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Brakes Shake after new pads?

11K views 18 replies 7 participants last post by  Sinister 
#1 ·
I just changed the front pads on my 04 wrx and now when i brake at 50mph or higher the wheel shakes and i can feel it in the pedal

just before i did the pad change i had no probs.
 
#2 ·
From what I know it sounds like your rotors need to be milled. As brakes wear down they also wear down the rotor, sometimes leaving grooves. When you put a new brake pad on to a worn-in and grooved rotor it can result in brake squeal and vibrations and shakes.

Take a look at your brake rotors and slide your thumb across the surface, if it feels uneven then take them off and get them milled. Should cost like $15 per rotor.
 
#4 ·
Exactly. You didn't get your rotors turned (milled)... and on top of that, did you bed your new brake pads properly? I'm guessing since you didn't know to turn your rotors, that you didn't bed the new pads. What kind of pads did you get, and what rotors are they on?
 
#6 ·
Probably not to bad... I haven't done a wrx brakes yet but I imagine they are similar... so you would pop off the wheel remove the caliper; there will probably be a set screw or two hold your rotor in place, you will have to pop that off... The set screw if probably seized pretty badly so some deep creep sea foam or PB blaster and an impact screw driver will help nice... You dont need the set screw with the new rotors. The set screw's are used during factory assembly. Heck your new rotors may not even have a hole for the set screw... So dont be afraid to drill the screw if they are seized badly.
 
#7 · (Edited)
Allow me to contradict everyone. :sadwave:

Modern rotors do not warp hardly ever and it takes a hell of a lot to do it. Vibrations come from heat causing uneven deposits - in your case as Kevin said probably from not bedding in the pads. Milling the rotors reduces their mass, then they heat up more. This causes them to be more likely to cause vibrations from uneven deposits. The cheap ass wearever rotors are every bit better than an old rusty milled rotor by far. If you go out and properly bed your pads it may cure it. Otherwise get new ones for marginally more than milling.

Oh, and they pop off after you remove the wheels & calipers (just FYI) there are no retainers. Make sure the parking brake is off for the rear though.
 
#8 · (Edited)
Mycologist,

First off, the OEM rotors have a spec that they can be turned (milled/resurfaced, etc) within. Secondly, the actual turning process only shaves down ~ .005 to .010 inches. Not enough to change the heat retention properties of a rotor that has a 12" face. At least not enough for an average driver to notice, or care. In addition, a larg part of the turning process is not only to remove deformities, but also to remove the deposits, and groovings that the previous brake pads with a different compound has left on the face of the rotor. One should always turn a rotor between brake pad changes unless the compounds are very similar. BigSky told me that the Ferodo 2500 and 3000's are so similar in compound make-up that I'm able to get away with not milling/turning the rotors after track day events. Just food for thought! :cool:

-Kevin
 
#10 ·
I could understand that for someone who is really going through pads and tracking etc. In this case, talking about 68K mile rotors getting milled, I would recommend replacing them much more than milling. Much of the mass lost is the actual previous pad wear (mine had a pretty big lip by 60K) but yes there is a spec they can test against. IMO a new $30 rotor beats the pants off an old worn rotor with chunks of rust coming off in other places etc. that is going to cost what like $20 to turn down (a bit of a guess).

got new rotors but broke the bolts holding the caliper to the wheel hub spindle thingy lol. they was on so tight could not even turn them a lil. now i gotta drill out the broken bolts
Bummer! PB blaster is crucial for this type of job.
 
#9 ·
got new rotors but broke the bolts holding the caliper to the wheel hub spindle thingy lol. they was on so tight could not even turn them a lil. now i gotta drill out the broken bolts
 
#11 · (Edited)
PB blaster is a god send... But I have found sea foam deep creep works a touch better... In fact I recommended both to him before he started this job, tisk tisk tisk...

As for mill pricing depends where you live I guess... Here we pay 3-5 dollars per rotor at most. Exceptions are larger super duty and up trucks. Those dudes can run about 20 a pop to turn, but the flip side is the rotors are 70+ each.
 
#16 ·
That first one is great. It elaborates on exactly what I had said before on milling, and "warped" rotors. Great articles Ron.
 
#18 · (Edited)
There used to be a product that you inserted on the face of the new pads during a new install. It basically wiped the rotor free of contaminants and cementite. Basiclly kinda what EBC puts on their brakes but this was a very thin "brake in pad" that just wore away as apposed to a coating.Not sure if they were effective or not. Can't find any info on them. I often wondered if blasting the rotor faces with aluminium oxide would work.
 
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