Warped Chinese Sprocket!

Discussion in 'Motorized Bicycle General Discussion' started by Retmachinist, Mar 18, 2009.

  1. Retmachinist

    Retmachinist New Member

    Joined:
    Oct 21, 2008
    Messages:
    637
    Likes Received:
    0
    I was getting some parts ready for another build and decided to stick this sprocket in the lathe and check it out. Some of these Chinese sprockets are terrible. This particular one ran out over .080. It just happened to come frome Zone 8. It's no wonder people have trouble trying to true up the rear sprocket coupling. It's hopeless with a sprocket like this. Lucky I had a couple spares I had purchased from Duane at Thatsdax that ran very true. Thanks Duane!

    John
     

    Attached Files:

  2. ...ladies

    ...ladies New Member

    Joined:
    Jan 27, 2009
    Messages:
    130
    Likes Received:
    0
    I'm having trouble trueing -sp- one of mine.. i hope this isn't the case..
     
  3. Pablo

    Pablo Master Bike Builder & Forum Sponsor

    Joined:
    Dec 28, 2007
    Messages:
    3,658
    Likes Received:
    5
    Nothing a BFH won't fix!

    Maybe check out Andyfrominchville.
     
  4. ibcnya

    ibcnya New Member

    Joined:
    Oct 29, 2008
    Messages:
    220
    Likes Received:
    0
    I have a stock 44T I can ship you...pm me with offer. Andyinchville is a great guy to deal with. i love my 36T.
     
  5. Creative Engineering

    Joined:
    Sep 20, 2008
    Messages:
    1,668
    Likes Received:
    1
    John, Are we having fun yet? laff

    I did the same thing, meaning I bought kits from many different suppliers to see what I was going to be up against as far as making replacement parts. Dimensionally they are all over the Granite and back again.

    Dax, Spookytooth, King up in Canada, and bike-to-moped in Kalamazoo MI, offer the best kits, the best service, and as an added bonus they speak English! Any of these guys can get bad parts from time-to-time, but at least the above mentioned will quickly take care of any manufacturing flaws.

    The rest are scrap peddlers.

    Jim
     
    #5 Creative Engineering, Mar 18, 2009
    Last edited: Mar 18, 2009
  6. Retmachinist

    Retmachinist New Member

    Joined:
    Oct 21, 2008
    Messages:
    637
    Likes Received:
    0
    Hey Jim, This sprocket was the weirdest one yet. That .080 came over a span of only 10 teeth, and the rest ran fairly true. I have been going back and forth between the lathe and the hydraulic press tweeking it a little at a time. I don't think it is worth it. Something is really CHINESE about this one. It may be heading to the scrap pile. I should send it back to the scrap peddler it came from.
    I enjoy working on these things, but some of this is rediculous!

    John
     
  7. Creative Engineering

    Joined:
    Sep 20, 2008
    Messages:
    1,668
    Likes Received:
    1
    John,

    The .080" deflection over a span of 10 teeth, was probably created during the stamping process of the sprocket. The die was not set right and that area became forged under the pressure of the stamping process. A trip to your favorite shop that has both a Rockwell "C" scale tester and a Brinell tester will prove this out. I'm willing to bet that the area that is warped is also tough as spring steel due to the die off-set.

    Jim
     
  8. Retmachinist

    Retmachinist New Member

    Joined:
    Oct 21, 2008
    Messages:
    637
    Likes Received:
    0
    I was wondering why it was all in that short span. I usually like to take these cheap sprockets, and drill a hole pattern in them then paint them so they look a little better. This one isn't worth it. The flat stamped ones are pretty easy to straighten if they are out a little.

    John
     
  9. toker_ace

    toker_ace Member

    Joined:
    Oct 15, 2008
    Messages:
    475
    Likes Received:
    1
    All I know is "Don't piss these people off if your a dealer!"Cause if you do "you've had it! LOL! You guys are harsh! laff
     
  10. HoughMade

    HoughMade New Member

    Joined:
    Apr 15, 2008
    Messages:
    624
    Likes Received:
    1
    I discovered a warp in my sprocket when I was mounting it last year. No fancy dial guages for me. A straight edge, a pry bar, a bench vise and some patience- and I got it true.

    There are generally low priced answers to most of these questions if we take some time...now ask me about my $100+ turn signals
     
  11. Bikeguy Joe

    Bikeguy Joe Godfather of Motorized Bicycles

    Joined:
    Jan 8, 2008
    Messages:
    11,529
    Likes Received:
    4
    I used a hammer on a couple of mine...both came from different vendors.
     
  12. Retmachinist

    Retmachinist New Member

    Joined:
    Oct 21, 2008
    Messages:
    637
    Likes Received:
    0
    I guess with the machinist mentality, I get into splitting frog hairs a little to often. The main reason I try to get this stuff as precision as possible is for safety reasons. I don't really want the chain coming off at 35 m.p.h.
    By the way I finally got the thing running true, still ordered a couple more good ones from Duane to have in stock.

    John
     

Share This Page