Brakes are weak

[GIJoeBob]

I'm getting a 1985 ATC 70 working for my 5 year old daughter and I am almost there. Right now I am chasing a brake gremlin.

The brakes were weak, meaning that I have to squeeze considerably to get some good stopping power out of the brakes - hard enough for me and way too hard for a 5 year old girl. The brakes would never lock up regardless of how hard I would squeeze.

There are new brake pads and a new brake cable already installed. I have tried two different brake drums, with both of them having been sanded and cleaned out.

The brake lever also has a weak return.

Any ideas?

Thanks for your help.

[Ken99287]

i have an idea - since the brake lever has a weak return, perhaps it's not disengaging all the way. since the lever is not disengaging all the way, there is always tension on the brake cable, and therefore the brakes. in order for the bike to be ridden this way, maybe the brakes have been adjusted so that even when the brake lever is halfway down, the brakes themselves are not yet engaged - and when the brake lever is squeezed all the way down, only half the braking power is applied at the actual brakes... makes sense at all?? maybe get yourself a new return spring, then readjust your brakes? I might be totally wrong, but just an idea to try.

[SWIGIN]

i was never impresed with the stoping power of a drum, cable hand brake....does the foot pedal work good?

[GIJoeBob]

i was never impresed with the stoping power of a drum, cable hand brake....does the foot pedal work good?

The 70 only has the hand brake.

[SWIGIN]

lol...shows what i know

anyway, the return spring should have nothing to do with stoping power...only maybe drag when not on the brakes.

it dont make sence but my old 90 had the best drum brakes i ever felt and my 110 didnt and nothing i did could make them as good as the old 90. untill i swaped the drum....then the 110 stoped on a dime and the 90 wouldnt.

[GIJoeBob]

lol...shows what i know

anyway, the return spring should have nothing to do with stoping power...only maybe drag when not on the brakes.

it dont make sence but my old 90 had the best drum brakes i ever felt and my 110 didnt and nothing i did could make them as good as the old 90. untill i swaped the drum....then the 110 stoped on a dime and the 90 wouldnt.

I have tried another drum but it is used as well. A new drum is over $100! I hope that is not the issue.

[Ken99287]

you don't think that because the return spring does not disengage all the way, that the the brakes have been adjusted so that they will not drag even when the spring does not return the brake to it's disengaged position? if they have been adjusted not to drag even when the little arm on the drum is not fully disengaged, don't you think the brakes would then be a bit weak when the arm is fully engaged? i'm not saying that the spring is why the brakes are weak, i'm saying maybe because the spring is weak, somebody may have adjusted.... point of engagement of the brake drum/shoes to account for dragging brakes due to a weak return spring.

[Ken99287]

lol...shows what i know

anyway, the return spring should have nothing to do with stoping power...only maybe drag when not on the brakes.

it dont make sence but my old 90 had the best drum brakes i ever felt and my 110 didnt and nothing i did could make them as good as the old 90. untill i swaped the drum....then the 110 stoped on a dime and the 90 wouldnt.

yes, a weak return spring may make the brakes drag when not on the brakes - maybe they have been adjusted to account for the drag? Instead of replacing the spring, maybe somebody just "loosened" up the brakes some? That way, even though the spring does not fully return the brakes, the brakes are adjusted to be disengaged. If that was done, then even when the brake lever were pressed fully, it would not be at full braking potential... maybe i'm not being clear - this makes perfect sense to me. i'm not saying the spring causes weak brakes. humph!

[Rustytinhorn]

Kinda pointing out the obvious, but is the brake lever itself cinched down too tight, or not operating smoothly? Just thought maybe it could have something to do with it not returning all the way either.

[XL-erate]

Not saying the other suggestions aren't correct, but:

Sure it's the right brake lever on handle bars? There's several that could fit and who knows what might have been installed following a wreck? Also I have modified stock levers, filing down where they come to rest on lever mount. That way lever sticks out farther but allows more total travel.

In order to adjust brakes or clutch I back off all adjustment at lever where cabel attaches, at knurled nut. Then adjust out all slack in brakes mechanical at drum linkage or whatever. After that fine tune the adjustment back up at lever. Otherwise if lever iadjustment s tight when you start you can't ever get where you're going on adjustment.

Even with a new drum and new shoes, or any combination of new/used, the way shoes fit drum is the question. I have marked shoes with chalkboard chalk [DON'T USE A GRAPHITE PENCIL!] and reassemble, then run breaks. Opening brakes up and checking remaining chalk dust tells if full drum contact is occurring. It's called 'arcing the shoes' to grind them in to fit.

Most brake lining material is toxic so wear a good respirator if you decide to arc them. Heavy & medium garnet paper on a block will do it, but don't use Emery paper. Emery can embed in shoe surface and drums are gone in no time. Blow them off with compressed and clean with brake cleaner solvent and a rag to remove garnet leftovers.

[Mr.Jake]

I may be wrong but doesn't it take a bit for new brake pads to be "broken in" to the drum, meaning if theres grooves in the drum the pad is only hitting the groove and not using the full drum to stop, thats why they say when you install new pads to be cautious and stop a bit ahead of time than you usually would until your brake pads start to match the drum grooves

[GIJoeBob]

The weak return spring idea sounds like a good place to start. I am lucky enough to have several other working 70's to compare it to so I will give that a shot.

[TeamGeek6]

make sure both pads are contacting at the same time, drum brake efficiency goes to crap unless both shoes hit at the same time with about the same force. If they dont, then one shoe tries to do the work, and the drum pushes it away. INspect the drum for glazing (metal is smooth). If the surface is shiny, the friction goes down and causes braking loss. If glazed, break the glaze with 600 grit sandpaper (that works for clutches too)

[GIJoeBob]

Can you repair a weak return spring? I cannot find them for sale anywhere.

[Ken99287]

.... it's only a spring

[Ken99287]

NAPA?? AutoZone? AdvanceAuto? Pep Boys? Home Depot, Lowes

[GIJoeBob]

It's not just a typical spring.

It's number 11 in this diagram-

http://i13.photobucket.com/albums/a291/GIJoeBob/7304Gif.jpg

[Dirtcrasher]

Maybe you could take a used spring, get it cherry red and bend it. May ruin the temper though but worth a shot if it is discontinued.

I'd lube that cable up even if it is new and the brake contact post check was a great thing to check too.

Last, I'd buy good quality shoes. EBAY cheapo shoes have cheapo compound. Sorry if I missed that your running OEM or other in your post somewhere...

When I USE to buy cheap pads for the truck, it would stop terrible in the rain and after it got used a few times and heated up. Now I spend more cash and get great results.

[dreadhed]

I think I should have some of those springs. I am working days and nights 7 days a week right now so it might take me a few days to check. You can have it for shipping. Just send me a PM in a few days to remind me.

[GIJoeBob]

I think I should have some of those springs. I am working days and nights 7 days a week right now so it might take me a few days to check. You can have it for shipping. Just send me a PM in a few days to remind me.

Awesome! Thanks!

[Ken99287]

i'm sure you could rig up an external spring as a last resort