STI lubricant?

Frank Krygowski

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Jul 21, 2021, 8:30:37 PM7/21/21

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I've got a good friend in a distant state who is an upscale trashpicker.
That is, he lives in a gated community, rides his bike around it a LOT,
and drags home people's trash that he thinks might be useful. Like bikes.

He scored an old Trek with (IIRC) 8 speed STI shifting. Except it wasn't
shifting. So he's phoned me many times for advice. He's new at this and
not particularly mechanical, so consulting has been a challenge.

It took several phone calls to explain that since we've checked
everything else (and Tom, he finally got the derailleur limit screws
approximately right!), that the biggest problem was the typical STI
gummed-up failure.

I coached him through days of flushing with a couple different
penetrants and lubricants. The right shifter now seems to be behaving,
but nothing would work on the left. He decided to try disassembling it.

As I expected, he said it has "waxy" stuff throughout. I said that was
probably the original factory grease, dried to hardness. He's cleaning
that out, and will attempt to re-assemble. While I'm not really
optimistic about that, he asked an interesting question:

"What should I use to re-lubricate it?"

If I'd been in charge, I'd have provided a port for a monthly shot of
oil spray instead of grease, but that's not the case.

So I suggested low viscosity lithium grease. What do people here think?

--
- Frank Krygowski

John B.

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Jul 21, 2021, 9:30:56 PM7/21/21

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I don't have 8 speed but I do have 9 speed STI shifters on one bike
and while I've never disassembled them - I did take the hoods off once
- I don't believe that I ever noticed any lubricant in the things. Not
that there isn't any, just that if there is it was so little as to not
be noticeable. Perhaps the waxy deposit was something that a previous
owner had applied?
--
Cheers,

John B.

jbeattie

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Jul 22, 2021, 12:48:15 AM7/22/21

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Ditto. There is no waxy factory grease in STI levers. Flush he snot out of it with WD40 and then relube with something very light like TriFlow or similar spray lubricant. No grease.

-- Jay Beattie.

Frank Krygowski

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Jul 22, 2021, 10:30:14 AM7/22/21

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OK, I've passed that advice on.

But if there's never been any grease inside STI shifters, exactly what
is being flushed out with the classic WD-40 flush? I always assumed it
was dried grease.

--
- Frank Krygowski

Bertrand

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Jul 22, 2021, 10:51:12 AM7/22/21

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A mechanic I trust told me to use Boeshield T-9. It does dry to a somewhat waxy
coating. Sometimes I'll flush first with wD-40, then after it looks pretty
clean give it a shot of Boeshield for lubrication.

Tom Kunich

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Jul 22, 2021, 11:00:41 AM7/22/21

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This occurs almost entirely with Shimano levers. I haven't any experience with SRAM so I don't know what their failure mode it. I don't have any idea what the hell allows the garbage in but they will seize with usually more lint than anything else and require a complete disassembly and reassembly with very light grease inside the mechanism. People get the idea that they should use a light oil but from the factory you can see a white probably lithium grease in the ratchet mechanism. Surprisingly although Campy has a lot of problems, this doesn't seem to be one of them.

jbeattie

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Jul 22, 2021, 12:08:27 PM7/22/21

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I was just taking issue with the "wax" part of it. Whatever lubricant is used at the factory, and to whatever degree it congeals, it can be cleaned out with a light solvent and then replaced with a light spray lubricant.

Looking into a new STI lever, you can see very light factory grease, and people report that pawls and springs can get gummed up by old grease -- so maybe your friend is having that problem. I would not re-lubricate with grease, and I doubt your friend wants to do the amount of disassembly necessary to grease the internals in any event. SOP is flushing and spray lubricating.

I've rebuilt older 8/9 STI levers that were more capable or rebuilding than current levers and that were used a lot in the rain, so the problem was lack of lubrication and dirt. I've had one lever death caused by the failure of some tiny internal pot-metal or plastic part like a pawl or retainer of linkage of some sort. When some little broken thing falls out into your hand, it really doesn't matter except for academic interest.

-- Jay Beattie.

Frank Krygowski

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Jul 22, 2021, 1:54:26 PM7/22/21

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Ahem: As I said.

> I would not re-lubricate with grease, and I doubt your friend wants to do the amount of disassembly necessary to grease the internals in any event. SOP is flushing and spray lubricating.

That's what I suggested above - that the original grease lube had dried
waxy. And following my advice, he flushed it repeatedly over a few days.
When the left one still didn't work he disassembled it.

I hope he doesn't stumble upon this statement, but: I know him well and
I honestly doubt he'll be able to get it back together and functioning.
I've already suggested he just install a friction shifter on the left,
ala Armstrong. I think that's a reasonable fallback solution. It's not
like STI is necessary, especially on the left.

--
- Frank Krygowski

jbeattie

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Jul 22, 2021, 4:42:57 PM7/22/21

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The old left levers weren't that complex, so he may be able to get it together. He can also get an old left lever cheap.

-- Jay Beattie.

Frank Krygowski

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Jul 27, 2021, 11:53:13 AM7/27/21

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The latest update: In an email, they guy asking my advice said he did
manage to get the STI shifter back together (I was a bit surprised), and
he did use light lithium grease.

He said the bike shifted well when heading south, but didn't shift well
when heading north. (Seriously!)

I'm continuing our long-distance email consultation, even though it's
not easy.

--
- Frank Krygowski