2005 Kia Rio Knocking/Grinding When letting off accelerator

VONSPYDER

MEMBER
2005 KIA RIO
4 CYL
FWD
AUTOMATIC
90,000 MILES

I have a 2005 Kia Rio Wagon, Automatic. Recently I noticed whenever I am coasting (let off the accelerator from ANY rpm) there is a knocking (And if slow enough a knock-then-short-grind) that is consistent with the vehicles speed and it is definitely coming from the front drivers side. Also, whenever braking FIRMLY (not hard, just firm) the vehicle will slow smoothly, then eventually shudder then proceed to slow down smoothly again. I checked the CV boot and it is entirely in-tact, the rotors are smooth and not worn. The car was recently in an accident (I rear ended someone at 30mph). The car drives fine, accelerates fine, makes no noise when accelerating gently or hard, this is ONLY when letting off the gas. Any ideas guys?

1 Reply

JACOBANDNICKOLAS

MECHANIC
109,896 POSTS

I would start by checking ball joints, control arm bushings and making sure the CV joint itself doesn't have too much play. Even thought the boot is good, the joint can go bad. Check for play in the axle where it goes into the transaxle. The frame may have slightly moved in the accident allowing the axle to move around too much.

If I had to guess, I would say it has to do with the axle itself. When under a load, there is too much force on the axle to have a problem. Once you back off the gas, it freewheels allowing play to surface.

Let me know what you find.