Drum brakes sticking & locking up?

[Millsie]

Hi there,

I'm about to try and replace the front and possibly rear drum brakes on my 50cc scooter, is there any thing I need to know before getting into this job?

The problem is that the front break locks up when I use it, but it's only in a specfic spot..
(It actually has a little guide showing on the side of the brake, when the 'pointer' runs off the end it seems to lock up - will a replacement of the pads correct this? - check photo )

Cheers!

[unstuck]

That mark is a wear indicator, needs new shoes, and possibly a skim of the drum if it is too worn.

[Millsie]

That mark is a wear indicator, needs new shoes, and possibly a skim of the drum if it is too worn.

Sweet! I'll have a looksee, I had the same problem about a month back.

They said they replaced the shoes but if the problem keeps occuring does that mean the drum needs to be skimmed?

[unstuck]

Yes, I would imagine so unless it has not been put back together correctly.

[neels]

I had the same problem with a drum brake even with new shoes in there, because the drum was worn enough that the cam could rotate to 90° and jam between the ends of the brake shoes.

Putting a shim around the post at the fixed end of the shoes sorted it, a strip cut from a coke can was enough, was on a trail bike though so didn't have to consider if it was a legal fix for on the road.

[Grumph]

The correct fix for oversize drums - which may have got that way through wear or skimming - is to have the shoes relined with thicker material. The backplate complete with shoes then has the lining machined back to match the drum diameter.

I'd assume that most main centers will have at least one automotive brake relining shop who will be able to do this.

I do this as a matter of course when working with classic race bikes but it's just as valid for road use.

[Millsie]

I had the same problem with a drum brake even with new shoes in there, because the drum was worn enough that the cam could rotate to 90° and jam between the ends of the brake shoes.

Putting a shim around the post at the fixed end of the shoes sorted it, a strip cut from a coke can was enough, was on a trail bike though so didn't have to consider if it was a legal fix for on the road.

Luckly with 50cc's only requiring WOF's no one other than me needs to know about it, Muhahaha

The correct fix for oversize drums - which may have got that way through wear or skimming - is to have the shoes relined with thicker material. The backplate complete with shoes then has the lining machined back to match the drum diameter.

I'd assume that most main centers will have at least one automotive brake relining shop who will be able to do this.

I do this as a matter of course when working with classic race bikes but it's just as valid for road use.

Alright, I'll have a look around see if I can find a company that provide that service..
Found one:
Safe Disks in Lower Hutt, lets hope they're not too expensive... Being able to brake again/safely would be really nice...

Cheers for your input everyone!

Now I just have to figure out how to adjust my carb it's caked in so much road gunk can't even see the screws..
I think I'll take it off/out tomorrow

[HenryDorsetCase]

Luckly with 50cc's only requiring WOF's no one other than me needs to know about it, Muhahaha



Alright, I'll have a look around see if I can find a company that provide that service..
Found one:
Safe Disks in Lower Hutt, lets hope they're not too expensive... Being able to brake again/safely would be really nice...

Cheers for your input everyone!

Now I just have to figure out how to adjust my carb it's caked in so much road gunk can't even see the screws..
I think I'll take it off/out tomorrow

just wear jandals and use your feet for outrigger braking, what could possibly go wrong?

[Millsie]

just wear jandals and use your feet for outrigger braking, what could possibly go wrong?

Shit! Never even thought of that, I just got a couple pieces of rope and a few cinder blocks. I just throw them out whenever I want to stop, your way is so much easier!

[imdying]

Yeah, to get those two shoes bonded oversize it'd be about $28. Make sure you take the drum with you so they can radius grind them to suit.