Help with old Shimano Deore XT Front Derailleur

[TomYoung]

Hi all:

My daughter bought an old Cannondale Mtn. bike (7 cog rear cluster) and
brought it home expecting me to put it to right. It has Shimano Deore
XT components. I'm having difficulty getting the front derailleur set
properly and wonder if I've screwed something up. Maybe somebody can
give me an assist.

This particular derailleur has a clamp set up that I'm not familiar
with. The clamp itself is a C-shaped piece of spring steel whose ends
go into the derailleur body. In removing the derailleur I kind of let
things "explode" over the garage; I THINK I found all the parts and I
THINK I've got them assembled correctly, but the derailleur keeps
sliding down the seat tube even though I've cranked down the bolt
pretty damn hard, so it seems like maybe it isn't correct after all.

The order of assembly of the pieces is: bolt is placed in derailleur
body from the right side; next, a short coil spring is slid over the
bolt threads from the left side , then a small silver washer; finally,
a cross-shaped nut is started on the threads; the C-shaped clamp is
placed on the seat tube and the ends are pressed into the derailleur
body.

The two ends of the C-shaped clamp have slots that fit over two ends of
the cross-shaped nut and as I tighten down the bolt the nut draws the
clamp into the derailleur body. At least, that's the theory I'm
working under. But, as I said, even though I'm tightening the bolt
about as snug as I dare, and the derailleur seems to be pretty solidly
attached to the frame, working the derailleur results in the derailleur
sliding down the seat post.

Can anybody tell me if I'm missing a piece, have the order of assembly
wrong, or can point me to an exploded diagram of this derailleur so I
can see what I'm doing wrong here?

TIA.

Tom Young

 

[maxo]

Ouch! I've had that "explosion" happen unexpectedly when working on
various vehicles and bicycles--the subsequent hands-and-knees hour in
the garage is not the most fun. Hopefully somebody more familiar with
that exact model will have an answer.

For the rest of us keyboard speculators, a photo would be most welcome
for seluthing. Most clamp-on derailleurs are pretty straight forward
and don't require fierce torque to stay put.

 

[m-gineering]

TomYoung wrote:
>
> Hi all:
>
> My daughter bought an old Cannondale Mtn. bike (7 cog rear cluster) and
> brought it home expecting me to put it to right. It has Shimano Deore
> XT components. I'm having difficulty getting the front derailleur set
> properly and wonder if I've screwed something up. Maybe somebody can
> give me an assist.
>
> This particular derailleur has a clamp set up that I'm not familiar
> with. The clamp itself is a C-shaped piece of spring steel whose ends
> go into the derailleur body. In removing the derailleur I kind of let
> things "explode" over the garage; I THINK I found all the parts and I
> THINK I've got them assembled correctly, but the derailleur keeps
> sliding down the seat tube even though I've cranked down the bolt
> pretty damn hard, so it seems like maybe it isn't correct after all.
>
> The order of assembly of the pieces is: bolt is placed in derailleur
> body from the right side; next, a short coil spring is slid over the
> bolt threads from the left side , then a small silver washer; finally,
> a cross-shaped nut is started on the threads; the C-shaped clamp is
> placed on the seat tube and the ends are pressed into the derailleur
> body.
>

washer first, then the spring I think. Makes assembly easier, doesn't
affect clamping


> The two ends of the C-shaped clamp have slots that fit over two ends of
> the cross-shaped nut and as I tighten down the bolt the nut draws the
> clamp into the derailleur body. At least, that's the theory I'm
> working under.

correct. Try reversing the cross shaped nut, the stamping has a high and
a low side

But, as I said, even though I'm tightening the bolt
> about as snug as I dare, and the derailleur seems to be pretty solidly
> attached to the frame, working the derailleur results in the derailleur
> sliding down the seat post.
>
> Can anybody tell me if I'm missing a piece,

No you did well

> have the order of assembly
> wrong, or can point me to an exploded diagram of this derailleur so I
> can see what I'm doing wrong here?

Make sure the cross nut engages with both ends of the band

You might resort to some tape under the clamp


--
---
Marten Gerritsen

INFOapestaartjeM-GINEERINGpuntNL
www.m-gineering.nl

 

[Peter Cole]

TomYoung wrote:
> Hi all:
>
> My daughter bought an old Cannondale Mtn. bike (7 cog rear cluster) and
> brought it home expecting me to put it to right. It has Shimano Deore
> XT components. I'm having difficulty getting the front derailleur set
> properly and wonder if I've screwed something up. Maybe somebody can
> give me an assist.

New front derailers are very cheap and compatibility isn't too hard to
work out, I wouldn't waste a lot of time on it.

 

[[email protected]]

Diagrams of all Shimano components are available on the Shimano web
site. You might download the appropriate one and check yours against
it.

 

[TomYoung]

Marten:

Thanks for the input. It does seem to me that the problem does come
down to the orientation of the nut, as I'm certain (well, as certain as
I can be in the situation) that the ends of the nut are both engaged in
the band.

So...

The nut has one face that's fairly smooth, glossy black, edges gently
rounded. The other face has more "square" endges and isn't as smooth
and glossy. Two ends of the cross - opposite one another - are shorter
than the other ends and these shorter ends are slightly bent towards
the non-glossy, non-smooth face of the nut. The longer ends of the
cross are longer than the other pair because they have short tangs that
project past what otherwise would be the square ends of their arms.

It looks to me that the longer ends, the ones with the tangs, go into
the derailleur body vertically, with the tangs riding in groves in the
body; this prevents the nut from spinning in the body while things are
in the process of being tightened down. The two short ends of the
cross look to be the ones to engage the clamp slots as their slight
bend towards the open end of the "C" provides a firm engagement with
the slots.

If I switch the orientation of the cross nut such that the short ends
are vertical and the long ends are horizontal, the short ends don't
engage the groves in the body and the length of the pair of long arms
prevents the nut from being pulled very far into the body.

If you agree that my orientation of the nut is correct, perhaps I'm not
getting the proper engagement of the nut to the band.

Thanks.

Tom Young

 

[TomYoung]

Ok, I got it right, finally. The problem really was that the band
*wasn't* engaging the ends of the cross nut correctly. It appears that
you really have to push hard on the derailleur to seat the clamp
properly in the derailleur body. Having done that, the band pulled
down just fine and the derailleur has stopped moving around.

Thanks to all that responded.

Tom Young