Brakes Coaster Brake Malfunction

Discussion in 'Bicycle Repair' started by Bean Oil, Dec 13, 2007.

  1. Bean Oil

    Bean Oil Guest

    I've seen all kinds of abuse inflicted upon coaster brakes in my day... racing downhill, slamming them on to slide the rear tire, etc... all on regular bicycles and not once have I seen one really "give up" or break.

    I bought a "heavy duty" cruiser wheel from the lbc; I bought it for it's 12 ga spokes and to put the wheel on my frame-mount motored bike.

    Before I ran the motor chain, I tested the normal bicycle function of the wheel so that the motor install would go smoothly with no surprises, but even then the brake seemed sensitive or a little too eager to stop the bike... I thought it would smooth out as the brake worn in.

    It didn't; the first gentle stop from 15 MPH tossed my feet off of the pedals... and then there was play in the rear hub's bearing adjustment... I limped the bike home and disassembled the rear hub to find that the bearings were gorgeous, clean and brand new (they were), but the brake arm had literally spun on it's flat (the left side bearing race and brake shoe anchor). This race/anchor is also galled onto the threaded alxle; I can only spin it through three turns in either direction... it won't come off as it should.

    Anyone seen this type of failure before? I'm headed back to the shop later today to see if parts are available; if not, I'll have to buy another rear wheel assembly. The shop obviously would say they can't honor any type of warranty since they saw the motored bike the wheel was installed on. D'oh!
     

  2. Haggard

    Haggard Guest

    Yes , bout a yr ago. Not sure what caused it. I assumed I neglected the wheel bearings and let them back off while fixing a flat or something but am not sure.
    I actually sheared a rear axle completely in half using coaster brakes on single speed. This was in Newwestminster. Nice city but I live in Surrey!!! Couldn't even push it . I could carry it or drag it!
    Luckily had some bros lived about a mile or so from where she calfed so threw the bike in some bushes and went and borrowed a rim , swapped the sprockets and was good to go. I haven't used coaster brakes since.
     
  3. DougC

    DougC Guest

    The Worksman bicycle I bought was like this at first, because there was no grease in it. It didn't sieze enough to do any damage, but it grinded pretty loud when stopping.

    The entire inside of the hub should be packed solid with grease, even the part where the coaster brake shoes are. Was there any grease in yours?
    ~
     
  4. Bean Oil

    Bean Oil Guest

    Thanks for your replies, fellas...


    Oh yeah; it had plenty. It too was packed.

    As I mentioned in my first post, this was a new wheel purchased from the local shop; it's a machine-laced 12 ga spoked deal and when new, I tested it on the bicycle even before I had put any motor torque through the line, "but even then the brake seemed sensitive or a little too eager to stop the bike... I thought it would smooth out as the brake worn in."

    It was real "grabby" but silent. Anyway, upon disassembly and cleaning, I noticed that the axle had some galled threads and two or three stripped threads right underneath the threaded brake arm shoe anchor bearing race (that's right; the piece does all three things). I'm thinking it was a bum axle + poor quality control. The local shop owner thinks it's because it may have been made in China as opposed to Korea... he gave me a used wheel (an identical HI-STOP assembly) with a good brake arm, but that's all I can use from that wheel set 'cause it had been trashed. The bearing races were toast. I had to cut my axle to get the good brake-arm-shoe-anchor-bearing-race thingy off.

    I'll have to use the bike's original axle... but nothing else from the original coaster brake, a Shimano, will work with the HI-STOP assembly. Yeesh.

    But I didn't have to buy anything... I hope this doesn't come back to bite me in the you-know-where.

    :)~
     
  5. Bean Oil

    Bean Oil Guest

    Update, one week later...

    Turns out that the threaded rear axle stud/shaft had 2 or 3 galled/stripped threads which were causing play in the anchor itself... obviously a defect arising from either the manufacture or factory assembly thereof... since (now that I remember) the nut that locks the brake arm was tightened almost to the point of no return... it was extremely difficult to loosen it (even more than it should have been considering that it needs to be very tight) when I needed to remove the arm when fitting the engine kit rear sprocket.

    I used the axle from the original rear wheel (the one with the too-small spokes), the brake arm from the newer, used-up donor wheel and the brake parts from the new wheel; all cleaned in a hot soap tank and regreased by yours truly. The bearing cone adjustment had to be done more than once over a few miles... it all seems good now, though.

    Of course, if within the next 100 views of this thread there's someone reading this who actually knows coaster brakes and finds an issue with my methods, PLEASE tell me. I would appreciate that very much!


    I also trued the rear wheel to eliminate the tire rub against the chain in one spot. Then, after not having ridden the thing in a few days took it out for an 18 mile round trip to see some guys at a local vendor from work. They LOVED it! One swears that he has to build one of his own... I told him to check us out here on MotoredBikes.com... The bike ran flawlessly! Brrrrrrrrrrrrrrrrap!

    I JUST made it home before another downpour; it had been cold and grey all day, but somewhat dry after yesterday's dumping... I got drizzled on for the last two miles but no wet stripe on the back of my jacket (I have no fenders).

    *phew!* 'cause it's raining cats and dogs right now!


    :)~
     
  6. Bean Oil

    Bean Oil Guest

    Rode another 6 miles today... Had even more brake use and everything's staying in adjustment... all's good!
     
  7. Dockspa1

    Dockspa1 Guest

    Hope it stays that way Bean.
     
  8. Bean Oil

    Bean Oil Guest

    Oka-a-a-a-y . . .

    This afternoon...

    Gently leaned into the rear brake at 20 MPH and held the pressure while adding front brake... and bam! the rear brake locked.

    This time, though, while the bearing adjustment stayed put (as it has for at least the last 80 miles of stop-and-go riding). this lockup completely tweaked the bike's left chainstay through the brake arm. The frame's in dire need of a straightening; the bike is unrideable.

    Why is this brake grabbing so hard without much foot pressure applied? Either way, though the brake had been acting normally, I can no longer trust this particular assembly. Sucks, too, because I have to buy a new one as well as seek some pro help in straightening (more $) this Scwhinn Cruiser frame's rear triangle.

    Me very disappointed; I had been putting some MILES on this fun lil' rig.
     
  9. srdavo

    srdavo Active Member

    bummer

    I've never heard of a coaster failing this way! Glad you stayed upright, as you skidded to a stop.

    when you take this wheel apart....how about some pics? I'm wondering if something is broken inside...maybe floating around?
    Were you able to pedal forward at all....to see if the brake would release?

    I'd also like to see pics of your frame damage. hopefully there are no sharp bends (creases, kinks, or cracks) in your chainstays.

    The good news..... these older schwinns are tough little buggers!

    Hang in there!
     
  10. Bean Oil

    Bean Oil Guest

    Thanks, Dave; your vast experience is valuable input.

    The plan now is to rebuild the heavy-duty-spoked wheel with the bike's original Shimano coaster-brake hub. That hub never showed the tendency to be grabby. Should be a good lesson in wheelbuilding...
     
  11. Take out the shoes and convert it to a freewheel when your stuck on the side of the road hopefully you have at least a front brake then you can coast home. I used to do this back in the way day when once upon a time freewheels were like gold,then get some hand brakes on there.
    Or maybe just get a freewheel rim.
    I'm guessing after a while,all coasters will eventually fail like this considering the many miles we are putting in our rides. Or at least it may eventually happen.
     
  12. Bean Oil

    Bean Oil Guest

    ^ ^ ^ Thanks for the input, Large; I appreciate it. Happy New Year to you.



    Well, before I start wheelsmithing, I wanted to get the thing rideable for a New Year's Day gearhead dealiebob at a friend's house... so I beat on the chain- and seatstays with a block of wood and a hammer. LOL. Throw in some bare-hands wrasslin' and I had a somewhat straight apparatus to chuck my rear wheel back into. I rode it the two miles over to the party where it was well-received then rode it home without incident though favoring the front brake.

    I rode it again for a couple of hours this afternoon since it stands to rain the next three days here where I live. The rear brake behaved itself all afternoon and showed no peculiar traits while on a slow, steep downhill test, but still... I'll never be able to trust it. It'll get that original coaster brake hub sometime soon.

    Like Dave said, those older Schwinns are tough. They also have a good sense of humor.

    :)~
     
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