guy53 Posted August 12, 2016 Report Share Posted August 12, 2016 Back in the days... Yes I am that old, the brake where made to slow your bike down to a complete stop, if you where brillant enough to judge the speed you where going in comparaison to the point you aimed for that complete stop. Now, I can understand that one wish to make old drum brake as good as new disk one, but, experience say's that the more effective you make those drum brake, the less time they work that good. I wish I would know why. Guy 1 Quote Link to comment Share on other sites More sharing options...
pschrauber Posted August 13, 2016 Report Share Posted August 13, 2016 You should even with a drum brake have the possibility to lock the wheel, that's mandatory for any rod registration at least where I live. Quote Link to comment Share on other sites More sharing options...
prelit Posted November 9, 2016 Author Report Share Posted November 9, 2016 Hi guys, Sorry for the lateness in feed back. I did eventually have the shoes re-lined with oversized woven friction material. I spaced the shoes from the cam with shims so once machined to the hub dia. l would have some lever free play and no binding. I also drilled some small holes through the shoes and lock wired them closed although l don't think this is was necessary now. The material was far easier to machine than l feared. I gave the tool a quick sharpen for the final cut. Anyway the brake after a few applications is by far the best I've experienced. Very progressive and powerful with a nice firm lever feel . With 1 finger pressure will perform nose wheelies. Cheers 2 Quote Link to comment Share on other sites More sharing options...
iconic558 Posted November 9, 2016 Report Share Posted November 9, 2016 (edited) You know that trick with disc brakes about getting them very hot then cooling the disc quickly with water? Well I wonder if this could be transferred somehow to drums....I don't know maybe, heating the drum brakeface using a flame? Just thinking out loud, some swear by that water on the disc method. Edited November 9, 2016 by iconic558 Quote Link to comment Share on other sites More sharing options...
bashplate Posted November 10, 2016 Report Share Posted November 10, 2016 not heared that one before....what is the outcome of heating then quenching the disc? Quote Link to comment Share on other sites More sharing options...
tony27 Posted November 10, 2016 Report Share Posted November 10, 2016 not heared that one before....what is the outcome of heating then quenching the disc? Generally gets rid of any film on the disc & improves braking as well as stopping the groan you quite often hear, possibly has an affect on any glazing of the pads. It does work although sometimes it requires more than 1 go. If the pads or disc have been contaminated with grease or oil it is likely to have no real effect Quote Link to comment Share on other sites More sharing options...
feetupfun Posted November 10, 2016 Report Share Posted November 10, 2016 Discs can be severely heated and not affect the hub, but if you heated up a drum to the temperature that people heat discs to to water-quench-clean them, the bearings would fall out and the grease would catch fire, and if you have a Bultaco hub with the replacement steel or cast iron liner fitted, the liner would probably fall out 5 Quote Link to comment Share on other sites More sharing options...
still trying Posted November 11, 2016 Report Share Posted November 11, 2016 Just a thought If you consider the cam as it rotates from horizontal (parallel to the shoes), say 10 degrees, the edge travels a larger distance vertically, than when the start point is say 60 degrees. This means that the mechanical advantage (or clamping force) is significantly greater when starting at 60 deg by almost a factor of 10 (if my maths is still functioning). That would mean that the clamp force would be 10 times greater, = better breaking. With the factory shoes thinned to match the drum, is this the cause of the increase in breaking effect? As mentioned above the sand blasting could be making the surface "slippery" as blasting can produce rounded indentations rather than sharp vee like indentations, depending on media and material being blasted. I'm guessing that the surface has worn from all your testing etc, and the blasting is no longer having an effect. If it is still there, then maybe it needs looking at. Thanks for all your testing as I will be heading down that road soon to. Let us know how it goes, cheers Quote Link to comment Share on other sites More sharing options...
guys Posted November 11, 2016 Report Share Posted November 11, 2016 You're assumption, that the brake force is much greater with the cam at 60°, is correct, but at that point you run the risk of completely locking the brake shoes with the cam at 90°, when you apply to much force. 1 Quote Link to comment Share on other sites More sharing options...
feetupfun Posted November 11, 2016 Report Share Posted November 11, 2016 still trying, you have ignored the friction at the interface between the cam and the rubbing plate and this friction causes loss of feel that gets progressively worse as the angle increases, and as guys says, jamming on of the brakes at higher angles. The best feel and strong braking is achieved by matching the shoes to the drum and minimising the cam angle. Depending on the cam width, 3 to 5 degrees cam angle is usually enough to provide a suitable working clearance for the shoes 1 Quote Link to comment Share on other sites More sharing options...
still trying Posted November 14, 2016 Report Share Posted November 14, 2016 The angles were only to illestrate the point. If the NOS shoes were a smaller dia then clamping force would be greater possibly giving the improved breaking. Making results difficult to compare. However, The good news is that Prelit has done the hard yards and got a solution. Prelit, Could you please find out the name/grade for this break material, as I would like to follow your lead. I'm in NZ and will use a local to reline the shoes. Like you I'll do the machining. The front break on my project KT is not the best, (one of many setup areas yet to sort out). Quote Link to comment Share on other sites More sharing options...
jc2 Posted November 14, 2016 Report Share Posted November 14, 2016 The other thing to consider is that as the actuator cam gets closer to 90deg, the amount each shoe is forced out into the hub gets closer to being the same for both shoes, potentially bringing the second shoe more into play for increased braking effect. That's not to say that I'm suggesting it should be run close to 90deg, for the reasons given above. It's always a trade-off, a compromise with pros & cons each way. 2 Quote Link to comment Share on other sites More sharing options...
shakennstirred Posted November 15, 2016 Report Share Posted November 15, 2016 (edited) Fitted some new brake shoes today on the Beamish While it was apart I moved the brake arm to where its meant to be, it had been in the wrong place since I bought the bike back in April. even without bedding the new shoes in, its feeling a lot better than before. Only one spline out but makes a difference How it was how it set now (there is even a mark on the cam to show where its meant to be) Edited November 15, 2016 by shakennstirred 1 Quote Link to comment Share on other sites More sharing options...
prelit Posted November 16, 2016 Author Report Share Posted November 16, 2016 Hi guys, Sorry can't give you the trade name of the 'woven' material. I rang Villiers Services who did my shoes yesterday and asked the question but they send the shoes to a 3rd party for then lining process. I believe the 3rd party is a supplier who services the truck and trailer industry. The description Villiers Services gave was 'Woven Sintered'. The material is light brown and has metal (brass?) particles in-bedded. As I said the brake performance now is the best I've ever experienced with a drum brake and would recommend this lining material, talking with some other guys who have also tried this material complain of them been a little too 'grabby', however I like the aggressive feel at very slow wheel speed as it instantly transfers the weight. The brake is still nice and progressive. I've not tried them wet as yet. Cheers Prelit 3 Quote Link to comment Share on other sites More sharing options...
eagle8 Posted November 16, 2016 Report Share Posted November 16, 2016 That sounds like the sort of lining i use for my tlr 250 & i've been told it's for fork lifts, so it's made for a harsh environment ie oil grease & other things that may be on a factory floor Quote Link to comment Share on other sites More sharing options...
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