Quote from: BSA_54A10 on 31.01. 2019 13:53Next is incorrect radiusing of the shoes.To work as intended the shoe must have a LARGER radius than the drum so the initial contact will be at the end only. ***The leading end digs into the drum which locks onto the shoe and forces it back against the pivot end which can not move so the shoe flexes into the drum.Thus the rotational energy in the drum is supplying the breaking energy , not your grip.Do you mean like this?A trailing shoe marked 68-5525 which is 197mm across and only touches at the extreme edges as seen in the second image, the gap is about 1.5mm. Next to it is a leading shoe which is 191mm across and has good overall contact as shown by the blue ink. Obviously not a matched pair so which size is the best fit?Yes rather like thatThe idea of the steel caps on the brake shoes is so you can shim the pivot end of the shoe to account for wear in the drum.just the same as the oval pivots on the Ariel type hubThe pivot end of the shoe should be as close to the drum as you can get it.The closer the better
Next is incorrect radiusing of the shoes.To work as intended the shoe must have a LARGER radius than the drum so the initial contact will be at the end only. ***The leading end digs into the drum which locks onto the shoe and forces it back against the pivot end which can not move so the shoe flexes into the drum.Thus the rotational energy in the drum is supplying the breaking energy , not your grip.Do you mean like this?A trailing shoe marked 68-5525 which is 197mm across and only touches at the extreme edges as seen in the second image, the gap is about 1.5mm. Next to it is a leading shoe which is 191mm across and has good overall contact as shown by the blue ink. Obviously not a matched pair so which size is the best fit?
Decided to have another go at my 58 A10 full width rear cross over (near useless) brake. Ground off about 35mm of the top of the leading shoe (cam end) lining and filed the cam on the trailing side of the cam so as the leading shoe came on a bit first.The result was a 50% increase in braking efficiency, but still not as good as it should be, but much better than it was. Peter