attleej Posted July 19, 2022 Share Posted July 19, 2022 Dear All, I have reposted this in a more appropriate place. I have a problem with some commercial trailer brake shoes and drums. In days of old it was common to grind the radius of brake shoes to match the diameter of the brake drum, especially if it had been skimmed. This was often achieved using a rig that would be mounted on the axle. On the internet I have also seen rigs where the shoes are mounted on a grinding rig. The drums have all been skimmed to different diameters depending upon how badly they were damaged. I have been told that matching the shoes to the drums will make for a big improvement in efficiency and it is easy to understand why. Nowadays it is more economic to start again and fit new shoes and drums. I would do that but for the fact that drums are not available. There are also quite a few drums involved. In terms of wear, the shoes are nearly new and will be non-asbestos. The first question is, does anyone know where there is a commercial vehicle brake grinding rig available to buy, rent or borrow? Condition does not matter because there is very little that I cannot rebuild. The second question is about the grinding material. I could make a bespoke brake shoe grinding rig by using my vertical milling machine, the rotary table, a jig to mount the shoes and a spindle mounted grinding ‘wheel’ or drum. Can anyone recall what grinding medium was used? I am thinking of using drums about 3” dia and 5” long, similar to the drum sander we would use with a die grinder but much bigger and more precise. Before anyone gets too excited about H & S I would use an industrial vacuum cleaner to suck up the dust. Any help or advice would be much appreciated. John Quote Link to comment Share on other sites More sharing options...
Johnny Posted July 22, 2022 Share Posted July 22, 2022 Grinding of brake shoes is quite common in the motorcycle world, but I'm struggling to find anything on it for larger vehicles. There are several methods used on bikes, and one of these could probably be scaled up for your use. Uneven shoes and poor braking is common with Lambretta scooters and there are at several methods in use. There is a modified hub setup which incorporates a series of files to trim the shoes. I have also seen a version of this which used razor blades instead of the files: Innocenti Lambretta Brake Shoe Skimming Tool in Action | TECH - (scooterlab.uk) There is another tool which mounts onto the axle and uses a blade to trim the shoes: BRAKE SHOE CUTTING TOOL LAMBRETTA (buzzsolomoto.co.uk) And this type which uses abrasive paper attached to a band. I have done similar by gluing coarse emery paper to the inside of the hub: Brake Shoe Sanding Tool | Cambridge Lambretta Workshops I also found this which uses an axle mounted rotary cutter for skimming both the shoes and hubs: Brake Arcing Service by Race Tech - Motorcycle Classics Quote Link to comment Share on other sites More sharing options...
attleej Posted July 25, 2022 Author Share Posted July 25, 2022 Johhny, Thank you for this. I think that I will go for a jig on the rotary table using either a shell mill cutter or an abrasive drum. I will have to do some experiments. It is surprising that no one else has come across this issue. Normally the forum can advise on any problem. John Quote Link to comment Share on other sites More sharing options...
edski Posted July 25, 2022 Share Posted July 25, 2022 Hi attlej, This was common practice some years ago but with the improvement of materials and tolerance of brake components now not carried out, the " Brake Doctor " as the rig was know as now been discarded. It was quite an agricultural affair and not as complicated as you might think. The cutting tool was a cranked carbide tipped bit in a adjustable head. One of the problems encountered was machining of the shoes too accurately which would then cause binding with the increase in temperature when in use. PS this was carried out at our workshops in Portsmouth. Quote Link to comment Share on other sites More sharing options...
roy meddings Posted July 26, 2022 Share Posted July 26, 2022 a company called nutexa ltd can regrind most lining/shoes.try them Quote Link to comment Share on other sites More sharing options...
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