Repair Sram twist shifter?

Dave said:

I have Sram 9.0 twist shifters and am having trouble with the rear
shifter. The shifter seems like it is not snapping to the center of
the shift detent, so on certain gears I have to nudge it slightly to
prevent noise and/or skipping. So two questions:

One, what's the expected service life of these shifters? I'd say I
have maybe 400 hours use on them in dry dusty conditions.

Two, anything I can do to service the innards?

I've used SRAM for a number of years.

Just in case the problem is not with your shifter, fastidiously check
the rear derailleur hanger alignment.

I've found SRAM indexing to be pretty tolerant of wear, dirt, dirty
cables, etc., BUT I have occasionally had indexing problems.

I tried a number of approaches to fixing these problems, and replacing
the derailleur hanger restored the shifting quality (for my cases
anyway). My hypothesis is that the rear derailleur hangers get a bit
bent and that the geometry of the SRAM rear derailleurs makes them
more sensitive than Shimano derailleurs to hanger misalignment.

I never did manage to realign a bent hanger adequately, but then I've
worked without the proper alignment tool in a poorly lit garage.

I've never had a problem with the shifters.

BP

Depends on the age of the shifters. Older ones (not sure specifically
of 9.0) were almost all plastic. I thought they were great and had no
problems (a lot lighter too). Last year at Interbike I asked SRAM why
they went away from plastic, after all they started as a plastics
company. First response was increased reliability and accuracy.

That said, your problem is much more likely to be related to cables
and housing. Usually, the more direct routing (and perhaps increased
cable travel) keeps shifting accurate for a long time without
maintenance versus Shimano. That would be the first thing I would look
at as your description of having to nudge the shifter fits right in
with a bit of excess friction. I'm not a cable lube guy, but if I was,
I wouldn't do it in your riding conditions. If you do, that could be
the problem.

After that, derailleur hanger alignment as already mentioned. Then
bent derailleur. Only then would I think about the shifter.

Dave said:

I have Sram 9.0 twist shifters and am having trouble with the rear
shifter. The shifter seems like it is not snapping to the center of
the shift detent, so on certain gears I have to nudge it slightly to
prevent noise and/or skipping. So two questions:

One, what's the expected service life of these shifters? I'd say I
have maybe 400 hours use on them in dry dusty conditions.

I'm not sure about the 9.0 shifters, but I had some cheaper ones wear
out after a couple of thousand miles with the same symptoms. On that
model the detents and the molding that held the spring could both wear
over time. The 9.0 design is somewhat different but it could run into
the same kind of problems if the internals are made of plastic.

Quoted message said:

Two, anything I can do to service the innards?

The first thing I'd do is replace your cables and housings. Excessive
cable friction will cause the same symptom. If that doesn't work, open
it up following the grip replacement procedure:

<http://www.sram.com/_media/techdocs/SL_X_9SL_9_7_Ro_At_Ins02_02.PDF>

If you don't see anything obviously wrong (excessive wear, broken or
disconnected coil spring, etc), you *might* try lubricating the
interface between the fixed and rotating parts. I'm not sure what lube
would be safe for that plastic though, so I'd exhaust all other options
first.

I have never worked on 9.0 twist shifters, so take this with a grain of
salt. I'm going off of my experience with another model plus the
drawings in the manual.

Dave said:

I have Sram 9.0 twist shifters and am having trouble with the rear
shifter. The shifter seems like it is not snapping to the center of
the shift detent, so on certain gears I have to nudge it slightly to
prevent noise and/or skipping. So two questions:

One, what's the expected service life of these shifters? I'd say I
have maybe 400 hours use on them in dry dusty conditions.

Two, anything I can do to service the innards?

Investigate control wires/casing first, especially f there are any
plastic ferrules in the system. We like skinny smooth wires running in
5.0 casing with 5.0 metal ferrules.

Then look at chain wear and derailleur tab alignment, more likely than
shifter wear.
SRAM suggests their own non-petroleum-based lube inside the shifter.
--
Andrew Muzi
www.yellowjersey.org
Open every day since 1 April, 1971

A Muzi said:

Dave said:

I have Sram 9.0 twist shifters and am having trouble with the rear
shifter. The shifter seems like it is not snapping to the center of
the shift detent, so on certain gears I have to nudge it slightly to
prevent noise and/or skipping. So two questions:

Quoted message said:

One, what's the expected service life of these shifters? I'd say I
have maybe 400 hours use on them in dry dusty conditions.

Quoted message said:

Two, anything I can do to service the innards?

Investigate control wires/casing first, especially f there are any
plastic ferrules in the system. We like skinny smooth wires running in
5.0 casing with 5.0 metal ferrules.

Then look at chain wear and derailleur tab alignment, more likely than
shifter wear.
SRAM suggests their own non-petroleum-based lube inside the shifter.
--
Andrew Muziwww.yellowjersey.org
Open every day since 1 April, 1971

Thanks all for the good suggestions.

I replaced the cable, housing, and aligned the der tab (which was
slightly off) all at once so I don't know what exactly fixed the
problem, but its fixed.

One interesting discovery...I had a difficult time installing the new
cable in the shifter and had to disassemble it. I discovered burrs in
the plastic all along the path where the cable bends to exit the
shifter which were jamming the new cable. Turns out older SRAM twist
shifters like mine need 1.1 mm cables, not the 1.2 mm shimano
standard. I had been using 1.2 all along and I think this is what
caused the burrs.