HerrOtto

Hello, I have a coaster brake bike with a Falcon coaster brake. When coasting, the brake makes a grinding noise that I know whats making the noise, but I do not know why. I am sorry that I do not know the exact terminology but I will do my best to describe the parts and the problem. It appears when coasting, the teeth at the end of the spring loaded clutch/driver assembly are touching the inside of the hub teeth, trying to engage the sprocket. I have disassembled and reassembled the brake numerous times looking for the cause, to no avail. I am not sure if the spring is supposed to be retracting the teeth or pushing them to engage. All parts appear visually to be ok. I have cleaned and greased the assembly. Thinking the spring may be worn, I placed a washer behind it to help take up any worn space, but this also was to no avail. There was already one washer, behind the spring, so this last time, I removed the original washer thinking the spring was too tight, this did not solve the problem either. Any help would be appreciated.

Sonofamechanic 

Does the noise you are hearing change when you slowly apply the brake? If its a weak spring then as you apply the brake that noise/chatter should remain the same pitch/cadence but get louder and then stop altogether when the brake catches. If that doesn't occur—ie the sound continues after the bike is engaged (and while the bike is still moving)—then you likely have a bearing issue instead.

Andrew R Stewart 

Spring loaded clutches tend to have a grinding as the end of the spring grates against the clutch and/or the washer in it. I have nicked the spring end to bevel it's end with both good and no benefits. The other common issue on old hubs is gummy grease that hinders the clutch from retracting from the driver fully. The comment about bearings is a good point too. Coaster hubs really like a tad of bearing slop, just like SA Aws do too. Andy

HerrOtto

The bearings were cleaned and greased and appeared to be in good shape. The noise appears as soon as you stop pedaling(coasting) and will dissipate when you slowly pedal backwards toward braking and will re-appear when slowly pedaling forward but is eliminated when you are actually pedaling(propelling) forward. I feel the noise is from the teeth at the end of the driver/clutch by the sprocket side. My question is, is the inside of the hubshell near the sprocket, supposed to be smooth or splined?

Geepig

The best place to answer that is a search, especially of strip and assembly videos.

The inside of the hub, the bore, is usually smooth, because it is merely the friction surface and allows the the internals assembled into either end - everything else attaches to the axle. Often old grease builds up in the bore, which can cause problems. On my ones I get a ring of solid grease that blocks engagement of the brake, for example.

HerrOtto

I have now watched numerous videos on the disassembly and assembly of coaster brakes. Unfortunately none of them mention the internal surface of the hub shell whether it is supposed to be smooth or serrated. Mine feels serrated and I feel that is were the noise is coming from. I am tempted to sand off the serration but hate to do so if the serration is normal. Can anyone definitively tell me whether the inside of the hub shell is supposed to be smooth or serrated? Thank you

Geepig

All the ones I have ever seen have been smooth, unless they are badly worn - but even then they generally wear smooth and you can end up with a step between the worn and unworn parts. For mine I can remove all the internals, and then refit them from the other side so that now the brake now runs on the part where the coaster part was.

The Falcon looks like it has a wider brake section than my Velosteels, but if you have a few hours to spare I would try it out.

The alternative is to look for a replacement hub - it is not an expensive type of hub and often you can pick up another wheel with or without the internals on internet sites secondhand. If you feel confident then you can strip the wheel down, fit a new hub and then build the wheel back up again. I have done several such rebuilds now, although usually due to spoke or wheel rim issues than the need to replace the hub. A replacement wheel does not even have to be off the same model of bike, and I have the same hubs on 20", 24" and 26" wheels.

ElliotN

HerrOtto, do you know the year of your coaster brake hub?
I have worked extensively on cheap coaster brake bikes for the last decade. (Think "rental fleet", and you have a rough picture of it.)

In 2014, there was a flood of defective coaster brakes. I fantasize (tongue in cheek) that the entire year's Chinese production of coaster brakes was made from a defective batch of steel, or that (not the least bit amusing) the 12-year-old slave-labor-girl operating the heat-treatment of the steel made a fundamental mistake which Da Boss Man did not bother to catch for months.

The grinding noise happens as is described above -- it is noisy when close to pedaling, and the noise goes away when moving the pedals closer to braking.

It took me a long time of inspecting and comparing parts from various sources (such as vintage Sturmey-Archer hubs) before I found the problem, but I found it.

Please forgive my clumsy terminology, as I never took time to learn the correct names of these parts.

But... the male conical drive part is serrated or splined or grooved, while the female cone is smooth. If you can see or feel marks in the female surface, then you have found the source of the noise: the female surface is too soft, and the male cone has forced its grooved shape into the female surface.

The bikes were all or mostly the Huffy Crankbroke bought new in the western US in the summer of 2014, and only that year to my personal experience.
At the time, there was quite a bit of discussion of it on various bicycle-related forums -- perhaps including this one.
But of course, I would not be surprised if the same problem has occurred in other production batches over the years.

Oh... on the same 2014 hubs, the bearing also loosened up something awful. While "slightly loose" is correct for such hubs (as mentioned in this thread), these went downright wobbly.

I hope you find a good hub soon!

bwilli88 

How much grease did you put in when you cleaned the hub?
I have a Shimano CB-E110 and it was making a nasty noise while coasting.
I took the hub apart and packed it full of grease and the noise went away.

mwdilday

I know this is an old post but I may have the solution. On the drive side of the coaster brake there may be grooves from the clutch. These grooves may need to be sanded out. I had the same issue and sanded out the grooves and it fixed the issue.

Andrew R Stewart 

This is mentioned in post 8. Andy

ElliotN

I am glad to hear that sanding helped it.
Did you sand it with just your fingertips, or did you glue sandpaper to the cone or some such?
I fear your problem will return, since the issue seems to be precicely that the surface is so soft that it can be sanded. But we learn something from everything we try.

mwdilday

Initially used a dremel with a sanding wheel to get most of it. Then finished with my fingers and sandpaper.