97 Civic front brake lockup problems...

Hey all,

Please help if you have any suggestions. I, along with every mechanic
I have seen, are completely confused.

I have a 97 civic. Whenever I drive my car and use the brakes
moderately, my front brakes start to drag after awhile. This only
happens if I use them and they start to warm up. They don't severely
drag, but enough to require 2 hands to move the front wheels when the
car is immediately jacked up and put into neutral. If you wait about
20 min or so (whenever they cool off) they free up and you can spin
them with one hand, no problem. I have replaced the following in
search of the problem with no success:

Master cylinder, calipers, rotors, hoses. (all new parts by an ase
mechanic)

I don't know what else there is?!?!? One mechanic said it might be the
distributor valve (after the master) but he says it's so rare that is
bad that its not even an aftermarket part. My rear breaks are fine
after I warm them up, only the front are sticking. Also, if you
release the presure in the valve when they are sticking, it will free
up. The piston on the calipers are free and great. It seems to be a
pressure problem somewhere. The right side is just slightly worse than
the left.

Please help with any suggestions!!! I'm dragging my brakes all day long
(once I heat them up)- although the wear on my pads and rotors have
been minimal after replacing them a year ago- little warping
(amazing!).

Thanks SOOO MUCH!

 

wrote in

Has anyone checked the master cylinder pushrod? Too little freeplay will
cause exacty what you describe.

http://www.tegger.com/hondafaq/mastercylinderreplace/adjustment.html

 

Tegger,

Thanks for the suggestion but I don't think that's the problem. First
off, it's diffidently a pressure problem, so you covered that, but it
is also a heat issue, which the push rod doesn't address. I can sit in
my car parked in the parking lot (when the brakes are cool) and
continuously pump my breaks and then check them again and they are
fine. So the pressure issue is not solely a pressure issue, it is a
heat issue that is causing pressure.

Here are what several different Honda techs had suggested. They don't
all make sense to me but let me know what you think about each one:

1)The fluid is contaminated. There is dirt or moisture in the fluid.
The fluid is not bleeding out of the calipers as fast as normal because
of the change in composition of fluid. Recommendation: vacuum flush
the lines, all 4. --- the only thing about this is I would have a
spongy pedal if it was contaminated, which I do not have. I have the
opposite which is the brakes are engaged too much.

2)The hoses are weathered and the rubber inside are expanding as the
fluid temp rises, which chokes the fluid from releasing but as the
fluid cools they release and bleed. --- the only thing with this is the
right front hose is brand new. The left one is not stiff (stiffness is
sign of a bad hose) Also, the right wheel drags a lot more than the
left, though both do drag. (sorry for not including that earlier).

3)the proportioning block's front valves have either been contaminated
or a wearing so that the gaskets are not operating correctly. --- the
thing is that this is a very rare problem. They don't even make
aftermarket proportioning blocks because it's so rare. Most Techs have
never heard of replacing this, unless they work 20+ years and they have
maybe replace one or 2 tops.


Those are the only things that the Honda techs can suggest, all from a
different Honda dealership. Just to clarify that it is a pressure
problem, the slides are greased, the pistons are free, and most
importantly the bleeder valve when opened will completely solve the
problem immediately.

To re-affirm the heat problem, I will not get pressure build up in the
parking lot pumping cold brakes, and it wont even build up if I drive
down the street to a neighbors house <1 mile away. It has to be about
6-10 complete stops from at least 25 mph-> hence the heat will begin to
occur in the break line.

I don't have 1500 to do all 3 of these suggestions. It's a 97 civic.
It's just not worth it cuz something else is bound to need fixing soon.
I would like to do one and get it done with. Which seems most
logical? Do you think it is something else? What is your logic?

Anyone else please feel free to give input. I have stumped so many
Honda techs and so many brake specialists that I'm bout ready to sell
the car and just start with another one (even though I love my car and
don't wana part with it).


Thanks!!

Mike

 

i'm with tegger on this one. you say you don't "think" the pushrod
adjustment is the problem but you don't say you've checked it & you
don't say what the free travel is.

as the system warms up, calipers from brake operation & general fluid
from engine heat, the fluid expansion occurs. master cylinders have an
expansion return valve - a tiny hole that is open when the pistons are
in their resting position. for braking, as soon as you press the pedal,
the piston seals move past this hole and pressure starts to build for
braking operation. for heat expansion, if the free travel is not
adjusted right, the master cylinder pistons/seals will not be fully
parked fully back in their resting position, so there's no way the fluid
can expand without increasing pressure in the system [unless the seals
are leaking]. i don't know what the free travel spec is on your car,
but you need to check it. on my 89 civic, book spec is 1mm-5mm of free
travel. to emphasize, that's /free/ travel, /not/ travel before the
pedal goes rock hard.

it's most unlikely to be the proportioning valve because that /does/
allow 2-way fluid flow.

 

wrote in

Yes it does!!

HAVE YOU CHECKED THE FREEPLAY?

Go here:
http://www.tegger.com/hondafaq/faq.html#brakes

See the three down at the bottom? Take a look at them, especially the
second from bottom, which takes you here:
http://www.tegger.com/hondafaq/mastercylinderreplace/howworks.html

If you check the pedal's freeplay and there is some present, then the
pushrod is not the problem. But this is your first culprit before anything
else is suspected.