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Wednesday, July 30, 2008

HOW TO REPAIR OR OVERHAUL A COASTER BRAKE HUB

There isn't much I can't fix or service on a bike, but I will freely admit that rebuilding a single speed coaster brake hub is not something I am very good at. Seriously, every time I try to rebuild a coaster brake hub, it commits suicide shortly thereafter.

Since many of you have been asking for information on this matter and I wouldn't be a reliable source to provide it, I have found a couple of great sites that can help you out. The first one is a step by step total rebuild from Steve Litt. Extremely well detailed and with lots of photographs. You can find the article here: http://www.troubleshooters.com/bicycles/1speed/1speed_overhaul.htm

The second valuable resource can be found at ratrodbikes.com's how-to section in the discussion forum. Member new_dharma and others have posted some diagrams of many hubs and this could also help you out. The information can be found here: http://ratrodbikes.com/forum/viewtopic.php?f=3&t=1162

There is one thing that I can contribute in your quest to overhaul a single speed or any other coaster brake hub:
  • Prepare a clean working surface, no piles of little knick knacks that can be confused with tiny hub parts.
  • Use a rag to cover your working surface that will prevent parts to bounce off into the 5th dimension of your workshop, never to be seen again until just before you move after selling the house.
  • If you have a camera, be smart and take pictures as you dismantle(This one applies to anything you ever decide to take apart for the first time, trust me.).

These 3 little simple steps will save you a lot of headaches and should keep your money out of the cursing jar! Don't rush things and you'll be fine.

Until I find a hub to rebuild and find the time to try Steve Litt's steps, this is the best I can do for you. Good luck to you all.

Til next time ride safe and Godspeed.

Gerry :)

4 comments:

Vojnov Stevan said...

I would like to share with you my little expirience with overhauling coaster brake on my "Pony Adriatico" bike (curently in precess of reparation). I was second or third year student on Mechanical faculty and mechanism and machine stuff are very interesting for me. I had problem with my coster brake. I was racing with my friends and due to great load on hub the sprocket just skipped. So every time i give it a harder push on pedals the sprocket would skip. Bike was almost impossible to ride. So i guess something must be wrong with mechanism inside hub. This brake type is ,as i could determine on the net, "Torpedo"(English). Here is the link to mechanism: http://sheldonbrown.com/coaster-brakes/sc.html

So i decided to fix it and detached hub form bike. I take apart brake and start analyzing and trying to understand how this thing works and where the problem is. I realized how braking works, but i couldn't see how force is transmitted over backside of the sprocket(driver) to the hub wall and thus rotating wheel. So i was sitting on the ground, holding brake in my hands and looking at it for some time. Then my mother approached me while she was on her way to take dried clothes from back yard and asked me :"What are you doing?" and i said :"I cant figure out how this thing works, i see how it brakes but i cant see in which way it makes wheel rotate". It didn't took her 5 seconds to say:"Well you see this little rolling cylinders! When you turn sprocket in direction of pedaling they are pushed-out against the hub wall ,by gutter on the driver , and then friction makes the wheel rotate!" I was stunned, my mother finished only elementary school, she never took apart or repared any bicycle. And she saw so fast how mechanism works. I told this story to mu friend on Faculty and we were laughing out loud. He told me:"Your mother kicks ass! She's better then you"

Back then i couldn't realize how to fix brake so i left it on the attic and this year i assembled it again, BUT now the chain is skipping. One some forums i red that this is caused because the sprocket is time-worn and the chain is too much deformed so it wont fit properly on sprocket. Second , i dont remember seeing chain skipping last year when i tried to fix brake, so there is possibility that driver of the sprocket is worn or the rollers are worn.I measured diameter of rollers and its average 6,4 mm but in shop catalogue standard dimension is 6,5 6,6 and 6,7 mm. Maybe the original diameter was 6,5. So Im thinking of replacing rollers and driver.
BUT if the hub wall is worn inside (which i doubt) then even new rollers wont be able to make enough pressure on the wall which may be the reason for skipping. Or maybe i should buy bigger rollers? But then, would they fit in driver cage???

In two days i plan to go to shop in Belgrade to buy this components. I guess that replacing driver(because it's broken), rollers and sprocket and even chain i will solve this problem but if somebody already had this kind of problem with coaster brake and solved it please reply!

PS
Sorry for my english :(

Stevan Vojnov

Gerry Lauzon said...

Stevan , great comment, great English and great story. Thank you so much for sharing it with us. I laughed my head off as well. Changing the sprocket and chain should take care of your problem, but I've seldom heard of this happening on coaster bikes.

Gerry :)

Vojnov Stevan said...

I am more than happy to announce that my "Pony Adriatico" bike is fully functional. I bought parts that i already mentioned( complet driver with cage+rollers+duster+2xBearings, new 18 spokes sprocket, new chain (better quality than the last one) and new bearings for crank, all this cost 15 dollars). Yet i made terrible mistake. While i was assembling crank i flipped bearings wrong side. They were smashed after 15min of riding :( What a shame!
But it was my first time to remove crank and i didn't remember how the bearings in cup was positioned :( Big mistake but NOT expensive. I can get 3 Bearings for 1 dollar). Now i remember what you said:"Take a picture while you take apart "anything" :)
So i had to reuse old bearings, just for few days, until i buy new ones.

PS
Im sorry if some of text is not related to HUB overhauling but my HUB is now WORKING :):):):)

Jacob said...

Hi, I'm a long time reader first time commenter, I have missed your postings over the past month. Anyway, a friend's parent came to me with a problem their coaster brake hub wasn't working and made a grinding sound when it did move. With the aid of the site you supplied in this post I was able to understand how it worked how to take it apart and how to put it back together. Everything is working now.

However, there is a clicking sound every time the bike coasts. We can't figure it out. We are guessing that the brake pads are rubbing up on the ridges of clutch assembly. How do you think this problem can be resolved?

Thanks in advance.