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Mid 1970s Shimano 600 RD Problems

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Mid 1970s Shimano 600 RD Problems

Old 12-04-17, 01:11 PM
  #1  
abshipp 
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Mid 1970s Shimano 600 RD Problems

I have been having a bit of a problem with the rear derailleur on my 1977 Super Le Tour 12.2.

When in the big ring, I cannot shift into the smallest cog on the 5spd freewheel. I can, however, shift into this cog when in the small ring.

This derailleur does not have a B-limit adjustment screw.

When in the big ring and I try to shift into the small cog on when the bike is on a repair stand, I can get the chain to shift into the smallest cog if I rotate the derailleur in the same way a B-limit screw would rotate the derailleur. It seems that the spring in the derailleur does not have enough tension to keep the upper jockey wheel close enough to the cogs when in the big ring. Again, in the small ring, there are no shifting issues.

Any suggestions on what I can do to help it along? I disassembled the derailleur, and there is only one position available for the spring to locate, so it looks like I am stuck with this spring tension. I took the opportunity to clean and lube this particular area, but have not overhauled all pivot locations.

H and L limit screws are adjusted appropriately, the chain is the correct length, and the chain is in good shape. I tried with two different chains with the same result.

I'm thinking I may have to replace the derailleur, but I figure I would throw the question out on here before I start spending money.
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Old 12-04-17, 02:17 PM
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Iride01
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How 'bout your front DR? Is the chain rubbing on the right side of that cage when trying to go to the small rear? If so, then see if you can adjust the limit on it to let the chain drop into the small without causing your chain to drop off the front.
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Old 12-04-17, 03:28 PM
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If the chain really is the correct length, then I would suggest you first check the derailleur hanger alignment (if separate from derailleur). If OK then yes, replace the derailleur.
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Old 12-04-17, 04:16 PM
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Originally Posted by Iride01 View Post
How 'bout your front DR? Is the chain rubbing on the right side of that cage when trying to go to the small rear? If so, then see if you can adjust the limit on it to let the chain drop into the small without causing your chain to drop off the front.
Nope, no rubbing on the FD.

Originally Posted by cny-bikeman View Post
If the chain really is the correct length, then I would suggest you first check the derailleur hanger alignment (if separate from derailleur). If OK then yes, replace the derailleur.
I can take a quick look at it. The frame is from 1977, so it does have an integrated derailleur hanger.

Thanks!
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