Disc brake question.

Vehicle in question is a 1993 Acord LX-A with 4 wheel disc brakes with ABS.

Question is; why are the "inside" brake pads showing 95% wear, while the
"outside" pads are only 10% worn?

This is noticeable on both front and rear, with the rear pads exhibiting this
the most, one was down to the rivets.
My son and I noticed this last night while rotating the tires.

TIA
-Steve

 

The calipers are not free to move. Have them serviced by a
competent tech, WBMA


mike hunt

 

the inside is where the piston is, that does the pushing. the other pad is
just a "backer" to give it something to push in to

 

The caliper is binding...get em checked.

 

Well I see you've gotten some real useful suggestions... like take it to a
"tech" to "get em checked".</sarcasm off>

Like most cars in its class your brake calipers are a single piston design.
For the rotor to be "squeezed" by both pads, the caliper piston assembly
has to be able to "float" on its frame - the Honda (Nissin ?) design, which
is quite a good one compared with some others I've seen, uses two pins, one
top and one bottom, which slide in sockets in the caliper frame. The
piston assembly mounts to the two pins which are lubricated in their
sockets with a high temp grease and have a pleated rubber boot to seal out
moisture.

I find that *some* uneven wear between the inner and outer pad is
inevitable, especially for the rear pads - I think partly due to the
self-adjusting handbrake mechanism inside the piston - but the usual cause,
where it's really noticeable, is corrosion. Either the rubber boot has
allowed water to enter the socket in the caliper frame, which prevents the
piston assembly from floating properly, or the pads are binding in their
mounts.

This is not a difficult job for a DIYer. You just have to take the pads
out, take the piston assembly off (hang it on some suspension part nearby
with a piece of coat-hanger wire) and take the slide pins out and check for
corrosion and relubricate. Honda sells a high temp urea grease for the
pins but you can use the Permatex synthetic grease, available at any auto
parts store, made for the purpose - the blue stuff which is a very sticky,
fairly thick, grease. Of course the rubber boots need to be replaced if
torn and they need to seat nicely in their grooves to keep moisture out -
silicone spray helps here.

Before putting it back together you neeed to clean any corrosion off the
caliper and the crud off the top and bottom retaining clips - I use a
Dremel with a wire brush attachment for the latter. Depending on where you
live, e.g. frost belt, this brake clean up needs to be done fairly
regularly. Certainly when you replace pads, you need to give everything a
good going over to clean out all the crud and crap - changing the pads is
easy and quick... doing the job right takes a bit of time.

Rgds, George Macdonald

"Just because they're paranoid doesn't mean you're not psychotic" - Who, me??

 

(SASCHOCH) floridly penned in

Because the brakes have not been serviced often enough.

If you remove the caliper, you will discover either:

1) that the outer pad is clamped firmly to the mounting bracket by the
action of rust under the stainless steel shims. This forces the inner pad
to do all the work

or

2) one (or both) of the slider pins are seized, preventing the caliper from
being able to move to re-center itself over the disc as the pads wear,
forcing the iner pad to do all the work.

Properly serviced brakes will see the pads remain more-or-less evenly worn
throughout the pads' life. Twice per year is proper in a northern climate.

 

|This is not a difficult job for a DIYer. You just have to take the pads
|out, take the piston assembly off (hang it on some suspension part nearby
|with a piece of coat-hanger wire) and take the slide pins out and check for
|corrosion and relubricate. Honda sells a high temp urea grease for the
|pins but you can use the Permatex synthetic grease, available at any auto
|parts store, made for the purpose - the blue stuff which is a very sticky,
|fairly thick, grease. Of course the rubber boots need to be replaced if
|torn and they need to seat nicely in their grooves to keep moisture out -
|silicone spray helps here.
|
|Before putting it back together you neeed to clean any corrosion off the
|caliper and the crud off the top and bottom retaining clips - I use a
|Dremel with a wire brush attachment for the latter. Depending on where you
|live, e.g. frost belt, this brake clean up needs to be done fairly
|regularly. Certainly when you replace pads, you need to give everything a
|good going over to clean out all the crud and crap

Just buy a new hardware kit. They are cheap, and the springy parts loose their
tension over the lifespan of a pair of pads.

 

The "springy parts" being the retaining clips? "Cheap"? The Honda parts
are not part of a "kit", are stainless steel and cost ~$11. each for a late
model Accord at the dealers last time I looked - some dealers will charge
as much as $15. each. 2mins with a Dremel+wire brush cleans them up like
new. $44. extra to do your front brakes is not "cheap" to me.

Rgds, George Macdonald

"Just because they're paranoid doesn't mean you're not psychotic" - Who, me??

 

|On Tue, 22 Jul 2003 20:22:02 GMT, (Rex B) wrote:
|
|>
|>|This is not a difficult job for a DIYer. You just have to take the pads
|>|out, take the piston assembly off (hang it on some suspension part nearby
|>|with a piece of coat-hanger wire) and take the slide pins out and check for
|>|corrosion and relubricate. Honda sells a high temp urea grease for the
|>|pins but you can use the Permatex synthetic grease, available at any auto
|>|parts store, made for the purpose - the blue stuff which is a very sticky,
|>|fairly thick, grease. Of course the rubber boots need to be replaced if
|>|torn and they need to seat nicely in their grooves to keep moisture out -
|>|silicone spray helps here.
|>|
|>|Before putting it back together you neeed to clean any corrosion off the
|>|caliper and the crud off the top and bottom retaining clips - I use a
|>|Dremel with a wire brush attachment for the latter. Depending on where you
|>|live, e.g. frost belt, this brake clean up needs to be done fairly
|>|regularly. Certainly when you replace pads, you need to give everything a
|>|good going over to clean out all the crud and crap
|>
|>Just buy a new hardware kit. They are cheap, and the springy parts loose their
|>tension over the lifespan of a pair of pads.
|
|The "springy parts" being the retaining clips? "Cheap"? The Honda parts
|are not part of a "kit", are stainless steel and cost ~$11. each for a late
|model Accord at the dealers last time I looked - some dealers will charge
|as much as $15. each. 2mins with a Dremel+wire brush cleans them up like
|new. $44. extra to do your front brakes is not "cheap" to me.

Depends on your definition of "cheap". Obviously you and I differ on that, but
that is entirely irrelevant.
Complete caliper hardware kits are $15/wheel in Raybestos, and you might even
find them cheaper. But call it $60/car. H15747 front, H15727 Rear.
The OPs issue is safety related, as opposed to something like brake squeal.
His is the only value judgement that matters in this case.

However, i'd suggest an experiment: If you have occasion to change brake shoes
on a relatively new car, Take one of the shoe return pull-springs and drop it on
concrete from about 18". You will hear a very dead "thunk". Do the same with a
new spring and the sound is very different - more like "tink". Now, you
can't really do this with pad clips because they don't weigh anything, but the
point is valid: The heat cycling of a brake takes the temper out of spring steel
over time. Knocking the surface rust off with a dremel doesn't restore that
temper. And think how much hotter a disc brake gets than a drum brake.

You pays your money and you takes your choice. I'll buy a hardware kit for my
cars.

 

For brakes I do not use generic parts... any longer.

I don't have a car with drum brakes for your little experiment.

There is no "rust" on the retaining clips on a Honda disk brake - no
corrosion of any kind - it's just umm, baked on crud. I know they are
reuseable... and I don't see the direct relationship between pad retaining
clips and brake shoe return springs - different part purpose, different
purpose.

Replace the $11. Honda parts with "cheap" generic pieces, which *will*
rust, if you want - I won't and don't see the point.

Rgds, George Macdonald

"Just because they're paranoid doesn't mean you're not psychotic" - Who, me??