Problem with Nexus hub

"Sven Agardh" <[email hidden]> wrote in message
news:[email hidden]...

Quoted message said:

I have a Shimano Nexus SG-7C21 7 gear internal hub. An exploded view of the
hub can be found here:

http://www.shimano-europe.com/cycling/phpimages/product/exp_view/SG_7C22.pdf

The bike is used 20-25 km/day all year round in southern scandinavia, with
lots of salt on the roads in the winter, so I guess I shouldn't expect it
to last forever, but I still hope it will survive a little longer.

Last year it started to be squeeky in first and third gear. After a while
the sound (and the extra resistance) spread to the other gears. When I
disassembled the hub it was quite dirty and some parts were defenitely
ruined. Because of a stupid mistake I ruined the threads on the axle so I
replaced the axle and driver unit (#10 in the exploded view), which I
guess means that it is actually a SG-7C22 hub now.

After that everything was fine for a while, but now I can't engage first
and third gear. The wire is adjusted and it seems to move freely while
changing gear, so I guess it is something inside the hub. Unfortunately I
haven't been able to figure out how the gears work, so I don't know which
parts are active in which gear. Which part should be replaced this time?
Or is it time to get rid of the hub?

/Sven

These hubs were sold as maintainace free but it is now recognised by shimano
that they need servicing every 12 months and they have set up trained
service stations with dealers.
The seals have been improved on the SG-7C22 compared to the seals on the
SG-7C21.
I would see what a service center could do with your hub before buying a new
one.

PK

In article <[email hidden]>, [email hidden] says...

Quoted message said:

I have a Shimano Nexus SG-7C21 7 gear internal hub. An exploded view of
the hub can be found here:

http://www.shimano-europe.com/cycling/phpimages/product/exp_view/SG_7C22.pdf

The bike is used 20-25 km/day all year round in southern scandinavia,
with lots of salt on the roads in the winter, so I guess I shouldn't
expect it to last forever, but I still hope it will survive a little longer.

Last year it started to be squeeky in first and third gear. After a
while the sound (and the extra resistance) spread to the other gears.
When I disassembled the hub it was quite dirty and some parts were
defenitely ruined. Because of a stupid mistake I ruined the threads on
the axle so I replaced the axle and driver unit (#10 in the exploded
view), which I guess means that it is actually a SG-7C22 hub now.

After that everything was fine for a while, but now I can't engage first
and third gear. The wire is adjusted and it seems to move freely while
changing gear, so I guess it is something inside the hub. Unfortunately
I haven't been able to figure out how the gears work, so I don't know
which parts are active in which gear. Which part should be replaced this
time? Or is it time to get rid of the hub?

I went to the Shimano Tech seminar at interbike. The tech there basically
said you can take it apart to a certain point and then stop. If there are
problems with the internals, part 1 in your diagram, just send it to shimano
to have them look at it. What you may want to try is pulling the internals
out of the shell. Then putting the shifting mechanism and the cog back on.
Then working the shifter and cog to see if you can see which parts turn
when you move the cog and the shifter is in 3rd gear.
----------------
Alex