Starter for a combustion engine of a motor vehicle, comprising: - an electric motor comprising a yoke and a rotor mounted on a shaft, - a drive shaft able to be driven to rotate by said rotor, - a speed reducer of the epicyclic type mounted between the rotor shaft and said drive shaft, - said speed reducer comprising a ring gear forming an annulus gear of said speed reducer, a pinion rotationally coupled to said rotor shaft forming a sun gear of said speed reducer, and a planet carrier rotationally coupled to said drive shaft, at least two planet gears being mounted in free rotation on said planet carrier and engaged between said sun gear and said annulus gear, - a base plate bearing said ring gear, said base plate being secured to said yoke of said electric motor, - the base plate comprising a plastic portion, which comprises abutment parts situated between the ring gear and the yoke, these abutment parts extending circumferentially around the ring gear, - said ring gear comprising tabs at its external periphery, damping pads being mounted between said tabs and said abutment parts, each damping pad having at least one rounded corner on a salient edge side of a corresponding tab of said ring gear, said rounded corner being rounded with a radius of curvature situated in a plane comprising all the corners of said damping pad, in such a way that there is space between said rounded corner and a right-angle corner defined by the intersection of planes (P1, P2) passing through lateral faces connected by this rounded corner, characterized in that the damping pad has a variable thickness at its ends, and in that the thickness of the damping pad follows a convex curvature in the form of a semicircle at its ends. - an electric motor comprising a yoke and a rotor mounted on a shaft, - a drive shaft able to be driven to rotate by said rotor, - a speed reducer of the epicyclic type mounted between the rotor shaft and said drive shaft, - said speed reducer comprising a ring gear forming an annulus gear of said speed reducer, a pinion rotationally coupled to said rotor shaft forming a sun gear of said speed reducer, and a planet carrier rotationally coupled to said drive shaft, at least two planet gears being mounted in free rotation on said planet carrier and engaged between said sun gear and said annulus gear, - a base plate bearing said ring gear, said base plate being secured to said yoke of said electric motor, - the base plate comprising a plastic portion, which comprises abutment parts situated between the ring gear and the yoke, these abutment parts extending circumferentially around the ring gear, - said ring gear comprising tabs at its external periphery, damping pads being mounted between said tabs and said abutment parts, each damping pad having at least one rounded corner on a salient edge side of a corresponding tab of said ring gear, said rounded corner being rounded with a radius of curvature situated in a plane comprising all the corners of said damping pad, in such a way that there is space between said rounded corner and a right-angle corner defined by the intersection of planes (P1, P2) passing through lateral faces connected by this rounded corner,