Bad vibration - think I found it

[Homerexplorer]

For about the last month and a half I have been getting a really bad vibration when I back up, turn the steering wheel to the right and apply the brakes (backing out of the driveway). This is the only time it happens and its usually when it sat for a while (6 hrs). It almost felt like a really bad tie rod that was letting the front end shimmy. I've recently replaced most of the front end suspension but I double checked it to be sure. I had bled the brakes 2x thinking I may have gotten air in the line. I took the rear brakes apart to make sure the parking brake wasnt hanging up. I checked the rear bearings, the differntial gears, seals...nothing.

Saturday, I jacked up the front driver's side to check everything again, including bolts, bushings, bearings, etc. I cleaned and inspected everything and couldn't find a thing. Just as I was going to recompress the caliper, I decided to press the pedal to check the pistons - There it was! One of the pistons was hung up. I worked it in and out (compress, push the brake pedal, repeat) about 6x until it would move somewhat freely and then I put it back together. I have not been able to get the vibration again. The puzzling part was that it wasn't pulling when I hit the brakes - the only symptom was in reverse like I described above. I'll probably have to replace the caliper but short term it is working. Just thought I would post in case someone else was beating there head against the wall.

 

[shamaal]

Odd, I would have thought there would be excess wear on the pad. Sounds like the caliper's a replace candidate. Thanks for the tip!

 

[Homerexplorer]

I thought the same thing but it looked decent.

 

[ExplorerDMB]

If the piston in the caliper is getting "hung up" then it may look ok but needs to be replaced! It's best to do both sides at the same time and to replace the rubber lines as well! Just a recommendation

-Drew

 

[Homerexplorer]

If the piston in the caliper is getting "hung up" then it may look ok but needs to be replaced! It's best to do both sides at the same time and to replace the rubber lines as well! Just a recommendation

-Drew

I was referring to the pad itself - it looked like it was worn evenly which was kind of surprising. I will probably replace it this weekend. Any advice? How concerned do I have to be about getting air in the master cylinder?