4-15-2014 From Caradiodoc - Expert
We go by feel, not number of revolutions. The number of revolutions will vary according to how hard you spin the wheel. That is not a valid indicator. If you recently replaced the shoes, and the drums are used or were machined, the diameters of the shoes are not going to match the diameters of the drums anyway. The shoes will only contact the drums in their center area. You won't have much stopping power from them for the first few hundred miles until that center area wears down. Over-tightening the shoes will cause them to wear and match the drums faster, but it will overheat them and melt the binders in the linings. That will cause glazing and brake fade.
The shoes can move out a lot during brake application without an unusual drop in the brake pedal. If you leave the shoes adjusted down so the wheels spin freely, they're just going to self-adjust on their own very quickly.
Also be aware that on most drum brake systems, as you manually adjust the shoes out, one will hit the drum first and can give the illusion they're properly adjusted. In fact, if you keep tightening them, the other shoe will get pushed out until it also hits the drum. If you go by how much the wheel spins by hand, the second shoe might not even be making contact yet.
With new shoes, I prefer to manually adjust them until the wheel can still be turned, but with a good amount of effort. It sure won't coast even part of a revolution on its own. That sets the shoes to where they'll wear the center area down quickly, and from there they'll self-adjust on their own.
Wednesday, April 16th, 2014 AT 9:26 AM