Setting up drum brakes

[Tommo]

I have a 1971 750sf with drum brakes. I took off the operating arms to have them re-plated as they were looking rather sad. Can anyone explain how to put them back on, and set them up. On the rear, trying to put on the longer operating arm seems to be a real puzzler, put on the short arm at the top connect it to the square shaft ok, try to put the longer arm on and somehow you seem to need to insert the pin and turn the square shaft to get it line up with the square hole in the arm????
i would really appreciate some help, either pictures or an explanation.
many thanks.
Martin

 

[Paul Marx]

It would appear that your 71 SF has the later series two type brakes, at least at the back.
You aim to have both shoes contact the drum at the same time.
It's easy on the first type brake with the two independent arms. More difficult on the second type brake with one long, one short arm and a rod with a spring in between.
Putting the arms on is easy. If you've had them chromed, you might need to relieve the chrome with a file to get the arm on.
If you have the second type brake, put the arms and linkage on before fitting the springs to the brake plate. Adjust progressively on the linking arm and when you're satisfied that both shoes are contacting the drum at the same time, in with the cotter pins and put the springs back on between the shoes.
If you've put in new shoes, it's vital to chamfer the leading edges of the shoes.
Paul