Vibration problem with 2005 Subaru Outback

I have an odd problem with my 2005 Subaru Outback. When driving on the highway, the car will experience vibrations which feel as if something is out of round or out of balance. The vibrations become quite strong and last for a few minutes. Brakes appear to be involved in some way since pulsation is felt in the pedal while this is happening. At other times the brakes seem perfectly normal with no hint of warped rotor or other brake problem.

The problem comes on quite suddenly and only lasts for a short while, then the car will behave normally. For quite a while the problem seemed to be eliminated by removing the fuse which powers ABS but recently I?ve encountered the problem with ABS disabled.

My dealer wants to replace front pads and rotors but the fact that brakes are fine with no hint of warped rotors except when this problem occurs causes me to question that. Note that the problem occurs on a straight road where brakes have not been applied. It feels as if higher heat is radiating from the front left disk when I stop the car during the vibration.

I?ve been wondering if a stuck caliper or piston or problem with pad retraction might cause such a problem.

Al Larsson

i would lean towards thinking it is a sticking caliper.

I recently had a problem with stuck calipers on my Legacy. Brakes pulsed like warped rotors even though they were not warped, and some unusual noise and vibration were felt.

Cleaning and lubrication of caliper slides, along with new pads and rotors, solved the problem.

Thanks to GregDonovan and mcparadise for your replies. Now I’m wondering if there is need to do more than clean and lubricate. The brakes seem fine when the problem is not occurring.

I’d have the pads replaced if they are significantly worn.

I’d want to know if the pads are worn evenly, or if one pad is worn more than the other. If they’re not even the caliper is probably sticking.