Front Brake Pulsation - Not All The Time

dodge
grandcaravan

#1

One tech wanted to replace both rotors and sanding down the pads to re-use (he said my brake pads can last up to one year). The guy in auto part said the surface of brake pads having hard spots could cause the pulsation, replace the pads. Of course, replace both rotors and pads is recommended but I have tight budget! What options do I have? can I just machine the rotors? I doubt any shop just machine them only, thanks.


#2

You want to replace both the brake pads and rotors.

The reason is, sanding the rotors won’t remove the run-out that’s beginning in the rotors. As the run-out gets worse, the pulsating brake pedal will get worse. Also, there won’t be the proper friction surfaces for proper break-in between the pads/rotors. This can lead to brake noise.

But finally, the brake pads/rotors on your Grand Caravan are about the same size as those on a PT Cruiser. Only your vehicle is much heavier.So the rotors warp faster.

Tester


#3

Agree with @Tester here and the exact reason you want to do it is the fact that you are on a tight budget (& Can’t afford to keep doing this back and forth).


#4

It could be just a residue build up on the rotors. First try a hard stop (just short of lockup) from about 60 mph. Do not quite stop but let up at about 5 mph. Repeat one more time if needed. This can smooth things out. If two cycles doesn’t fix it, then the problem is more serious.


#5

Residue?

Where does this residue come from? And what is it made of?

Tester


#6

Its cheap and it usually works.


#7

The residue comes from the binders used in the brake pad material. It is designed to create a “transfer layer” that coats the rotor’s friction surface. Sometimes it builds in a single spot, usually after hard use - stop and go traffic can do it - because that’s where the pad is when the van stops.

I’ve gotten rid of it by driving around the block repeatedly accelerating to the corner, braking and then turn. Repeat until you just start to smell the pad through an open window then drive to cool things down.


#8

What you describe is what is done when new brake pads and rotors are installed.

Once the break-in procedure is performed on the new brakes, you burn off the binding agent just below the friction surfaces of the brake pads, and also perform a transfer of friction material between the brake pads and rotors. Once the brakes have been broken in correctly, the break-in procedure is never needed again.

Tester


#9

I vote with Tester on this one. New rotors and pads are just part of the cost of car ownership.
I tip my hat to the mechanic for suggesting that he try sanding the pads to save a few bucks, and Keith’s suggestion of a hard-stop is worth a try (hey, it’s free and MIGHT work!), but in my experience these things have very limited success rates.


#10

Remind your shop to thoroughly clean the new rotors before installing them. New rotors usually come with an anti-rust coating that needs to be removed, otherwise will clog the new pads.


#11

can it be ABS issue? the pulsation happens less frequently now. There was on time ABS light came on while driving. Once engine turned off and turned on, ABS light went a way since. It’s now one week after and the light is still not coming back and break less pulsation, thanks.


#12

I know it more costly but new rotors are the way to go. But give a try to the above mentioned idea to seat the pads…it’s a free fix!!! Also check to be sure that a caliper is not binding. A binding caliper can quickly overheat a rotor and cause it to warp…which will give the pulsation in the pedal. An infrared heat gun can check this in seconds.
If one caliper is binding this could also mean that the flexible brake hose to that caliper is deteriorated from the inside. This causes the fluid to pass and lock the brake, but not allow it to release. We don’t know the age or make of this vehicle, but the lines do get bad at about 10 years.
There is no way to really tell if it is the caliper or the hose that is causing the problem. Whenever I replace a caliper on a vehicle that is more than 8 years old, I always replace the flex hose along with it, Instead of taking the chance of having to tear it apart again.

Yosemite


#13

The added information presents an ABS possibility, probably the wheel speed sensor.

One way you can test it is to elevate the front of the car with the tranny in neutral (ENGINE OFF) and spin the wheel by hand while a friend slowly applies the brakes. If it’s the ABS system, it’ll feel smooth, if the friction while you’re spinning it feels “pulsing”, new rotors are in order.

Note: your opposite wheel will spin in the opposite direction while you’re doing the test, so don’t be alarmed. This is normal.