The BSA A7-A10 Forum
Technical (Descriptive Topic Titles - Stay on Topic) => Frame => Topic started by: tony on 14.10. 2017 19:24
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I want to replace my front brake. I don't know whether my drum has been skimmed out, so I need to know if the standard size is 8" inside the hub or more. I haven't taken it apart yet to measure things up. I've seen on the internet different size shoes but I'm a bit confused of the types, as the brake shoes I have fit on the pivot pin as they have a curve on the end. But all the ones I've seen have flat ends and say they are for full width hub 8".
If my drum size has been over sized, I can't buy any, I need to get my shoes re lined. But if not can anybody advise where I can get shoes that fit or a good company that would re line them over sized to fit hub.
Appreciate any help or advice you can give. Thanks, Tony
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The flat ended shoes are floating shoes, claimed to provide an improved brake.
See photo of A10 8 inch full width brake. Leading shoe at bottom and trailing above.
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I'm probably way wrong, but I'd've thought the leading shoe would be more effective/ wear more evenly if the lining is further towards the cam ? *dunno*
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I once assembled the shoes the wrong way and found that the braking was severely reduced.
The self servo effect pulls and slides the leading shoe towards the pivot.
From what I have read the leading shoe lining was so positioned to prevent grabbing.
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If your shoes are the 29 mm wide type as on my 58' SA FWH you'll have to get them relined anyway. New 29mm shoes can't be found anywhere. In desperation I bought a couple of the same form but 35 mm wide bonded shoes which I machined down to 29 mm but they where rubbish. I ended up relining the original (riveted) shoes with NOS Ferodo linings which I should have done in the first place. 100% improvement that was!
Mine also have the curved ends like yours. If set up well and lined with the correct linings they will work very well.
When installing them, loosen the pivot pin and apply and hold the brake as hard as you can and then tighten. This action will push the pivot pin outwards and give you a maximum contact surface when braking.
Having the drum skimmed don't necessarily mean you'll need thicker linings. After all it should only be a couple of thou that needs to be removed.
A quick Google made these people come up who seem to offer a good service in relining;
http://villiersservices.co.uk/index.php?main_page=product_info&cPath=21_99&products_id=146&zenid=1pc4anrpmi9qv2nb4asp1teib6
But I'm sure there's others close to you