H: Hubs, Wheels and Tyres Extended brake linings
- Thread starter Eric
- Start date
Eric,
Carleton Palmer had Vintage Brake do up a set of full length shoes and linings. Despite a lot of expense, he did not like them. As I remember, he said that they were "dead" feeling. I can only guess that the addition of material although increasing the contact area, also increased the flexing of the shoe in a way that created more of a problem.
I don't think there is much you can do with the stock brakes to make them better because the shoes flex so wildly. I think this was covered here in the Brake thread, recently. I would think the best improvement could come from high friction lining materials. By this I mean higher friction that is currently available from Vintage Brake, which seems to apply the most acclaimed lining material. Because there is no commercial interest in these products for drum brakes I don't think there will be any progress made.
David
Carleton Palmer had Vintage Brake do up a set of full length shoes and linings. Despite a lot of expense, he did not like them. As I remember, he said that they were "dead" feeling. I can only guess that the addition of material although increasing the contact area, also increased the flexing of the shoe in a way that created more of a problem.
I don't think there is much you can do with the stock brakes to make them better because the shoes flex so wildly. I think this was covered here in the Brake thread, recently. I would think the best improvement could come from high friction lining materials. By this I mean higher friction that is currently available from Vintage Brake, which seems to apply the most acclaimed lining material. Because there is no commercial interest in these products for drum brakes I don't think there will be any progress made.
David
You will have a better brake if you remove half of the material, the half nearest the pivot pin.
I have run such a system for over 40 years. You can get about 60% more lining area each side. I have twin brake cables with thick and strong inners and outers, long, rear, brake arms and have done away with the balance beam entirely. Aluminium brake plates are used for stiffness with an enlarged centre hole to allow centering of the shoes before tightening up the Tommy bar. If you want even more area then one can get rid of the two pivot bolts and replace them with a single pivot which requires new shoes to be cast and machined.
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No scientific evidence but I can tell you that after carrying out a brake roller test on a car it can be quite amazing to inspect the condition of the discs. Discs with heavy erosion and showing signs of only operating on 1/3 of the usual surface area will provide a brake force pretty similar to new components. I can only infer that reduced surface area is compensated for by increased pressure on the existent area. Perhaps increasing area will only decrease pressure.
Of course the ability to dissipate heat under prolonged braking is another matter.
I suspect that the only way to get a better brake is to increase the overall lining to drum pressure.
I suspect that our wooden shod friend has already achieved this with his twin leading system.
Of course the ability to dissipate heat under prolonged braking is another matter.
I suspect that the only way to get a better brake is to increase the overall lining to drum pressure.
I suspect that our wooden shod friend has already achieved this with his twin leading system.
I have the "Vintage brake" linings in my front brakes using replica Lightning plates and the front brakes work very well. The rear has asbestos linings which have some mileage on them now and don't work as good as they use to. The comments about the brakes not working so well after some use seems to be true, as I have found on several bikes now, the linings and drums look perfect but they don't seem to pull up as good as when they were first set up. Even two up my brakes pull the bike up very well really, although the last time I took it around Lakeside race track after the first "Hard stop" into the "Bus stop" which is very hard on brakes and back to first gear out........The brakes were useless......... It really made me wonder how the old school racers from years ago use to pull up on these bikes.
The physics for frictional force says F=muR where F is frictional force, mu is constant for materials in contact and R is Reaction or the applied force. So the only ways to improve Frictional force is to change the materials or increase the applied force. i.e. the lining area does not change the Frictional force. It probably does improve fade resistance).
Bill
Bill
I think it is the fade resistance some thread here discussed the option of only increasing lining area on leading shoe thus increasing the pressure on the linings over two extended linings while increasing fade resistance where it matters does the same apply by reducing the lining area next to the pivots?