pschrauber Posted May 8, 2011 Report Share Posted May 8, 2011 I just replaced the brake shoes to my Bultaco, got replacement ones and installed them. when I mount them without axle all seems OK, there is some space so they should run free. BUT when mounting the axle they don't fit the pads slide very strong. Some options: - mill away a mm or so on each side of the supports to the cam, (they look thicker) - mill away the sharp edges at the beginning and the end of the linings? - get another pair of shoes that fit - ... Any better or other suggestions how to align the lining so they fit again. It's "difficult" to see where the problem is. By the way the axle is not bend! Quote Link to comment Share on other sites More sharing options...
nigel dabster Posted May 8, 2011 Report Share Posted May 8, 2011 I just replaced the brake shoes to my Bultaco, got replacement ones and installed them. when I mount them without axle all seems OK, there is some space so they should run free. BUT when mounting the axle they don't fit the pads slide very strong. Some options: - mill away a mm or so on each side of the supports to the cam, (they look thicker) - mill away the sharp edges at the beginning and the end of the linings? - get another pair of shoes that fit - ... Any better or other suggestions how to align the lining so they fit again. It's "difficult" to see where the problem is. By the way the axle is not bend! I would go through the process of making the shoes fit and taking material off these unless they are a long way out? If you can be bothered then make sure the whole shoe is touching, engineers blue is good for this job. are your hubs re-lined? The other thing is to bush the pivot point to make sure there is no play her make a real difference to how the shoes work. If you ride in water grooving the shoes (correct direction) can help also. finally longest brake arm you can get. Quote Link to comment Share on other sites More sharing options...
hewson Posted May 8, 2011 Report Share Posted May 8, 2011 Is that a bush fitted in the back plate ???? Quote Link to comment Share on other sites More sharing options...
trialsrfun Posted May 8, 2011 Report Share Posted May 8, 2011 (edited) Brake lining material comes in different thicknesses, possibly the new shoes are fitted with thicker linings and need to be reduced (thinned down) to fit in the drums. You could chamfer the leading and trailing edges to begin with then if they still do not fit remove a little material from the whole surface area with a rasp or sandpaper, not very easy though to keep the shape. Edited May 8, 2011 by TrialsRfun Quote Link to comment Share on other sites More sharing options...
nigel dabster Posted May 8, 2011 Report Share Posted May 8, 2011 Is that a bush fitted in the back plate ???? Yes, bronze or similar, usually, and not without obvious reason the splined shaft wears against the ally back plate. this allows distortion and inefficiency. Quote Link to comment Share on other sites More sharing options...
pschrauber Posted May 8, 2011 Author Report Share Posted May 8, 2011 (edited) Thanks for the good advice. Unfortunatly I don't have any engineers blue, only tracing paper and chalk. In my destitution I therefore chose chalk, which worked somehow. It looks like the lining of the one brake shoe is completly too thick, (beside one triangular edge, which must be a production failure). The other side touches the hubs "only" in one quarter of the "shoe area". Milling down so much, without any special equipment, mmmh ... sounds like a job where you have to use a lot of "elbow grease" without knowing if it ever will turn out right. I will sleep about it, we'll see what the next day will bring. BTW.: - My hubs are not re-lined, they are still ok. - I believe I have the right brake arms, they are very long and out of steel. Yes, theese brakes are not so good, they are crap in water, the chrome plating inside the of the hubs have the tendency to chip of. The action is bad, the front brake arm looks out like a figurehead of a sailing ship. the rear brake "feeling" is bad because of the long cable. ... It's a Bultaco ..., I have a 1979 TY too, switching the bikes is a complete different experience when it comes to braking. Edited May 8, 2011 by PSchrauber Quote Link to comment Share on other sites More sharing options...
nigel dabster Posted May 9, 2011 Report Share Posted May 9, 2011 Thanks for the good advice. Unfortunatly I don't have any engineers blue, only tracing paper and chalk. In my destitution I therefore chose chalk, which worked somehow. It looks like the lining of the one brake shoe is completly too thick, (beside one triangular edge, which must be a production failure). The other side touches the hubs "only" in one quarter of the "shoe area". Milling down so much, without any special equipment, mmmh ... sounds like a job where you have to use a lot of "elbow grease" without knowing if it ever will turn out right. I will sleep about it, we'll see what the next day will bring. BTW.: - My hubs are not re-lined, they are still ok. - I believe I have the right brake arms, they are very long and out of steel. Yes, theese brakes are not so good, they are crap in water, the chrome plating inside the of the hubs have the tendency to chip of. The action is bad, the front brake arm looks out like a figurehead of a sailing ship. the rear brake "feeling" is bad because of the long cable. ... It's a Bultaco ..., I have a 1979 TY too, switching the bikes is a complete different experience when it comes to braking. ...........which is why with a little effort you can gain alot! A rasp (rough file) should be fine for removing brake material, avoid the cable and use a rod will help alot. Brake arms should be aluminium. Re lining will give a better brake than chromed ally. Tracing paper thats novel? ooooohh forgot a lovely mod on the brake spring, shall I share with you?????? Quote Link to comment Share on other sites More sharing options...
pschrauber Posted May 9, 2011 Author Report Share Posted May 9, 2011 ...........which is why with a little effort you can gain alot! A rasp (rough file) should be fine for removing brake material, avoid the cable and use a rod will help alot. Brake arms should be aluminium. Re lining will give a better brake than chromed ally. Tracing paper thats novel? ooooohh forgot a lovely mod on the brake spring, shall I share with you?????? OK, will get a rough file rasp, when I understood right I should better use a rod file then a flat one? The 175cc Bultaco had alloy ones, this bike have steel ones front and back! These where the original ones that came with this bike, they are really loong, but my model has been made for Italy in 08/1981? "tracing paper thats novel" sounds very british sadly I'am not so sure what it means. Oh yes please, I'am very interested in any modification that helps, (I mounted a slightly heavier spring to the rear brake shoes, so the brake action might be a little bit more clearly (I hope)). Quote Link to comment Share on other sites More sharing options...
nigel dabster Posted May 9, 2011 Report Share Posted May 9, 2011 OK, will get a rough file rasp, when I understood right I should better use a rod file then a flat one? The 175cc Bultaco had alloy ones, this bike have steel ones front and back! These where the original ones that came with this bike, they are really loong, but my model has been made for Italy in 08/1981? "tracing paper thats novel" sounds very british sadly I'am not so sure what it means. Oh yes please, I'am very interested in any modification that helps, (I mounted a slightly heavier spring to the rear brake shoes, so the brake action might be a little bit more clearly (I hope)). Take the pea i share nothing. Quote Link to comment Share on other sites More sharing options...
pschrauber Posted May 9, 2011 Author Report Share Posted May 9, 2011 Take the pea i share nothing. Oh are we a little bit the prince on the pea this evening? (*) (after Hans Christian Andersen, some Danish world literature might fit here too). Please keep in memory, to bring the vegetables here to the "table" was not my idea. 1 Quote Link to comment Share on other sites More sharing options...
nigel dabster Posted May 10, 2011 Report Share Posted May 10, 2011 Please keep in memory, to bring the vegetables here to the "table" was not my idea. I gave you an olive branch you failed to take it. Shame on you. Quote Link to comment Share on other sites More sharing options...
toofasttim Posted May 10, 2011 Report Share Posted May 10, 2011 Peter, if you take your shoes, backing plate etc and hub (wheel) to a brake relining shop they will machine the shoes to fit. Quote Link to comment Share on other sites More sharing options...
pschrauber Posted May 10, 2011 Author Report Share Posted May 10, 2011 Peter, if you take your shoes, backing plate etc and hub (wheel) to a brake relining shop they will machine the shoes to fit. Good idea, I have phoned with my lokal KTM shop here in northern Germany they will mount the complete brake (backing plate with assembled shoes) on a mill and then align the brake linings. I send them the brake unit by post wednesday. When I pick the brake up on saturday it will cost me a pound coffee they said. @Nigal Dabster: I still wonder why I should be getting red? Olives and peas does this fit / taste together? Which dish recipe do you mean? Quote Link to comment Share on other sites More sharing options...
pschrauber Posted May 14, 2011 Author Report Share Posted May 14, 2011 Got the brake unit back, that cure worked very well. The chalk contact pattern that was visible is now milled away. (The brake was centered to the axle while milling). It works perfect now. Thanks again. Quote Link to comment Share on other sites More sharing options...
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