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Suntour Barcon Power Control Servicing

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Suntour Barcon Power Control Servicing

Old 09-06-18, 11:16 AM
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Adamwsanders
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Suntour Barcon Power Control Servicing

Hey all - first post. I need to take apart a Suntour Bar-con Power Control left (front derailleur) shifter bought off ebay. It is the SunTour SL-BC00 Bar Con and velobase has images if you do a quick google ( I can't post links yet per forum rules)

The left shifter has the ratcheting mechanism but is slipping (unratcheting) under tension. It may just be worn down and old, but I'd like to take the unit apart for a closer look but this is proving difficult. The d-ring screw does not come out of the "paddle" half. If you look at the third image on the velobase item page, d-rings side, the power control unit does have a GRAY TRAPEZOID piece that can rotate out of it's place and you can see a spring underneath. That is the closest I've come to disassembling the unit.

Looked everywhere for a diagram or instructions, and including this forum I've only found diagrams of similar barcon models, or the stem-style suntour shifters.
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Old 09-06-18, 02:28 PM
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Pretty sure someone has a line on a schematic. If you have the right side, the parts and order of assembly should be analagous.
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Old 09-06-18, 07:43 PM
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Here ya go. Right and left levers are identical:

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Old 09-06-18, 09:48 PM
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Jeff Wills
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Here's a bigger version. If the shifter is slipping under tension, all you need to do is tighten the center screw (#14) a smidge. Note that the other end has a nut (#15) and a locknut ((#16). Loosen the locknut, tighten the screw enough to eliminate the slippage, then tighten the locknut.

I wouldn't be surprised if the locknut is missing. Back when I was working in a shop this part was often lost- we had a bunch sitting around to replace them.

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Old 09-07-18, 05:47 AM
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I think the OP has the later Accushift version as the ones posted donít use D-rings. I am not sure how the innards compare with the original version.
Can we assume you have tightened the D-ring but canít get enough friction in the shifter to hold position? Are you running them in friction mode?
(edit) I forgot it was the left shifter. I believe that is always friction.

Last edited by due ruote; 09-07-18 at 06:18 AM.
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Old 09-09-18, 10:38 PM
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Jeff Wills
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Originally Posted by due ruote View Post
I think the OP has the later Accushift version as the ones posted donít use D-rings. I am not sure how the innards compare with the original version.
Can we assume you have tightened the D-ring but canít get enough friction in the shifter to hold position? Are you running them in friction mode?
(edit) I forgot it was the left shifter. I believe that is always friction.
Hmmm... I believe you are correct.

Adam, do your shifters look the ones pictured here?
VeloBase.com - Component: SunTour SL-BC00 Bar Con (SL-BC01-R6 / SL-BC01-L)
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Old 09-10-18, 03:08 AM
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Originally Posted by Adamwsanders View Post
The left shifter has the ratcheting mechanism but is slipping (unratcheting) under tension.
Is the shifter slipping from insufficient friction on the friction plate, or is the ratchet mechanism itself slipping from losing engagement with the pawls?
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Old 09-10-18, 09:17 AM
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Follow up - Yes, the ratcheting itself was slipping once friction on the D-ring was dialed in enough to hold the gear change.

The diagrams everyone posts for Suntour Barcons (as were posted in this thread) do not apply to the units I have. They are indeed the velobase link Jeff Willis posted.

The main screw on the shifter was being held in place by a tight fitting washer - a few hammers later and I had the unit disassembled. From there, I could see a bit of wear on the knurling of the ratchet and the engaging piece (looks like a tiny staircase), both made of plastic. I reconditioned their geometry with an X-acto and some jeweler's files I had around. I also reinforced the spring by well, jamming some plastic behind it so it had more force. It now seems like the unit holds gear, not thoroughly tested however.

I hope this helps anyone with the same problem. Buyer beware on these units. If the ratchet and engaging piece were both made of metal, I'd feel a LOT better.

Last edited by Adamwsanders; 09-11-18 at 09:29 AM.
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