Brake pulsation

[Guest]

I have a 1997 and 2001 Outback. Both cars suffer from warped rotors and
brake pulsation. I can somewhat understand my 97, because I drive 30 miles
to Miami and back every day. Ninety percent of the people down here do not
know how to drive. So, it's brake hard, brake hard, and hope the idiot
behind me is not reading the paper or asleep. I've replaced the rotors, and
had them turned twice. After only about two months, the vibration and
pulsation are back. Has anyone tried ceramic pads? I'm told that there is
less heat build up. I've checked the temperature of my rotors after I get
home and both fronts show about 165 degrees.

Thanks,

Captain Marty

 

[Todd H.]

I have a 1997 and 2001 Outback. Both cars suffer from warped rotors and
brake pulsation. I can somewhat understand my 97, because I drive 30 miles
to Miami and back every day. Ninety percent of the people down here do not
know how to drive. So, it's brake hard, brake hard, and hope the idiot
behind me is not reading the paper or asleep. I've replaced the rotors, and
had them turned twice. After only about two months, the vibration and
pulsation are back. Has anyone tried ceramic pads? I'm told that there is
less heat build up. I've checked the temperature of my rotors after I get
home and both fronts show about 165 degrees.

Dunno about ceramics with respect to lowering rotor temps--I'd imagine
they're certainly better at handling heat froma pad perspective, but
in terms of being friendlier to the rotor, the opposite may actually
be the case with the harder material.

One thing you don't mention is the importance of proper lugnut torque.
A pimple faced jackhole teenager at a tire store armed with an an
impact wrench without a torque stick can easily overtoruqe various
lugnuts leading soon to warped rotors as well. It's best to retorque
things yourself with a calibrated torque wrench after any time your
wheels are removed.

Another thing worth mentioning is that modern rotors aren't terribly
thick, and reportedly don't respond well to turning. Once turned,
their reduced thickness makes them more prone to warping. Be sure to
check the runout specs.

Best Regards,

 

[Jim L]

I have a 2K outback wagon with 70 K miles on it. Pulsing rotors seem to be
a fact of life for me. At 20K, they started pulsing a little, after being
improperly torqued. I lived with it until 35K and then turned them and
replaced the pads.(even though they still had some wear left) I used some
softer pads that tend to dust the wheels. I have been very carefull to
watch the torquing on them and I now notice at 70K that the brakes are just
starting to pulse a little at higher speeds. I suspect that I will get
about 40K this time around. I live in the Pacific Northwest, where driving
up and down hills daily is a fact of life, although my wife is fairly easy
on the brakes and it is her car. Good luck! Jim Lofgren

 

[Carl 1 Lucky Texan]

Often, vibration on braking can be bad tires. They usually won't cause
much pedal pulsation, but they will cause vibration/shuddering. If your
tires are old (not just worn) they may be suffering from a little tread
separation. Rumor has it, many newer tires do not hold up as well as in
the past due to some 'adjustments' made to tire manufacturing process
prompted by EPA/Kyoto-type mandates.

I dunno

Carl

 

[ed]

Another thought...when you replace rotors, get good ones. The cheaper "white
box" rotors are OK, but the metal rusts much easier if you are in a salt
area (ie either winter salt or sea salt), and are sometimes thinner than
better rotors (same o/s dimension, but the vent holes are wider, therefore
less metal thickness between the vent and the rubbing surface, making them
more prone to warping). More expensive rotors seem to be better, with Brembo
being the most durable, but the original Subaru ones are good too.
Turned rotors never seem to last, you remove metal, making the rotor
thinner, and if the machine has any play in it, it will not remove the
runout completely. Also make sure the back of the rotor and the hub are
clean, any spec of rust or dirt can cause a wobble.
Ed B

 

[Rat]

One thing you don't mention is the importance of proper lugnut torque.
A pimple faced jackhole teenager at a tire store armed with an an
impact wrench without a torque stick can easily overtoruqe various
lugnuts leading soon to warped rotors as well. It's best to retorque
things yourself with a calibrated torque wrench after any time your
wheels are removed.

Agreed - lugnut torque has a huge effect on the pulsating feeling
commonly misdiagnosed as warped rotors.

 

[M. Butkus]

Did you replace the pads?... I had a warp in the back after getting the
brakes hot by going down hills. Replaced the pads with semi-metalic types.
Drove 20k with no problems before I sold it at 58K. Never had a problem up
front. My new Saturn Vue. 30K and both rotor insides were scored, outsides
were fine.