In a snowmobile track suspension the slide frame that contacts the ground-engaging run of the track belt is carried on front and rear suspension arm assemblies. The front suspension arm assembly is pivoted to the vehicle on the axis of the sprocket drive shaft. The rear suspension arm assembly is articulated, having upper and lower sections that are rearwardly angled and pivotally interconnected and support in the region of the pivotal interconnection the idler wheel that maintains the track under tension. The arrangement eliminates stretching of the track and lengthens the track life. Furthermore the rearwardly angled arrangement of the rear suspension arm assembly allows easier backward motion of the snowmobile because the lower arm section provides an angle of attack to help the track rise above an obstacle.