Un-jamming STI's?

[Cab]

Talking about early 90's 7 spd with 2 unequal size triggers, one above the other. When I got the project, rear shifter worked fine & still does. Front, however was unmovable. Assuming the original grease could be solid in there, I sprayed IPA cleaner & GT 85 in there & it freed up for a week or so & worked across all 3, but now won't shift middle to top. If I take it apart, will loads of tiny bits spring out & get lost? Is there an exploded drawing available? should I just go for thumbies?

 

[NeilM]

You can take the plastic covers off the unit without bits flying all over the place.

If you then operate the shifter, you should be able to spot the little detent that is sticking. Sometimes they still have a bit of old dried up grease stuck to them.

Once you have spotted the sticky bit, get some light lube onto it and work the mech until it's all ok, then apply a little touch of modern grease to it.

 

[Jussa]

Pretty much as Neil said, Its usually a pawl which is sticking or a spring thats gunked up. If i remember this weekend I will take some pics, I am bringing some shifters back to life.

I purchased some de-greaser from my local motor discount shop (£1.99) and give it a liberal spray, the gunk breaks down and can be washed out with some warm soapy water, thoroughly dry, light lube and grease. Exercise the levers through the full gear range and then refit cover, good idea to fit new cable whilst you have with the cover off, can make the job easier. Then just put the shifters to one side ready to re-fit as required.

Jussa

 

[FluffyChicken]

I can add more specific advice if you post the
Model number and a picture.

 

[rider]

I had (again) trouble with mine repaired XT ST-M095, spraying GT-85 did not helped in this case and when I was almost decided to bin it, I slightly loosen nut which holds whole assembly together and it started to work again!

This may help if anything go wrong:
http://www.cs.hmc.edu/~geoff/deoredx/index.html

 

[MIKEYBOY]

I once took some early 90's shifters apart for what sounds like the same thing. It took me 4 or 5 hours to get them back together due to a flat spring that I couldn't seat. When I got them back together they wouldn't work, loosen the screw and hey presto. If I remember right I ended up blasting them with gt85 and it sorted it. I remember my fingers were killing the morning after!

 

[jaypee]

I've tried two methods.

Taking them apart didn't work as they're too fiddly (for me).

Immersing them in white spirit, soaking for a while, attacking them with a toothbrush and repeatedly shifting up and down whilst immersed worked a treat. I used thick oil once they were dry and they're still going strong.

I took the plastic cover off first, which can just about be done with the cable still in place if you're careful not to snap the plastic.

 

[FSXStumpy]

I've used Jaypee's method too, with similar success. Solvent bath + shifter manipulation followed by thorough oiling, on my XTR pods.

J

 

[Cab]

Thanks for the advice, got the confidence to take the cover off with no bits popping out, also removed the cable & found outer had pushed through ferrule at one end so I guess that wasn't helping! all seems to work fine now, hoping I get time to get out & give it a good testing Sunday.