5:1 pocket bike gearbox, is it worth replacing the bearings?

Discussion in 'Transmission / Drivetrain' started by dchevygod, Apr 16, 2014.

  1. dchevygod

    dchevygod Member

    I have one on my current bike. I heard some odd noise coming from my bike off throttle today, I thought that the grease needed replenishment. I took the motor off to grease it and the bearing on the drum shaft is shot. I didn't open it up completely. I'm afraid of the carnage to behold! I noticed a bit of slop in the reduction gears so should I just get another one, or rebuild this one?

    I am thinking of changing my drive from axle mount to rack mount so I can use my Flowsystem tuned pipe for my ported G43L circa 2002. And if I do the 5:1 wouldn't be used unless I try a DIY shifter. I've thought about that and I don't think a motor driven cassette will shift properly " the pedal power would be on a LSD hub.

    Any thoughts or past experience would be appreciated!

  2. lowracer

    lowracer Member

    What bearings are used in the transmission?
    Should have an imprint on its side & then found for cheap on eBay.
    I got a new PB 5:1 tranny that has a bad noise to it and I'm thinking bearings as well, though its new.
    I haven't the time or need to take it apart yet to investigate.
  3. dchevygod

    dchevygod Member

    I haven't opened it up either. I seem to remember that they looked kinda dinky. But for $30 shipped, if the bearings are $5 a piece. I think pulling it apart and R&R the bearings is worth $10. Who knows how chewed up my reduction gears are.

    The noise your hearing is new gears. It will quiet down after some use, and change to a lighter grease in the gear box. Mine has done over 1,500 miles before this bearing failure. And I'm sure its because I'm over geared for these hills.
  4. dchevygod

    dchevygod Member

    I opened it up and the clutch shaft is what's worn!?!
    IMG_20140417_123918390_HDR.jpg IMG_20140417_123835683_HDR.jpg

    The bearing was kinda stiff but not siezed, I used some loctite green "bearing locker" on the shaft and re greased the gear box and bearings. The loctite needs to cure before I test out the fix. But I think it will be sufficient for now.
  5. dchevygod

    dchevygod Member

    That will just be a temporary fix because of the wear on both gears. I'll run it till it breaks or wears off teeth! And then install the new gearbox that will be gear oil filled, instead of grease.

    I'll take off the bearing seals on the inside of the box and see if the bearings run cooler in an oil bath, extending their life.

    The seals may leak a little if its over full or set on its side but we will see.
  6. lowracer

    lowracer Member

    While your in there, what bearing markings are on them?
    I'm being lazy...lol
  7. dchevygod

    dchevygod Member

    The larger ones I think were 6202rs. And the small ones were melted so your guess is as good as mine. I know that they're smaller than my 6001rs bearings, I keep a few of those on hand for my goped motors.