Help required, Shimano Rapidfire cable replacement

[John Henderson]

My son's bike is fitted with Shimano Deore SL-M510 rapidfire
gear levers.

The left-hand cable (for front derailleur) has snapped off
within the rapidfire mechanism. The few mm of frayed cable
remaining have helped jam the head of the cable firmly within
the mechanism.

The mechanism is shown at http://tinyurl.com/cl39k and I have
removed all parts shown as removable in that diagram. But I
can't get the head of the old cable out. I'm unable to get
anything into the small hole to grip it. And pushing a fine
rod in from the wire end just seems to jam the frayed ends
tighter into the housing.

Without advice, I'd like to avoid further disassembly at this
stage, because the mechanism bears an uncanny resemblance to
intricate clockwork.

Short of taking the whole thing to our LBS, any advice on the
way forward from here is appreciated. I prefer to buy parts,
but be otherwise mechanically self-sufficient. I carry spare
gear cables and tools when cycle touring, for example.

John

 

[A Player]

The head is pretty soft metal, so you could try drilling a very small hole
into the centre of it, then turn in a small self-tapping screw. Pull on the
screw to get the head out.

"John Henderson" <[email protected]> wrote in message
news:[email protected]...
> My son's bike is fitted with Shimano Deore SL-M510 rapidfire
> gear levers.
>
> The left-hand cable (for front derailleur) has snapped off
> within the rapidfire mechanism. The few mm of frayed cable
> remaining have helped jam the head of the cable firmly within
> the mechanism.
>
> The mechanism is shown at http://tinyurl.com/cl39k and I have
> removed all parts shown as removable in that diagram. But I
> can't get the head of the old cable out. I'm unable to get
> anything into the small hole to grip it. And pushing a fine
> rod in from the wire end just seems to jam the frayed ends
> tighter into the housing.
>
> Without advice, I'd like to avoid further disassembly at this
> stage, because the mechanism bears an uncanny resemblance to
> intricate clockwork.
>
> Short of taking the whole thing to our LBS, any advice on the
> way forward from here is appreciated. I prefer to buy parts,
> but be otherwise mechanically self-sufficient. I carry spare
> gear cables and tools when cycle touring, for example.
>
> John

 

[[email protected]]

John Henderson wrote:
<snip>
> The left-hand cable (for front derailleur) has snapped off
> within the rapidfire mechanism. The few mm of frayed cable
> remaining have helped jam the head of the cable firmly within
> the mechanism.
>
> The mechanism is shown at http://tinyurl.com/cl39k and I have
> removed all parts shown as removable in that diagram. But I
> can't get the head of the old cable out.
<snip>

>From my reading of your description, you can see the end of the old
cable, but can neither push it through from the "cable" side, nor get a
grip on the cable end to pull it out.

If so, could you put a small blob of super-glue or epoxy resin onto the
end of a suitable implement (an old spoke?), push it against the head
of the old cable, wait for it to set, then use it to pull the head out?

If you're trying this, use as little adhesive as possible - if it runs
between the head of the cable and the plastic part it's sitting in, it
won't make it any easier to get out ;-)

hth,

bookieb.

 

[John Henderson]

A Player wrote:

> The head is pretty soft metal, so you could try drilling a
> very small hole into the centre of it, then turn in a small
> self-tapping screw. Pull on the screw to get the head out.

Many thanks to you and "bookieb" for your suggestions.

As noone's suggested dismantling the mechanism further, I'll
avoid doing that and instead persevere with pulling and/or
pushing the cable head out.

Drill and screw first, I think, and then glue if that doesn't
work. The drilling will give the glue a better surface area
anyway.

John

 

[Vee]

John Henderson wrote:

> The left-hand cable (for front derailleur) has snapped off
> within the rapidfire mechanism. The few mm of frayed cable
> remaining have helped jam the head of the cable firmly within
> the mechanism.

A sharpened spoke usually pops them right out. You can put a nice,
sharp tip on a spoke with a bench grinder.

-Vee

 

[John Henderson]

Vee wrote:

> John Henderson wrote:
>
>> The left-hand cable (for front derailleur) has snapped off
>> within the rapidfire mechanism. The few mm of frayed cable
>> remaining have helped jam the head of the cable firmly within
>> the mechanism.
>
> A sharpened spoke usually pops them right out. You can put a
> nice, sharp tip on a spoke with a bench grinder.

Thanks. I've already tried a spoke and a thinner (1.4 mm diam.)
steel "rod". But I'll grind an old spoke thinner still and try
that.

One reason for the post was to see if I'd overlooked some design
feature that made extraction trivial (so that it could be done
without recourse to a workshop).

John

 

[john]

John

I'd be very afraid of any kind of glue. That head is very small. Way
too small for the control of a runny fluid.
Another thought, drill out the head, not too deep, to a little more
than the minor diameter of the smallest spare spoke you have and thread
the spoke in. Some aerosol lube to the head and spoke prior to
threading to spoke can't hurt. I doubt that it will take much, once you
get a half way deceit purchase.

Let us know how it goes, John

 

[John Henderson]

john wrote:

> I'd be very afraid of any kind of glue. That head is very
> small. Way too small for the control of a runny fluid.
> Another thought, drill out the head, not too deep, to a little
> more than the minor diameter of the smallest spare spoke you
> have and thread the spoke in. Some aerosol lube to the head
> and spoke prior to threading to spoke can't hurt. I doubt that
> it will take much, once you get a half way deceit purchase.
>
> Let us know how it goes, John

Still no joy.

I've managed to remove a piece of the plastic housing, breaking
it at its thinnest section in the process, but I don't think
that would affect anything when reassembled.

I've now got good access to the wire end of the cable head. I
can easily move the head in and out by 3 or 4 mm, but I can't
push it out any further - it just won't move further. And
there's nothing obvious obstructing it.

Given the force I an now able to exert, I'm sure that any
attempt to pull the head out from its recess using glue or
drilling and tapping will fail. Exploratory drilling has
created a lot of metal filing. Any more would contaminate the
indexing mechanism to the extent that a complete disassembly
would be warranted anyway.

It's off to the LBS when I get time to see how much a new
Rapidfire assembly is.

(a defeated) John

 

[John Henderson]

Earlier, I wrote:

> Still no joy.

The LBS got it out for me, but it took a couple of blokes and a
hammer.

John