Rear Brake problem

[gold33]

Had a nice 50 mile run today between showers with a couple of 50MPH stretches but mostly 30-40MPH.
I have noticed more at lower speeds a tendency for the rear brake to change from a nice progressive feel, not too spongy and great for low speed work to a wooden block with no feel and a lot of power?
I get a sense of a little rotation and then clunk brakes on, nose dives and I lift my foot to avoid a lock-up (feels as if it might lock anyway but I haven't had the heart to find out).

I haven't changed anything at the rear for a while and 2 out of three times today it felt normal.

[muskrat]

G'day Darren,
                  your not playing in that city traffic again. It may be getting hot from all those traffic lights and stop signs, or adjusted a tad tight and dragging a bit.
 Another thought is that the shoes are past their use by date and the cam is at full lift.
Cheers

[bsa-bill]

Hi Darren
Having a few rear brake issue myself, got a load of travel before anything happens (new shoes fitted, drum not worn unduly).
Things I've checked, brake shoe pivot tight, brake anchor arm tight at both ends and the correct length, there are two different lengths for this arm, don't know if this is helpful but worth checking

[gold33]

Thanks Muskrat & Bill,
I have played with the adjustment and know it is not dragging so I will check the linings.
I haven't pulled anything apart yet but I have a lot of grease splatter on the hub.

It takes so long to get out of the city I end up heading up the beaches most trips, all stop start apart from one 50MPH stretch and that is littered with people that won their license in a lottery and Lycra wearers on weekends.

[muskrat]

Some of that grease might be finding it's way onto the shoes.
Cheers

[MG]

Could be one of the brake linings coming off the shoe (loose rivets maybe?), probably on the leading edge.

[BSA_54A10]

I have played with the adjustment and know it is not dragging so I will check the linings.
I haven't pulled anything apart yet but I have a lot of grease splatter on the hub.

try a finger test.
Go out for a ride but do not use the suspect brake
Get off the bike and feel the hub temperature
If it is hot then the brakes are trailing.
A very small amount of wear in the bearings/ axel can allow the brakes to trail when you are on the bike

[gold33]

Thanks Trev'

Yes the drum did get hot...
I can spin the wheel freely when I on the centre stand?
I found the lever was catching on the silencer so kept riding (couldn't miss this magnificent winter weather) but now have to pull it all apart and have a look.
I did a 40 mile ride yesterday and limped home without using the back brake, it started grabbing... like the drum wasn't round.