I still have vibrations when braking even though I just replaced discs and pads all around.


What can be causing this?

 

The large bushings at the front lower control arms are known for causing a shudder while braking, and commonly wear out on these cars. OEM replacement is Lemforder p/n 2978301, you will need two of those.

This does not eliminate the hub-to-rotor surface irregularities, but I assume you cleaned this surface before installing new rotors. Really the only way to check is with a dial gauge and to measure the runout in the new rotor. This should be done with the caliper removed.

 

HI,
I'm hunting the same problem.
I changed all disks/pads and measured with with a dial gauge.. everything within specs.
I changed tyres from winter to summer. Winter tyres seemed to have a flat spot..

I rattled at my tyres, while the car beeing jacked, but I didn't notice any defects.
How can one diagnose the bushings to be defective ?

 

If the bushings are failed,it should be visible. The bushings will have cracked rubber, offset enter, or be ripped out.
The issue here sounds like ripped out if this is the failure. Cracked should not cause wobble.

 

Safety first. Properly lift and stand your vehicle. One wheel at a time is fine.

I take the wheel off and use my hands first (hands at 9 and 3 o'clock on the rotor) Any wiggle? No? I don't stop there. I use a cheater bar (large pry bar) next and attempt the same thing. You see movement in the bushing? You shouldn't. A partner helps but not necessary.

How confident are you in the quality of the brake parts?
Back in my mechanic days, I found many a customer wanting the cheapest parts and some rotors came from the factory had to be turned.
I only help my kids now and won't put low end car parts on their cars so I haven't seen this happen in years. Perhaps Brutal or another Tech could weigh in here?

Low Tech DIY check for warped rotors:
You can jack up the wheels one at a time and hand spin for resistance. Get the wheel spinning fast and let go. There will be slight drag of course as you have new pads and rotors but if the pads are defective or the rotor is badly warped, you can feel a spot of resistance as the wheel will stop or brake on its own. If you experience this, take it back to the shop and have them check the rotors and pads again. If a rotor is turned correctly, resistance should be even as you spin the wheel. Of course the pad could be the cause too, but shouldn't.

Is the vibration happening only when breaking or at speed also?

 

My questions would be:

Can you feel the vibrations in the brake pedal? That would indicate rotor warp.

Vibration in the steering wheel would tend to indicate suspension faults.

Does it vibrate all the time or only during hard braking. The heavy loads of hard braking would also indicate suspension pieces moving around on you.

I have seen alignment problems cause a shimmy that can show up under braking.

Hope that helps a bit.