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mrcheerful<nbkm57@hotmail.com> wrote in
news:8QHOf.30836$wl.17519@text.news.blueyonder.co.uk:[color=blue][color=green]
>> I just realized that replacing the rotor and pads will not solve my
>> brake vibration problem if the pistons are sticking!
>> Do they make a brake piston force guage which works on 4 piston
>> calipers?[/color]
> Use your hands.
> With the pistons pushed out a bit (by carefully pressing
> the brake pedal) it should be possible with strong hand
> pressure to push each piston back in to the caliper[/color]
[color=blue]
> the easiest way for you to satisfy yourself as to the ease of piston
> movement is to strip the caliper completely, with no piston seals at
> all the cleaned pistons should be able to fall freely in and out of
> the caliper.[/color]

Hi Mr Cheerful,

Thanks for the advice. I guess I just assumed there was a tool to measure
brake piston sticking. If there isn't a tool, I can do what you say and
test it by hand with the calipers disassembled.

Luckily these 1998 Toyota 4Runner front calipers are the easiest I've seen
in my life to work on. We don't even need to remove a single bolt to get
the brake pads out. All we do is remove a clip by hand, then pull two pins
by hand, pop out the anti-vibration spring by hand, and then pull out the
two brake pads and two anti-squeal shims per pad.

Looking in my Toyota Repair Manual, I can see that it only takes two bolts
to remove the calipers from the car (in addition to the brake line).

Then it says to pry out the four "cylinder boot set rings and boots" per
caliper, which at first I presumed was the same as the "piston seals" you
speak of. But, reading on, Toyota says to blow out the pistons with
compressed air (placing a wood plate in the space where the rotor was).

Only then, the repair manual says to pry up the four "piston seals" with a
quarter inch flathead scewdriver. The Toyota Repair Manual exploded diagram
shows four "set rings", "boots", "pistons", and "piston seals", in that
order, outward from the rotor in both directions.

The problem then becomes, how does one test piston force after removing the
piston seal when the pistons are already out of the calipers by this time.

Still, there's no harm in taking the calipers apart.
The shop manual says to lubricate some areas with "lithium soap base glycol
grease" and others with "disc brake grease". Aren't they the same thing?

So many questions ... so much to learn!
Stu