Question: Brakes 'popping' on first use...

[BD]

Hey, all.

02 WRX Wagon, manual.

I'm finding that when I start the vehicle, back out of my parking
spot, and tap the brakes to stop, several of the brake mechanisms seem
to 'pop' slightly as they engage. It's almost as if the mechanism is
'sticking' slightly, and the fluid pressure is causing it to release
as the pedal is depressed.

Only happens if the car's been sitting idle or off for awhile. Doesn't
only happen if I 'slam' on the brakes; car velocity also doesn't seem
to be a factor.

Anyone else get this?

Tx,

BD.

 

[Todd H.]

Hey, all.

02 WRX Wagon, manual.

I'm finding that when I start the vehicle, back out of my parking
spot, and tap the brakes to stop, several of the brake mechanisms seem
to 'pop' slightly as they engage. It's almost as if the mechanism is
'sticking' slightly, and the fluid pressure is causing it to release
as the pedal is depressed.

Only happens if the car's been sitting idle or off for awhile. Doesn't
only happen if I 'slam' on the brakes; car velocity also doesn't seem
to be a factor.

Anyone else get this?

Is what you're feeling consistent with rotors or pads oxidizing a bit
when left to sit? The first movement backing out unsticks the pad
from teh rotor, and the first braking action will sound a little
grindy, but after that initial oxidation is worn off, all is well
and normal?

Best Regards,

 

[Clifford Heath]

I'm finding that when I start the vehicle, back out of my parking
spot, and tap the brakes to stop, several of the brake mechanisms seem
to 'pop' slightly as they engage.

I suspect that it's a forwards/back thing. Try doing it in reverse,
you'll find it doesn't happen twice in a row. Then do it once in
reverse, then brake from the forwards direction, and when you do
it in reverse again, it'll pop again once every time.

At least, I've had that behaviour with my Alfa, and I think it's
just control arm bushings slightly worn and loose, popping to one
side or the other.

Look for loose or worn bushings or *steering tie rod ends*.

Clifford Heath.

 

[BD]

Is what you're feeling consistent with rotors or pads oxidizing a bit
when left to sit? The first movement backing out unsticks the pad
from teh rotor, and the first braking action will sound a little
grindy, but after that initial oxidation is worn off, all is well
and normal?

Best Regards,
--
Todd H.
2001 Legacy Outback Wagon, 2.5L H-4
Chicago, Illinois USA- Hide quoted text -

- Show quoted text -

Minus the grindyness - the only weirdness I detect is the pop (which
doesn't happen all the time, and only happens once per 'session'), -
and there is also a slight 'sag' in pressure if I sit at a light with
the brake pedal down for more than 30 seconds or so. The pedal feels
like it sinks a little towards the floor, as if pressure is being bled
out somewhere. If I let the pedal go and then reapply it, the pressure
is back to normal. This second symptom is completely unrelated to the
first, and I gather it is normal for stock brakes, but can be
eliminated with a modification. Er sump'n...

 

[BD]

I suspect that it's a forwards/back thing. Try doing it in reverse,
you'll find it doesn't happen twice in a row. Then do it once in
reverse, then brake from the forwards direction, and when you do
it in reverse again, it'll pop again once every time.

At least, I've had that behaviour with my Alfa, and I think it's
just control arm bushings slightly worn and loose, popping to one
side or the other.

Look for loose or worn bushings or *steering tie rod ends*.

Clifford Heath.

Fair enough. I know it doesn't do it twice in a row in one direction,
but I never thought to see if changing direction would bear different
results. I'll see.

 

[Mike]

I have a 03 WRX sedan that does this as well. Mine will make like a loud
snap or click. Mine only does it when i pull out of a parking space. I back
in most times, as i pull out of my space, turn, then strighten out the car ,
then soon as I touch the brakes I get the click. I did hear it once when I
backed out of a parking spot. I backed out ,cut the wheel to the right ,
strightened out the wheel, started to pull forward to the exit, touched the
brakes to stop and then the click. I'm thinking maybe it has something to do
with the parking brake/rear brakes. I always use it when I park, and only
hear the noise the first time I hit the brakes after I disengage the parking
brake. I know its time for pads in the rear. I changed my fronts about a
year ago the rear looked ok so I skiped them, now it's time for both.

 

[lkj]

Hey, all.

02 WRX Wagon, manual.

I'm finding that when I start the vehicle, back out of my parking
spot, and tap the brakes to stop, several of the brake mechanisms seem
to 'pop' slightly as they engage. It's almost as if the mechanism is
'sticking' slightly, and the fluid pressure is causing it to release
as the pedal is depressed.

Only happens if the car's been sitting idle or off for awhile. Doesn't
only happen if I 'slam' on the brakes; car velocity also doesn't seem
to be a factor.

Anyone else get this?

Tx,

BD.

My 02 WRX Wagon does this too.

 

[nobody >]

My 02 WRX Wagon does this too.

Same with my '00 fullsize Outback (4-wheel disks) and to a lesser
degree, my wife's Impreza Outback Sport (front disks only). I've also
noticed it on other disk brake vehicles, some not only pop, they squeal
for the first few applications.

It's worse when it's been humid and the vwhicle has sat for a few days.

Surface rust on the disks....... not to worry . It's a disk brake
"feature" that just seems to be more prevalent on some vehicles and some
brake pads.

The pads skate on the rust for just a part of the turn and then break
thru the thin film of rust and grab.

 

[Bugalugs]

Same with my '00 fullsize Outback (4-wheel disks) and to a lesser
degree, my wife's Impreza Outback Sport (front disks only). I've also
noticed it on other disk brake vehicles, some not only pop, they squeal
for the first few applications.

It's worse when it's been humid and the vwhicle has sat for a few days.

Surface rust on the disks....... not to worry . It's a disk brake
"feature" that just seems to be more prevalent on some vehicles and some
brake pads.

The pads skate on the rust for just a part of the turn and then break
thru the thin film of rust and grab.

From earlier correspondence here the problem seems to be that there is
a tiny amount of play between the brake pad and where they fit into the
caliper. When you are reversing and apply the brakes and stop the pads
move to the rear. When you next move forward, the first time you apply
the brakes those pads move forward in the caliper and 'click'. Only does
it once. It's only a very small movement and they are never going to get
out. Annoyance only

 

[BD]

From earlier correspondence here the problem seems to be that there is
a tiny amount of play between the brake pad and where they fit into the
caliper.

Sounds good to me. I'll ask the dealer when I'm next in for a regular
servicing.

Thanks!