Drum Brakes....

[Guest]

I'm currently bring a bike back to life for a good buddy of mine. It's a 1981 Yamaha SR250 with drum brakes in the front and rear. This is my first go around with drum brakes. I'm currently struggling with getting the brakes to work efficiently. The pads have plenty of life left, and the drums are clean of any gunk. I've adjusted them so there isn't any slop in the lever/pedal. It'll stop at slow speeds, but at 20+ mph, they just don't stop the bike like brakes should.

Does anyone have any tips/tricks to get them to work properly? Are 30+ yr old drum brakes just that crappy? Thanks guys.

 

[tkent02]

They can work OK, at least OK for a 250. Try sanding the shoes and then cooking them in again.

 

[GregT]

Depending on how it's been stored the linings can go off with age.
If they don't come back with a sand/scuff to the surfaces I'd replace.
These shoes are still available, Vesrah or EBC I believe do aftermarket replacemants.

Greg T

 

[Suzuki_Don]

If you really want the bike to stop well you need to have the drums skimmed on a lathe to return to a good surface. Then have your brake guy put oversize lining on the shoes and have them assembled on the backing plate and machine the linings down to just fit inside the drum. Your brake guy will know how much clearance to leave.

The idea is to get the drum and brake shoe diameters as close to a perfect circle as possible so that you have the largest possible lining surface on the brake drum surface. If you have the lining circumference out of round then only a small amount of the lining will contact the drum, maybe as little as 10%.

 

[Billy Ricks]

If the front is a double leading shoe there is a special way to adjust it for maximum contact. It's been 30 years or more since I fiddled with a double leading shoe. IIRC you adjust the linkage with the cable a bit loose then adjust the one that connects the two shoes opposite the cable until the shoes just contacts the drum. Then adjust the end with the cable. I think each shoe at the cable end has an individual adjustment. After all those points are adjusted loosen the cable at the handle to back the shoes off the drum. I might still have my T305 manual. If you have a DLS front brake I'll see if I have the manual and confirm this. The DLS is identified by the adjuster at the end of the shoes opposite the cable side.