severe braking vibrations and soft pedal on 05 Impreza Outback Sport

[Dave Botsch]

So, the car is just over three years old with about 20K on it (yes, I
don't drive that much).

While there has always been some vibration when braking (presumably due to
the antilock brakes grabbing and releasing), I just noticed that even if I
brake a little bit, say to slow down 5 mph from around 55 or 60mph, there
is severe vibration that I'm even feeling in the steering. Could this have
anything to do w. my pads starting to get close to the replace point or
tire rotation (just done)/etc? Normal ride/coast feels just fine, and at
lower speeds, not nearly (if any) vibration -- car also seems well aligned
and stays straight when braking/accelerating/letting go of wheel).

I think this is not normal, but need to know what to tell them since they
will probably tell me everything is within spec and it's normal for this
age of pads/etc.

Since the NYS annual inspection about two years ago, when I picked up the
car after that inspection, I discovered that I suddenly had to press the
brake pedal down much further before the brakes would physically engage
(the brake light still lights as soon as the pedal is barely tapped)
whereas before that inspection, the brakes were quite tight (I did not
have to touch the pedal much at all for the brakes to slow the car). Went
back to the dealer and told them, they checked, told me that the distance
to pressing the pedal was normal, everything was within spec, and that if
I pumped the brakes a little it would get better (which it does, but it
always goes back down to that point after a while and I've occassionally
felt the pedal sink down while stopped back to that point). It's never
gone below having to press the brakes more than that.

So, they claim everything is right... but clearly something changed during
that one inspection (which included checking the brakes).

Any thoughts on either or both of these issues w. things I can tell them
to check?

Thanks!

 

[AS]

It sounds as if your rotors (discs) need to be resurfaced. Since you
drive so lil, i think the rotors may get rusty between uses and cause
all sorts of issues. At 20K i doubt you need new pads.

The vibration when slowing down the 5 mph you say, could be warped
rotors, uneven surface on them, alignment (doubt it) or suspension wear
(really doubt it).

Warped discs or air in the brakes hydraulic system may cause the pedal
to feel soft.

In NY, do you have the car inspected at a mech. shop, right? Was it the
dealer that you refer to? Tampering? Do they have the equipment to
test all wheel drive vehicles? Was the awd disconnected during the test?

Good luck!

 

[.._..]

So, the car is just over three years old with about 20K on it (yes, I
don't drive that much).

While there has always been some vibration when braking (presumably due to
the antilock brakes grabbing and releasing),

No.

-- not specifically to poster --

HEY GUYS. WITH MODERN CARS, YOU REALLY REALLY SHOULD LEARN WHAT ANTI-LOCK
BREAKS ENGAGING FEELS LIKE. GET OUT FIND SOME GRAVEL IN A SAFE AREA, GET
SOME SPEED AND STOMP ON THE BREAKS.

THIS LITTLE BIT OF EDUCATION CAN SAVE YOU PANIC WHEN IT HAPPENS IN REAL
LIFE, WHEN YOU SHOULD BE THINKING ABOUT GETTING OUT OF WHATEVER SITUATION
YOU ARE IN.

-- end not specifically to poster --

Knowing what ABS does is as fundamental to driving a modern car as locking
it in the parking lot is.

I just noticed that even if I

brake a little bit, say to slow down 5 mph from around 55 or 60mph, there
is severe vibration that I'm even feeling in the steering. Could this have
anything to do w. my pads starting to get close to the replace point or
tire rotation (just done)/etc? Normal ride/coast feels just fine, and at
lower speeds, not nearly (if any) vibration -- car also seems well aligned
and stays straight when braking/accelerating/letting go of wheel).

I think this is not normal, but need to know what to tell them since they
will probably tell me everything is within spec and it's normal for this
age of pads/etc.

Since the NYS annual inspection about two years ago, when I picked up the
car after that inspection, I discovered that I suddenly had to press the
brake pedal down much further before the brakes would physically engage
(the brake light still lights as soon as the pedal is barely tapped)
whereas before that inspection, the brakes were quite tight (I did not
have to touch the pedal much at all for the brakes to slow the car). Went
back to the dealer and told them, they checked, told me that the distance
to pressing the pedal was normal, everything was within spec, and that if
I pumped the brakes a little it would get better (which it does, but it
always goes back down to that point after a while and I've occassionally
felt the pedal sink down while stopped back to that point). It's never
gone below having to press the brakes more than that.

So, they claim everything is right... but clearly something changed during
that one inspection (which included checking the brakes).

Any thoughts on either or both of these issues w. things I can tell them
to check?

Thanks!

I'd suspect rotors.

 

[Steve Daniels]

While there has always been some vibration when braking (presumably due to
the antilock brakes grabbing and releasing), I just noticed that even if I
brake a little bit, say to slow down 5 mph from around 55 or 60mph, there
is severe vibration that I'm even feeling in the steering.

There is a good chance that your caliper has frozen. It's
supposed to be able to float over the disk, and if it quits doing
that, you'll get the symptom you describe. That, or a warped
rotor, or both.

OBTW, anti lock breaks don't kick in under normal driving
conditions, unless you normally go into panic stops.

 

[Dave Botsch]

With respect to rustiness, we do have the salt on the roads up here in the
winter. And, the car is stored outside, unfortunately.

I would say it seems like it's somewhat worse since the last NYS
insepction (which was combined with a regular subaru maintenance interval).

I only take my car to the local Subaru dealer - for any repairs, subaru
maint. intervals, and for New York state inspections.

The pads are getting down there... I would have to look, but I believe
they are now under 50%.

Are the rotors something that can be easily tested? The stuck caliper
mentioned by a previous poster?

and any thoughts on the "soft" break pedal?

thanks.

 

[Dave Botsch]

Hi.

While I appreciate the suggestion, the brakes do feel significantly
different as compared to braking at high speeds versus low speeds. And
while I do, every year, take the car to a parking lot to remind myself of
how it responds and skids to braking at low speeds (say 20 mph) on snow
and ice, I'm not about to try that test on any surface of slamming on the
brakes at 60mph.

Yes, even normal stopping coming up to a stop sign at 30mph, a nice and
gradual stop, it's not a completely smooth stop as if the brakes are not
grabbing the wheel consistently (and back when I had a GM car, the then
dealer told me that that was a symptom of the antilock brakes constantly
grabbing and releasing a bit) -- not sure I buy it since I thought
antilock brakes were only supposed to really release if the wheels were in
danger of a skid.

 

[Dave Botsch]

thanks for the response!

Let me ask the following:
1. would any of these symptoms be related at all to what I described as
the brake pedal softening (having to push it down further) -- as if when
they took it apart for that first inspection it never got put back
together quite right?
2. Presumably, there's some adjustment that tells the antilock brakes when
they need to do their thing -- could that be off?
3. Warped rotor/stuck caliper - can one lead to the other, and is it easy
for the dealer to test for these?

Thanks!

 

[Steve Daniels]

thanks for the response!

Let me ask the following:
1. would any of these symptoms be related at all to what I described as
the brake pedal softening (having to push it down further) -- as if when
they took it apart for that first inspection it never got put back
together quite right?

No, but it's certainly a serious issue in its own right.

2. Presumably, there's some adjustment that tells the antilock brakes when
they need to do their thing -- could that be off?

Got me. But if you drive on salted roads, the chances of your
calipers being frozen are a lot higher than your ABS going on the
fritz.

3. Warped rotor/stuck caliper - can one lead to the other, and is it easy
for the dealer to test for these?

It would be unusual for a rotor to be warped at 20K miles, but
the salt may have done Bad Things to your brakes. It is easy for
the dealer to check. All he needs to do is test the rotor for
runout, and while the rotor is off for that test, to see if the
caliper can be slid back and forth a bit.

Were I you, I'd get a complete brake inspection and fix whatever
is wrong. If you motor quits, you can't go. If your brakes
quit, you can't stop. Guess which condition will get you into
the most trouble?

 

[Carl 1 Lucky Texan]

No, but it's certainly a serious issue in its own right.




Got me. But if you drive on salted roads, the chances of your
calipers being frozen are a lot higher than your ABS going on the
fritz.




It would be unusual for a rotor to be warped at 20K miles, but
the salt may have done Bad Things to your brakes. It is easy for
the dealer to check. All he needs to do is test the rotor for
runout, and while the rotor is off for that test, to see if the
caliper can be slid back and forth a bit.

Were I you, I'd get a complete brake inspection and fix whatever
is wrong. If you motor quits, you can't go. If your brakes
quit, you can't stop. Guess which condition will get you into
the most trouble?

Good post except rotors can have uneven pad material deposited in the
first mile. Whether someone at the dealership is responsible - who knows?
Assuming you are not a do-it-yourselfer, I'd suggest taking your
concerns and your car to another dealership or GOOD independent
mechanic/brake shop.

A single hard stop - followed by holding the car stationary for a few
minutes with the brake pedal, CAN create what most folks call 'warped'
rotors. check;
http://www.stoptech.com/tech_info/wp_warped_brakedisk.shtml

Carl