louky

This RD is on a 30-40 yo Schwinn 10 speed with little wear but (apparently) hasn't been ridden for years. The pivot point is stiff. I have sprayed it with WD and penetrating oil; there has been some improvement but still not right. I can get the derailleur off if needed but am concerned that taking the spring off shown in the middle of the pic could end in disaster.

Should I just keep applying WD for a few days? If I do need to take it off and disassemble to clean and lube, is there any tricks on getting the spring off and recoiled when reassembling? TIA!

Kontact

Which part is stiff? The parallelogram that makes the lateral shifts, or the jockey pulley cage pivot with the coil spring? The latter is actually not hard to deal with.

Schweinhund

Twer it I, i'd remove the jocky wheels and back plate and soak the rest of it in penetrating (diesel) oil for a few days.

louky

Kontact: Pretty sure it is the jockey wheel pivot. I can move the parallelogram easily, and it will shift up and down fine, but when I return to the small gear the chain is slack. I can manually move it back to position but the spring isn't strong enough to overcome the stiffness.

Hondo6

OP: out of curiosity,did you remove some sort of cover and/or knurled knob that fits over that spring? I ask because photos of all of the Suntour AR RDs on Velobase show one, held on by a screw. I'm not seeing one here.

79pmooney

To remove that spring - unscrew the set screw just behind the pivot. (Takes a JIS screwdriver which is a Phillips with the tip ground off. A Phillps may work or you may find another (square perhaps) bit that works. Or visegrips that will scar the chrome.) Once that set screw is off, remove the RD from the bike. Unwind the cage and spring. Undo the nut or threading of the pivot into the cage and remove the cage. Spring will just slide out. If you look inside, you will probably see a line of holes the spring can fit into, If so, you can fine tune your spring tension.

Once the spring is out, you can see and assess what is needed. Slide spring back in, lube generously, attach cage, rewind and go. (The set screw is not needed and it is often easier to replace after you put the RD back on the bike and use the chain to hold the arm. I never felt I was given enough hands to insert that screw with the RD on the work bench.

I haven't done this with an AR. SunTour made changes from model to model so my instructions are a little vague but they all come apart and roughly the same way.

Edit: (and kinda fun) - I rebuilt a Cyclone for a couple of decades, unscrewing the cages and replacing either cage or body as needed. I'd go to shops, look through their box of trashed Cyclones and pay $5 for a crashed one where the half I needed survived. Mine with many thousands of miles rode like brand new!

Second edit: I see the nut at the outboard end of the spring. Hold that with a wrench as you turn the cage to unscrew. (I could be wrong about this. I've never seen this before. The older SunTours had cast bodies with no access to the outboard end.)

louky

Hondo6: Yes, you are correct. Gray plastic knurled "bottle cap" held on by a phillips screw. I took them off, saw the spring, and called for help.

dedhed

https://www.disraeligears.co.uk/site...83_scan_3.html

Hondo6

That might help.

SurferRosa

Why not just remove the rear derailleur and overhaul it? Add fresh grease where necessary (wheel bearings, spring, and threads). Spray the riveted pivots with WD-40. It's very simple once you have it in your hand on a workbench and remove the grub screw in the middle of this photo:


.

louky

Success! I had two of these to do. I had a learning curve experience on the first one and the second one went like clockwork. The pivot pin (part 18 on the link that dedhed provided) was the issue. It wouldn't pivot at all. No rust, just a little gummy but enough to make it too stiff to work. Great tip about replacing the grub screw after the derailleur went back on the bike. I appreciate all the help. This is a great forum.

SurferRosa

Why would you do that after remounting the derailleur on the frame?

The grub screw is usually the first thing you remove when overhauling a rear derailleur on the workbench and the last thing you replace before returning the overhauled derailleur to the bike.