1991 Trek 6000 - shifting problem

[HerrOtto]

Hello, I just purchased a 1991 Trek 6000 with Suntour Xpress accushifters and Suntour XC LTD derailleurs. I am having a hell of a time dialing in the rear derailleur. The problem is, after tightening the derailleur cable, I can get it to shift from 7th to 1st by tightening the barrel adjuster quite a bit, but it wont shift from 1st to 7th w/o me loosening the barrel adjuster quite a bit. There is no happy median. The limit screws are set correctly and the hanger is aligned and visually the derailleur appears in good shape. The shifter cable was replaced. The shifters were gummed up but I was able to free them up and it is indexing correctly. If the problem is the shifter, what shifter should I use as a replacement, as I believe it has to be Suntour compatable? Any suggestions are appreciated. Thank you

 

[J-wagon]

Hmmm....possibly cable sticking inside housing. If so, new housing. Alternatively pull cable from housing and apply thin oil, like gun oil, droplets at one end and gravity lube down the cable.

 

[J-wagon]

Note: since you can shift into lowest gear (large cog) and the high gear (small cog) means the limit range and shifters are fine. Likely cable to housing interface issue with stickiness gummy damage inside segment disturbing cable tension.

 

[HerrOtto]

Thank you for those suggestions, unfortunately, I have lubed the cable and made sure the outer cable housing was not impeding the cable movement.

 

[HerrOtto]

I just replaced the outer cables and re-lubed the cable. Still no success.

 

[fattyre]

A Weak spring in the derailleur?

I seem to remember some of that 90’s Suntour stuff running pretty low tension springs for lower effort at the shifter.

 

[HerrOtto]

I went to a local bike guy who doesn't have an official bike shop but he buys, sells and repairs bikes. After checking the bike out, he recommended replacing the shifters. I purchased Shimano thumb shifters from him, replaced them at home and the problem is actually worse with the new shifter. I am not sure if the Shimano shifter is compatible with the Suntour derailleur. At any rate, I guess the only thing left is the rear derailleur.

 

[HerrOtto]

Before I replaced the shifters to Shimano, all the bikes components were Suntour. Suntour Xpress Accushift Plus shifters, Suntour XC LTD derailleurs and Suntour AP freewheel.

 

[J-wagon]

Based on description of situation, sounds like prior setup achieved chain shift into lowest and highest gear albeit with barrel tension adjustment. So og shifter and derailleur functioning and capable of achieving. Seems still a tension issue. I would shift to smallest rear cog, loosen the cable at rear derailleur, screw in both barrels at shifter and rear derailleur (clockwise turning), reattach cable at firm tautness, then see how it goes. Fine tune tension with barrels.

 

[J-wagon]

Side note: I have suntour accushifter mated to Shimano rear derailleur and no issues.