Cycling and bicycle discussion forums. 
   Click here to join our community Log in to access your Control Panel  


Go Back   > >

Bicycle Mechanics Broken bottom bracket? Tacoed wheel? If you're having problems with your bicycle, or just need help fixing a flat, drop in here for the latest on bicycle mechanics & bicycle maintenance.

User Tag List

Reply
 
Thread Tools Search this Thread
Old 11-25-12, 02:14 PM   #1
fairmount1981
Newbie
Thread Starter
 
Join Date: Nov 2012
Bikes:
Posts: 4
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Bendix 20 Hub Operation - Need Assistance

Hi all,
I recently found an old derby bicycle in a garage. The Bendix 20 hub does not seem to work properly. The sprocket spins without turning the hub. I took the hub apart but cannot seen to locate the issue. Can someone advise on this, or explain how this hub is suppose to work. Thanks, Andrew
fairmount1981 is offline   Reply With Quote
Old 11-25-12, 02:27 PM   #2
FBinNY 
Senior Member
 
Join Date: Apr 2009
Location: New Rochelle, NY
Bikes: too many bikes from 1967 10s (5x2)Frejus to a Sumitomo Ti/Chorus aluminum 10s (10x2), plus one non-susp mtn bike I use as my commuter
Posts: 30,839
Mentioned: 21 Post(s)
Tagged: 0 Thread(s)
Quoted: 866 Post(s)
I'm not familiar with the specific model 20 hub, but the basics of all Bendix hubs are the same. They work on the principle of a spiral clutch on the driver (attached to the sprocket). When you pedal forward the spiral draws the clutch to the right where it engages the hub shell. When you coast and the hub is spinning faster than the sprocket, the clutch goes down the spiral and disengages. When you back pedal the clutch moves to the left to engage the brake side of the hub and apply the brake (the actual brake side varies from hub to hub).

Usually there's a spring on one side or the other to start the process.

There are lots of free tutorials on rebuilding coaster brakes, so I suggest reviewing a few until the light goes on and figure out what you're missing (either part or understanding)
__________________
FB
Chain-L site

An ounce of diagnosis is worth a pound of cure.

“Never argue with an idiot. He will only bring you down to his level and beat you with experience.”, George Carlin

“One accurate measurement is worth a thousand expert opinions” - Adm Grace Murray Hopper - USN

WARNING, I'm from New York. Thin skinned people should maintain safe distance.
FBinNY is online now   Reply With Quote
Old 11-25-12, 02:52 PM   #3
Dan Burkhart 
Senior member
 
Dan Burkhart's Avatar
 
Join Date: Oct 2004
Location: Oakville Ontario
Bikes:
Posts: 6,058
Mentioned: 2 Post(s)
Tagged: 0 Thread(s)
Quoted: 59 Post(s)
Also, check that the 3 drive tabs on the cog are not sheared or worn off, and the cog spins without turning the driver. Best way to check that is to remove the snap ring holding the cog on, and lift the cog off. I have seen this happen more than once, although that was on bikes (trikes actually) in heavy duty usage. Still worth checking before you get too deep into it.
__________________
Gearhubs demystified and other cool stuff.


WANTED: Dead or broken gearhubs for failure analysis.

Like the shop
Dan Burkhart is online now   Reply With Quote
Old 11-25-12, 04:00 PM   #4
FBinNY 
Senior Member
 
Join Date: Apr 2009
Location: New Rochelle, NY
Bikes: too many bikes from 1967 10s (5x2)Frejus to a Sumitomo Ti/Chorus aluminum 10s (10x2), plus one non-susp mtn bike I use as my commuter
Posts: 30,839
Mentioned: 21 Post(s)
Tagged: 0 Thread(s)
Quoted: 866 Post(s)
Quote:
Originally Posted by Dan Burkhart View Post
Also, check that the 3 drive tabs on the cog are not sheared or worn off, and the cog spins without turning the driver. ....
This is a good point, and worth checking if you haven't taken it apart yet. You can check it without popping the snap ring, by simply turning the sprocket while looking at the center of the driver. If the driver doesn't turn, then it's simply a matter of a new sprocket. As Dan said, this is bery rare, but why not check first. Once you have it apart, it's harder to check this without popping the snap ring since it's hard to apply enough torque.
__________________
FB
Chain-L site

An ounce of diagnosis is worth a pound of cure.

“Never argue with an idiot. He will only bring you down to his level and beat you with experience.”, George Carlin

“One accurate measurement is worth a thousand expert opinions” - Adm Grace Murray Hopper - USN

WARNING, I'm from New York. Thin skinned people should maintain safe distance.
FBinNY is online now   Reply With Quote
Old 11-26-12, 11:12 PM   #5
bikeman732
Senior Member
 
Join Date: Sep 2012
Location: Tampa FL
Bikes: 2004 Cannondale R3000, 1972 Raleigh Professional, 1976 Raleigh International 1990 Jamis Explorer, 1989 Bottecchia SLX
Posts: 69
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Most common cause for this symptom is old grease hardened up and not allowing the clutch cone to engage. disassemble, clean in solvent and reassemble with new grease. Barring the forementioned tabs on the cog being worn off, and rarely the clutch one being worn out, 9 times out of 10 this will fix your problem.
bikeman732 is offline   Reply With Quote
Old 11-26-12, 11:18 PM   #6
Jeff Wills
Insane Bicycle Mechanic
 
Jeff Wills's Avatar
 
Join Date: Mar 2008
Location: other Vancouver
Bikes:
Posts: 8,065
Mentioned: 4 Post(s)
Tagged: 0 Thread(s)
Quoted: 75 Post(s)
Quote:
Originally Posted by bikeman732 View Post
Most common cause for this symptom is old grease hardened up and not allowing the clutch cone to engage. disassemble, clean in solvent and reassemble with new grease. Barring the forementioned tabs on the cog being worn off, and rarely the clutch one being worn out, 9 times out of 10 this will fix your problem.
+10... Bikeman beat me to it. Back when I was working on Bendix hubs (30 years ago now), old, dried up grease was the only real problem they ever had.
__________________
Jeff Wills

Comcast nuked my web page. It will return soon..
Jeff Wills is offline   Reply With Quote
Old 11-27-12, 08:50 AM   #7
fairmount1981
Newbie
Thread Starter
 
Join Date: Nov 2012
Bikes:
Posts: 4
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Quote:
Originally Posted by Jeff Wills View Post
+10... Bikeman beat me to it. Back when I was working on Bendix hubs (30 years ago now), old, dried up grease was the only real problem they ever had.
Hi all, thanks for the quick responses. The 3 drive tabs on the cog are not worn down. The cog & sprocket are engaged tightly. When the sprocket is rotated via the bike chain, the entire inners of the hub (spiral clutch, shaft, brakes,) all spin as one unit. Nothing seems to catch the hub from the inside to make it spin. The grease inside is original to the bike and extremely viscous. Almost like spackle. I will clean it with solvent and re grease. I'll also try to find some videos on Youtube, and will post my results in a couple days.

Thanks again,
Andrew
fairmount1981 is offline   Reply With Quote
Old 11-27-12, 08:02 PM   #8
Jeff Wills
Insane Bicycle Mechanic
 
Jeff Wills's Avatar
 
Join Date: Mar 2008
Location: other Vancouver
Bikes:
Posts: 8,065
Mentioned: 4 Post(s)
Tagged: 0 Thread(s)
Quoted: 75 Post(s)
Quote:
Originally Posted by fairmount1981 View Post
Hi all, thanks for the quick responses. The 3 drive tabs on the cog are not worn down. The cog & sprocket are engaged tightly. When the sprocket is rotated via the bike chain, the entire inners of the hub (spiral clutch, shaft, brakes,) all spin as one unit. Nothing seems to catch the hub from the inside to make it spin. The grease inside is original to the bike and extremely viscous. Almost like spackle. I will clean it with solvent and re grease. I'll also try to find some videos on Youtube, and will post my results in a couple days.

Thanks again,
Andrew
That's your problem. The clutch cone and the driver need to slide against each other, not stick. A good cleaning and light grease should be all you need.

Below: driver is part #13, clutch cone is #10

__________________
Jeff Wills

Comcast nuked my web page. It will return soon..
Jeff Wills is offline   Reply With Quote
Old 12-03-12, 07:13 AM   #9
fairmount1981
Newbie
Thread Starter
 
Join Date: Nov 2012
Bikes:
Posts: 4
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
I disassembled the hub and soaked all the parts in acetone. I cleaned everything thoroughly, then greased and re-assembled. Works like new. Thank you to everyone who helped.
fairmount1981 is offline   Reply With Quote
Reply


Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off



All times are GMT -6. The time now is 07:20 AM.