What's this on my rotor?

[lcbjr77]

I think I found what is causing my pulsated when braking... I recently did my front brakes and noticed after the brake job there was still a little pulsated when braking... With the help of the forum there was different opinions on what it could have been... Alignment, re torquing the wheels, somebody mentioned maybe the back brakes.

Do you think these marks on my rotors are causing the pulsating?

After seeing this yesterday I bought new brakes from Napa, hopefully I can change these out soon.

[URL=http://s464.photobucket.com/user/lcbjr77/media/777_zpsntxhnycc.jpg.html][/URL]

[URL=http://s464.photobucket.com/user/lcbjr77/media/888_zpsqjx2cft1.jpg.html][/URL]

Thanks
Larry

 

[KidVermicious]

Those are deposits from your brake pads, and they're almost definitely causing your pulsing. You get those from coming to a hard stop with really hot brakes. You can prevent them to an extent by bedding in your new brake pads, but mostly by not overheating the brakes and by stopping gently if you do.

You can take them off with a wire wheel on an angle grinder, or by having the rotor turned. Do it before you put the new pads on. Unless your rotors are cracked, or below the minimum thickness, you don't need new rotors.

 

[morphious]

Here is a good article about it (NOT Warped Disks):

Tech Article: Warped Brake Discs

 

[lcbjr77]

Thanks for the info

I bought the 4Runner last May and the maintenance record was a little sketchy based on stuff I already have done. I bought new pads and rotors yesterday... When I replaced the fronts on Sunday I bed them in per instructions, I'll make sure to do it again for the rears.

Those are deposits from your brake pads, and they're almost definitely causing your pulsing. You get those from coming to a hard stop with really hot brakes. You can prevent them to an extent by bedding in your new brake pads, but mostly by not overheating the brakes and by stopping gently if you do.

You can take them off with a wire wheel on an angle grinder, or by having the rotor turned. Do it before you put the new pads on. Unless your rotors are cracked, or below the minimum thickness, you don't need new rotors.

 

[shahsmerdis]

Those are the rear brakes? Clean your where your brakes pads meat the caliper. mine had a good few mm of rust on them. I had the same issue. looks like your pads are seized into place. They should come out and be pushed in effortlessly if you have to jam them something is wrong.

follow this video ( all his brake videos) new hardware, and clean area where the hardware goes will make for happy brake pads.

https://www.youtube.com/watch?v=Yhw_d_EWrOQ

 

[EdmundGTP]

Those are deposits from your brake pads, and they're almost definitely causing your pulsing. You get those from coming to a hard stop with really hot brakes. You can prevent them to an extent by bedding in your new brake pads, but mostly by not overheating the brakes and by stopping gently if you do.

You can take them off with a wire wheel on an angle grinder, or by having the rotor turned. Do it before you put the new pads on. Unless your rotors are cracked, or below the minimum thickness, you don't need new rotors.

What he said.. Most likely the brakes weren't properly bedded. Somebody stomped on them pretty heavy heating them up (emergency stop perhaps), and then left their foot on the brake pedal, holding the vehicle in place while allowing pad deposits to bake on to the hot rotor in just that one spot.

Result is one spot on your rotor that has a different friction coefficient between the rotor surface and the pad than the rest, and the pulse you feel is the "grabbing" of that extra friction in that spot.

Bedding in the brakes correctly allows the pad/rotor combination to heat cycle without having this type of adverse result.

Having a caliper seize up and start to go bad can cause similar results.