SunRace DT Shifter 7 Speed Remove Indexing
10-14-21, 05:04 PM
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SunRace DT Shifter 7 Speed Remove Indexing
Tuning up my latest Franken Build I had to remove the indexing from an old set of SunRace down tube shifters. The shifters were originally supposed to be compatible with Shimano 7 speed freewheels. I had used them on an old bike that had a SunTour 5 speed freewheel and they worked fine. After ending up in the parts bin for 10 years I tried to set them up for a 6 speed Shimano freewheel. The indexing just did not work. Either the indexing was off or maybe my freewheel was off cause besides the rear shifter being 12 years old I used a freewheel that was also a franken build. I restored a Shimano TZ30's worn gears from a new Shimano MF TZ31 7 speed. I could not find any real instructions on converting the SunRace rear shifter to pure friction so I opened it up.
I noted that there were two small ball bearings on one of the shims and assumed that gave the line distance and click when shifting.
Removing the ball bearings stopped the clickbut I also had to reverse the two shims that covered the ball bearings in order to get enough friction to hold the gear setting.
SunRace alloy down tube shifters go for about 20 USD. That's a real deal. If your indexing is not working with them just take out the little balls. Pure friction shifting is the real ticket. So far its working but remains to be proven. I'll post any failure.
I noted that there were two small ball bearings on one of the shims and assumed that gave the line distance and click when shifting.
Removing the ball bearings stopped the click
SunRace alloy down tube shifters go for about 20 USD. That's a real deal. If your indexing is not working with them just take out the little balls. Pure friction shifting is the real ticket. So far its working but remains to be proven. I'll post any failure.
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No matter where you're at... There you are... Δf:=f(1/2)-f(-1/2)Last edited by zandoval; 10-20-21 at 09:57 AM.
10-19-21, 07:03 PM
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UPDATE: OK... by removing the ball bearings I got rid of the click. The friction on the lever would not stay in place. So I twisted and tightened the "D" ring on the lever. Nothing happened no matter how hard I turned it. What I finally figured out is that the "D" ring and lever unit only deal with the click. Tighten the "D" ring and get a stiffer click. Loosen it and ya get a softer click. The friction on the lever itself is dependent on the plastic rings underneath the leaver and the Allen bolt holding it in place. So remember, friction is from the plastic rings and Allen bolt, not the "D" ring. I don't really adjust the friction on my levers when ridding so getting out an Allen key to tighten up a lever is no big deal. On my set up I needed a 19mm ID 24mm outer daimeter ring about 1mm thick. I found several in my junk washer jars. Try a 19mm ID copper crush washer, a washer made out of milk jug plastic, left over parts from other old shifters, piece of fishing string wound around the Post and other things. I just dusted off my Ender and printed one off. Its 24mm OD x 19mm ID x 1mm. I don't know how long PLA will work but it fit and works perfectly so far. I will put the .stl on Thingyverse if anyone wants it. OK... Off to ride...
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10-20-21, 11:41 AM
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I’m glad you got it to work. Sunrace DT index shifters are probably the worst shifters I have ever encountered. I have a set in a bin just to remind me to never entertain the thought of buying another set.
I don’t have a good recommendation for new inexpensive DT friction shifters. It is unfortunate that they have become difficult and somewhat expensive to find online. Suntour Cyclone, which were an old standby, are getting so much these days. And Simplex Retrofriction are gold. In the late 80’s I bought a new pair for $5. Looking back I should have bought the whole bin.
My only recommendation for somewhat reasonable exceptional old friction DT shifters are Shimano’s L-422. You’ll need to file the stop and add a lever stop washer to go from stem to downtube installation. But they are spring loaded, to offset the derailleur spring, and have a micro ratchet, that can be removed. I call them a poor man’s Retrofriction shifter.
John
I don’t have a good recommendation for new inexpensive DT friction shifters. It is unfortunate that they have become difficult and somewhat expensive to find online. Suntour Cyclone, which were an old standby, are getting so much these days. And Simplex Retrofriction are gold. In the late 80’s I bought a new pair for $5. Looking back I should have bought the whole bin.
My only recommendation for somewhat reasonable exceptional old friction DT shifters are Shimano’s L-422. You’ll need to file the stop and add a lever stop washer to go from stem to downtube installation. But they are spring loaded, to offset the derailleur spring, and have a micro ratchet, that can be removed. I call them a poor man’s Retrofriction shifter.
John
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