Cycling UK Forum

I think I may be cursed. Just measured the thickness of the pads on some new, in the bag, Sturmey 70mm shoes. You can just about tell by eye in this pic that the top pad is thicker than the bottom ( by about a mm)

But if I flip it over .....it' still top is thicker than bottom by a similar amount i.e.the pads thin across it's width.

Would seem in any final shaping/ grinding that the pad was out of perpendicular to the plate ....and once installed I presume they will initially touch only on the proudest edge?......or should I presume there will be some slack at the posts and the shoes will twist a bit to allow more contact ?

So am I right to think this is a dodgy set of shoes?....Or does this ' uneveness' sound like it's within normal/ acceptable/ functional tolerance ?

Perhaps simple DIY brake arcing could bring back to true?
eg
https://www.britbike.com/forums/ubbthre ... ber=523012
http://www.cafehusky.com/threads/homema ... hing.7300/

Someone (D W-S of HighPath?) turned down the inside of a spare drum shell the thickness of the sandpaper for more accuracy.

and if the drum itself is out of true causing pulsing:
https://web.archive.org/web/20191103001 ... ruing.html
https://bootiebike.com/sbf/sbf.htm

hoogerbooger wrote: ↑2 Oct 2024, 9:29am I think I may be cursed. Just measured the thickness of the pads on some new, in the bag, Sturmey 70mm shoes.

You can just about tell by eye in this pic that the top pad is thicker than the bottom ( by about a mm)

But if I flip it over .....it' still top is thicker than bottom by a similar amount i.e.the pads thin across it's width.

Would seem in any final shaping/ grinding that the pad was out of perpendicular to the plate ....and once installed I presume they will initially touch only on the proudest edge?......or should I presume there will be some slack at the posts and the shoes will twist a bit to allow more contact ?

So am I right to think this is a dodgy set of shoes?....Or does this ' uneveness' sound like it's within normal/ acceptable/ functional tolerance ?

I wouldn’t like to say whether the shoes are as they should be or not, but suggest asking the supplier.

You might choose to fit them and see how they work in practise, and in time they’ll ‘bed-down’.

Cursed? Some while back I came to the conclusion that only some SA products were - what I would regard as - sound investments and that design changes by later owners of the brand name weren’t necessarily improvements that I’d find helpful. Maybe pushing your luck with what you have? Well I couldn’t possibly say, but there are reasons why I’ve stuck with a rim braked AW . Admittedly that simple arrangement is not ‘perfection’, but there’s still a lot to be said for it.

Some interesting ideas in the post above, be mindful of (the health hazards of) brake shoe dust.

hoogerbooger wrote: ↑2 Oct 2024, 9:29am.... So am I right to think this is a dodgy set of shoes?.....

yes, I would have said so. As I said in your other thread it looks as if the shoes you have, have not been finish-ground. Normally, part of the bedding in process allows the linings to wear slightly, so as to conform more exactly with the drum. However, we are talking of small fractions of a mm here; the finish-grinding process needs to be pretty good. If the backings are in any way flexible, this is usually fatal. In such cases, the usual result is that the brake works most efficiently when used in the usual way, for only then does the drum radius exactly match the radius of the linings. Some folk think that in this respect, the SA 70 mm brake is superior to the 90 mm version.

btw SA brake shoes have been asbestos-free for a very long time. Nonetheless, it is a bad idea to breathe any of the dust in.

I am cursed then. Two different sets of shoes. One NOS Nottingham: unfinished ......the other new SA Taiwan: mis- finished.

The latter was supplied by a reputable source.....so I will go back to them.

the only other possibility IMHO is that there is something disastrously wrong with your brake plate.

hoogerbooger wrote: ↑2 Oct 2024, 3:23pm ...
Two different sets of shoes. One NOS Nottingham: unfinished ......the other new SA Taiwan: mis- finished.
...

SJS Cycles have this. Is it the right part?
https://www.sjscycles.co.uk/hub-spares/ ... mm-hsb356/

Jonathan

Brucey wrote: ↑2 Oct 2024, 4:55pm the only other possibility IMHO is that there is something disastrously wrong with your brake plate.

It's nothing to do with brake plate as neither set of shoes have been used. Both appear to have been badly finished........although as I appear to be cursed....if I get a good pair of shoes......I'll then find there is also a plate problem!!

( I'm staring at a baked bean tin currently, OD 73mm ish mm....wondering if I could line this with emery cloth and spin this rather than the brake plate ......might then be able to use the brake arm to slowly advance the pads onto the cloth?....... Lining it up could be an uggr tho)

Can I ask who is supplying your brake shoes.. ? A quick squiz on sjsc's website shows the kit having uniform thickness brake pads in both shoes, a new cam and spring. Further more there's recommendations from customers adding that they found the replacement shoes easy to fit.