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Luna Gates Belt Drive slipping, a full write-up.

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    Luna Gates Belt Drive slipping, a full write-up.

    The purpose of this thread is not to denigrate Luna, or their belt drive. This thread is so that we can provide feedback to Luna's engineers, and hopefully help other people who have this issue.

    To start, a short description of my riding style. I ride 80/10/10 pavement, gravel road, dirt singletrack. The bike is used for a commuter vehicle, as well as a hobby bike. I ride hard, and fast, but do not jump the bike, do wheelies, or otherwise perform stunts of any kind.

    After only 5 miles, the belt drive began to squeak. Now, this is something that can be expected to some degree with any belt drive system but was nevertheless disappointing considering the main draw of the belt is a stealthier ride. The squeak began to worsen by the day, driving me insane little by little. The belt was visually aligned, but the side of the belt did have a tendency to hug the right side of the front pulley, which I suspect was the cause of the squeak. One afternoon, while on a ride, I noticed the belt had become very loose. A light press of the belt caused it to bend about an inch. I rode home, and tightened the belt to an app-measured 100Hz, and double-checked tension using a belt tension gauge. An afternoon ride ended early when I accelerated into a turn, resulting in a loud CLACK CLACK CLACK. Puzzled, I tried to recreate the noise, and every time I accelerated hard, CLACK CLACK CLACK. Out of caution, I ended my ride and headed home. Once home I inspected the bike more thoroughly. I noticed the teeth of the belt had signs of damage. 4 consecutive teeth were split right down the middle, not good. I rode the bike the next day, taking it easy around the neighborhood. At first, the belt would only slip when I applied heavy throttle. After only a couple laps around the neighborhood, the issue had gotten so bad that I could barely make it home. The belt was all but destroyed. A row of many consecutive teeth had been completely ripped off, and many other teeth had been severely damaged. The bike was officially a paper-weight. I have contacted Luna about this issue, and they have thus far been helpful, though we are pending a resolution. I am reserving all judgement of their customer service until the end of this fiasco. Luna has agreed to ship me the stock chain and sprocket so that if this happens again, I will have a back-up. This is, after all, my commuter vehicle. Today, I disassembled the bike in anticipation of my new belt replacement arriving tomorrow afternoon. Once disassembled, the damage to the front pulley became more evident. There were two rows of perfectly uniform holes on either side of the pulley's teeth. I am at an absolute loss as far as what could have caused this. I wonder if this contributed to the failure of the belt, or resulted from it.

    Hopefully, the community of Sur Ron owners will shed some light on what may have happened. Again, I am not attempting to criticize the belt system, or Luna Cycles, only to get some answers. Has anybody seen anything like this before? I have worked with various belts in the past, and have never run into this. Thanks guys!

    A video of the issue.
    https://streamable.com/j0nc7m

    #2
    Any update on this issue or the resolution? I have my bike with a belt coming in with the next shipment and concerned that I should have stuck with a chain.

    Comment


      #3
      The only holes I see are the pulley's vents, they help to keep air & debris from being trapped between the belt & pulley. It is also said that they help cool & quiet the system.

      Comment


        #4
        Having the same issue on my Sur-Ron. The front pully's splines are worn down until they are sharp like yours. Did you go back to the chain drive, or did you get a new front pully for the Gates belt?
        Last edited by RLP65202; 04-28-2021, 06:34 AM.

        Comment


        • Kauaiguy
          Kauaiguy commented
          Editing a comment
          Aluminum isn’t up to the task for a cog/ belt sprocket,I think it’s better to go chain.

        #5
        I wonder if it's a heat treatment issue. 6061 T6 Aluminum starts off as softer 6061 T4 and is heat treated to the harder T6 state. Maybe somebody skipped a step?
        Then there's the matter of hard anodizing which converts the outer layer of Aluminum to a very hard wear resistant Aluminum oxide surface. This can be clear or colored.
        Last edited by Retrorockit; 04-29-2021, 10:48 AM.

        Comment


        • Kauaiguy
          Kauaiguy commented
          Editing a comment
          It needs to be steel,aluminum even hardened will wear rapidly with dirt on the belt grinding away all day.

        #6
        I'm also curious if this issue was taken care of. I installed the belt kit about 2 weeks ago. I'm really enjoying how quiet it is. Luna should, at the very least, sell replacement front pulleys.

        Other than that, they should make the front pulley from a stronger material and update all the kits moving forward.

        Comment


          #7
          One solution would be to spray weld a layer of steel onto an Aluminum pulley for a harder wearing surface. Maybe stainless steel?
          Engine bores are made of high Silicon Aluminum, then etched with chemicals to leave a hard wearing Silicon surface behind.
          I'm wondering if the belt was too tight. Unlike Vee belts these don't rely on friction to work. They need very little tension to operate.
          Last edited by Retrorockit; 05-03-2021, 05:17 AM.

          Comment


            #8
            I just ordered my 2nd Surron and got the gates belt. I REALLY wish I hadn't. I'm getting the knocking noise and I've loosened and tightened both belts and it never goes away. It gets a little better, but honestly it is more annoying and loud than just using the chain.

            My advice to anyone thinking about it is to skip it.

            Luna says the noise will go away after 100 miles. Can anyone confirm this that has had this problem? I'm a little concerned about that response.

            Comment


              #9
              I think the excessive wear is from a tight belt and debris. I think this is one of those areas where it's a good idea to check before every ride. 11,000 HP dragsters have aluminum blower pulleys and are over driven for more RPMs, so I don't think aluminum is a bad choice for materials, even though I really like the hard anodize idea. I also like the 219 chain idea that Luna puts out.

              Comment


                #10
                Don't know why the issue was just on that particular Sur-Ron (my brother's). Mine and my other buddies are working fine (front pulleys look good)...

                Comment


                  #11
                  Does anyone know the factory-recommended belt tension for the primary drive belt?

                  Belt tension is pretty critical and it's easy to set with the Gates app. But what to set it to? I've seen a few people use 100 Hz but whenever I use the "PowerGrip Tension Calculator" on the Gates website it gives me numbers closer to 300 Hz.

                  Luna have said 100 Hz but that's for the secondary belt conversion, which is a much longer belt.

                  (And I've seen way too many people on the internet just winging it and wondering why their belt broke.)

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