|
|
Thread Tools | Display Modes |
#21
|
|||
|
|||
understanding the rear sprocket
James writes:
I must have done something wrong reassembling the sprocket because tho the break and everything seems to work at first glance I have now detected an unexpected behavior which isn't always but often enough and that is when I pedal sometimes there is no resistance for perhaps a quarter (plus) of the full circle before normal resistance kicks in and there is forward force. So there is an unpleasant "leap", like falling through a trap door. Do you recognize this problem? Is it indeed related to the sprocket? Was there a ratchet mechanism that allowed the sprocket to free wheel? Did you grease the ratchet? Sometimes grease or heavy oil can prevent the pawls in a free wheel from engaging. I don't know what a "ratchet mechanism" is - do you see in in these pictures? http://user.it.uu.se/~embe8573/bike/sprocket/ But yes! I did put grease on the ball-bearings and a thin (but still) layer on everything else. So probably that is it! Should I disassemble it and wipe it dry or will it start working automatically in time? -- underground experts united http://user.it.uu.se/~embe8573 |
Ads |
#22
|
|||
|
|||
understanding the rear sprocket
On 10/04/15 12:10, Emanuel Berg wrote:
James writes: I must have done something wrong reassembling the sprocket because tho the break and everything seems to work at first glance I have now detected an unexpected behavior which isn't always but often enough and that is when I pedal sometimes there is no resistance for perhaps a quarter (plus) of the full circle before normal resistance kicks in and there is forward force. So there is an unpleasant "leap", like falling through a trap door. Do you recognize this problem? Is it indeed related to the sprocket? Was there a ratchet mechanism that allowed the sprocket to free wheel? Did you grease the ratchet? Sometimes grease or heavy oil can prevent the pawls in a free wheel from engaging. I don't know what a "ratchet mechanism" is - do you see in in these pictures? http://user.it.uu.se/~embe8573/bike/sprocket/ But yes! I did put grease on the ball-bearings and a thin (but still) layer on everything else. So probably that is it! Should I disassemble it and wipe it dry or will it start working automatically in time? Ah, I see. Couldn't remember what you had. It could be that the clutch mechanism is worn or not moving freely, or the spring is weak. Mr Muzi would know best what to do. http://www.troubleshooters.com/bicyc...d_overhaul.htm "If the clutch were to lose its friction, the clutch body would simply rotate with the sprocket, and no screwing in would occur, and therefore either propelling would never occur, or would occur slowly and only with a great deal of pedal spinning. I had that happen once, and the problem was fixed by replacing the clutch assembly." -- JS |
#23
|
|||
|
|||
understanding the rear sprocket
On 4/9/2015 10:10 PM, Emanuel Berg wrote:
James writes: Was there a ratchet mechanism that allowed the sprocket to free wheel? Did you grease the ratchet? Sometimes grease or heavy oil can prevent the pawls in a free wheel from engaging. I don't know what a "ratchet mechanism" is - do you see in in these pictures? http://user.it.uu.se/~embe8573/bike/sprocket/ But yes! I did put grease on the ball-bearings and a thin (but still) layer on everything else. So probably that is it! Should I disassemble it and wipe it dry or will it start working automatically in time? Have you looked at these sites? http://sheldonbrown.com/coaster-brakes.html http://www.parktool.com/blog/repair-...edal-brake-hub It's been years since I overhauled a coaster brake, but I don't remember pawls or ratchet mechanisms. I remember coarse square threads that moved an internal component side to side, causing it to either engage the brake surfaces or drive the hub forward. Sheldon's site mentions the "retarder spring" as being a source of irregular action. I can't identify that in your photos, but perhaps you can. OTOH, I suppose yours may be very different... -- - Frank Krygowski |
#24
|
|||
|
|||
understanding the rear sprocket
On 4/9/2015 7:22 PM, Emanuel Berg wrote:
I must have done something wrong reassembling the sprocket because tho the break and everything seems to work at first glance I have now detected an unexpected behavior which isn't always but often enough and that is when I pedal sometimes there is no resistance for perhaps a quarter (plus) of the full circle before normal resistance kicks in and there is forward force. So there is an unpleasant "leap", like falling through a trap door. Do you recognize this problem? Is it indeed related to the sprocket? The clutch is not grabbing the hubshell. Did you set the bearing to a trace of play at the rim? Are the driver threads lubricated and clean where they engage the clutch carrier? When it was open, did you notice significant wear or glaze on the clutch and mating surface in the hubshell? -- Andrew Muzi www.yellowjersey.org/ Open every day since 1 April, 1971 |
#25
|
|||
|
|||
understanding the rear sprocket
AMuzi writes:
I must have done something wrong reassembling the sprocket because tho the break and everything seems to work at first glance I have now detected an unexpected behavior which isn't always but often enough and that is when I pedal sometimes there is no resistance for perhaps a quarter (plus) of the full circle before normal resistance kicks in and there is forward force. ... The clutch is not grabbing the hubshell. Yes, that sounds exactly right! But: I don't remember any clutch. The "hubshell" - is that the outer, rim shell or the little bronze (?) shell inside the sprocket? - i.e., the forth piece on this picture, in comic book reading order: http://user.it.uu.se/~embe8573/bike/...et/parts-2.jpg Did you set the bearing to a trace of play at the rim? I remember three bearings: one on the outside which is big, one small on the inside of the chainwheel but still visible, at the edge, and one in the "inner shell" that wasn't exactly a bearing but it looked somewhat like that. If we are at the rim one right now I don't remember doing anything in particular to that one save for putting some fat on the balls. I don't remember seeing different traces but if they are there let me disassemble it again and see if I can detect them. Are the driver threads lubricated and clean where they engage the clutch carrier? Everything was very dirty with mud and God knows what but now it is clean. The bearings are lubricated but everything else I just put on a thin layer because I didn't know what was the right thing to do. From your post I've been able to conclude that: The bearing should be at a trace of play at the rim. The driver threads engage the clutch carrier. The clutch should grab the hubshell on the mating surface. If you can help me identify those parts and properties I think that'd be a good start! (Boy, this is exiting by the way!) When it was open, did you notice significant wear or glaze on the clutch and mating surface in the hubshell? No, everything looked good, so I think disfunction is on the account of the mechanic -- underground experts united http://user.it.uu.se/~embe8573 |
#26
|
|||
|
|||
understanding the rear sprocket
On Friday, April 10, 2015 at 8:00:46 AM UTC-4, AMuzi wrote:
On 4/9/2015 7:22 PM, Emanuel Berg wrote: I must have done something wrong reassembling the sprocket because tho the break and everything seems to work at first glance I have now detected an unexpected behavior which isn't always but often enough and that is when I pedal sometimes there is no resistance for perhaps a quarter (plus) of the full circle before normal resistance kicks in and there is forward force. So there is an unpleasant "leap", like falling through a trap door. Do you recognize this problem? Is it indeed related to the sprocket? The clutch is not grabbing the hubshell. Did you set the bearing to a trace of play at the rim? Are the driver threads lubricated and clean where they engage the clutch carrier? When it was open, did you notice significant wear or glaze on the clutch and mating surface in the hubshell? -- Andrew Muzi www.yellowjersey.org/ Open every day since 1 April, 1971 an elegant post of beauty and grace on a subject worth considering |
Thread Tools | |
Display Modes | |
|
|
Similar Threads | ||||
Thread | Thread Starter | Forum | Replies | Last Post |
Nexus 8 rear sprocket removal | Motty | Techniques | 6 | September 16th 05 09:14 AM |
Fixed gear rear sprocket help | Dale | Techniques | 4 | April 26th 05 03:21 AM |
A little understanding, please | Andy Simmonds | General | 55 | August 25th 04 01:08 PM |
rear der sprocket capacity | David Nutter | UK | 8 | September 13th 03 02:42 AM |
TDF understanding | Milton | Australia | 30 | July 18th 03 02:01 PM |