Atom Freewheel Disassembly
 

I have an Atom 77 Compact freewheel that I need to clean. I figure the best way would be to take it apart, but I'm unaware of how to disassemble it. Any help would be great!

Beware disassembly, lots of pawls & gimcracks to lose and or/destroy if you are not PastorBob.

If your FW is loud & gritty remove it from the wheel and immerse in a mild solvent like WD-40.
Spin and re-immerse until it spins smoothly, use compressed air to blow it out or let drain overnight.

"Drip oil onto the crack between the turning part and the stationary part. Gravity and capillary action will help work oil into the freewheel."
-Sheldon Brown: http://sheldonbrown.com/freewheels.html

Lightly grease the FW body threads & re-install. Re-oil when it sounds dry.

-Bandera

Thanks, I've removed it from the wheel and it doesn't spin well at all (very gritty and rough sounding) so I'll try immersing it. Would kerosene work for immersion?

Anything that is formulated specifically to burst into flames would not be my 1st choice.

-Bandera

Dont.. tear down is a fruitless effort

dunk it in a bucket of Kerosene. take it out blow it down with compressed air and flow fresh clean oil through it .

or just oil it from one side grit should leak out with excess oil out the other .

Just stay away from open flame .. butt out the Gauloise, Garçon ..

Aside the explosion hazard, kerosene and diesel fuel is one of my top degreasers that still have some lubrication in it to prevent surface rust in short term.
Gasoline, paint thinner, acetone, methanol, and other stuff like this is for cleaning parts spot clean and removing all lubrication that it had - not great for a freewheels or chains, but great for cleaning the raceways for a headset, BB, and stuff where you want to asses the condition of a surface for pitting and wear.

About the explosion hazard.. depends on the surrounding area, and diesel and kerosene do not emit fumes easy (like gasoline does), and only the fumes can ignite but the liquid will not burn easy even from an open flame (unless you boil it on a stove and pressurize it a bit until self detonation - but it's a very long way).

When I soak components in any inflammable liquid (especially gasoline), I put it in an airtight container with very little air in it, like a jar full of gasoline and a screw cap, carefully set at the back of the shelf not to bump into it and shatter it.
About safety is another discussion. A lot of advocates of excessive safety to make everything idiot proof, but in use can reveal a lot of apparently hazardous practices that works without a hitch for decades until a mistake is done. - Valid for ultra-safe methods as well - there will always be the one idiot that overcome every safety feature and still can mess up wildly. So whatever suits you comfortable with.

Regarding to overhaul or not.. depends a lot. As a first try .. will get messy and frustrating - http://www.slugsite.com/archives/1461
nowadays will not justify such a thing unless it's collectors value, but if you like to tinker complex mechanical objects, a freewheel is not so hard to do

Yes, that will work fine. Give it a long soak, then remove and spin to loosed crusty stuff, and re-immerse. repeat a few times until it spins free and feels clean. Note it'll be kind of noisy.

When finished, drain on a paper towel, then leave out in the sun a while to dry. When finished, put some oil at the gap, spin to work some in, and keep going until oil comes out the back. Drain, and you're good for the next decade or so.

I will just add to Francis' good advice to look at the distarge coming out when you flush the FW. Is it brown/red with rust or grey/black from grime? Red is bad as rust never sleeps and leaves a pitted surface behind. Black is better as it's then just old lube/gunk/grime and that tends to have less long term effects. Andy.

Do yourself a favor and replace it with a new Shimano. Even the ones made in Singapore are better than that Atom. You won't believe how much better the twisted tooth design makes them shift.

I paid $8 for the last one I bought.

Will do.

As much as I'd love to try, I won't be taking it apart (don't have time to tinker). I've been using kerosene for degreasing other parts and I've got a good place to put it and I'm comfortable using it, so I'll do that. Thanks

Sounds good thanks for the advice.

Hi, I hope its OK to slightly hijack this post; I don't think I am going off topic.

My question is, should I follow the same dunk, spin, oil procedure for these 2 wheel/pulley thingies off an old and very weird derailleur (BGA Velectrik) I am cleaning.

....or can they be non-destructively dissasembled for greasing?

http://bikeforums.net/attachment.php...hmentid=333368

Predictably the morningstar grease didn't get to the bearings, Would Chain-L be a good choice for oil (it may be too thick to spin-and-lube; so maybe just lube the gap and wait for it to soak in, then spin, then repeat)?

if you are curious, I am detailing the strip, clean, rebuild of this bike here.

Bruce,

Nice vintage bike, and should be a beaut when fully restored. I love the vintage U-brakes.

Chain-L will be fine as a freewheel lube, and will get in there by a combination of spinning and gravity, keep adding until it drains out the bottom, then don't use the freewheel until it stops draining so you don't fling oil all over the bike.

The soak and flush will be fine for the pulleys, and Chain-L will be fine for those too. (to other readers, I'm not flogging Chain-L here, I know Bruce has it already). However, the smaller pulley, and maybe both have ball bearings, so I suggest loosening them until you have enough room and working some grease in there rather than using oil. This will offer much more durable lubrication and weather protection. If you have a small grease gun with a pointy tip, it'll be easy to get grease inside without opening them to where you risk dropping the balls.

Free Wheels
 

In the bottom of my tool box with numerous freewheel removers , I have a freewheel injector , pat pend . The inventer was probably a ex bike wrench , maybe the same guy who made freehub injector. If you are addicted to your atom , follow cleaning instructions . But the shimano replacement advice is best {new chain ?**

Thanks FB, yes both the pulleys pictured have ball bearings, I have a small grease gun, but I have no idea how to "loosen up" the pulleys enough to get the tip of the grease gun in... can you please provide some guidance on this?

I don't know about the larger one because the cover hides the mechanism, but the smaller one has the cone exposed. The two sides are threaded to each other and the bearing is adjusted by holding one side while turning the other. They use a split screwdriver similar to a chainring nut tool. You can make the tool with any flat blade of the right width, by notching out the center, but usually they can be turned and adjusted by thumb pressure alone, and stay locked when installed and tightened between the cage plates.

If you really want to save one of the worst freewheels ever, here's the way to do it right:

http://www.bikeforums.net/showthread...!!-Photo-heavy

I can think of a number of other FW brands/models that are worse then the Sun Tour pictured, many others. Andy.

I was referring to the OP's Atom. Suntour made excellent freewheels.

That's an awesome thread - great pictures. The kerosene soak is working great, but I may still take it apart sometime when I have the time. If not, very useful for future endeavors.

I disassembled and rebuilt two of these Atom 77 freewheels a few months ago. I never had any problems with their performance, but they were due for some fresh grease and new balls. The process of accessing the pawls and bearings is the same level of difficulty as servicing a Suntour or a Shimano freewheel. Hammer and punch to loosen the locking cone. After you clean the races, use Park grease or something similarly thick to stick the balls in place while you screw it back together. Best to use a pin wrench to tighten the lock cone, and some kind of thread locker on those threads. Be patient and work in an area where the balls won't roll away and disappear. I always work above disposable paper plates with a raised lip around them. Then you can toss 'em when you're done. Don't be afraid to splash out for new balls if the old ones look trashed. If you do it right it will be good for a long, long time (assuming you don't leave it outdoors year round.)

The seriously flawed part of the Atom freewheel design is the way that cogs screw onto the body instead of sliding on with splines. It's super easy to customize Suntour or Shimano freewheels, but removing individual Atom cogs is an amazing PITA and sometimes impossible. If you don't care about customizing your freewheel ratios it's irrelevant.

In my experience dismantling freewheels of different brands, Atom was the only one I have found with broken ball bearings and chipped pawls. All of my freewheels have seen decades of use and some abuse, but the metallurgy of the Atom internal components was a little cheaper. My Atom freewheels with chipped pawls worked perfectly fine despite the minor breakage. The bearings that broke managed to shear exactly in half!! There were two broken bearings in the same race, but I never heard or felt anything amiss. Replaced with fresh new grade 25 balls.

I've ridden bikes with Dura Ace and bikes with Atoms, and the build quality and design are certainly different, but the performance difference is really not as drastic as Atom's rap in the popular culture. If anyone wants to get rid of an Atom freewheel, I'll happily provide a new home. :)

I've got one last question, I'm cleaning the rusted chain that went with this freewheel and I'm wondering how impossible it will be to get the two functioning together smoothly when finished.

Now you have me really interested in taking it apart haha - I want to see the balls and make sure they're all intact as well as to re-grease them.

You'll have to try it. Sometimes they're OK. However, a chain with rust on the outside probably has rust on the inside, and that's going to cause it to wear quickly once you get it lubed. Then you'll want a new chain, and the new chain probably won't play well with the old freewheel. But then again, it might be OK.

All of the above tells you why we usually recommend replacing the freewheel and chain together. Unless the parts are extremely rare and of great sentimental value, it's far easier and sometimes cheaper to replace them both.

I did rebuild a freewheel once - can't remember the reason but given that I was a mechanic and service manager for over 20 years that gives you some idea of how common it is to do so. I would not even bother with cleaning a freewheel without first checking the wear on the chain and looking at the small cog to see if it's worn noticeably. If the chain is worn so that 12 full links (inner/outer) measures more than 12 1/8," or if the small cog is worn there's no sense in working on the freewheel in my opinion - replace both.