- Wed Aug 31, 2016 11:13 am
#62350
Hi Egg,
to clarify, if yours is a 2001 bike it is most likely fitted with a drum brake up front. Specifically this will be a 7 inch internal diameter brake hub, with a pair of brake shoes operating against it, it is a "Twin Leading Shoe" design that tries to maximise brake lining to drum contact by pushing the front edges of both brake shoes into contact with the drum simultaneously.
There are a number of reasons why any drum brake might not be operating properly:
1. Contaminated brake linings, eg with grease as mentioned - use a solvent degreaser to clean out the drum and clean the linings
2. Corrosion in the brake drum, as mentioned, needs de-rusting.
3. Worn-out brake shoes, replace.
4. Seized or partly-seized operating linkage, quite possible if the bike has been standing for a long time, strip the brake down and clean/re-grease the operating cam spindles, but only with just enough grease, too much and you're back to problem number 1.
5. The brake plate carrying the operating linkage is distorted or incorrectly machined meaning the shoes won't line up properly and therefore won't contact the drum properly when the brake is applied. Replace it for a new one.
6. The brake drum has distorted and is oval rather than properly round. This needs to be machined to remove just enough metal to make the brake surface truly round again, which has to be done with the wheel fully built, ie leave the wheel rim and spokes on. This is a specialist job, ideally followed by fitting a new set of oversize brake linings to the brake shoes and having them machined down to match the diameter of the re-machined drum! If the drum is too badly distorted or worn, you'll need a new front wheel, probably yours isn't that far gone.
7. This is particularly important with a Twin Leading Shoe brake, the operating linkage might not be adjusted properly. This would mean that only one brake shoe is coming into contact with the drum, instead of both shoes contacting at exactly yhe same time. Our hosts have some technical notes on this website about how to set the brake up properly, though not all of our experts agree with those notes! Tim NZ has posted on this. You can search back through the forum posts about the Twin Leading Shoe or TLS brakes for more info.
Whew.
You can convert a set of drum-brake forks to take a disc brake front wheel, though it is probably better to fit a set of disc brake front forks as they are designed to cope with the extra stress of the more powerful brake and are (in theory) safer!
A.