Rat3d M

We just bought a 970 Panamera 4 which has a very nasty vibration when braking. Speed doesnt really matter. It does it basically all the time and seems to vibrate worse/faster the faster the car is going. I thought I would try brake pads which were replaced today but it did not help at all.

The front rotors measured at 35.5mm and seem to be in great condition. The rears are basically done and need replacement but I wouldnt expect this much vibration from front rotors alone. Also the car pulls to the right so it definitely needs an alignment. Wheels are aftermarket 22" Rohannas (I know, I know..).

When I had the car on the lift I checked for wheel play and there was none up and down but I could move both front wheels side to side a good inch or so. This may have just been the steering rack allowing the wheels to turn as normal because I did not see any play in any bushings or anything and all bushings looked to be in good shape.

My next step is to replace front and rear rotors but is there anything else we should look at or try?

K777

If its pulling when not braking and vibrating when braking could be a caliper piston is seized. I had a similar thing many years go with an Lexus IS200, One of the pistons in one caliper was stuck out. The vibration was because the bottom piston was working and so when activated the pads were squeezing the disk/rotor at an angle top to bottom.


I levered it back in /peddled it out a few times and then it was fine. - at least for the 6 months i had it after that.

Although i suppose if you have changed all the pads then you would find if a piston was seized. So maybe not.

justabout

The wheel could be bent. I would check the runout. In my experience a warped rotor will get worse as the disk heats up. If it’s a constant vibration it probably the wheel or the tire is bad if the bushings are okay.

ciaka

If you are on flat road, drive to a stop while depressing brake pedal hard (press pedal really hard just after you stop, to generate a lot of hydraulic pressure in system).
After you stopped, release the brake pedal and observe if your car is moving forward or not.
If your car is not moving forward, means one or more of your caliper pistons are binding. You will also know pistons binding if when you park car, the rotor will be extremely hot (spit at it and see if it boils).
If pistons binding, you gotta replace or at least recondition caliper affected.
If not binding, you could have warped rotor. If your rotor is old, recommendation is to replace rotors and pads together. Rotors cannot be machined (floating).
If you exclude calipers, rotors, and have new pads, the remaining choices are your control arms, tie rods, upper control arms.
Of the three, most likely affecting ones are tie rods, then lower control arms.
Lower control arms have rubber bushings that wear out, giving a lot of play in the steering area, and can easily be manifested as shake during braking.
Tie rods too. Their parts can wear, resulting in more play which can cause vibration during braking.
Upper control arms very similar to lower arms, but because of where the rubber bushings are, it is less likely to cause such shaking, but not impossible depending on how much damage is in the bushings.

So i would eliminate one by one. Start with the cheapest ones, and work your way. It is also likely that more than one thing is causing this, especially if car was not maintained for long time suspension wise.
Of course, it goes without saying that good 4 wheel alignment is a must on this car, regardless of what you do.