Help with vibration under braking
 

So I recently changed my rear brake pads from my carbotech xp8 to some project mu club racers. I am getting some very bad vibration in the back when I brake slightly from at least 70 and up to about 60 mph. I noticed this when I exited the freeway

Some background that happened on the same day

Drove 50 miles to get an alignment with no issues
Drove 59 miles home no issues.
Changed front and rear pads no rotors to project mu club racers
Did not resurface rotors or clean with brake cleaner
Drove around town for 30 minutes not breaking in the pads
Took car home and upon freeway exit very bad vibration
I've removed wheels and no bends. Don't notice any missing weights

The pads are seated fine. I grind down the numbs so I can flip pads so it's not caliper alignment.

My rotors have about 5 track days on them and I don't see how I could warp them just city driving considering it was fine before

I will be replacing the rotors tomorrow night but want to see what else it might be. I have a track weekend coming up this Saturday

Thanks guys

similar happened to me too before. 2 track days with new track pads + one month of street driving = the rear rotors had got warped. the rotor was only 8 months old and didn't see track pads before.

I think quality or thicker rear rotors are the way to go

Weird part is it happened right after I changed pad compounds and did some regular city driving.

I'm wondering if maybe it's wheel weights or alignment is off

I've never warped a rear before so I'm not sure

Likely it's an issue with the transfer layer of the old pad still being on parts of the rotor with the new transfer layer on other parts. Take the car to an open and empty parking lot. Do a proper bed-in on the pads to try and remove as much of the old transfer layer as possible and see if it goes away. It likely will..

^^this

I tried to bead in yesterday with a bunch of hard stops. No help. I also tried to drive and pull the parking brake a few times. I'll try some more and report back

I might just change the rotors and keep this set as spares

I'm not necessarily suggesting you aren't doing it properly, but just to make sure here's StopTech's guide:

http://www.stoptech.com/technical-su...-system-bed-in

"For a typical performance brake system using street-performance pads, a series of ten partial braking events, from 60mph down to 10mph, will typically raise the temperature of the brake components sufficiently to be considered one bed-in set. Each of the ten partial braking events should achieve moderate-to-high deceleration (about 80 to 90% of the deceleration required to lock up the brakes and/or to engage the ABS), and they should be made one after the other, without allowing the brakes to cool in between."


The last part is critical.

Did you figure out what the problem was? Warped rear rotor or not proper bedding.

I just did the same thing but changed my Xp10/Xp8 to club racer project mu pads. As soon as I tried driving the car to bed in the brakes I got vibration in the brake pedal (worse at higher speeds). I took off the front wheels and reinstalled pads to make sure they were properly placed. Also checked for warping of the front rotor but don't think it is. Prior to switching the pads I had no vibration at with braking.

Only thought I have is maybe rear rotor is warped. but I feel I should of felt that vibration prior to changing the brakes. I didn't switch those this year like I did with the fronts. Also I noticed uneven wear with the outside rear pads on both sides. The inner section was worn more compared to outside.

I am thinking of getting new rear rotors now with stoptech slotted solid rears. Mine are still centric premium blanks.

My front rotors are stoptech slotted.

I would suggest getting some good heat into them, like heat you can only get from the track. Rule out the rears being warped by pulling up on the handbrake.

Yea when I pull on ebrake I do not feel any vibration in car or steering wheel. So most likely rear rotors are not warped then. I cleaned the front rotors with brake cleaner prior to switching pads to remove old residue but didn't see to help.

Also I think I will block the front brake ducts in order to help with temperature. I only didn't go hard on the brakes since I was reading that Club Racer or project mu brakes require "light bedding in"