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Rotors act only when hot

So I am curious about something. My car has bad rotors. My brake pedal shakes when I brake including some car/steering wheel shake. Only between 25 and higher speeds.

So here is the catch it only happens when I have been driving, braking for a while so I am curious why it only vibrates when the rotors are hot is the question basically.

Everything expands when it gets hot. The runout in your rotors is more pronounced when they get hot and so you can feel it more. Just for grins, when they are heated up and vibrating the pedal, do a couple hard stops where safe to do so. Sometimes, pad material accumulates on the rotor surface causing pulsations and this helps scrub that off. If no improvement, you’re getting close to brake job time…

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Agree with Twin Turbo.

You also have another problem I believe. Change out the rubber brake lines along with your rotors. The rubber brake lines are holding pressure on your calipers and that also will cause shaking. They do this as they age since the rubber breaks down inside and doesn’t allow the brake fluid to return to the master cylinder. It’s a problem that’s as common as dirt. You will often smell hot calipers after a trip if you use the brakes often enough. The culprit is usually bad rubber hoses.

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When was the last brake service and what parts did they replace? How many miles on the rotors and pads?

Also make/model/year/miles?

Yes. It actually does lessen the shaking but it still shakes. But thank you for the tip. I am just gonna replace pads and rotors I found a good deal.

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Dont know if it is related but got a rumbling in the brakes sometimes after a long drive. After 3k miles pads went from 8mm to 4mm, rusted rotors they said, Waiting till after salt season to have new brakes and rotors.