brakes throbbing - how to proceed?

Question

'04 Cavalier. Considerable pulsing in the pedal when the brakes are applied. The pulsing is speed-dependent - I think it's probably one throb per wheel revolution. There's no significant shaking of the steering wheel. Stopping seems unimpaired. There may be some variability in the pulsing: it may be worse after coming off a short run at higher speed. (That is not certain, though.)

What I've done so far:

- Changed the (front) pads. Outer pads had more wear. Calipers now moves freely.

- Replaced one rotor. Inside plating was deteriorated.

- Replaced one hub assembly. (see (1) below.)

- Replaced the other hub assembly last fall, to fix a noise.

Things I can do next:

- replace the other rotor. My gut says, this won't help. Sometimes, my gut is wrong.

- look at the rear (drum) brakes. The rears on this car are mostly cosmetic, IMO. Not to mention, Getting the drums off is a PITA.

- get the balance checked on the wheels.

Or something else?

Any thoughts/experience appreciated.

G

(1) re hub assembly replacement: When I ran the car (low gear) with one control arm jacked up, wheel removed, lug nuts snug on the rotor, wobble was visible in the rotor. It was pushing against the brake pads, and I thought for sure this was the problem. No joy.

hls · Accepted Answer

As you probably already know, this is almost always due to rotors, and can be (1) warp, (2)out of parallel rotor faces, or (3)rotors installed with dirt or rust between them and the hub.

There could be other contributing factors

jim beam · Answer

yeah.

there's nothing "gut" about brakes. it's all about understanding what goes on, observing the situation that exists, then using both sets of data to figure out the result. real simple.

george, you posted about this march 18th. try re-reading the thread and acting accordingly - all the answers to your questions are in there.

either that or just cough up the money to have a professional take care of it.

jim beam · Answer

very unlikely. we've discussed this before.

how do you think that's possible? you think that a brake pad can somehow index then abrade a disk in just one arc sector and not others?

how do you install rust?

yeah. but none as likely and the propagating of myth without bothering to consider or learn the facts.

N8N · Answer

Replace the other rotor. They should always be replaced in pairs anyway, and also the likely cause of your pedal pulsation is rotor runout.

Make sure the the caliper sliders are well lubed.

Reinstall wheels by hand, with a torque wrench. (inconsistent torque can cause the rotors to warp slightly... really!)

If you still have pulsation, you may need to replace or turn the rear rotors also.

Oh, and if the pedal pulsation bothers you, never NEVER buy a Chevy Impala, it's the only vehicle I've owned that is showing signs of warped rotors less than 1K miles after a full brake job (pads/rotors all around.) What a POS.

nate

g · Answer

As I have found out, replacing brakes on the cavalier is common. Remember to keep the rears adjusted, wil lengthen life of fronts. Greg

George · Answer

If was the (2nd) rotor.  Thanks to all, apologies to any who feel they need them.

hls · Answer

I dont think anyone needs apologies.. We all told you basically the same  thing and you have resolved the problem. Congrat!!

jim beam · Answer

"we"???  i hope you're not trying to include your own divergent myth  propagation in that statement.  unless you have delusions of royalty of  course.

jim · Answer

Well we know the "we" didn't include you since you offered no solution.

jim beam · Answer

are you delusional?  or just dishonest?  and why am i asking rhetorical  questions?

jim · Answer

You said nothing useful. That includes this response. The response before that. Time before that etc etc etc

maybe sometime in the distant past you said something useful, but nobody remembers what it was

brakes throbbing - how to proceed?

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