2005 Silverado transmission shudder

My Silverado has a shuddering feeling in the steering wheel when shifting.Auto. trans fluid looks clean.Seems worse @ lower speeds.

Tires??

transman

I dont think so.It also will bang a little on accel. to pass.I have also noticed their is a pop sound when rocking the wheel side to side,I can see the rack and pinion flexing left to right a little (almost like tie rod ends).Also feel it with your hands on rack.