Gartenmeister

Clearly this is not working properly, but I don't understand the inner workings of it enough to diagnose its malady. Spring tension seems to be pushing the body rearwards, but the cage seems to be under no tension at all. It moves in and out (shifts) more or less properly, but is messed up in the chain tension department. Any ideas? Is it dead?

ramzilla

Sorry but, looks like one of the main springs broke. Too bad. I've got no idea how to fix it. Probably a real PITA to find a replacement part & repair. You should move this over to the Mechanics Forum. Good luck. Be good.

Bad Lag

Could it be that it's not so much a broken spring but that someone took it apart and did not know how to re-tension the springs during reassembly?

Perhaps the spring(s) just need to be tensioned to provide adequate chain tension.

That could be a nice derailleur if you can get it working.

brian3069

Is the stop screw missing? Remove the chain from the derailleur and and rotate the cage counterclockwise 360 degrees. That should wind the spring up if it's not broken.

eschlwc

i'm not familiar with da rd's. here are the questions i would ask.

1. does the rd have a dropout arm spring that surrounds the hanger bolt? campy record and suntour cyclone don't have these, and those derailleurs swing freely in the dropout. simplex and s600 do have them, and these springs need to be working for the rd to function properly.

2. or is the problem solely with cage tension? if so, can the stop pin in the cage be removed with a screwdriver to allow you to easily overhaul this part of the derailleur? the stop pin in my s600 derailleurs can't be removed, making an overhaul very difficult, but not impossible. campy and suntour have removable stop pins. if the stop pin can be removed, do so. then carefully unwind the cage before removing the cage from the derailleur for overhaul.

Gartenmeister

This worked. Thanks so much!! Thank you to the others who replied as well.

So where would the stop screw be? There does seem to be a screw missing, and the unit was a real handful after I got it wound up.

Missing screw hole:

Grand Bois

That screw keeps it from unwinding when you take off the derailleur. It's not needed if you leave it on the bike.

JohnDThompson 

Yes, that's where the stop bolt goes. I suspect you could use an M3 x 0.5mm set bolt from the hardware store to replace it, or salvage from another old Shimano derailleur in your LBS's scrap bin. Grand Bois notes that it isn't strictly needed unless you remove it from the bike, but it does make it easier even for mundane tasks like removing the wheel to fix a flat. The stop bolt on my Crane derailleur has a short tube covering it, but I doubt that is strictly needed either.

dddd

If that is a 3mm bolt, then the short sleeve greatly stabilizes the bolt/screw as well as holding the screw head at the most correct height/length.

cyclotoine

I bet a newer style shimano bolt that is one piece as seen on derailleurs right through the 1990s would work. I know I even have lots kicking around but think shipping from northern canada would be silly. If you have a nice lbs I'd stop buy and ask if they has a scrap metal bin and see if you can source one there.

JohnDThompson 

Yes, it does do that, but it's only an issue if/when the chain is off. Campagnolo, for example, doesn't bother with it on the stop bolts found on Nuovo and Super Record derailleurs. Perhaps some stand-offs such as those found on electronic circuit boards might work?