so like the title says...when the brakes are applied i will feel a bump, like something is on the rotors, feeling. at first i thought it was just me until now i realize that everyone in the car can feel it. i've taken my wheels off and looked at all my rotors. did not see any imperfection on the faces of the rotors.

now FYI i did change out all 4 my brake pads about 450 miles ago.

does anybody have any ideas what it possibly could be? thank you so much.

 

Simple, your rotors are warped. You need new ones. You can get them resurfaced at a shop if they arent too bad, or have reached the minumum thickness yet. But you can probably get new ones for cheap enough and swap them out yourself for around the same price a shop will charge you for labor + resurfacing.

 

next time your drive check the frequency of the "bump" if it vibrates faster at higher speeds and slows as you slow, you have warped rotors.

 

really? thats interesting...cause apparently at around >20mph theres no vibration. above that yeah you'll start feeling it. and it goes as you say higher speeds the higher the frequency...

ok i'll look into the rotors. thanks a lot guys.

 

Yeah, you won't really feel it going slow unless you're braking. My OEM rotors warped within I'd say at least 50k miles, probably less than that. Might as well upgrade to some new rotors, the Alien Performance ones in the 6th gen classifieds seem to be a pretty good deal (I got slotted RTP ones a while back).

 

yea buh 30k miles? i felt thats a lil low don't you think? i think it was cause of the winter...i left my car un touched for almost 2 month. and waiting for endlinks was no better. finally got it all in and new tires...so now i'm feeling these "vibrations". i'mma see if i can get a good resurfacing cause i feel like rotors still got a good 20k miles on them.

 

Honestly, I'd believe it. When I asked about the rotors when mine were warped I got the feeling that it was fairly common (maybe doesn't happen to every Maxima, but many said theirs warped too). I would ask if you got an alignment, but you said that you feel it when you're braking at low speeds. Weigh out the cost of resurfacing versus getting new rotors. If you've ever thought about getting drilled or slotted rotors, you might as well do it now, don't want to resurface those rotors and then end up changing them again later on.

 

I suppose the rotors could be warped, but I think a more likely explanation is that they rusted in spots during that 2 months you didn't drive it. Look at them closely and you should be able to see dark places on them if this happened. You'll still have to recut them, though...

 

you got warped rotors, end of story, thread complete

 

Not necessarily so. Cars with damp/wet pads will rust rotors and make rough spots if allowed to sit undriven for a few weeks, which will cause that bumpy feeling when braking.

 

Either way its not something you can really see just by looking at the rotor, point is that the solution is to resurface or replace the rotors.

 

well before you go and do that you should first bed your brakes. its easy to do, requires no tools ill add a tutorial in my next post in case someone wants to sticky it. i supplied this on another thread but it was old and didn't appeal to everyone. bedding your brakes could fix your problem, especially if you have rust spots.

also about the rust spots, i've had them, they rub off in a matter of days/week. if you've had this problem for a while its probably not rust. also you CAN see rust spots if you take your tire off and stick your head in there not to mention you can feel them by rubbing your finger around the rotor.

bed your brakes with my tutorial and report back.

 

*HOW TO BED (BREAK IN) YOUR BRAKES*


Why is it a good idea?
Bedding allows your brakes to reach their full potential. Until they are bedded, your brakes simply do not work as well as they can. If you've installed a big brake kit, changed your pads and rotors, or even purchased a brand new car, you should set aside time to bed the brakes according to the instructions below. Proper bedding improves pedal feel, reduces or eliminates brake squeal, prevents (and often cures) brake judder, reduces brake dust, and extends the life of your pads and rotors.


Removing the Mystery from Brake Pad Bed-In.
Caution: Immediately after installing new pads, rotors or a big brake kit, the first few applications of the brakes will result in very little braking power. Gently use the brakes a few times at low speed in order to build up some grip before blasting down the road at high speed. Otherwise, you may be in for a nasty surprise the first time you hit the brakes at 60 mph.
If you have just installed rotors with zinc or cadmium plating, or if the rotors have an

Read and understand these bedding instructions completely before starting. Do not substitute higher speeds for the 60mph called for in these instructions. The heat in your brakes goes up exponentially as you increase the speed from which you brake. If you make repeated stops from 80 or 90mph with street pads, you will overheat the brakes and may end up having to replace pads and/or rotors not to mention ruining the bedding process.
When following these instructions, avoid other vehicles. Bedding is often best done early in the morning, when traffic is light, since other drivers will have no idea what you are up to and may respond in a variety of ways ranging from fear to curiosity to aggression. A police officer will probably not understand when you try to explain why you were driving erratically! Use common sense! Follow each direction in order and to the T:

1. From 60mph, gently apply the brakes a couple of times to bring them up to operating temperature. This prevents you from thermally shocking the rotors and pads in the next steps.
2. Make eight to ten near-stops from 60mph to about 10-15 mph. Do it HARD by pressing the brakes firmly, but do not lock the wheels or engage ABS. At the end of each slowdown, immediately accelerate back to 60mph and then apply the brakes again. DO NOT COME TO A COMPLETE STOP! If you stop completely and sit with your foot on the brake pedal, you will imprint pad material onto the hot rotors, which could lead to vibration and uneven braking.
3. The brakes may begin to fade after the 7th or 8th near-stop. This fade will stabilize, but not completely go away until the brakes have fully cooled. A strong smell from the brakes, and even some smoke, is normal.
4. After the last near-stop, accelerate back up to speed and cruise for a while, using the brakes as little as possible. The brakes need only a few minutes to cool down. Try not to become trapped in traffic or come to a complete stop while the brakes are still very hot.
5. If you are using full race pads, add four near-stops from 80 to 10 mph. DO NOT DO THIS UNLESS YOU HAVE BONAFIDE RACING PADS. YOU WILL RUN THE RISK OF WARPING YOUR ROTORS AND RUINING THE PADS.

After the break-in cycle, there should be a slight blue tint and a light gray film on the rotor face. The blue tint tells you the rotor has reached break-in temperature and the gray film is pad material starting to transfer onto the rotor face. This is what you are looking for. The best braking occurs when there is an even layer of of pad material deposited across the rotors. This minimizes squealing, increases braking torque, and maximizes pad and rotor life.
After the first break in cycle shown above, the brakes may still not be fully broken in. A second bed-in cycle, AFTER the brakes have cooled down fully from the first cycle, may be necessary before the brakes really start to perform well. This is especially true if you have installed new pads on old rotors, since the pads need time to conform to the old rotor wear pattern. If you've just installed a big brake kit, the pedal travel may not feel as firm as you expected. After the second cycle, the pedal will become noticeably firmer. If necessary, bleed the brakes to improve pedal firmness.


Please be safe, remember to obey all traffic laws, and enjoy your newly bedded brakes.

 

^ I always read about that but TBH they bed themselves in under normal driving, it just takes a bit longer, its not something thats really necessary unless you rip on the gas/brake pedals every day.

The problem that the OP is having is likely not caused by the lack of him performing the above procedure, sometimes its just cheap rotors that develop vibrations regularly (I've had this before) or they weren't cleaned properly when installed.

 

yeah i agree, i only suggested this procedure in the case that he developed some rust spots or scratched his rotors with some dirt or debris. bedding would help with those problems.

but yea, the more likely cause is they are cheap, warped, or as you said they weren't cleaned properly when installed.

its all process of elimination when dealing with this kinda stuff.

 

sounds like it's the rotors
just drive to your local brake tune up shops and ask them if the rotors have to replaced they will tell you what to do

 

Why matter with a slightly pulsating brake pedal? I wonder because my rotors have been like that for 3 years. Even replaced the pads on those pulsating rotors. No issues....

 

Thanks for the "How to Bed" your brakes. Just recently changed mine and it helped. Thanks.