Discussion in 'General Questions' started by battery, Nov 4, 2014.

  1. battery

    battery Member

    Would it be possible to make a hardened 5/8 shaft? I have problems with swelling and bending of the shaft. mainly due to jamming of parts like the chain binding in the engine case. (problem should be solved with the left side tensioner) Also both the left and right side chain tensioners came with some wrong size nuts for the bolts. I'll get the right ones Just fyi. also you may consider a extra hole in the left side chain tensioner or to make the tensioner bar shorter to better center the tensioner wheel on the chain. with the half link I could not find a way to tension the chain without the 21T gear and the tensioner idler wheel touching. possibly the tensioner is not meant for the 21T? but designed for the 17T? I am gearing my bike down for off road only.

  2. darwin

    darwin Well-Known Member

    Ask Pablo at SBP's ad on the left side of the page.
  3. Ghost0

    Ghost0 New Member

    Battery, thanks for the input. We always like feedback. I have a hard time understanding how one could bend a 5/8 steel shaft. No one to my knowledge in the thousands of kits we sold have ever bent a shaft. The amount of force required to bend that much steel is far beyond anything that a 2, 3, 4 or 5 horse motor can put out.

    Now on the hardware, sorry if some of the hardware was incorrect but also be aware that at times we use say a 6 mm nut as a spacer on a 5 mm bolt. So it is meant to be too large and slide over the threads. Can you be specific about what was not correct so we can look into it. We have a 3rd party kit our hardware so the possibility does exist for an error.

    You may have a point on better centering the tensioner arm, I designed it with the 17 as we hadn't released the 21 yet. Adding a second hole to shorten it for he 21 makes some sense. I will look into that.
  4. battery

    battery Member

    Thank you ghost! I may have used the spacers and lock nuts in the wrong place. I will still just buy new nuts as I don't care to take anything apart. The 5/8" shaft possibly bent in the past due to chain slack and binding in the engine case. But it does swell extremely easily if I tap it with a hammer in any way. Making it very difficult to remove the sprockets. I feel if it were to be hardened it would do away with this issue. For the price I do not mind replacing it every now and then. But I would pay double not too struggle removing sprockets. In another note. I must use three large washers and of course a small washer to space my right side 10T to match up with my 44T free wheel gear I have the extended crank that came with the sbp shift kit. Which leaves little room for the 5/8 shaft to sit in the bearing in the left side tensioner. It works fine I share the lack of space. And p.s. I love the left side tensioner!!! And the new 21T & 44T now I can peddle with the engine in proper proportion :)
  5. Fabian

    Fabian Well-Known Member

    I find it impossible to believe that even a mild steel 5/8 shaft can bend from engine power alone. The only way that the shaft could potentially bend is if the centre-to-centre distance between 5/8 shaft and the engine output shaft is too great, thereby having the left hand side chain being far too tight. Even if that were to be the case, you wouldn't be able to attach the master link onto the left hand side chain.

    The OP is clearly doing something wrong.
    Secondly, when installing the left hand side chain tensioner, the extra bearing on the left hand side effectively halves the bearing load and doubles the bearing surface area on the shaft.

    My experience with the left hand side chain tensioner has shown it to dramatically increase the life of the shaft, with almost 4,000 kilometers (2,500 miles) on the thing with virtually no wear. That is a huge improvement over the system without a left hand side chain tensioner because the shaft had a wear grove of 1/16" after 6,000 kilometers (3,500 miles).

    Maybe the OP needs to watch these videos:

    Last edited by a moderator: Dec 15, 2015