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Old 06-24-10, 10:15 PM   #1
ueyteuor
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How can I disassemble an old Shimano freewheel?

Hi. So I took off a Shimano freewheel from the hub... but now I want to disassemble the freewheel so I can access the ratchet pawls, and have everything freshly greased... this thing was filthy so I cleaned it up on the outside, now i want the inside... Can anyone help?

I was thinking i need a special tool to unscrew that first ring on top of the small gear, but I may be wrong?

Any and all help is really appreciated!

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Old 06-24-10, 10:42 PM   #2
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Basically, yes. A pin tool and a tool to hold the inner body. Be careful or you will lose bearings... there are many and they are small.

One thing we used to do in one shop I worked at was to flush the freewheels with solvent in a parts washer. We had a special attachment that would go on the back and provide a tight seal. Then we'd sit it in the washer for a good 20 minutes with solvent blasting through it. After it dried we'd use the same type of attachment to pump a light grease through it.

Taking freewheels apart is a PIA. Make sure it is worth your time to save that freewheel first.
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Old 06-24-10, 11:49 PM   #3
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Quote:
Originally Posted by ueyteuor View Post
Hi. So I took off a Shimano freewheel from the hub... but now I want to disassemble the freewheel so I can access the ratchet pawls, and have everything freshly greased... this thing was filthy so I cleaned it up on the outside, now i want the inside... Can anyone help?

I was thinking i need a special tool to unscrew that first ring on top of the small gear, but I may be wrong?

Any and all help is really appreciated!
I think that the top ring is a lock ring that hold the sprockets on. To get at the bearings, you need a freewheel vice and a pin spanner. Sheldon took one apart on this page:
http://www.sheldonbrown.com/mega7/

I agree with KH- disassemble at your own risk. It's far more practical to run a bunch of solvent through the bearings and then heavy oil (like Phil Tenacious Oil) to lube it.

The tool he refers to is a Stein freewheel injector, #FI-U:
http://www.jastein.com/Html/Tools_for_Wheels.htm

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Old 06-25-10, 05:38 AM   #4
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Flush it with WD-40 and then drip heavy oil through it.
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Old 06-25-10, 05:54 AM   #5
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Flush it with WD-40 and then drip heavy oil through it.
+10 Flush it.

If you want to take it apart, be prepared to buy a new one. Read Sheldon Brown on disassembling a freewheel.
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Old 06-25-10, 07:05 AM   #6
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aebike.com just got a new freewheel from them for about 13 bucks. at that price hard not to just buy new. But of course this could be someone just looking to tinker!
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Old 06-25-10, 07:59 AM   #7
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Flush it with WD-40 and then drip heavy oil through it.

Yes, this is how to do it!

No grease.

If you really want to disassemble it, use some locking pliers to get the lockring off.
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Old 06-25-10, 07:30 PM   #8
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You are not supposed to use grease in there, just oil. Grease will keep the pawls from working properly. There aren't any big loads on the freewheel components when the freewheel is freewheeling, so it doesn't take that much lube anyway.

However if the freewheel gets too gummed up then the little pawls will stick and the thing will freewheel both directions. (not good). I had a freewheel that did this. I was going to flush and lube it, but it had a stiff seal to keep stuff out. I used a small screwdriver blade to force open the seal slightly and used the thin straw on my spray lube to get some lube in there. It worked fine afterwards.
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Old 06-25-10, 07:52 PM   #9
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Yes, this is how to do it!

No grease.

If you really want to disassemble it, use some locking pliers to get the lockring off.
As I said, the lockring holds the cogs on. To get at the bearings and pawls, he needs a pin spanner.
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Old 06-25-10, 08:12 PM   #10
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There's no lockring. It's actually a bearing cone. Calling it a lockring sets you up for a pitfall because the only thing holding it accurately adjusted is a stack of paper thin metal spacers that it stops against. There is no way to adjust it, as if it were a lockring with a cone underneath. If you take it apart, be very careful not to lose or warp the spacers underneath. Of course, if you get new balls, they may be of a slightly larger tolerance and it won't go together right anyway.
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Old 06-25-10, 08:26 PM   #11
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To clean it on inside just put the freewheel into a container with gasoline/diesel/paint thinner/mineral spirits and let it soak and jiggle it around.

To lube it is best to install the FW onto the wheel, and onto the bike. Lift the rear of the bike off the ground, get the back wheel spinning and coasting. Angle sideways the bike at ~45degree angle and drip oil (75W90, or motor oil, or chain oil) between that two hole cone (that is spinning) and cog body (that is not spinning, is coasting). By capillary action the oil will be sucked into the mechanism.

Or if you have enough space between the body of cogs and the fixed part (the cone on the front and the threaded body on the back) insert oil with a syringe and a thin needle attached (stationary! not when the wheel spins, it will jam the needle and mangle it into the mechanism causing other problems)
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Old 06-25-10, 08:28 PM   #12
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Quote:
Originally Posted by ueyteuor View Post
Hi. So I took off a Shimano freewheel from the hub... but now I want to disassemble the freewheel so I can access the ratchet pawls, and have everything freshly greased... this thing was filthy so I cleaned it up on the outside, now i want the inside... Can anyone help?

I was thinking i need a special tool to unscrew that first ring on top of the small gear, but I may be wrong?

Any and all help is really appreciated!

The outer ring just holds the cogs in place, it does not provide access to the bearings and pawls.
That ring in the centre is the bearing cone. It is left threaded, so just use some kind of tool to engage one or both of those depressions and rotate it clockwise to remove.
Be ready to contain about a zillion little runaway bearings when it comes apart.
Lots of others will chime in to tell you not to bother, but what's the fun in that, eh?
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Old 06-25-10, 08:28 PM   #13
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You are not supposed to use grease in there, just oil. Grease will keep the pawls from working properly.
Depends on the grease. We used Bullshot on many hundreds of freewheels and never had a problem. It's very thin compared to say, Phil.
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Old 06-25-10, 11:03 PM   #14
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Originally Posted by garage sale GT View Post
There's no lockring. It's actually a bearing cone. Calling it a lockring sets you up for a pitfall because the only thing holding it accurately adjusted is a stack of paper thin metal spacers that it stops against. There is no way to adjust it, as if it were a lockring with a cone underneath. If you take it apart, be very careful not to lose or warp the spacers underneath. Of course, if you get new balls, they may be of a slightly larger tolerance and it won't go together right anyway.
Take another look at the OP's pictures and the dissassembly sequence on Sheldon's page. On that freewheel, there's a lockring that holds the cogs on. It's the Shimano Hyperglide design- there are no threaded cogs.
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Old 06-26-10, 05:34 AM   #15
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http://blog.harriscyclery.com/custom...ed-freewheels/

If the OP wants disassemble the FW, it sure looks like a lockring to me, just like in the above link.

By disassemble , I'm referring to taking the cogs off to clean them and the spacers, not taking the body apart too, as this is only needed in rare cases and a sure road to anxiety for most people.

I do this with Sachs FW's all the time, also because there is a lube port underneath the cogs.
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Old 06-26-10, 07:33 AM   #16
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I've overhauled enough freewheels that I can claim I'm good at it. But I won't do it ever again. It's just not worth it. If flushing doesn't work, and it probably will, replace it. The trouble to overhaul it is large, and the payoff is small.

To reassemble it, I did put grease in the races. This was to keep the balls in place. After it was all back together, I diluted the grease with oil, so there was little or no grease remaining in the freewheel. But this is altogether moot, since I maintain my recommendation not to disassemble a freewheel!
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Old 06-26-10, 08:53 AM   #17
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I've done it lots of times with a hammer and punch, or even a nail, since I don't own a pin spanner. Stick the punch in one of the holes in the bearing cone and tap it loose (it's a left-hand thread, so clockwise to loosen). Easier to do if you screw it back onto the wheel. Obviously the whole thing falls apart when you lift the outer body off which is why most people say not to do it at all. I use white lithium grease to hold all the bearings in place whilst reassembling. It's thin enough not to cause me any trouble until I get down to about -30 degrees C.
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Old 06-26-10, 10:09 AM   #18
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The reasons it takes a long time:

- Getting the pawls into position can be difficult
- The balls fall all over the place, and you lose some
- You have to buy more balls
- The balls are 1/8", not found anywhere else on the bike, so you have to buy more
- Picking up the balls is tricky because they're so small
- Putting the balls in because they're so small and there are so many of them. They tend to fall out of the layer of grease, because they are so small and there are so many of them. They fall and get lost again.
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Old 06-26-10, 10:42 AM   #19
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the worst nightmare was installing rubber springs onto pawls (an odd spring to use, a block of rubber that is attached to the pawl on a Regina FW, 3pawls, 3such springs that are not held by anything but the fact that it cannot slip out once the pawls and the ramps on the gear body is installed)

Another nasty thing is to install individual steel springs like a safety pin (that is looped around into a recess of the fixed part and a recess hole on the back of the pawl) - it must be installed at once (the pawl and the spring) - in a XB3 hub/fw combo (since the fixed part of the FW it is cast with the hub itself, not removable, when the ratchet mechanism is toast, the hub is toast)

There are some times, lamellar individual springs that are usualy not removable since they are being clamped by force into a small slot into the fixed part (and since the spring is not removable or at least not installable again, the pawls cannot be removed) - in a maillard FW (non-helicomatic)

In shimano silent FW/hub you will find lots of rollers and lots of springs inside. That is a badass to put in again (it does not have pawls but lots of rollers that wedge themselves onto ramps in one way of turning and slip in the other way)

In a single speed freewheel i had found a coiled band that it was tight to the hub when coasting and it would unwind and expand and stick to the exterior housing (the gears part) like a drum brake. (on a "Ukraina" utility bike)

Most newer FW have 2-3 pawls held by a ring spring, which is pretty convenient to dissemble/reassemble. (use some grease to hold the balls in the raceway, and some tweezers to manipulate the small balls)

On the bottom line: if the FW do not have play side to side, the mechanism works (it does not slip in forward resulting in free pedaling, and it does not stick when back pedaling) then do not dissemble the unit.
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