need Suntour Cyclone repair advice
 

I have a nice late 70s rear Cyclone GT derailleur that I'd like to put on a 83 Takara, but the pulley wheels are a little chewed up. I have a donor ARX that I can take wheels from, but I'm hesitant to take apart the Cyclone for fear I won't be able to get it back together properly. It looks a lot more complicated than the ARX. How hard is the Cyclone to disassemble and reassemble, and where might I get instructions? My wrenching skills extend to tune ups and overhauls of bearing races, and that's about it.

Should be relatively easily to replace the pulley wheels if you have basic tools.

Check this out and tell us which yours is, the long (GT) or short cage.

http://www.yellowjersey.org/cyclone.html

he says it's a GT so long cage.
Super easy to take off the bottom pulley, especially easy to put back with the help of that nice exploded diagram^, the only trick is the nut for the jockey pulley: I've used needle-nose pliers but you might have to improvise something. Don't be tempted to remove the stop pin (22) cause you don't want to have to guess at the tension if the cage unwinds!
Good opportunity to clean everything up and don't forget a little lube in the sleeve bearings and under the dust caps.
Good luck!

+10 Easy/peasy job!

Whoops, didn't read the GT part. I thought that removing the stop pin (22 on the diagram) and unwinding the cage was necessary on the GT since the crown nut (20) has to come out anyway to release the pulley wheel. You might have trouble getting 23 off without the tool in the picture but I have done it with a pair of needlenose pliers.

I have the GT long cage. How do I get it apart, and do I have to worry about messing up the adjustment of the tension screw?

Unworthy can correct me because it is a pain getting the tension right after unwinding, but this is how I do it:

1. Unscrew 23 with needlenose pliers. Make sure you can get this out first because you don't want to take apart everything and not be able to remove this.
2. Hold the cage and unscrew 22. Feel the tension and after you unscrew it, count how many times it turns around to where there is no tension.
3. Remove 18
4. Remove 19. There should be 3 holes in the body that the end of the spring goes into, remember which hole it is in.
5. Remove the main body of the derailleur from the cage. You should have the cage with 20 still on it.
6. Unscrew 20. A long flathead is the easiest way for me to do it.
7. You should be able to remove the pulley wheel now and you can put in a replacement. Remember to put in 15 and 16 on the new wheel.
8. Clean everything that you can and put a little lube inside the main cylinder.
9. Screw back in 20.
10. Replace 19 in the same hole and screw on 18.
11. This is the part where people with more expertise can chime in because you need to rewind the cage to the previous tension or if the original tension was low either put 19 into a different hole or wind up the spring more. Also by lubing and cleaning the spring, that can change the tension if there was a lot of muck in there.
12. Holding the cage in place, rescrew 22. This will be hard with just two hands.

Use only oil on the oilite pulley bushings. Grease clogs their pores.

30 weight?

take it all apart and take (or draw) notes while you do it. then lube it all up and reassemble. the worst that can happen is you have to send it to one of us to put it back together for you.

helluva post (7), folkform.

edit: it's extremely helpful to have a magnetic screwdriver when replacing the stop screw. i sometimes will spend countless minutes trying desperately to tension the cage with one hand while holding the wrong screwdriver with a propped screw on its tip with the other. it's also nice to have a vice to help with this task as well.

This

No I think you are right: you will have to unscrew the cage to remove the jockey pulley (it's been so long since I've done this job that I forgot) so just follow folkform's steps and try to keep all the rest of the pivot bolt/spring in place and tensioned so you just have to re-install the cage, the back nut and the stop-pin when ready. It might help to have a helper to hold things while you work (quickly) on the pulley nut and stop-pin. The tension (bottom) pulley WILL be easy-peasy, and so would the entire job if it was a short-cage Cyclone!

I need to pull out one of my Cyclone GTs, just sold a couple of them.