Tag Archives: Shimano freewheel

Overhauling a Freewheel, Part II

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2016-02-20 024

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.

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Maillard freewheel body with rubber band holding the pawls in place.

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.

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Shimano freewheel with top set of bearings installed, after applying a bead of grease.

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Spacers going back in over the top bearings.

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.

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Cover plate back on.

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Pin spanner and chain whip, to tighten the cover plate.

I removed the freewheel from the wheel, spun it, and was satisfied with the result. Voila – mission accomplished.

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Suntour Perfect 5 speed freewheel

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.

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Suntour spacers

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Suntour pawls – held in place with a clip

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Suntour freewheel body, beautifully machined

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.

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Lower bearings installed in a bead of grease, a small bit of grease added to each pawl.

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Top bearings installed, ready for spacers and cover plate.

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.

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Cyclo 4 speed freewheel

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.

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Cyclo freewheel pawls part of cog body

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Notches in freewheel body, instead of cog body

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Pawls which fell out on disassembly

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.

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Suntour Winner 7 speed freewheel

Overhauling a Freewheel, Part I

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2014-11-20 001 015

1941 French 3 Speed Freewheel

Vintage bicycles generally use freewheels, and not freehubs, as part of their drive trains, although it is interesting to note that the first freehub was actually invented by the British company Bayliss-Wiley back in 1938, and used thread-on cogs. Later, BSA created a splined freehub in 1948, which was set up for 4 cogs. And, Stronglight, Maxi-Car, and a few other manufacturers developed and marketed cassette freehubs in the late 1940’s through the 1950’s.  Shimano came out with its first freehub in 1978, and the rest is history.  Freehubs with splined cassettes are now the standard equipment on all modern bicycles.

Shimano, Sunrace, Ventura, DNP and IRD still manufacture freewheels, but the style, number of speeds, and spacing of the cogs, as well as the overall width of the freewheel often makes them inappropriate choices for a vintage bicycle restoration project.  Plus, weight and reliability can be an issue with any new non-Shimano freewheel (see below).

It is still possible to find NOS or good quality used vintage freewheels, such as Suntour, Regina, and Cyclo, on eBay or even Craigslist, but sometimes the cost is just too high to justify the expense in dollars.

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1940’s Cyclo Freewheel

I can attest to the reliability of virtually all vintage freewheels, having had no failures even after riding and restoring hundreds of bicycles. With a bit of lubrication, by dripping automotive oil into the space where the freewheel turns on its body, most freewheels can be brought back to their original functionality.  Sometimes, with a very dirty freewheel, I will first lubricate the body with a light oil, to clean the debris out, then follow that up with heavier automotive oil (the same 30 weight that I use for lubricating internal hubs).  The 1940’s freewheel pictured above came back to life easily after this simple process.

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1929 Peugeot Freewheel and Fixed Cog

Some freewheels don’t even need that much attention.  This 1929 Peugeot single speed freewheel with its helpful hinged lubrication port (part of the 1929 Griffon that I am restoring) didn’t require much lubrication – it was still working perfectly after 87 years of service!

Freewheels require a precise bearing adjustment, accomplished by the use of spacers and the torque on the cover plate.  While pawls can wear out over time, the stress on the bearings themselves is quite low, compared to bearings found elsewhere on a bicycle, and that is one reason why so many older freewheels work perfectly with simple cleaning and lubrication.  Hence, some mechanics have never found the need to perform a freewheel overhaul, myself included.  There are a number of resources on the web which provide detailed freewheel overhaul instructions.  There is even a business called the “FreeWheelSpa” which has dedicated itself to this zen-like work. Not wanting to deprive myself of the joy of tearing apart a mechanical device on a grey, rainy Portland winter day, I decided to tackle the job myself.

My Suntour New Winner 7 speed freewheel, installed on my winter bike, had begun making clunking sounds while under load, and grinding sounds while freewheeling.  I replaced it with a different vintage freewheel from my dwindling stock so I could keep riding the bke, but before attempting to overhaul the Suntour freewheel, I decided to take apart a number of other vintage freewheels on hand, to make sure I understood the process.  Possibly, this was a bad idea.

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From left to right: French freewheels, including Cyclo, Atom, Maillard and Milremo, Suntour freewheels including Perfect, New Winner, and Pro-Comp, and various Shimano and Shimano copies, both vintage and new.

I have a small collection of vintage French and English threaded vintage freewheels, plus a number of newer freewheels from Shimano, IRD, and DNP.

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This is an IRD freewheel that had previously failed after only a few hundred miles.  I marked it with a zip tie so that I would never use it again.  This seemed like the first obvious choice for an overhaul in my quest to master the freewheel overhaul process.  Unfortunately, the cover plate on this freewheel could not be removed, even after much pounding on the cover plate with a punch and hammer.  After that failed experiment I tried removing the cover plates on all the newer Shimano and Shimano copy freewheels on hand.  In each case, the cover plate could not be removed, partly caused by the tinier holes present on the newer freewheels – which would not accept my Park pin spanner.  Clearly these freewheels were meant to be tossed when they failed, part of the now de rigueur built-in obsolence doctrine in the cycling industry.

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So I grabbed an early 80’s made-in-Singapore Shimano freewheel, and had no trouble at all getting the cover plate off.  You need to mount the freewheel to a wheel first, before attempting to loosen the cover plate, so that the freewheel body is held in place.  I used an old rear wheel with English threads that I didn’t mind abusing for this process.  Once the cover plate is loose, you want to remove the freewheel off the wheel, and the take the cover plate off.  The cover plate is REVERSE THREADED, so you turn it clockwise to loosen it.

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When the cover plate was off, I was able to see the first set of 1/8″ bearings resting quietly in the top cup of the freewheel body.  There is another set of bearings at the bottom of the freewheel body.  I used my magnet to remove the bearings, and placed each set of bearings in a separate container.  I did not intend to replace the bearings, so I cleaned them with a little alcohol and let them dry out, planning to re-use them.

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Then I applied a bead of grease to the lower cup first, and began the mindful process of placing each bearing back in its rightful spot.

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Shimano freewheel pawls

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Maillard pawls on the left.

But, before doing so I noticed that this Shimano freewheel’s pawls differ substantially from this earlier Maillard freewheel that I had previously disassembled.  The Maillard’s pawls are held in place only by gravity, and there is one pawl on each side of the freewheel body, but the Shimano has double pawls on each side, held in place with a clip.

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After the lower bearings are installed, you need to screw the freewheel body back onto the wheel, then very, very carefully put the freewheel cogs over the top, and seat the pawls.  That’s where I ran into trouble, and decided to take a break before proceeding further.  It can be quite tricky to get the pawls back into the ratcheting mechanism.  Sheldon Brown used a technique involving a rubber band and some thread.  Reading about it gave me a headache.

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Meanwhile, my failed IRD freewheel is taking up its rightful position as a doorstop.