lousy brake peformance / best practices for DIY brake job

[Todd H.]

I'd be grateful for any sage advice on a long standing brake puzzler.

I can barely recall the last time I was happy with my brakes on this
frigin vehicle. My 140k mile 01 Outback has warped its rotors
again, and has had lousy braking performance since about a month after
the latest top-of-line third party pads and new top quality third
party rotor went on it (done by a non-Sube tech)...oh, probably just
25k miles ago. The brakes since the most recent set of top of the
line pads have felt soft to me, and stopping performance seems lousy.
Pedal travel seems to be a bit more than it should as well, though the
techs did bleed the brake system, and on a return trip insist that a
hydraulic issue isn't at play and that those particulra pads are just
a bit soft in feeling. I'm a family guy with an anemic engine'd
vehicle, drive with one foot, and decelerate slowly and smoothly, so
aggressive driving certainly can't be the issue. My brake rotors
don't look shiny on the front for what it's worth--they look more
black.

Q1: is this blackness of the rotors indicative of an overtemp
condition at some point in the past?

Q2: if so, what could be causing that? Tab of non-OEM brake pad a
bit too large causing it to hang up? Or could there be an issue with
booster or master cylinder at play? How do they test for booster or
master cylinder issues?

Q3: is it true that if a pad overheats, it chemically changes and will
never stop the same ever again? Most recently a tech who looked at
the issue mentioned this and shook off any of my questions about
possible master cylinder or booster problems.

Q4: on pad replacement, aside from going OEM with pad and rotor (which
I'm going to do this time), I'd like to know what are the best
practices to doing the brake job.

I plan to do this one myself again--since the pros I left it to the
last 2 times it'd been in didn't seem to do any better, and want to
leverage the savings of subarugenuineparts.com--and am interested in
what goodies are best to clean up the calipers, caliper slides, and
that and what sort of lubricant should be used on the slides (does
Subaru sell a kit for such?).

Also, looking in the OEM catalog--anyone know what the front brake
backing plate is that sells for about $15 each? Is that the backing
plate for the pads?

Thanks for any insight or time in hanging with an overlong question.

 

[johninky]

Have been driving now for 40+ years and have never experienced warped
rotors. My understanding is just about the only thing that will warp
a rotor is overtorqued lug nuts. If the rotors are "black" that
suggests to me the calipers are not working. Don't believe
overheating the brake pads changes them in any way. I once many years
ago had a 66 Corvette with the 427/425 and turned all 4 rotors red
after a panic stop from 100 m/hr. Never noticed any difference in the
braking performance after the rotors cooled. The brake pedal will be
super hard if the booster fails. Bad MC and the pedal goes to the
floor when pushed. I installed front rotors and calipers from a 2002
WRX on my 95 wagon about 4 years ago and haven't had a bit of problems
with them. Thinking your newer wagon uses the same parts as the WRX.
When you install the new rotors, make sure the surface behind the
rotor where the rotor presses up against the hub is clean. Not much
help but like I said, never had this problem.

Did take your advice when I had all the rear wheel bearing problems
and went with a used knuckle. So far so good.

 

[1 Lucky Texan]

I'd be grateful for any sage advice on a long standing brake puzzler.

I can barely recall the last time I was happy with my brakes on this
frigin vehicle.   My 140k mile 01 Outback has warped its rotors
again, and has had lousy braking performance since about a month after
the latest top-of-line third party pads and new top quality third
party rotor went on it (done by a non-Sube tech)...oh, probably just
25k miles ago.  The brakes since the most recent set of top of the
line pads have felt soft to me, and stopping performance seems lousy.
Pedal travel seems to be a bit more than it should as well, though the
techs did bleed the brake system, and on a return trip insist that a
hydraulic issue isn't at play and that those particulra pads are just
a bit soft in feeling.  I'm a family guy with an anemic engine'd
vehicle, drive with one foot, and decelerate slowly and smoothly, so
aggressive driving certainly can't be the issue.    My brake rotors
don't look shiny on the front for what it's worth--they look more
black.

Q1: is this blackness of the rotors indicative of an overtemp
condition at some point in the past?  

Q2: if so, what could be causing that?  Tab of non-OEM brake pad a
bit too large causing it to hang up?  Or could there be an issue with
booster or master cylinder at play?  How do they test for booster or
master cylinder issues?

Q3: is it true that if a pad overheats, it chemically changes and will
never stop the same ever again?  Most recently a tech who looked at
the issue mentioned this and shook off any of my questions about
possible master cylinder or booster problems.

Q4: on pad replacement, aside from going OEM with pad and rotor (which
I'm going to do this time), I'd like to know what are the best
practices to doing the brake job.  

I plan to do this one myself again--since the pros I left it to the
last 2 times it'd been in didn't seem to do any better, and want to
leverage the savings of subarugenuineparts.com--and am interested in
what goodies are best to clean up the calipers, caliper slides, and
that and what sort of lubricant should be used on the slides (does
Subaru sell a kit for such?).

Also, looking in the OEM catalog--anyone know what the front brake
backing plate is that sells for about $15 each?  Is that the backing
plate for the pads?

Thanks for any insight or time in hanging with an overlong question.

I only know what I've read and a little experience. I DO believe that
less-than-careful torqueing of wheel lugnuts can cause problems with
drums and rotors but that MOST of the so-called brake warpage is
actually 'cementite' or pad deposits or other localized changes in the
rotor material from overheated pads and rotors. Just about the worst
thing that you can do is have an emergency stop followed by a lengthy
time sitting with the pads clamped in one spot. The heat under the pad
will not dissipate and can alter the 'temper' of the rotor in one spot
and/or deposit pad material in that one area. And supposedly having
rotors turned will not remove the altered metal sufficiently in many
cases. Possibly driving through a deep puddle after heating up the
rotors could cause a problem ? - dunno.

I've also read that mix/matching rotors and pads can lead to
suboptimal brake performance. That is, Akebono pads may not work as
well on Stoptech rotors as Stoptech pads would. I can tell you I am
experiencing this at present with some Wagner pads I put on the wife's
03 Outback. They are noticeably worse than the OEMs were. I will go
back to OEM after these become worn-out, (or maybe a little before)

Brakes stop your wheels, TIRES stop your car. Don't run low
performance tires and expect high performance from high performance
brakes.

Stoptech has a 'white paper'/w'ever on warpage as well as other good
info.

http://www.stoptech.com/tech_info/wp_warped_brakedisk.shtml

 

[1 Lucky Texan]

I'd be grateful for any sage advice on a long standing brake puzzler.

I can barely recall the last time I was happy with my brakes on this
frigin vehicle.   My 140k mile 01 Outback has warped its rotors
again, and has had lousy braking performance since about a month after
the latest top-of-line third party pads and new top quality third
party rotor went on it (done by a non-Sube tech)...oh, probably just
25k miles ago.  The brakes since the most recent set of top of the
line pads have felt soft to me, and stopping performance seems lousy.
Pedal travel seems to be a bit more than it should as well, though the
techs did bleed the brake system, and on a return trip insist that a
hydraulic issue isn't at play and that those particulra pads are just
a bit soft in feeling.  I'm a family guy with an anemic engine'd
vehicle, drive with one foot, and decelerate slowly and smoothly, so
aggressive driving certainly can't be the issue.    My brake rotors
don't look shiny on the front for what it's worth--they look more
black.

Q1: is this blackness of the rotors indicative of an overtemp
condition at some point in the past?  

Q2: if so, what could be causing that?  Tab of non-OEM brake pad a
bit too large causing it to hang up?  Or could there be an issue with
booster or master cylinder at play?  How do they test for booster or
master cylinder issues?

Q3: is it true that if a pad overheats, it chemically changes and will
never stop the same ever again?  Most recently a tech who looked at
the issue mentioned this and shook off any of my questions about
possible master cylinder or booster problems.

Q4: on pad replacement, aside from going OEM with pad and rotor (which
I'm going to do this time), I'd like to know what are the best
practices to doing the brake job.  

I plan to do this one myself again--since the pros I left it to the
last 2 times it'd been in didn't seem to do any better, and want to
leverage the savings of subarugenuineparts.com--and am interested in
what goodies are best to clean up the calipers, caliper slides, and
that and what sort of lubricant should be used on the slides (does
Subaru sell a kit for such?).

Also, looking in the OEM catalog--anyone know what the front brake
backing plate is that sells for about $15 each?  Is that the backing
plate for the pads?

Thanks for any insight or time in hanging with an overlong question.

Another thought - sometimes with age the rubber brakelines can balloon
with pressure and will feel a little spongy. New OEM or perhaps
stainless braided brakelines might restore some more 'solid'-feeling
performance.

as for parts pricing - try an on-line source like
subarugenuineparts.com.(Jamie is the contact there - she's helped me a
lot. and she rallies www.subiegal.com !)) Sometimes you can even get
the local dealer to match prices. I think the backing plate is spot
welded on? maybe that depends on the model.

 

[Todd H.]

Have been driving now for 40+ years and have never experienced warped
rotors. My understanding is just about the only thing that will warp
a rotor is overtorqued lug nuts.

I've exepreinced that before. It's possible, but I do manually
retorque after wheel servicing and have a torque wrench. I'm also
annoying in making a point of asking for manual or at least torque
stick torquing to avert that, yet here I am. . :-\

If the rotors are "black" that suggests to me the calipers are not
working.

Hanging up ?

I'm wondering if maybe teh aftermarket pad maybe has tabs that are
just a tad too large preventing them from sliding easily. I recall
someone saying here that they've ground those down a bit to address a
difference between aftermarket and OEM. I guess I'll find out when my
oem pads get here and I can measure them against what I'm taking out.

Don't believe overheating the brake pads changes them in any way. I
once many years ago had a 66 Corvette with the 427/425 and turned
all 4 rotors red after a panic stop from 100 m/hr. Never noticed
any difference in the braking performance after the rotors cooled.

The brake pedal will be super hard if the booster fails.

Hard how? As in you have to put a lot of pressure on the pedal to get
braking? If so, that may be an issue I have. If you mean hard as in
it doesn't move at all and feels like you're pushing on a solid piece
of metal, then it's definitely not that. I have to push pretty hard
and the pedal will nearly go the the floor, but does stop shy.
Squishy is the best way I can describe it.

Bad MC and
the pedal goes to the floor when pushed.

Hrmm. I don't have that either, so I don't have what I envision MC
blow by would feel like.

I installed front rotors and calipers from a 2002 WRX on my 95 wagon
about 4 years ago and haven't had a bit of problems with them.
Thinking your newer wagon uses the same parts as the WRX. When you
install the new rotors, make sure the surface behind the rotor where
the rotor presses up against the hub is clean. Not much help but
like I said, never had this problem.

What pads/rotors did you use?

Did take your advice when I had all the rear wheel bearing problems
and went with a used knuckle. So far so good.

Woo hoo!

Thanks for the response. I'm feeling a bit more relieved that at
least I probably don't have mc or booster problems.

Carl's theory about bulging brake lines has me intrigued though--that
makes sense to me. We'll see how it feels when my new OEM rotors and
pads get here.

Thanks also for the reminder to clean up the hub where the rotor
interfaces.

 

[Todd H.]

I've also read that mix/matching rotors and pads can lead to
suboptimal brake performance. That is, Akebono pads may not work as
well on Stoptech rotors as Stoptech pads would. I can tell you I am
experiencing this at present with some Wagner pads I put on the wife's
03 Outback. They are noticeably worse than the OEMs were. I will go
back to OEM after these become worn-out, (or maybe a little before)

I've gathered a few of those over the years here too. These pads
though I never got told exactly what they were were expensive and
matched to the rotors, and were requested to be high-end aftermarket.
Who knows what the guy selected though--I've had soem issues where he
wasn't entirely straight with me and I've since moved on, so who
knows!

Brakes stop your wheels, TIRES stop your car. Don't run low
performance tires and expect high performance from high performance
brakes.

I've got some non-cheap Michelin's on em so that shouldn't be too
awful, but it's really a matter of pedal feel vs every rental car and
the 1 year old van I have that lets me know something is definitely
amiss in how much deceleration I get for how much I have to push on
the pedal. The pads and rotors just don't seem to be all that grippy
to each other.

Stoptech has a 'white paper'/w'ever on warpage as well as other good
info.

http://www.stoptech.com/tech_info/wp_warped_brakedisk.shtml

Cool. I 'll give it a look.

Thanks also for the subarugenuineparts/Jamie lead years ago. I'd
actually just traded emails with her and ordered pads/rotors from her
before posting that yesterday!

 

[XR650L_Dave]

I'd be grateful for any sage advice on a long standing brake puzzler.

I can barely recall the last time I was happy with my brakes on this
frigin vehicle.   My 140k mile 01 Outback has warped its rotors
again, and has had lousy braking performance since about a month after
the latest top-of-line third party pads and new top quality third
party rotor went on it (done by a non-Sube tech)...oh, probably just
25k miles ago.  The brakes since the most recent set of top of the
line pads have felt soft to me, and stopping performance seems lousy.
Pedal travel seems to be a bit more than it should as well, though the
techs did bleed the brake system, and on a return trip insist that a
hydraulic issue isn't at play and that those particulra pads are just
a bit soft in feeling.  I'm a family guy with an anemic engine'd
vehicle, drive with one foot, and decelerate slowly and smoothly, so
aggressive driving certainly can't be the issue.    My brake rotors
don't look shiny on the front for what it's worth--they look more
black.

Q1: is this blackness of the rotors indicative of an overtemp
condition at some point in the past?  

Q2: if so, what could be causing that?  Tab of non-OEM brake pad a
bit too large causing it to hang up?  Or could there be an issue with
booster or master cylinder at play?  How do they test for booster or
master cylinder issues?

Q3: is it true that if a pad overheats, it chemically changes and will
never stop the same ever again?  Most recently a tech who looked at
the issue mentioned this and shook off any of my questions about
possible master cylinder or booster problems.

Q4: on pad replacement, aside from going OEM with pad and rotor (which
I'm going to do this time), I'd like to know what are the best
practices to doing the brake job.  

I plan to do this one myself again--since the pros I left it to the
last 2 times it'd been in didn't seem to do any better, and want to
leverage the savings of subarugenuineparts.com--and am interested in
what goodies are best to clean up the calipers, caliper slides, and
that and what sort of lubricant should be used on the slides (does
Subaru sell a kit for such?).

Also, looking in the OEM catalog--anyone know what the front brake
backing plate is that sells for about $15 each?  Is that the backing
plate for the pads?

Thanks for any insight or time in hanging with an overlong question.

I had what felt like a warped rotor on my '03 OBW, but it was actually
pad material that had transferred to the rotor and made an extra-high-
friction high-spot.

I have had to file brake pad backing plates to get them to fit on my
car.

I'd advise using the good pads that come with the stainless shims, get
at least mid-grade rotors (the $35 ones at napa seem to be decent),
and clean the rust off the caliper/pad holders where the shims/pads go
on.

Make sure the caliper pistons slide back smoothly, make sure the
sliders the caliper bolts to slide easily, make sure the pads go into
place and can move back and forth without a lot of effort, and use the
high-temp silicone grease both on and under the stainless shims (if
the material under the shims rusts it could force the shim into the
pad, causing it to bind).

Make sure the hub where the rotor goes is clean and smooth, and put
some anti-seize on it.Scrape it with a screwdriver and a wire brush,
whetever it takes.

Make sure the wheel where it goes on the hub is clean and smooth, my
AL rims had a nasty, hard glassy buildup where the AL and the rust
reacted, I had to break it off with a screwdriver (it was like welding
slag).


Dave

 

[XR650L_Dave]

I had what felt like a warped rotor on my '03 OBW, but it was actually
pad material that had transferred to the rotor and made an extra-high-
friction high-spot.

I have had to file brake pad backing plates to get them to fit on my
car.

I'd advise using the good pads that come with the stainless shims, get
at least mid-grade rotors (the $35 ones at napa seem to be decent),
and clean the rust off the caliper/pad holders where the shims/pads go
on.

Make sure the caliper pistons slide back smoothly, make sure the
sliders the caliper bolts to slide easily, make sure the pads go into
place and can move back and forth without a lot of effort, and use the
high-temp silicone grease both on and under the stainless shims (if
the material under the shims rusts it could force the shim into the
pad, causing it to bind).

Make sure the hub where the rotor goes is clean and smooth, and put
some anti-seize on it.Scrape it with a screwdriver and a wire brush,
whetever it takes.

Make sure the wheel where it goes on the hub is clean and smooth, my
AL rims had a nasty, hard glassy buildup where the AL and the rust
reacted, I had to break it off with a screwdriver (it was like welding
slag).

Dave

Oh, and maybe you're not using the brakes hard enough?

After the rotors get wet (dew, rain) you have to use them hard enough
to clean off the rust, and you have to use them hard enough early on
to bed the pads in, and wear the rotor in. It is possible you glazed
the pads by being too gentle on 'em, especially early on.

I don't really reccommend sanding the pads to break glazing, but you
can wet sand them. If the rotors are really pretty new (and really the
good ones) it may be worthwhile to turn them. Also, turning them will
leave a rougher finish, which is better if you are having glazing
problems from being a very gentle braker.



Dave

 

[johninky]

When the booster fails, best way I can describe the sensation is it
takes both feet to stop the car. Your booster is probably not bad.
Would think the engine would also idle badly with the huge vacuum
leak.

The WRX rotors/pads/calipers all came from a low-mileage wreck. I
didn't do anything to any of the parts other than install them.

You stated something about top of the line pads. Do know lots of high-
performance pads don't stop worth crap until the pad temperature is
increased to some value.

The braking system has a proportioning block somewhere. Never heard
of one going badbut something else to think about.

 

[clare]

Have been driving now for 40+ years and have never experienced warped
rotors. My understanding is just about the only thing that will warp
a rotor is overtorqued lug nuts. If the rotors are "black" that
suggests to me the calipers are not working. Don't believe
overheating the brake pads changes them in any way. I once many years
ago had a 66 Corvette with the 427/425 and turned all 4 rotors red
after a panic stop from 100 m/hr. Never noticed any difference in the
braking performance after the rotors cooled. The brake pedal will be
super hard if the booster fails. Bad MC and the pedal goes to the
floor when pushed. I installed front rotors and calipers from a 2002
WRX on my 95 wagon about 4 years ago and haven't had a bit of problems
with them. Thinking your newer wagon uses the same parts as the WRX.
When you install the new rotors, make sure the surface behind the
rotor where the rotor presses up against the hub is clean. Not much
help but like I said, never had this problem.

Did take your advice when I had all the rear wheel bearing problems
and went with a used knuckle. So far so good.

Well you are one lucky son-of-a-gun, because warped rotors ARE a
reality, and not just (or even) from overtorqued lug nuts.

And as for overheated brake pads, a lot of the crap being sold out
there today (and for the last 20 years) WILL deteriorate from repeated
overheating. The pad material gets hard and brittle, and in extreme
cases comes right off the pad. In less extreme cases the brakes just
lose their effectiveness, requiring more pressure to stop, or they get
noisy.

In several decades working as a mechanic, from the inception of disc
brakes on american cars, I've seen a lot of both.

 

[clare]

I had what felt like a warped rotor on my '03 OBW, but it was actually
pad material that had transferred to the rotor and made an extra-high-
friction high-spot.

It's not pad material transfer - it is corrosion - intergranular
corrosion that causes the rotor to "swell". If you go to machine it,
you will find a "crater" under the bulge.

I have had to file brake pad backing plates to get them to fit on my
car.

Generally the pad mountings SWELL with rust - cleaning up the steel
makes tha new pads fit just fine.

 

[clare]

Oh, and maybe you're not using the brakes hard enough?

After the rotors get wet (dew, rain) you have to use them hard enough
to clean off the rust, and you have to use them hard enough early on
to bed the pads in, and wear the rotor in. It is possible you glazed
the pads by being too gentle on 'em, especially early on.

I don't really reccommend sanding the pads to break glazing, but you
can wet sand them. If the rotors are really pretty new (and really the
good ones) it may be worthwhile to turn them. Also, turning them will
leave a rougher finish, which is better if you are having glazing
problems from being a very gentle braker.



Dave

I read some brake break-in instructions a week or two ago - said to
stop from 60mph to almost a stop 3 times in a row, then let cool by
driving for 5 - 10 minutes and repeat - do it 3 times and the pads are
mated to the rotors and the brakes are broken in. By the third stop of
each cycle you should be feeling the brakes fade - but eack set of 3
they will get better and the pedal will get firmer.

If using the ATE premium rotors (with the special coating and grooves)
2 or 3 good hard stops will seat the pads adequately. I figured they
were a "gimmick", but they were something like 30% off when I needed
to do the brakes on my wife's car so I tried them. They've been
excellent so far (almost 2 years now) and I just put a set on my car.
Kevlar pads on the wife's and hybrid ceramics on mine.

 

[StephenH]

I will speak from the other side of the brake pads.
I have seen countless warped rotors, On customers vehicles and my own.
It does happen. Ford Taurus were famous until you put aftermarket
rotors on it.
Warping rotors by excessive torque is a possibility, especially in the
older style rotors where the hubs were part of the assembly. I think
the amount of warpage from torque issues is smaller due to the fact
that the rotors are now trapped between the hub and the wheel, the
force doesn't pull on the rotor as much.
Why do they warp? I don't know. Poorer metal content. too hard of
pads, riding brakes.
just my opinion

 

[Chico]

Hrmm.  I don't have that either, so I don't have what I envision MC
blow by would feel like.

Not too long ago, I decided that I was well overdue for new brake
fluid on m 03 OBS. I figured I was close to 100k kms on the same
fluid. The brakes were feeling a little squishy, so I got the brake
fluid replaced.

Afterwards, the brakes felt worse. I was suspicious that they were
not properly bled, as unlikely as that seemed. I even scheduled a
subsequent check-up with the dealer, but just before the appointment
it started feeling better so I cancelled.

Now they feel reasonable, although still not nearly as good as a
rental car I recently had.

My suspicion is that the seals in the master cylinder were at the same
water saturation point as the old fluid, but the new fluid was nice
and dry. Water seeps from the seals to the fluid, and the seals
shrink, no longer providing a good seal. Brakes feel squishy.
Eventually, a new equilibrium is reached, and things felt better.

That's the best I can come up with!

Good luck. I would have done the brakes myself if I wasn't afraid of
brake fluid! I did the pad / shoes / drums / rotors last year.

 

[XR650L_Dave]

It's not pad material transfer - it is corrosion - intergranular
corrosion that causes the rotor to "swell". If you go to machine it,
you will find a "crater" under the bulge.




Generally the pad mountings SWELL with rust - cleaning up the steel
makes tha new pads fit just fine.

Well, caused by the pad somehow- the area was in the shape of the pad.

I had already cleaned the bracket under the shims, the shear line on
the pad backer was smeared because they were stamped with a poorly
made or worn die.


Dave