skoolieman

Hi I have been following along for a while but this is my first post. I bought an '85 Schwinn High Sierra off an elderly gentleman a few weeks ago that he has had since new. The Suntour Mountech RD was feeling gritty-which is apparently a common design flaw with this RD. Anyway, I took it apart to clean it and in the process found that the spring inside the upper pulley (see the red arrow) is broken.



I am assuming that I broke it somehow because it worked fine before I messed with it and now the chain has too much slack after reassembly. My question is would I be able to find/replace just this spring or am I better off just getting a new RD?

(Thank you to bluesdaddy for the exploded photo)

HillRider

Except to maintain period "correctness" (see the C&V forum) it would be both easier and possibly cheaper to replace the derailleur with a modern one.

bikeman715

You be better off at this point to get a new derailleur , but if there a old bike shop in town , you might be able to go thou their use part bin and come up with another Suntour derailleur than you can use parts from . When you put the derailleur back together did you wind the cage to put tension back on the chain . maybe this will help , Park Tool Co. » ParkTool Blog » Rear Derailleur Overhaul . Look at step 16 , I know it not your derailleur in the photo but it give you the idea I am talking about when it come to wind the cage .

0.2HP

Can anyone give me any pointers on disassembling a Suntour MountainTech rear derailer, to clean/re-pack the upper pulley and the spring inside? Or point me to a web page with instructions? The internet tells me this is pretty difficult.


Thanks in advance for any assistance.


(Back-story: I got a free '85 Schwinn Le Tour Luxe this weekend, with MountainTech derailers. Mine works fine on the big and middle chain rings (50 and 46 teeth), but leaves way too much chain slack on the 30 tooth granny ring. An internet search revels the spring-in-the-upper pulley is a fatal design flaw on this derailer; dirt/water gets in the and gunks up the spring until it breaks under load. Since mine sort-of works, I'm hoping the spring has not broken yet and I can fix it by cleaning.)

bikeman715

If you read my earlier post (3) , you would had notice I already did . Hit the link and it take you to the info .you looking for .