help 2001 altima brakes

I will admit to never having replaced this model before. REAR breakpads on
01 altima worn down to about 8th inch thickness, are the calipers
overextended and in need of replacement?
On any other car I have been able to compress brake calipers' piston to
replace brake pads but this configuration appears different and piston will
not compress even with a heafty c-clamp.
When I discovered both rear calipers not compressing, I became suspicious.
Nissan did not use hydraulics all the way to the caliper but cables with
levers and springs attached to the calipers, then there is a separate
hydraulic line.
How can I tell if the caliper is frozen?
So I had to put the old pads back in, the rear wheels spun fairly free.
Started the engine and depressed the brake with rearend lifted from ground,
I was UNable to manually rotate either rear wheel while brakes engaged, but
was able to manually spin either rear wheel when brake was again released. I
can only assume that the calipers still work to that point, but why can they
not be depressed to a point where new pads can be installed... and should I
replace them?
Is there a mechanism that can be adjusted for this unusual configuration to
release the break pistons?
Thanks,
John

On 3/3/07 6:26 PM, in article 9P6dndxSnuSqj3fYnZ2dnUVZ_uqvnZ2d (AT) comcast (DOT) com,
"john" <jfdoug (AT) comcast (DOT) net> wrote:

I will admit to never having replaced this model before. REAR breakpads on
01 altima worn down to about 8th inch thickness, are the calipers
overextended and in need of replacement?
On any other car I have been able to compress brake calipers' piston to
replace brake pads but this configuration appears different and piston will
not compress even with a heafty c-clamp.
When I discovered both rear calipers not compressing, I became suspicious.
Nissan did not use hydraulics all the way to the caliper but cables with
levers and springs attached to the calipers, then there is a separate
hydraulic line.
How can I tell if the caliper is frozen?
So I had to put the old pads back in, the rear wheels spun fairly free.
Started the engine and depressed the brake with rearend lifted from ground,
I was UNable to manually rotate either rear wheel while brakes engaged, but
was able to manually spin either rear wheel when brake was again released. I
can only assume that the calipers still work to that point, but why can they
not be depressed to a point where new pads can be installed... and should I
replace them?
Is there a mechanism that can be adjusted for this unusual configuration to
release the break pistons?
Thanks,
John

There is probably nothing wrong with the calipers. On cars that also use
the rear disk brakes as the emergency brake, you have to screw the pistons
back in when you change pads. If you look at the front of the caliper
pistons, you notice there is a fat cross cut into them. Take a needle nosed
pliers, or you can buy a tool specifically for it, and screw them back into
the piston. Make sure the grooves are aligned when you are done such that
the pins on the back of the new pads are set into the grooves as you
reassemble them.