Preheat the oven to 325° and butter and flour a 9-inch springform pan.
In a bowl, using your fingers, combine the flour, brown sugar and salt. Add the butter and mix until smooth. Add the pecans; press the mixture into clumps.
In a bowl, whisk the flour, baking powder, baking soda and salt. In a large bowl, beat the butter and sugar at medium-high speed until light, 3 minutes. Beat in the eggs 1 at a time; beat in the sour cream and vanilla. Add the dry ingredients and beat at low speed until incorporated.
Spread two-thirds of the batter in the pan. Fold the peaches into the remaining batter and spoon into the pan. Scatter the streusel crumbs on top. Bake the cake for 1 hour and 30 minutes, or until a toothpick inserted in the center comes out clean; loosely cover the cake with foil for the last 15 minutes of baking.Transfer to a rack and cool for 30 minutes, then remove the ring and let the cake cool completely before serving.