Scrub Brake Performance Improvement

[thebronc4019]

I am finishing my current project and just went for a test ride which revealed a problem. The bike is equipped with a scrub brake and does not stop the bike adequately. I would like to modify it a bit to improve braking and need feedback from others in this area. I have seen the pieces that are shaped to the circumference of the tire that are on a pivot but my scrub brake set-up won't allow for this. I can add some material to the flat face of the brake as to improve the leverage of the pedal so contact is made with the tire sooner. I am not concerned about tire wear as I will seldom use the brakes but I need to have the confidence that I can stop short if I need to. I would prefer to modify the original scrub brake than to have to add a drum or band brake. Any help would be appreciated.

 

[Havasu Dave]

I had to chuckle on this one. Imagine a scrub brake not stopping a bike adequately. :thumbsup: It's a step above using your feet as brakes.

Is this on your K&S? I just looked at the photo and noted the brake arm is straight. Most of the scrub brakes I've seen had an upward bend on the arm which provides a better fulcrum for more pressure on the tire itself. This results in the foot lever sitting a bit higher.

I'd thought about gluing and riveting rubber on the pad, but that would wear pretty quickly. Some of that "molded to the tire" look is from the tire wearing the plate down over the years.

Scrub brakes- they are what they are. Bend the arm, and it'll help, but plan your stops a day in advance. :wink:

 

[bikebudy]

Scrub Brake & Performance don't usually go in the same sentance,:wink:

What I have done in the past is use the rear sprocket as a brake disc.

Install the caliper between the chain, make up a bracket, install a cable and lever. If you can install a bracket without welding? Then you don't really change the bike any, as all would be bolt on parts.

Just a thought for ya. :shrug:

 

[Fat Boy]

Add a clutch brake and both will stop it just fine :thumbsup:

 

[mckutzy]

A clutch band brake will just add more heat to a part that doesnt need it. Also if the chain throws a link, you wont have brakes. If room use a disc/drum band brake on the rear axle.

 

[5horsebriggs]

Take an old tore and cut a square of rubber out and jb weld it the paddle:thumbsup:

 

[Fat Boy]

A clutch band brake will just add more heat to a part that doesnt need it. Also if the chain throws a link, you wont have brakes. If room use a disc/drum band brake on the rear axle.

Ya I have heard all these old wives tales for the last fifty years and I have never had any of these issues with clutch brakes in the same time and I must live right because I can't ever remember a chain coming off when riding :laugh:

 

[rmm727]

I think my Golden Pinto's scrub brake works well enough and it has the aftermarket steel replacement. It stops better than a DB30 disc does.

 

[dwarfbike]

My Bonanza & Cat Scrub brakes always worked great too. It has four tapped holes in all four corners, I have always run rubber pads with counter sunk screw on all four corners. This will now cup the rubber pads rather than the scrub brake steel plate.

 

[george3]

I had to chuckle on this one. Imagine a scrub brake not stopping a bike adequately. :thumbsup: It's a step above using your feet as brakes.

Is this on your K&S? I just looked at the photo and noted the brake arm is straight. Most of the scrub brakes I've seen had an upward bend on the arm which provides a better fulcrum for more pressure on the tire itself. This results in the foot lever sitting a bit higher.

I'd thought about gluing and riveting rubber on the pad, but that would wear pretty quickly. Some of that "molded to the tire" look is from the tire wearing the plate down over the years.

Scrub brakes- they are what they are. Bend the arm, and it'll help, but plan your stops a day in advance. :wink:

Scrub brakes- they are what they are. Bend the arm, and it'll help, but plan your stops a day in advance. :laugh::laugh::laugh:

 

[george3]

I have had some mini bikes with scrub that worked great and some that worked like crap.

 

[tundrabeagle3]

Yea scrub brakes don't work the best and when they work ok ur tire is gonna get worn down real quick

 

[buckeye]

Fat Boy nailed it.
The scrub brakes weren't designed to stop these bikes for adults with 40 hp engines.:laugh:

Add a clutch brake and you will have plenty of stopping power.:thumbsup:

 

[Havasu Dave]

Scrub brakes- they are what they are. Bend the arm, and it'll help, but plan your stops a day in advance. :laugh::laugh::laugh:

:thumbsup: And I don't get all the applauding on the sprocket brakes working as a disc-type system.

My scrub brakes always work better than the chain oiled sprocket. My old Fox kart uses two scrubs on the slicks and it stops very good.

Simple is always good, and that's what mini bikes were designed to be. Simple.

 

[thebronc4019]

Thanks for the responses. I will try and add something to the face of the scrub brake in hopes of increasing the leverage as contact will be made sooner when I step on the brake. If that does not work to my satisfaction I will add a drum brake and actuate it with the original brake pedal.

 

[jeep2003]

Ya I have heard all these old wives tales for the last fifty years and I have never had any of these issues with clutch brakes in the same time and I must live right because I can't ever remember a chain coming off when riding :laugh:

only time iv ever had a problem with a clutch brake is when going down a big hill through the woods on a gokart and the chain fell off. cant put your feet down. had to ride it out. now im more carefull going down there and vere off before i build up too much speed :laugh: but thats worst care senario for sure. never a problem on a minibike. definatly just words from guys that havnt used one

 

[midtown mini]

I was building a M bike for my granddaughter...went on to the OldMiniBikes warehouse site, found a scrub brake attachment from a JC penny bike. it was 25 bucks..did some red neck engineering and hooked it up to the existing scrub,
To make it simple it was an aluminum block shaped as the radius of the tire if you want pics let me know as I will provide them....locks the bike up

 

[Havasu Dave]

never a problem on a minibike. definatly just words from guys that havnt used one

I have had chains fall off right after new builds during the test drive. Usually because something is out of alignment that didn't show up during the "garage rev." (Where I really hope I don't get a chain slap on the top of my flip flop covered feet)

However, the times the chain has come off, my biggest worry was the fact that something was locked up, chain being jammed against (take your pick) and using the brake was my last worry.

Never had a chain just "fly off" and actually exit stage left, though I am sure it's possible. Jammed chain makes a great brake. :thumbsup:

 

[boostdoctor]

You could try extending the arm for more leverage. My buddy's scrub brake will slide the rear tire at 40+ mph. His brake arm is very long. It stops better than the drum brake crap that was on my bike. He also told me that the scrub brakes are crap when they get wet. I'm thinking about integrating a scrub brake to my bike, I don't ride in the rain.lol

 

[bandit 40]

Bolt a chain around a stock 97cc engine and toss it off the back at least this way you will still have some sort of brakes when your tire gets wet., there you go :laugh: