub. I replaced all of the new hub internals with what I had kept from the original installation and replaced the bearings as well.
Finally satisfied with the new bearing assembly, I decided to try to find out why the tire would not hold any air pressure.
While performing this investigation, I discovered the tube had been punctured by a long spoke left in the wheel untrimmed.
I didnt even bother to check anything else. I knew right then I was destined to get into the wheel building business.
I had already purchased a good set of spoke wrenches, tire spoons and wheel protectors on my last trip home. What I didnt have was a truing stand.
A truing stand is a simple contraption really; something to hold the wheel in a position where it can be measured and adjusted. The wheel must be able to spin just as if it were mounted on the bike.
My original intention was just to buy one, but I couldnt manage to explain to anyone what I was looking for. I guess I shouldnt be surprised, if the guys in Beijing cant build a wheel, what should I expect out here in the woods?
We do have a steel yard though; and a hardware store. I know how to point to what I want and I know that duo shao qiŠn? means How much money?
It didnt take long for me to round up what I needed. A stick of 50mm galvanized angle iron for my frame, a couple of long shank 30mm bolts for the axle pins, two 10mm cap screws, a length of 10mm all-thread and a handful of nuts to hold it all together.
I started with the base. My wheels are 19, which converts over to about 50cm. I wanted the base a little longer for stability, and because I might want to use it on a larger wheel later. I decided on 60cm. Before I drilled my bolt holes, I lined up and clamped the two pieces of angle together back to back. Both pieces were drilled together, thus guaranteeing the alignment. After cutting and de-burring, the base was bolted together with three long pieces of all-thread. The all-thread was cut long to give the base an adjustable width.
The two vertical pieces were cut and drilled the same way. The two bottom holes would be on the same plane as the holes in the base, which would automatically align the two top holes. The two top holes would mount the axle pins. The vertical pieces are 40cm tall with the pin mounting hole a little over an inch (30mm) down from the top.
I only made one diagonal brace. With the vertical piece on one side of the stand held firmly, the other side should line up perfectly when the wheel is installed. The other reason is because I am doing all this assembly by hand. I have long known I am not a machine and I will never be able to match the precision laser guided CNC equipment used to cut parts in the factory. Plus I like to keep things simple. The more pieces I cut, the greater the likelihood that I will be off by just the one red hair that puts the bearings in a bind. The diagonal brace is also a good spot to mount the lateral adjustment indicator.
I cut a short piece of angle to be used as a mount for the radial adjustment indicator. The radial indicator mount is not rigid and attaches to the front of the frame using the existing all-thread. It will have to be adjusted up or down depending on the diameter of the wheel being trued, as well as the mounting configuration of the dial indicator used.
I knew I did not want to mount the wheel to the stand using the axle spacers in the wheel. The spacers are not the same diameter as the inner bearing race and they are loose in the wheel hub. The wheel rides on the bearings, the axle pin would have to extend all the way through the spacers into the bearings to accurately true the wheel. To make the axle pins, I first cut the head and threads off the 30mm bolts. I used bolts because I didnt want to buy a whole stick of round stock just to make two short pieces. I chucked up the remaining bolt shank in the lathe and cut a 35mm long step to slightly over 20mm diameter. I wanted the pin to fit snugly into the bearing; not so tight I needed to press it in, but not so loose it would wobble. I left the pin in the lathe and polished it gradually with emery cloth until the bearing slid on with very little pressure. With the bearing side finished I flipped the pin over in the lathe, cut the bevel and step at the mounting end then drilled and tapped it for the 10mm cap screw I would use to mount the pin to the stand.
The hardware store I go to only had one style of dial indicator and a very limited selection of magnetic bases. Normally I would have used an indicator with a back centered vertical lug and a Mighty Mag base; but here I would settle for a flat back indicator and a couple of small yet powerful magnets I could glue to the back of the indicator.
The end result is a pretty sturdy stand that isnt too heavy and is actually fairly convenient to use. The wheel spins freely and the indicators give a good account of where the wheel is. The benefit of using dial indicators is you can actually see how much you are moving the wheel as you tighten or loosen the spokes.
Wheel truing is a bit of an art form. It takes some practice. But if you have a good piece of equipment to help you along, it makes life a whole lot easier.
Take care, ride safe, and have a great day!!