Friction lever slipping, am I missing something?

Here's an issue with a 105 front shifter, an older downtube bike with a
SIS 7 speed. When in the big ring in the front derailleur, the shifter
will slip and have to be re-trimmed off frequently, I have not tried to
see if it will drop to the small ring, but it will drop the cage down
and rub the chain. It's a fairly NOS 105 shifter. It moves freely, no
matter how much you tighten the center screw. I took it apart and there
are only 4 parts, the shift lever itself, the bushing that fits the
frame, a bushing that fits between the frame bushing and the lever and
the screw. Is is missing something? It's also clean and dry, it would
seem to me that you would want a bit of grease on the metal to metal
surfaces, but I think it would slip even more then. TIA

wrote:

Here's an issue with a 105 front shifter, an older downtube bike with a SIS 7 speed. When in the big ring in the front derailleur, the shifter will slip and have to be re-trimmed

It's a fairly NOS 105 shifter. It moves freely, no matter how much you tighten the center screw.

Do you have standard Campagnolo type bosses on the frame? And is that
what the shifters are supposed to mount on? Some older bikes had
different type bosses. It sounds like the screw is bottoming out before
getting tight. Maybe you can add a washer.

Art Harris

I'm not sure what the campy bosses are supposed to look like. It is not
a clamp on strap type, there is a boss on the frame, then a spacer,
another part that fits the first one, then the lever, then the screw
that holds it all tight. It does seem like the screw is bottoming out.
I always thought you could tighten down the center screw until the
lever was as tight as needed, in fact you could tighten it down to
where the lever could not be moved.

On 27 Jul 2005 15:05:33 -0700, "
wrote:

that holds it all tight. It does seem like the screw is bottoming out.
I always thought you could tighten down the center screw until the
lever was as tight as needed, in fact you could tighten it down to
where the lever could not be moved.

So put in an extra spacer or grind off a bit of the screw. Sheesh.

Jasper

I finally got my hands on the bike a few days ago. I replaced the lever
and lubed the cable guides and it works fine now. I was wrong, you can
not tighten the screw down to where the lever will not move at all,
that will only result in cracking the cover on the lever. I think the
main issue was the lack of lube in the metal cable guides. It would
really start to slip when you spinted or stood up and climbed. I think
the guides were catching the cable. The lever also did not feel "right"
so there may have been an issue there too. Sheesh.

wrote:

I finally got my hands on the bike a few days ago. I replaced the lever
and lubed the cable guides and it works fine now. I was wrong, you can
not tighten the screw down to where the lever will not move at all,
that will only result in cracking the cover on the lever. I think the
main issue was the lack of lube in the metal cable guides. It would
really start to slip when you spinted or stood up and climbed. I think
the guides were catching the cable. The lever also did not feel "right"
so there may have been an issue there too. Sheesh.

Counterintuitively, friction levers work best when clean
with a film of machine oil on all the internal surfaces.
Loosen the tension screw, run oil between all the various
washers, tighten the screw and ride.

Yes, if you have steel cable guides, smear a dab of grease
on the wire where it slides on the guide.
--
Andrew Muzi
www.yellowjersey.org
Open every day since 1 April, 1971