When I left off from my last post, I was midway in the process of overhauling an early 80’s Shimano freewheel. I was having trouble getting the freewheel cogs seated over the freewheel body, after cleaning and reinstalling the lower set of bearings at the base of the freewheel body. The process of mounting the cog body over the freewheel body involves turning the cogs counter clockwise, while somehow not dislodging the lower bearings, but every time I tried it I failed because I couldn’t see the bearings, as I was using the “top down” method.
So, I took a break and did some reading and experimenting with other freewheels. Older freewheels have pawls held in place only by gravity, which is fine if the freewheel body when disassembled is right side up. But, what I read was that the best way to get the cogs back on is to turn the freewheel body upside down first, then turn the cog body counter clockwise over the base of the freewheel. However, the only way to keep the pawls from falling out is to secure them with a rubber band, attached with a string. This was the method described by Sheldon Brown. When you flip the freewheel body upside down after installing it loosely on a wheel, you hope that you can get the string, rubber band, pawls and bearings to all end up in their rightful positions while maneuvering the cog body into the bearings. I tried this as a “dry run” – sans bearings – a few times on the Maillard freewheel that I had disassembled, and was never able to get the string to pull the rubber band out, and this was without having any bearings to worry about.
But, the Shimano’s pawls were held in place with a clip, and I realized that I could just turn the body upside down, position the cogs, and slowly turn them counter clockwise as I gently seated them over the bearings. Having the freewheel body upside down for this step allowed me to be sure that all the bearings stayed in place during the process. I did this while the body was attached to the wheel. After that it was easy to apply a bead of grease to the upper cup of the freewheel body, install the bearings, place the spacers, and then re-thread the cover plate BACKWARDS (because it is reverse threaded). Then, by taking a chain whip to the cogs, you can tighten the cover plate back down with your pin spanner. Some experts suggest applying thread locker to the cover plate, but I instead used a bit of grease.
I removed the freewheel from the wheel, spun it, and was satisfied with the result. Voila – mission accomplished.
Meanwhile, I recently purchased a used Suntour Perfect freewheel on eBay that I wanted to have on hand because of its useful wide gear range. Unfortunately, this freewheel was shipped in a small box surrounded by “popcorn” – that horrible stuff which clings to everything – and in this case imbedded its tiny carcinogenic particles into every possible opening of the freewheel during the shipping process. While described as being in “great condition” by the seller, I found that this Suntour freewheel was totally dry and did not spin freely. So, it became another candidate for an overhaul. As you can see from the above photo, the cover plate is easily accessible, with normal sized holes which my Park pin spanner fit perfectly.
As I was removing the cover plate, once the body was off the wheel, I had a small mishap when I accidentally bumped the body, and the bearings went flying around my shop. Fortunately, with my magnet in hand, I believe I recovered all of them. It’s important to have all of the bearings if only for the purpose of counting them, top and bottom, even if you aren’t going to re-use them. And, this venture definitely gives new meaning to the phrase “losing one’s bearings.”
I noticed right away, as I observed the Suntour’s freewheel body and cogs, how nicely engineered these are compared to the Shimano freewheel. The Suntour’s freewheel body has a wider base and a larger cup, which makes installing the bearings much easier. It has one pawl per side, held in place with clips. The top spacer has lock rings, another nice feature. However, you can see from the photo above that there is some wear on the pawls, which I think was caused by the complete lack of lubrication over the life of this freewheel. The pawls seemed robust enough to be re-used, so I proceeded to the next step.
I was able to easily install the cog body over the freewheel body by using the “upside down method”, and from there it took no time at all to apply a bead of grease to the top cup, install the bearings and spacers, and secure the cover plate. This overhauled Suntour Perfect freewheel now spins beautifully, with that pleasing tick-tick sound that Suntour freewheels emit.
So, I kept going. I wanted to overhaul this Cyclo freewheel which, even after lubrication, was fairly unresponsive. I believe it dates to the 60’s or 70’s. It is French threaded, but accepts a Suntour two prong removal tool. While it was fairly easy to get the cover plate loose, the tedious process to unscrew it all the way made me think that the cover plate had been cross threaded, and I worried about getting it back on again.
When I took the Cyclo freewheel apart, I was intrigued to see that its pawls are part of the cog body, and not the freewheel body, which instead houses the notches which allow for the freewheel to lock under forward motion. And, the pawls fell out of the body immediately, as they are not held in place by any kind of clip. So, this Cyclo will require a different method for getting the pawls to stay in place while mounting them over the freewheel body. And now I am getting another headache.
One thing I learned from this process is that nicely engineered freewheels are easy to overhaul as long as the pawls are clipped into the body (but probably almost never need to be overhauled). In fact, the only procedure you may ever need to do, aside from routine lubrication, is to remove the cover plate to add or remove a spacer. If the freewheel is too tightly adjusted, you add a spacer, and if it’s too loose you remove a spacer. Poorly engineered (and badly adjusted) newer freewheels are time consuming to overhaul, if you are even able to do it, as the cover plates on some freewheels are difficult or impossible to remove. Meanwhile, my 7 speed Suntour Winner freewheel, which was the impetus for this undertaking, is now working better. I tightened the cover plate, lubricated it with a bit heavier oil, and now it is working fine, without the need for an overhaul.