sticking caliper?

hey all,

this past summer ( early august maybe) I replaced the pads on the rear
of my 03 accord.
the left side was worn badly, the right, not so much, but I did them
both with OEM pads,
this week my wife said the brakes were squeeling, and sure enough,
the rear left was making noise.
looking at the outer pad on the left side there is 1/2 of the material
worn off, compared to the right side already, maybe 7,000 miles into
the new pads...
I haven't had a chance to take the wheel of and look at the inner pad,
but, I'm starting to think that that rear is dragging constantly,
so, what can I do to fix this? is a new caliper in my future or ???

thanks for the thoughts and ideas.

Dave

 

Not likely a bad caliper, but a sticky pin or pad.

See here for a (badly in need of updating) writeup:
http://www.tegger.com/hondafaq/rustybrakes/brakes1.html

 

Tegger, thanks for the beauty link, you put a lot of time in that
obviously...
hey, I watched that vid of you turning in the piston on the caliper
on the rears, I remember when I had to do that back in the summer it
took WAAAY more force for me, I ended up putting the screwdriver
lengh twise to the groove and used the shaft of the screwdriver in the
groove of the piston to turn it... ( did that make sense?) I tried to
turn it with the screwdriver normally, but that did not work at all...
the other side did turn a fair bit easier...
I know the pins looked decent at the time, and I could pull them free
with my fingers.

based on all that info I'm thinking that that the piston is a bit
sticky, If I remember right, the inside pad was much more worn than
the outside pad this summer, and I'm guessing the same has happened
again...

 

hmm, I'm rethinking it again, after re reading your bit about rust
under the shims.. I know I had to pry off the the old pads with a
screwdriver and they popped out of place pretty smartly after getting
a bigger screwdriver... I gave lip service to cleaning under the
shims with a screwdriver, and was able to place the new pads in by
hand, but, it wasn't loose.
I live in SE Michigan, on a dirt road where they put calcium chloride
down in the summers... can't think of many worse places for steel
brake parts to live...

 

If the inside and outside wear at different rates, it points to the
pins not moving freely. Did you disassemble and re-grease them, then
put them back together right, or did you just test that they moved,
then leave them be?

The rears (especially) need the full service done each time. They get
a lot of crap from the road splashed on them.

 

Invest in good steel files. Nice meaty ones. There's a lot of rust,
and needs to be taken off. Then, make sure you lube up all of the
contact points.

 

The Brembo brake pads on my BMW motorcycle wore so unevenly that I rotated
them at every oil change. I forget which side wore faster, but I presume
it had to do with a single piston, essentially pushing one pad against the
disc which then had the added burden of moving the caliper before the other
pad touched.

 

Hopefully, you didn drive too far with the caliper dragging like that.
Mine did the same thing on my CRV and the excess heat roasted my wheel
bearing.

Good thing the wheel bearing was under warranty.

Now I do the spring brake cleaning ritual as well.

 

"Lip service" doesn't help much. You have to clean ALL the rust off. Those
pads must be LOOSE.

Both pins, plus both pads, on each side, MUST be /perfectly free/ to move
in their positions. ANY stickiness will create uneven pad wear.

It's possible the hydraulic piston is sticking, but that would cause uneven
wear on that side (on BOTH pads) versus the pads on the other side. It's
even possible you have a combination of problems.

To easily check for a sticky piston, you can do one of three things:

1) Get an infrared thermometer for between $30 and $80. The sticky side
will be much hotter than the non-sticky side.
<http://www.tegger.com/hondafaq/misc/infrared-thermometer.jpg>

2) After a drive, feel the wheel nuts with a fingertip. The sticky side
will be much hotter than the non-sticky side.

3) Elevate the end of the car with the suspected sticky piston. Remove both
road wheels, remove the calipers from the mount brackets and hang them
properly. Push the pistons back in all the way. Now step on the brake pedal
all the way to the floor about eight times. Is one piston ejected LESS than
the other? Then that piston is sticky.

Make sure there is sufficient fluid in the master cylinder that it doesn't
run dry when you do #3. And do not perform #3 if the brake fluid has not
been changed in five years or more.

By the way, I've been experiemnting with high-build zinc primer as the
anti-corrosion medium in place of grease between the slide shims and the
mount bracket. It's worked well, and I've been meaning to update the site
to show that.

 

Or one pad being clamped much more than the other on account of rust.

The primary problem with the rears is that they never get very hot, so
moisture doesn't boil off them. This means they rust like crazy.

I can't quite remember how hot the fronts got last time I checked, but the
rears only get up to about 90-100F max. I think the fronts get up to about
140-160F under normal use.

 

K, so I got a night to look at the wheel in question
its the rear left.. rear right is in perfect fine shape... The
inside pad on the rear left is down to the squeely (whatever you call
it "wear indicator" ) the outside pad is at least twice as thick as
the inside, though probably only half the thickness of the outside
pad on the rear right ( and yes, they were replaced at the same
time... )
The upper of the two pins was a little sticky, I could spin it free
by hand, but compared to the lower pin it was a bit tight... I sanded
it down and put some syl-glyde in there, and it seems good...
Now the fun...
I had a beast of a time turning in the caliper piston, that is at
first, the first 4 or 5 quarter rotations were very difficult..
( one hand holding the caliper, the other with a flat file laying in
the groove of the X pattern on the piston head, pulling to the point
of my file flexing) After a few rotations, though it was much easier
to turn, though no where easy enough to spin with a large
screwdriver. Once I finally got the piston in far enough I notice
that the piston boot was dislodged though... not sure If I just did
it now, or if it had been that way. but, I have part of the rubber
boot coming free, so. I think I'm going to order a new
caliper..

hopefully short term I can get the boot back in a decent place so that
I can still drive till the new caliper gets here.

So the question is this, I only need to get the one side right, I
couldn't think of a reason to get the other side as well as it seems
to be in good shape, but, Just though I would post to get all of your
opinions.

thanks again to all

Dave

 

Then you still have a sticky pin or outer pad. No way around this, my
friend.

What the piston itself is doing isn't important in the context of that
inner pad.

 

Although it does indeed appear that the piston is sticking as well.

I did earlier give a method of diagnosing a sticky piston, but for the rear
brakes you need to cut the number of pedal presses to 2 or 3, NOT eight.
The rear pistons eject a _LOT_ farther than the front ones do!

 

I went back to the pads and compared again, holding them side by
side. They actually are much closer in thickness than it first
appeared, I looked at the boot on the caliper piston, and there
was junk on the inside edge of the seal that has been sitting for a
while, so, I'm pretty sold on the caliper being sticky for a while
now... At the rate these pads wore out I'm thinking it must have
been March or April that the caliper started to go as the rear pads
before were definitely worn heavier on the left than on the right as
well. So, I'm going to order a new caliper tonight. I'll be
checking back in once it arrives for some insight on installation...
Looks straight forward, one bolt for the lines, and slip off the
clip for the e-brake. Just have to get some help with the bleeding of
the lines. Maybe this is a good time to replace the fluid? I'll
have to read up on how to do that.

thanks again

Dave

 

That's pretty much it. It's best if you get a couple of new copper washers
for the hydraulic fitting.

You MUST do a thorough bleed, as anything less will leave air in the new
caliper and you'll have a soft pedal.

That caliper is really complex inside, with many nooks and crannies that
trap air bubbles. Get a nylon mallet while you're at the parts place;
you'll need it.

 

So, I got the new caliper on last night, went on without any major
issues, biggest problem was finding hose to help with the line
bleeding, ( ended up using some gas line from an old weed whip)
Everything went on just like it should have, no stuck bolts that
couldn't be freed ect.. Thanks to all for you help!

Once I got the old caliper off and could pull at the piston boot
without worry, I could definitely tell what the problem was. There
was a good amount of rust on the side of the piston.

thanks again.

Dave

 

Good news! Glad to know it went well.

I've had trouble in the past getting the pedal to feel as firm as it should
be without some work knocking bubbles free. Surprised yours didn't present
that issue.

For some odd reason Honda, unlike Toyota, does not use semi-stainless
pistons. Always wondered why.

In any case, rust can be prevented through the judicious use of silicone
grease. I rebuilt my fronts about eight or nine years ago, using silicone
grease. The pistons are squeaky-clean at this moment. The originals rusted
up and seized pretty badly.

Anytime.