Intermittent brake pulsation

[nmikmik]

This is the first one for me. My wife's 05 Camry needs new pads on a regular basis - see signature.
Last time I replaced pads with Monroe CX908 and bought new Raybestos rotors (and saved used for the next time turning) from Kragen. All was well until last week I noticed a weird vibration in the brake pedal. The reason I call it weird:
a. It pulsated at about the same frequency on low and high speeds
b. it sometimes completely disperses
I've never experience intermittently warped rotors, have anyone here?

Side note - i overhauled the rear brakes about 20k ago, cutting drums and replacing shoos and hardware because she rode with PB on. So i doubt it could be the rear brakes but who knows.
Any ideas, please let me know.
Thanks!

[zorobabel]

I believe one or more or your rotors is overheating and then warps. That's why it's intermittent. I had a similar problem and for me it was a bad master cylinder, but you could also have a stuck slide pin or stuck caliper; maybe uneven braking. When it's pulsating, stop and check the wheels to see if one of them is really hot. Go from there (I had pressure in the brake line - easy to check for that). You'll probably want to change the rotor, but I suggest doing it only after solving the cause of warpage, or you might have to do it twice. Being cheap, I didn't change it a second time, it works fine for me after replacing the master cylinder.

[GTS767]

I had the same problem on on 2003 Camry, Just replaced the master cylinder over the weekend and the pulsation went away. Your car is 2005 and I thought that only 2002 thru 2004 were affected by the toyota TSB where it refer to pulsation of brake pedal during inital deployment. I suggest you turn the engine On, and keep it in park, and then try to depress or simulate any situation where the brake pedal pulsates, if yes, then replace the master cylinder. There is an improved master cylinder for 2002-2004, and maybe the pipeline did miss some of the early 2005 which you may have a master cylinder that need replacment with the modified version. My car did the pulsation when drining at speed or in park with engine on. It is good now.

[nmikmik]

Hey, thanks for the headsup!

I'll check out the TSB see if my vehicle falls under the VIN# range.

[jdmccright]

About all I'd care to add would be to make sure the rear brakes are properly adjusted so that the front brakes aren't doing all the braking.

They should just barely drag when rotating the rear drum and pulling the parking brake handle one or two clicks should be enough to make it difficult to turn them.

When it's right, the rears will engage first, but as more pedal pressure is applied the fronts engage and increase pressure faster than the rears (due to the master cylinder valving). As a result, front-end dive is reduced. Hope this helps!

[joshspeed]

This is most definitely caused by one of these factors:

Warped rotors
over-worn pads
under spec rotors

If the rotor is warped you can look into getting them resurfaced, if there is enough of a rotor left you can do this, and it is normally around 20 bucks per rotor.

if the pads are worn improperly, or just overworn replace them. I would also recommend replacing the hardware if the pads are worn improperly to assure proper wearing of any new pads.

When the rotors get under specs, they will start to "glass" over meaning that good connection between the pads and the rotor itself is not being achieved. At this point you want to change the rotors. You will also want to look at the caliper, caliper piston seal, hardware, and everything else. Reason being is that the heat of a normally functioning rotor is much lower than that of an under spec rotor. This additional heat can cause multiple malfunctions, and shorten the life of other parts of the braking system.

I hope this was helpful...

[joshspeed]

Pulsation is not normally caused by the master cylinder either.... A faulty master cylinder will cause a low brake pedal, "spongy" brakes, or a feeling of air in the the lines.... look at the rotors and pads as the culprit to begin with, and if you are experiencing anything like I mentioned above THEN look into the MC. If the pads, and rotors are all wearing properly, and are within specs, try bleeding your brakes if you are experiencing the low or spongy petal, if the issue isn't fixed at that point.... Replace the master cylinder. You don't want to go and replace the most expensive single piece of the braking system just on an idea that is the problem.... brakes take testing, and research to properly assess....

A professional

[NotoriousPhil]

The discs could have come out of the box warped, if you can get your hands on a dial gauge check the run-out