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Vintage derailleur out of tension - Shimano Gt-400

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Vintage derailleur out of tension - Shimano Gt-400

Old 08-01-16, 10:18 AM
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Austj42
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Vintage derailleur out of tension - Shimano Gt-400

I have a Shimano GT-400 derailleur off a Schwinn Le Tour that`s out of tension and I wasn't sure if there was a fix for this or if I just need to get a new derailleur. I`ve had the derailleur apart a few times trying to figure out how it would be retensioned and I haven`t had any luck with it, any help?Thanks
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Old 08-01-16, 10:22 AM
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corrado33
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Pictures would help to diagnose the problem. My guess is a spring slipped it's mounting location and is spun around the wrong way. It happened to me when I broke my hanger by making my chain too short. Wasn't too hard to fix. But again, we can't know until you show us what you mean.
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Old 08-01-16, 10:31 AM
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I can get some pictures later and put them up. When I took it apart and put it back together, the spring ends were their mounting locations, both inside the barrel and where it connects to the pulley cage
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Old 08-01-16, 10:37 AM
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Originally Posted by Austj42 View Post
I can get some pictures later and put them up. When I took it apart and put it back together, the spring ends were their mounting locations, both inside the barrel and where it connects to the pulley cage
Sometimes the springs have to be pre-tensioned when assembled (Or the derailleur has to be assembled while twisted). That's what holds the tension against the chain.
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Old 08-01-16, 10:45 AM
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I was figuring it had to be something like that because I put it back together the same way it was when I disassembled it, so I guess I`m just gonna have to get another one?
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Old 08-01-16, 10:47 AM
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Originally Posted by Austj42 View Post
I was figuring it had to be something like that because I put it back together the same way it was when I disassembled it, so I guess I`m just gonna have to get another one?
Not at all, you just have to figure out how to put the spring in the correct way when you're assembling it. It can only go a couple of ways. It took me a few minutes to figure it out on my modern derailleur.
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Old 08-01-16, 11:03 AM
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okay I`ll take a look at it tonight and see if I can figure it out
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Old 07-31-18, 01:05 PM
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Did you ever resolve this? It seems that I, too, have a problem with spring tension on my 1974 Schwinn Le Tour GT-400 derailleur.
There are two springs:
one near the hub for what I'll call the "inner arm" and
one near the outer (lower) pulley for what I'll call the "outer arm."
(I tried to post an image but this forum won't let me as I don't have enough points or something).

Anyway, the spring on the inner arm is the weak one.
With the chain off, it seems to work fine.
But, with the chain on, the more powerful outer arm spring comes into play and counteracts the force of the inner arm spring.
The inner arm then does not open all the way as it should.
I can push it back and forth. It seems almost at equilibrium. It will stay wherever I put it instead of always opening as it should.

I disassembled the derailleur, cleaned it up, relubricated it and reassembled it to no avail.
It just seems that the inner spring is weak.
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Old 07-31-18, 02:09 PM
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If there is a co-op in your area, find a nice used Suntour model from that era. I really like the Suntour Vx rear derailleurs, can still find them used at a reasonable (low) cost.
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