2003 LEXUS GX470 Power Trainautomatic Transmission Problems

THE TRANSMISSION DESIGN IS DEFECTIVE. THE VEHICLE LUNGES AND THRUSTS FORWARD WHILE THE BRAKE IS FIRMLY ENGAGED AS A RESULT OF THE DEFECT WHICH IS QUITE STARTLING. THE REAR DRIVE SHAFT ALLOWS THE FULL WEIGHT OF THE VEHICLE TO SLIDE FORWARD CAUSING A LOUD THUMP AND PROPELLING THE VEHICLE IN A FORWARD MOTION SEVERAL INCHES DESPITE HAVING THE BRAKE ENGAGED. THE SPLINES ON THE SLIP YOKE FOR THE REAR DRIVE SHAFT ARE NOT DESIGNED APPROPRIATELY.*AK

I BOUGHT THE 470 GX WITH 7 MILES ON IT. IT BEGAN TO "LURCH" AT ABOUT 2500 MILES. WHEN I REPORTED IT TO LEXUS, THEY AGREED THAT THIS WAS A PROBLEM ON SOME OF THE NEW GX'S. THE PROBLEM BECAME WORSE, AND THEY RECEIVED AUTHORIZATION TO REPLACE THE DRIVESHAFT. THIS HAS NOT CORRECTED THE PROBLEM AND THEY ARE AGAIN ORDERING A NEW DRIVE SHAFT. THE REASON I BELIEVE THIS IS A SAFETY ISSUE IS BECAUSE IT ALWAYS HAPPENS AT A FULL STOP, AND IT FEELS LIKE SOMEONE IS HITTING THE CAR FROM BEHIND. THE SAFETY CONCERN IS THE SENSATION OF MOVEMENT OF THE CAR, THIS IS STARTLING AND COULD POTENTIALLY CAUSE A DRIVER TO REMOVE THEIR FOOT FROM THE BRAKE. I CAN'T TELL IF THE CAR ACTUALLY MOVES, HOWEVER IF IT DOES, THIS COULD POSSIBLY LEAD TO AN ACCIDENT (IE. "FENDER-BENDER" OR WORSE AT A PEDESTRIAN CROSSING).*AK

WHEN DESCENDING A HILL AT 40-45 MPH IN DRIVE AND GENTLY PRESSING THE BRAKE PEDAL TO MAINTAIN SPEED TRANSMISSION DOWN SHIFTS TO "4" AND OFTEN TO "3". THIS OCCURS REPEATEDLY, BUT IS NOT PREDICTABLE. WHEN REACHING THE BOTTOM OF THE HILL AND ATTEMPTING TO ENGAGE THE TOP GEAR, I MUST EITHER (1) DEPRESS THE GAS PEDAL HALFWAY AND RELEASE IT OR (2) MANUALLY MOVE THE SHIFT LEVER FROM "D" TO "4" AND BACK.THIS DOWNSHIFTING IS ABRUPT AND UNPREDICTIBLE. I AM CONCERNED IF IT HAPPENS ON SNOW OR ICE, THAT THE VEHICLE WILL LOSE TRACTION AND SLIDE.*AK