Early STI shifter won’t shift.

[peetee]

I’m looking for some suggestions as to how to unstick a RSX 7 speed shifter.
I’ve come across this issue many times with older Shimano and spraying loads of GT85 in the workings does the job every time.
Not this one, oooooh no. It’s from 1990’s Cannondale which, because of its age and condition, I purchased about a year ago. The bike has prob never done more than a few hundred yards since new, there’s no wear or marks on anything. Consequently the shifter has lain idle for over 20 years and although the levers move well and everything looks pristine, the internal ratcheting doesn’t work.
Its been sprayed from every angle possible and left for days/weeks with the occasional encouragement and gentle tug at the cable but no joy.
I don’t want to disassemble it myself.
Ideas?

[rareposter]

Silly question but have you taken the cables out?

Contrary to popular belief, you can actually take those things apart but it requires a watchmaker's degree to put them back together again! At some point though you're going to have to at least peel the rubber hood off it to get an idea of what is catching.

It's a lot easier with the whole shifter unit off the bars although that does of course require re-taping the bars and re-cabling the gears and brakes...

[peetee]

Rareposter.
The entire shift assembly is housed in the pivoting lever on these early units.
Yes, the cable was removed - it doesn’t suffer from cable fray like the later style shifters. The cable was pristine like the rest of the bike and the inner ran free - I replaced it and ran the shift up and down to creating mech-like spring tension with my hand to help it along, but the ratchet doesn’t engage.
I’m not keen on disassembly. Ive seen the video tutorials and I’m a bike mechanic not a watchmaker.

[slowster]

If the problem is that the factory lubricant/grease has dried out so much that the solvents in GT85 are not significantly able to dissolve it, I think iso-propyl alcohol (IPA) is likely to be a stronger solvent and should be more effective. I would try repeating what you have done but with an IPA aerosol spray. Alternatively it might be possible to immerse the part of the STI containing the ratchet mechanism in IPA, but you would need to find a suitable small container, and I think you would need to wrap and securely fasten a plastic bag around the container and STI to inhibit the evaporation of the IPA.

I've not attempted to do anything like this myself, so I cannot give any assurance of the outcome, and obviously it would be at your own risk.

[pwa]

Does dried up lube respond to heat application, in addition to use of solvents? I'm thinking of a hair dryer. Perhaps the expansion and contraction of heating / cooling might help break bonds.

[cycleruk]

I know you said you don't want to strip the STI but it's fairly easy :-
https://www.youtube.com/watch?v=xkGNN_2CfCY

Whether you would need to actually strip to clean will depend on how clagged up the mechanism is.
At least the above allows access to the ratchet parts.

[TheBomber]

Nice video from RJ. I’d always wondered what that little Shimano ‘tool’ was for; I've had one for years as it came with some STI levers. Speaking of tools, if that ‘Phillips’ screw is tight you might want to get a JIS screwdriver on it as a Phillips version is bound to cam out.

Overall, while there are springs involved, disassembling to that point is hardly in watchmaker territory.

[colin54]

There's a post by Brucey with photo's in the 'too good to lose' section showing how to get access to the pawls etc in these early shifters.
Encouragingly subtitled 'not quite so horrifying inside after all'.
viewtopic.php?t=124472
Good luck.

[peetee]

I agree that, on viewing the vid kindly linked by RJ, the process is not as convoluted as I thought. Certainly a lot easier than later/current designs.
I’m currently soaking the thing in hot water to see if that softens the goo. It will click up and down two notches which I think is an improvement over the last time I tried a fair few months ago, but I’m not certain as lots of bike jobs have been and gone in the intervening time.

[Brucey]

IIRC I found it possible to loosen the rear cover, then poke a bent paper clip inside, directly at the pawl that usually sticks. The reason GT85 has failed thus far is almost certainly because the solvent is flashing off before it really has a chance to work as intended.

I suggest you remove the thing from the bars (you shouldn't need to re-tape if you are careful) and remove the rubber hood. Then spray it with GT85 and bag it (in a ziplock bag or similar which is pretty well airtight) in quick succession. If necessary, repeat the spraying immediately prior to closing the bag, which should be left overnight. If this doesn't work, it is worth trying WD40 instead because it has a different solvent in it.
If it still hasn't worked, you could try putting it into a coffee can with half a pint of paraffin and leaving it on a radiator. This will degrease just about anything, but if it all boils away too quickly, you will have to top it up, or fit a proper condenser. You can make a condenser by grafting a coil of small-bore copper tube to the lid of the coffee can, as a vent. The idea is that any vapour condenses in the coil and runs back into the can as a liquid. If you want to get reet fancy, drape a damp cloth over the coil, to ensure that the temperature is held down.

[plancashire]

I second use of paraffin or lamp oil. If that fails the next one to try is white spirit. One of those will dissolve just about any grease used on bikes. If you could get access to an ultrasonic bath, that would speed up the process.

[peetee]

Thanks for the ideas folks.
Will try a few and get back yo you all.