Everyday TR1 - doing drumbrakes

Whenever I talk to someone, pretty much everyone is quick to point out that drumbrakes don't work as well as disks or don't really work too well at all. After all, disk brakes were the future back then...

Let's start with one Yamaha TR1 rear drum brake, which performs very, very poorly.

The wear pattern looks pretty good, a bit glazed, but looks like it touches on pretty much the whole surface? Wrong.

 After scribing a line with some chalk on the shoe, you see it only touches in one spot.

So what do you do? You get your best handfile (or an electrical one, if you're feeling lazy) and file down that high spot a bit.

Then you draw a new line...

... assemble the whole lot and notice that not much has changed.

So you file it down a bit further.

Rinse and repeat ...

 ... and at some point the wear pattern (and the spots where it actually touches) will start to change.

At this stage you file down the (new) high spots down again, making sure to take off less material every single time.

And once you reach the point, where the spots are distributed pretty evenly over the whole pad, they will actually bed in nicely by themselves. But beware... your rear tire may all of a sudden start locking up under hard breaking even at relatively high speeds (70kph), as I got reminded when testing my work...

Now there's one more aspect that needs some attention, when working on drumbrakes: And that's the mechanics. At full compression of the brake lever the one on the drum should be close to 90 degrees in order to achieve the maximum mechanical advantage.

So in order to do that, the lever had to be moved on the shaft for a better angle. 

And lastly all internal friction are losses, so cleaning and lubing the shaft and the cam is totally worth it.

After lubing the shaft, it would do almost a full rotation just from the weight of the brake lever. Before... well it was more like it was filled with sand. 

The outcome of all this work? After just 80km (50mls) the wear pattern on the shoes looks like this. (Which means, now you touch up the high spots again and after some more kilometers they will actually have bedded in and touch on 70-80 percent of the surface, which is more than plenty...)

Yes, this is a tedious process and you could (of course) go with relatively soft pads, which just mandate you to dust out your drum more often and wear faster, but a good drumbrake-compound actually has to be hard to be able to last some time.