4" Manco Style Drum Brake Problems

[ArcticMinibike]

I'm thinking of starting a "I hate drum brakes" support group. Is it just me or are they a pain in the ass to get them to actually work without a gorilla strength grip? I'm talking about the very common 4" stamped zinc plated style that fits Manco wheels.

I have an Arctic Cat with 6" Manco wheels on it and these are the standard brakes. I was having stopping issues, so I disassembled, cleaned the drum with brake cleaner, and installed NOS shoes. They performed just as poorly as the ones that were on there from 40 years ago. I replaced with a new lever and shoe assembly, keeping the old drum which looks in good shape, but well polished inside. They still sucked. Finally I replaced the drum and now I get moderate stopping power but I have to really pull hard.

Is this a known flaw of this style of brake? I have the exact same problem on my Arctic Cats with 10" wheels, which I've been told never worked well on any bike. Unlike the 4" ones, I can't replace the drum on those since they are built into the wheel. Can the drums get TOO smooth over time and wear?

Interestingly enough, my 4" front brake grips instantly and will throw you over the handlebars, so I know they are capable of working.

Thoughts anyone? Tips for fixing? Should I rough up the drums a bit to make sure there's no glazing? The shoes are brand new. Is there a break in period?

 

[george3]

the prob. is the skinny shoes and small diameter. ruff the drum up a bit should help.

 

[Havasu Dave]

ruff the drum up a bit should help.

X's 2.

Might try adjusting the cable so the fulcrum of the arm gives you more torque on the brakes themselves too.

By the way, crappy drum brakes are way better than Cat disc (sprocket) brakes. :hammer:

 

[ArcticMinibike]

Thanks guys! I'll give it a shot.

Unfortunately on the 4" the arm is fixed rather than splined and adjustable. Even on the brand new one, the arm uses up half the travel before it engages. I'll try adjusting the hand lever a little. On my 10" wheels I'll have more flexibility. I think they are splined.

As for roughing up the drum, what grit sandpaper would you recommend? 80? 100? 220?

 

[Havasu Dave]

Thanks guys! I'll give it a shot.

Unfortunately on the 4" the arm is fixed rather than splined and adjustable. Even on the brand new one, the arm uses up half the travel before it engages. I'll try adjusting the hand lever a little. On my 10" wheels I'll have more flexibility. I think they are splined.

As for roughing up the drum, what grit sandpaper would you recommend? 80? 100? 220?

I'd go for a cross hatch 80 or even 60 grit on the drum, and a slight rough up on the shoes with the same stuff.

 

[creia]

Thanks guys! I'll give it a shot.
Even on the brand new one, the arm uses up half the travel before it engages.

In that case you will have to "pre-load" it before you secure the cable to the arm.
Michael
Sidebar: My .02 cents-Most drum brakes that I have experienced really and truly do not stop very well at all. My recommendation- install a clutch band brake (They work unbelievable), get your drum brake working as best you can and use it as your backup/emergency brake only in the event you break a chain.
Michael

 

[ArcticMinibike]

I'd go for a cross hatch 80 or even 60 grit on the drum, and a slight rough up on the shoes with the same stuff.

I cleaned up the rear drum on one of my 10" Prowlers and installed new shoes. They use the same shoes as a Honda Trail 70. I used an old chunk of 100 grit floor sanding belt. It's got a very stiff backing cloth so you can get some leverage. I worked my way around the inside of the hub at a 45 angle, then the opposite direction to make a cross hatch pattern. Cleaned thoroughly with brake cleaner spray. Stopping is greatly improved. I'll try the 4" drum bike next. Thanks for the suggestion!