Accord 92 front brakes

I changed my front disks and pads 2 years ago and now they are warped . Also
had a seized caliper. So I changed them again. 3 weeks later I get vibration
again once in a while. . I know that these disks are pressed fit , has
anybody else have issues with this generation Accord front brakes.

 

I've had this problem on several of the cars I've owned. The problem was
caused by just pushing the pistons all the way back in with a c-clamp or
whatever, and installing the new pads. Sometimes you can get away with
this, and sometimes you don't. The main thing holding the pistons in
position is the friction of the rubber seals. When you release the brakes
the pressure is released but they don't retract that few thousands of an
inch they need and are still rubbing significantly enough to cause heat,
which expands everything causing more pressure and more heat, until the
rotors warp, then the high part of the rotation makes more heat. My theory
is that the heat wears away the pads rapidly until rubbing decreases back to
normal and the rotors cool off and straighten out and everything is OK,
until you press on the brakes again, then the whole process repeats. With
front brakes, you can usually smell them buring, in addition to feeling the
steering wheel shake.

The reason the pistons don't retract a few thousanths of an inch is because
when they were previously all the way extended, when your old pads were
thin, dirt and road grime and dirty water got in, despite the rubber boot
cover, and messed up the outside part of the piston that was external to the
seal. Then when you forced the piston all the way back in to allow room for
the new pads to be installed, you make that crusty part of the piston now
come into contact with the rubber seal, and it doesn't slide too well.

The solution is to install new or rebuilt calipers, or rebuild the ones you
have. I used to get a rebuild kit for a few bucks. It included a new seal
and dirt boot. To rebuild a caliper.............remove the caliper from the
wheel suspension but keep the hose connected. Pump the brakes until the
piston is pushed all of the way out. At this point brake fluid will
probably be leaking out all over. Now disconnect the brake hose from the
caliper and remove the caliber completely. Pull out the piston.
Completely pull out the dirt boot and discard it. Reach inside the bore
with a little screw driver or knife and remove the seal. Using one of
those small three stone rotary hones that fits on a drill, and using brake
fluid as a libricant, clean up the inside of the cylinder. Clean
everything, and install the new seal using brake fluid as a lubricant. Now
take the piston and get it all clean and smooth. I use a wire wheel if the
piston is metal (I've seen plastic ones (a hard plastic similar to
bakelite). After it's clean on the outside, polish it smooth (I use a
buffing wheel and rouge). Then clean the piston with brake fluid. When
everyhting is clean and smooth, using brake fluid as a lubricant, install
the piston all the way into the cylinder. This is sometimes hard to do,
Try turning the piston to get it past the seal. I once had one that just
would not get past the seal. I ended up making the radius of the back edge
of the piston larger using the grinding wheel and buffing wheel. After the
piston is in, install the dirt boot over the piston, install the caliper
assembly back on the car, and connect the brake hose. Bleed the air out by
having someone pump the brakes, or use a hand vacuum pump with the little
sealed container that usually comes with them.

You should have no more problems until the next time you re-seat the piston
without cleaning it

Good luck

 

binding is indeed caused by the pistons not retracting far enough, but
the "warping" is much more likely incorrect lug not torque procedure.

mostly. yes, crud fouls up the workings, but the real reason why the
pistons retract on a correctly functioning system is because of a small
ramp on the cylinder wall.

| |
__ / |
||----|| ^
|| C || |
||____||
____ |
| |
A | | B

where A is the cylinder, B the piston & C the seal. in this case, the
piston would be squeezed upwards by hydraulic pressure. the piston
doesn't slide against the seal in normal application of pressure, just
wear, so pressure will deform the seal into the ramped area at the top
of the cylinder seal groove. when pressure is released, the elasticity
of the seal from the ramp will move the piston back to resting position.

what happens when the system gets full of crud is that the groove gets
full of dust & corrosion, etc. and so the seal doesn not have anywhere
to spring into, and thus nowhere to spring back from.

rebuild is simple & cheap. need the right hose clamp to prevent excess
fluid loss and the correct hydraulic grease for reassembly, but fllow
tegger's faq's on caliper rebuilds & you'll be just fine.

with hondas, you need to be careful not to remove the chrome on the
piston. removal leads to excess wear and accelerated corrosion. unless
you live in the rust belt, rubbing the piston on a piece of wood removes
rubber gums & general sticky crud. if rust is severe, consider piston
replacement. they are purchasable separately.

genuine silicone brake grease is a better lubricant. [don't use that
silglyde garbage.]