freewheel dismantling

[Steve W]

I have a 6 speed screw on shimano freewheel set and I would like to
dismantle it. Can it be done with two chain whips or do i need a special
spanner to undo what appears to be a slim lock ring with 8 semi circular cut
outs in the outside of it.

 

[Qui si parla Campagnolo]

Steve W wrote:
> I have a 6 speed screw on shimano freewheel set and I would like to
> dismantle it. Can it be done with two chain whips or do i need a special
> spanner to undo what appears to be a slim lock ring with 8 semi circular cut
> outs in the outside of it.

I use a pin tool to take off the lockring, then it will come apart. It
is right threaded.

 

[Jasper Janssen]

On Sat, 3 Dec 2005 14:34:01 +0000 (UTC), "Steve W"
<[email protected]> wrote:

>I have a 6 speed screw on shimano freewheel set and I would like to
>dismantle it. Can it be done with two chain whips or do i need a special
>spanner to undo what appears to be a slim lock ring with 8 semi circular cut
>outs in the outside of it.

Depends which bit. The lockring holds on the cogs (and there may or may
not be a second lockring behind the large cogs), but the bearings & pawls
come apart if you undo the other lockring.

Jasper

 

[Sheldon Brown]

<[email protected]> wrote:
>
>>I have a 6 speed screw on shimano freewheel set and I would like to
>>dismantle it. Can it be done with two chain whips or do i need a special
>>spanner to undo what appears to be a slim lock ring with 8 semi circular cut
>>outs in the outside of it.
>
Jasper Janssen wrote:
>
> Depends which bit. The lockring holds on the cogs (and there may or may
> not be a second lockring behind the large cogs), but the bearings & pawls
> come apart if you undo the other lockring.

See: http://sheldonbrown.com/freewheels

Sheldon "Not Worth The Trouble" Brown
+--------------------------------------------------------------+
| When I think back on all the **** I learned in high school |
| It's a wonder I can think at all |
| And though my lack of education hasn't hurt me none |
| I can read the writing on the wall --Paul Simon |
+--------------------------------------------------------------+
Harris Cyclery, West Newton, Massachusetts
Phone 617-244-9772 FAX 617-244-1041
http://harriscyclery.com
Hard-to-find parts shipped Worldwide
http://captainbike.com http://sheldonbrown.com

 

[Steve W]

How do i know if mine is a hyperglide freewheel?


"Sheldon Brown" <[email protected]> wrote in message
news:[email protected]...
> <[email protected]> wrote:
> >
> >>I have a 6 speed screw on shimano freewheel set and I would like to
> >>dismantle it. Can it be done with two chain whips or do i need a
special
> >>spanner to undo what appears to be a slim lock ring with 8 semi circular
cut
> >>outs in the outside of it.
> >
> Jasper Janssen wrote:
> >
> > Depends which bit. The lockring holds on the cogs (and there may or may
> > not be a second lockring behind the large cogs), but the bearings &
pawls
> > come apart if you undo the other lockring.
>
> See: http://sheldonbrown.com/freewheels
>
> Sheldon "Not Worth The Trouble" Brown
> +--------------------------------------------------------------+
> | When I think back on all the **** I learned in high school |
> | It's a wonder I can think at all |
> | And though my lack of education hasn't hurt me none |
> | I can read the writing on the wall --Paul Simon |
> +--------------------------------------------------------------+
> Harris Cyclery, West Newton, Massachusetts
> Phone 617-244-9772 FAX 617-244-1041
> http://harriscyclery.com
> Hard-to-find parts shipped Worldwide
> http://captainbike.com http://sheldonbrown.com
>

 

[Jasper Janssen]

On Sat, 03 Dec 2005 14:27:41 -0500, Sheldon Brown
<[email protected]> wrote:

I wrote:
>> Depends which bit. The lockring holds on the cogs (and there may or may
>> not be a second lockring behind the large cogs), but the bearings & pawls
>> come apart if you undo the other lockring.
>
>See: http://sheldonbrown.com/freewheels

|the tricky part is the pawls. In days of yore, there were special
|bobby-pin-like clips to hold the pawls compressed against their springs
|while you re-assembled the freewheel. These are no longer available.
|
|Instead of the special clips, you can use a rubber band with a piece of
|thread looped though it. Assemble the pawls to the freewheel core, then
|wrap the rubber band around them to hold them against their springs.

What I always do with the Sturmey cores is sort of apply pressure and then
rotate in the direction of free running. The friction between the tops of
the pawls and whatever they butt up against is usually enough to get the
pawls in with a bit of wiggling. Doesn't that work for freewheel cores?

Or is it that it works but the gyrations make you lose balls?


Jasper

 

[David L. Johnson]

On Sat, 03 Dec 2005 14:34:01 +0000, Steve W wrote:

> I have a 6 speed screw on shimano freewheel set and I would like to
> dismantle it. Can it be done with two chain whips or do i need a special
> spanner to undo what appears to be a slim lock ring with 8 semi circular cut
> outs in the outside of it.

What do you mean by "dismantle", and why do you want to do it? If you
want to replace the sprockets (in the extremely unlikely event that you
can get replacement sprockets), then the chain-whips will let you unscrew
the screwed-on cogs (maybe just the smallest 1 or 2, depending on model).

But if you want to get inside the freewheel part, you are asking for
trouble. There are 3,287 little tiny bearings in there, plus 2 or 3
little tiny springs pushing up the pawls that engage the freewheel when
pedaling. To put this back together you have to get all the bearings to
stay put on the races, and at the same time compress the pawls down so
they will fit in where they are supposed to be. This is an impossible
task. I find it hard to believe that they can be built in the first
place, but rebuilding them is a nightmare.

If you liked taking Dad's pocket watch apart just for fun, go ahead. But
toss it when you're done. If you have a problem with grit or gumminess
inside the freewheel, flush it out with solvent, dry it out, and work some
oil in there.

To take the freewheel apart, look at the plate in the center. There
should be two little indentations, which you can fit a pin wrench to (or a
drift pin and a hammer). I believe the threads are left-handed so it
won't loosen during use.

Good luck.

--

David L. Johnson

__o | Anyone who is capable of getting themselves made President
_`\(,_ | should on no account be allowed to do the job. -- Douglas Adams
(_)/ (_) |

 

[Sheldon Brown]

Steve W wrote:

>>>>spanner to undo what appears to be a slim lock ring with 8 semi
>>>>circular cut outs in the outside of it.

>>>> How do i know if mine is a hyperglide freewheel?

The presence of that lockring indicates that it is a Hyperglide freewheel.

> I wrote:
>
>>See: http://sheldonbrown.com/freewheels
>
> |the tricky part is the pawls. In days of yore, there were special
> |bobby-pin-like clips to hold the pawls compressed against their springs
> |while you re-assembled the freewheel. These are no longer available.
> |
> |Instead of the special clips, you can use a rubber band with a piece of
> |thread looped though it. Assemble the pawls to the freewheel core, then
> |wrap the rubber band around them to hold them against their springs.

Jasper Janssen wrote:

> What I always do with the Sturmey cores is sort of apply pressure and then
> rotate in the direction of free running. The friction between the tops of
> the pawls and whatever they butt up against is usually enough to get the
> pawls in with a bit of wiggling. Doesn't that work for freewheel cores?
>
> Or is it that it works but the gyrations make you lose balls?

Bingo! Actually, many older freewheel designs didn't secure the pawls
all that well when disassembled too, so the pawls easily get knocked out
of position. Newer freewheels are less tricky in this respect due to
use of a different type of spring.

Sheldon "Don't Bother" Brown
+------------------------------------------------------------------+
| Honestly, I think we should just trust our president in every |
| decision that he makes and we should just support that. |
| -- Britney Spears, September 4, 2003 |
+------------------------------------------------------------------+
Harris Cyclery, West Newton, Massachusetts
Phone 617-244-9772 FAX 617-244-1041
http://harriscyclery.com
Hard-to-find parts shipped Worldwide
http://captainbike.com http://sheldonbrown.com

 

[Vee]

David L. Johnson wrote:
> On Sat, 03 Dec 2005 14:34:01 +0000, Steve W wrote:
>
> But if you want to get inside the freewheel part, you are asking for
> trouble. There are 3,287 little tiny bearings in there, plus 2 or 3
> little tiny springs pushing up the pawls that engage the freewheel when
> pedaling. To put this back together you have to get all the bearings to
> stay put on the races, and at the same time compress the pawls down so
> they will fit in where they are supposed to be. This is an impossible
> task. I find it hard to believe that they can be built in the first
> place, but rebuilding them is a nightmare.

There's less than a hundred bearings, and it's not that hard to
overhaul a freewheel. My first couple attempts took a while, and I
made a mess. But after you've done it two or three times, it becomes
straightforward. I don't possess extraordinary mechanical skills and I
have no trouble overhauling freewheels.

Sheldon's site is a good place to start. I would only add: work on the
freewheel while it's held in a vise via a freewheel tool because you'll
make less of a mess and it's far easier if you can turn the freewheel
upside down.
Pull the freewheel apart over a rag. Spend a few minutes figuring out
how the freewheel works once you've got it apart. Try to visualize the
best reassembly sequence. The trick is the sequence, and the position
of the freewheel during each step (i.e., facing up or down).
Soak everything in degreaser before reassembly. Lots of grease will
keep the bearings in place. Put some Phil Oil or other thick lubricant
on the pawls.
Other useful tools: a cow magnet (Farm and Fleet) to keep the wee
bearings from fleeing across your basement floor, and an awl to push
the bearings into place during reassembly.

I'll take some pictures of the reassembly sequence the next time I
overhaul a freewheel. I always read about how arduous the procedure
is, but it's really not hard. The real question is whether it's
worthwhile. It's winter, I say go for it.

-Vee

 

[m-gineering]

Vee wrote:
>
> David L. Johnson wrote:
> >
> > But if you want to get inside the freewheel part, you are asking for
> > trouble. There are 3,287 little tiny bearings in there,
>
> There's less than a hundred bearings,


Or not even that. I've opened freewheels which held only six balls and
peices of bent wire to keep them apart! Later Sachs freewheels have the
bals in a cage


I would only add: work on the
> freewheel while it's held in a vise via a freewheel tool because you'll
> make less of a mess and it's far easier if you can turn the freewheel
> upside down.

This works with the splined type. For notch type freewheels clamp an old
hub in a vise (drop a bolt in the housing to keep it from squashing).
spin the freewheel on, it tightens when you knock the bearing ring loose
and vice versa.

Regina's were indeed hopeless to work on, but an Atom body was
dimensionally the same and took all the cogs



--
---
Marten Gerritsen

INFOapestaartjeM-GINEERINGpuntNL
www.m-gineering.nl

 

[Mark Janeba]

m-gineering wrote:
> Vee wrote:
>
>>David L. Johnson wrote:
>>
>>>But if you want to get inside the freewheel part, you are asking for
>>>trouble. There are 3,287 little tiny bearings in there,
>>
>>There's less than a hundred bearings,
>
>
>
> Or not even that. I've opened freewheels which held only six balls and
> peices of bent wire to keep them apart! Later Sachs freewheels have the
> bals in a cage
>
>
> I would only add: work on the
>
>>freewheel while it's held in a vise via a freewheel tool because you'll
>>make less of a mess and it's far easier if you can turn the freewheel
>>upside down.
>
>
> This works with the splined type. For notch type freewheels clamp an old
> hub in a vise (drop a bolt in the housing to keep it from squashing).
> spin the freewheel on, it tightens when you knock the bearing ring loose
> and vice versa.
>
> Regina's were indeed hopeless to work on, but an Atom body was
> dimensionally the same and took all the cogs

While we're offering actual practical advice here, here's some more
pointers to make your reassembly job easier:

Open the freewheel over a large rag. If possible, count the bearings on
each side before removal, but if not, the rag will catch them. This is
much easier than estimating how many will fit during reassembly.

SunTour New Winner freewheels require a special tool for opening the
body - they had adjustable bearings, a design that was eliminated in the
next incarnation, "Winner Pro". For all others, a screw cover with
pinholes has a left-hand thread. A drift punch will work, but a pin
tool allows more control.

Put a very thin film of grease on the bearing surfaces before
reassembly. The balls will "stick" in place. If you are worried that
the grease was enough to gum up the pawls, you can flush with WD-40
after reassembly, allow to dry, then oil - but a thin film shouldn't be
a problem.

I agree that this work isn't worth it if your time is more valuable than
your money - unless you're just curious, or have a vintage freewheel
that has some collector's value. Back when I was a college student with
more time than money, I resurrected a few friends' rusted-out freewheels
this way.

Mark

 

[[email protected]]

Here's another suggestion.

If you really want to catch ALL the balls, put a strong magnet inside
the rag, and/or set it all inside a shallow tub or tray when you open
the thing up.

Some will argue about the dangers of magnetizing ball bearings, but
any evil that results isn't nearly as bad as having to reassemble the
thing with one or two balls missing.

 

[A Muzi]

Steve W wrote:
> I have a 6 speed screw on shimano freewheel set and I would like to
> dismantle it. Can it be done with two chain whips or do i need a special
> spanner to undo what appears to be a slim lock ring with 8 semi circular cut
> outs in the outside of it.

Hold the low gear in a freewheel vise and unscrew the
lockring, ideally with a pliers-type lockring tool such as a
Var #16.

Older Shimano MF cogs can be cut to fit the mid and low gear
positions on these new freewheel bodies. There's an extra
square cutout in addition to the traditional serrated pattern.
--
Andrew Muzi
www.yellowjersey.org
Open every day since 1 April, 1971