7" Brake shoes...Too Tight?

Thanks Dave...you've made a nice job of it...Pretty sure I did not put the message in the title box, but it all went haywire when I pasted the message in the correct box but presumably in a non-compatible font style.....Les

Thanks Gordon for getting back on this, it certainly proves that the problem with the shoes was not just a one off. I was thinking that one way to prove the incorrect size is to make up the pivot end on a small piece of steel so the pivots are spaced at the correct distance equivalent to the double hole washer and locking tab that fits on the pivot pins. Then insert the shoes and open them fully to contact the drum. Then measure the distance between the flats of the shoes pressure plates, which should be at least equal or slightly more than the width of the operating cam. If this is less then the shoes will never fit the drum, perhaps I'll email Roger at RGM to suggest this as I believe quite a few buyers have had this problem. By the way, The only difference between the front and rear brakes in my case was the cam spindle profile. The front one was a full oval shape whereas the rear one was a rectangular block shape with just the ends rounded off. However as far as I know the maximum width across the cam is the same in both forms and indeed is the same as the actual cam spindle diameter.

The real negative is that as I have sanded the shoes down by hand they are far from a perfect match to the drums circular shape and will need extensive running in to get full contact (they hardly work at all at present) and of course I have also reduced the life of them by turning the shoes into dust just to get them to fit...so not pleased.....Les

PS. It would nice to hear from as many others as possible who have had this problem so I can get this info to RGM to make it absolutely clear to them there IS a genuine problem...Thanks....Les

PPS...Just an amusing anecdote. Way back in the very early sixties, my friends older brother replaced the rear brake shoes on his 150cc D3 Bantam. These were very tight and rubbed badly but he thought he could overcome the problem by greasing the brake shoes!. After spending lots of time and cursing he did all the work again and took the little bike for another ride. After 5 minutes he returned looking and sounding very depressed. "Oh dear" he sighed sadly "They don't work at all now"......

Oh the joys and wonderful memories of learning motorcycle mechanics........

Thanks David and Bob.

David, as regards the possible deliberate over sizing of the linings that very same thought also occurred to me, but I reasoned that the numbers of these people would be far in the minority compared to the bulk of purchasers who just want to fit the shoes normally and bed them in over a few miles usage. Furthermore Roger at RGM never mentioned this when we discussed the shoes, saying that he had others who had had this problem might have fitted the end slippers by mistake, reiterating that they are made to fit as standard. (Note this conversation was had before I had tried the second set for my rear brakes so had not encountered the problem myself at that time). I have also pondered on the friction aspect of area vs pressure but what can be safely assumed is that the bigger the diameter of any rotating brake compared to the wheel diameter the more powerful the brake. For example: an 8" brake will inherently be that much more powerful than a 7" brake simply due to the mechanical advantage (levering action) the bigger brake has from the spindle. Conversely, a smaller size wheel will also be more effective in braking terms for any given size brake for the opposite reason in that there is less mechanical advantage to oppose the braking force compared to a larger diameter wheel...

Thanks Bob. yes I should have done the same as you...file the pressure plate ends down. I was rushing somewhat and didn't want to remove the bolted in shoes so I thought I could do a quick sand down of the friction surface and they would fit. Unfortunately I hadn't realised just how much I would need to remove and I didn't save anytime in fact I had to remove the shoes anyway to be able to fully sand them enough...I also realised later that a quick method to get the plates reduced would have been to have a belt sander set up or held by a second person and simply use this to remove the metal reasonably accurately and squarely rather than attempt to file them.

So it does look like Roger will have to look into this sizing aspect for these otherwise excellent shoes.

Les