Originally Posted by mber
No, I checked the shoes. They are ok. On the right way. I even checked to make sure that the assemblies were on the right side.
I've dismantled all the magnet and ohm them. They all read about 3.2 ohms no short. Amp reading about 3.2amps.
Question, have self adjusted brakes been around for a while? The magnet are extremely small compared to dexter manual brakes. See pictures. I'm wondering if this could be the issues.
Also, has any seen a drum with this type of pattern in it?
I suspect this drum will need to be re-turned. Does anyone know if they turn the part were the magnet contact or should I get two new drum.
I'm not impress with AL-KO brakes.
I think I will replace all the brakes assembly with dexters and get all the drums turned just to make sure there nothing wrong with them as well. As you can see I the picture, they are suspect.
Looking at the picture of your magnet I would say the wear shows poor contact with the brake drum. The way these drums heat up I would not have them turned. Replace them and replace the magnets.
It is the surface contact with the drum and how hard the magnet tries to stick to the drum that determines the braking effort. More power applied to the magnet the more powerful the magnet becomes and the harder it sticks to the drum. By the look of the wear on the magnet I would say you are getting 50% contact to the drum.
The way the brake works is the magnet tries to rotate with the drum when the brake is applied. It can't of course, so it slips. On trying to rotate it pushes the front shoe into the drum. The front shoe now tries to rotate with the drum and does, a little. As it tries to rotate it pushes the back shoe tight into the drum via the adjuster on the bottom. Thus the term, 'self energizing brakes'. This is also why the rear shoe will wear out while the front shoe still looks new. That is also why the long shoe goes on the rear as it does most of the braking while the front shoe just shoves the rear shoe back tight into the drum.
So, to sum it up. If you are only getting 50% contact to the drum with the magnet, full power to the magnet will equal only 50% effort.