Problem here... you guys see anything wrong with my brakes?

[mardyn]

Manco Chopper band brake on the rear wheel doesn't stop worth a crap.

I thought it might be the powder coated brake drum contaminating the brake band, but I disassembled it today, cleaned off all the powder coating from the drum surface and brake band material, put it all back together and it still doesn't want to stop...

Cable is tight, but you just can't squeeze the brake lever hard enough to get good stopage.

It's almost like the lever system doesn't have enough mechanical advantage to clamp the band tight enough to stop the thing.

mardyn

 

[Neck]

Adjust(back off the set screw and yank on the cable with a pair of pliers and push the band towards the front of the drum, then tighten the set screw) that cable poking through the shaft on the brake band till the band is contacting the drum all the way around, then try it.

 

[mardyn]

Yeah, that's what I did today when I was reassembling it... still, not enough stopping power.

mardyn

 

[Neck]

how far from the handle bar does the brake lever stop?

 

[derekbmn]

What style brake lever are you using ?

 

[TeamCheap]

Does the band hang free on the bolt that holds it to the frame or is it tight and if tight how much clearance is there between the band and the drum close to the band mounting bolt.

 

[minibikin']

When you cleaned off the powder from the band, did you scuff it with a rough sandpaper like 80 grit? It may be glazed over and not getting a clean bite?

 

[mardyn]

Does the band hang free on the bolt that holds it to the frame or is it tight and if tight how much clearance is there between the band and the drum close to the band mounting bolt.

The brake lever currently only moves about 1" total, not even close to bottoming out on the handle bars... the adjustment has very little free play in the cable.

The brake band swivels on the anchor bolt, clearance between the band and drum is minimal... I have a slight drag with no cable pressure on it.

Drum and band were cleaned and scuffed today before reassemble..

I've got a generic brake lever from one of the usual suppliers... could it be possible a different lever might offer better leverage-M/A and hence more pulling force on the cable? Seems logical to me, but I didn't realize there were big differences between brake levers...

Keep those ideas coming...


mardyn

 

[derekbmn]

I have had the best luck with this style on brake band setups. Adjustable and more "travel" then the smaller cherry style levers.
http://OldMiniBikes.com/images/P/brakelever.jpg
Edit: just found your pics in your other thread and I see this is the lever you are using.

 

[Harleys Papa]

Just a thought, but the band looks like its smaller than the drum and its only grabing on the high sides and not the whole drum :shrug:

 

[mardyn]

Just a thought, but the band looks like its smaller than the drum and its only grabing on the high sides and not the whole drum :shrug:

Hmmm...

The current band hits about 75% of the drum. I wonder,should it be more?

I originally ordered the band based on the diameter of the drum... maybe a slightly larger band would offer more surface/friction area.

mardyn

 

[The Restore Kid]

I think the most of the problem is like you said, and the handle pulling a cable at the end of the band, can't dump enough friction load into it to really get any stopping power.. If the drum was the size of the tire you'd have a better chance, OR putting them on the clutch gains you a %14,000 advantage...

But a strap around a drum half the size of the rear wheel they are bolted to, is why they built those levers that give you like a %300 pull gain by hooking your brake cable at the long end, and the band to the lower end of the lever, to gain leverage on it..

I'm not sure who I saw had one.. Yellowhand is good with stuff like that.. :laugh: I think they were factory built for that purpose though..

 

[Harleys Papa]

Hmmm...

The current band hits about 75% of the drum. I wonder,should it be more?

I originally ordered the band based on the diameter of the drum... maybe a slightly larger band would offer more surface/friction area.

mardyn

If you look at the pic you can see the bottom of the band hanging down below the drum and the huge space between the band ends and the spring and cable dragin on the drum, most band brakes I've seen the ends have been a lot closer

 

[TeamCheap]

Hmm.....and there is no binding of the cable any where...how does the cable and brake lever feel when disconnected from the drum.

 

[mardyn]

Here's a few more detailed pics of what I'm working with...

Lever assy:

Band/Drum/Cable assy #1:

Band/drum assy#2

I appreciate everyone's help... more thoughts and ideas are welcomed.

 

[Harleys Papa]

Can you take a pic of the drum while pulling on the brake?

 

[mardyn]

If you look at the pic you can see the bottom of the band hanging down below the drum and the huge space between the band ends and the spring and cable dragin on the drum, most band brakes I've seen the ends have been a lot closer

I think you're on the right track there HP....

a larger band may be the answer.

 

[mardyn]

Can you take a pic of the drum while pulling on the brake?

Maybe... give me a few minutes.

Okay, here it is with me squeezing on it pretty hard.

mardyn

 

[TeamCheap]

IDK....looks good to me might just be as stated earlier......contaminated or glazed brake pad.

 

[derekbmn]

Yeah it really looks like a larger band is needed. What is the diameter of the drum ? The band looks to be the standard 4". I know Manco used an odd size drum on some of there bikes.