Brakes Pulsing


#1

Yesterday, I replaced the rotors and the pads on my 04 Mazda Tribute. When I went for a test drive afterwards, I get a lot of pulsing feedback to the pedal. We did not bleed the brakes at the time so I am wondering if this is causing the pulsing or did I do something else incorrectly? I don’t want to drive it any further and cause damage to the new parts. Appreciate any help.


#2

I doubt if it was bleeding, but some cars do require bleeding. My first guess would be a bad rotor or over/miss tightening lug nuts possibly resulting in a warped rotor, or maybe a defective new rotor.

This would not be a ABS pulse would it? If you have ABS did you take care with the ABS sensors?


#3

The vehicle is ABS equipped, but I don’t recall touching anything there. Is there someway to check these sensors myself or should I take it to a pro?


#4

If your brakes need bleeding, the most likely symptom wouldn’t be pulsation. It’d be low pedal which you can bring up temporarily by pumping. ABS shouldn’t kick in on gentle stops. If you feel pulsation even with the brake barely engaged, it’s likely not ABS.

A pulsation that varies in frequency with the speed of the car is probably caused by a warped rotor; loose lug nuts (I’ve been known to forget to tighten them more than finger tight. I suspect I’m not alone); by failure to tighten the caliper bolts on one side or the other; or some other problem with putting the parts on wrong.


#5

Did you make sure the mounting surface of the hub was free of dirt or rust? If the surface was not clean and smooth it would cause a pulsation while braking.


#6

Did you torque the lug nuts evenly in a star pattern? Torquing the lugnuts improperly, believe it or not, can cause this.


#7

New rotors have ABS rings stamped into them. You should clean the sensor with electrical cleaner and the new rotor’s ABS sensor ring with brake parts cleaner and allow everything to dry before reassembling.

But if this IS an ABS pulsation, you’d know, because it’d feel like the pedal were physically fighting you.

If it’s just a normal pulsation, the first thing you should check are the lugnut torques. Find the specs and use/borrow/buy a torque wrench to set them all correctly. Follow a cross tightening pattern.

Next I’m wondering if the rotors were stuck when you removed the old ones. If so, did you hammer them off? Banging off rotors can lead to worn/broken wheel bearings, which can immitate a warped rotor feel.

Finally, if all the fasteners are at the correct torque, pull the rotors and return them for a new set. It’s possible that they’re just defective. Especially with todays thin rotors and cheaper parts.

Oh and no, bleeding will have nothing to do with this.

-Matt


#8

We did have to hit them (I used a rubber mallet) to get them off. How do I inspect the wheel bearing? Starting to wish I just paid a mechanic. Oh well, what’s done is done. Thanks for the info.


#9

did you look for a bleeder on anti lock master you might have an air lock in the anti lock control box.air raises to the top. buy a book and read up this brake system. I had and old ford and had to use a hand vacuum pump on master cyc to bleed out the air and raise the front of car so air went to the top.