Drum Brake "Wunka-Wunka"

My 91 Civic's right rear drum brake makes a "wunka-wunka" noise every now
and then when I press the brake pedal while driving and coming to a stop.

This began two days ago, after a heavy snowstorm (8 inches or more, so
around brake drum height), parking lot (at the top of a mountain) not
plowed, so I was driving through the stuff for around 100 feet. The noise
started as I drove down the mountain (in low gear, but still tapping the
brakes a lot).

I pulled off the wheel and brake drum and inspected the shoes an hour ago.
The most obvious discrepancy is that the trailing shoe's top half is much
shinier and smoother than the bottom half. This is noticeable both by sight
and touch. The leading shoe looks fine. Drum and shoe thicknesses are in
spec. Wear is even, except maybe the bottom half of the trailing shoe is a
smidge thicker than the top half.

So it seems the top half of the shoe is making good contact, while the
bottom half now is not.

Car has 161k miles on it. I took the rear brakes apart last summer, but I
only cleaned and lubed everything; no replacements.

I have the bucks to do a more serious overhaul (spring and piston/cylinder
replacements) if folks think it's worth it, here in my car's probably late
mid-life. I want to keep it around five more years/60k miles, if possible.

I'm going to get a can of brake cleaner and some proper grease, disassemble
the whole thing, clean it, and then re-assemble sometime in the next couple
of days.

Anything I should look for in particular? Should I replace the shoes? The
springs?

 

the only thing that can cause an irregularity like that is the drum
either machined off center [unlikely given that it's been ok for this
long] being asymmetrically worn [unlikely unless raced], dented [also
unlikely] or it being mounted ever-so-slightly off center. there's a
noticeable amount of float on those drums relative to the wheel studs so
you can get "sticky" patches seen just after a drum has been
reassembled, the wheel put back on and spun.

the solution is, after servicing the brake assembly, put the drum &
wheel back on, but finger tight only. turn the wheel 90 degrees, then
finger tight again, etc, until the wheel's on, but could still be moved
if force greater than hand were applied. then spin the wheel so that
it's in the middle of an sticky patch. whack the wheel gently with a
soft faced hammer. the disk should then center under the wheel. spin &
repeat if required. torque the lug nuts as much as possible without the
wheel on the ground. the drum should stay centered. lower to ground &
finish torquing.

this is not normally an issue under heavy braking because the shoes will
float relative to the backing plate as they follow the circle of the
drum. under light braking however, like in snow, this relative
eccentricity can be either felt or heard. particularly if the shoes
have gotten wet and there's a little rust between the shoe edge & the
backing plate causing there to me more than normal float resistance.

 

Jim,

Sounds like your impression is that the brake pretty much lost its float
ability. I guess this is due to the dirt, rust, and muck that gets in there
over time, perhaps "triggered" by an influx of snow/water (past the middle
of the wheel, I'd say).

After I pulled off the drum and blew out some of the dust last week, the
"wunka-wunka" went away. I even drove down the same mountain recently (but
this time, no snow in the lot or on the road) and it didn't come back. It's
been several days.

Nonetheless, today I took both rear brakes apart, brake cleaner-ed and
greased them, and, while I was in there, adjusted the parking brake. The
guilty brake certainly looked more mucked up, while the good brake still
showed a little of the brake grease I applied last summer on the adjusting
screw. The one shoe that was looking irregular seemed a bit more even in
wear appearance. I tried to tighten evenly and torqued down a good deal
with the wheel off the ground, as you described. So we'll see.

Darn those trailing arm front bushings are beat up...

Thanks for sharing your experience.

 

There are three legs. How many are torn on yours?

 

very common - first thing to check when looking at a civic. part #
52385-SR3-000

 

Jim,

I remember seeing yours and others posts on these bushings over the last
year or so.

One thing I don't remember is whether people report these bushings failing
in a catastrophic way.

I can live with a creaky sounding car. But does the rubber in these
bushings ever deteriorate such that, I dunno, parts in the suspension drop
an inch or so, causing some sort of domino effect such that one runs the
risk of doing serious damage to the car?

Replacing a rear control arm last autumn was instructive but laborious
(frozen bolts and bushings, specifically). As I posted at the time, I
realized I should have left well enough alone. If I can get away with not
fussing over these trailing arm bushings for another five years (whence
I'll probably replace the car), then I'd rather leave them be. They just
appear all torn up (from road salt, I suppose, as a consequence of much
Northern U.S. winter driving), but I dunno how deep that deterioration
goes.

I figure there's gotta be a lot of rubber in there, given what these
trailing arms support.

Tegger,

It's the large one in the front of the trailing arm itself, very visible
when one has the rear wheels off and looks forward on the car's frame a
bit. I'd specify more precisely but I don't know at what you're getting.

 

They don't. Even if all three legs break, nothing else will get destroyed.

Don't worry about it and get it replaced when you feel like it.

I know which bushing it is. Look here, right at the very bottom of this
page:
http://www.tegger.com/hondafaq/rustybrakes/brakes4.html

I was just curious to know how many legs were torn on yours, that's all.
One is ripped on mine (top one). The others are fine for now.

 

my opinion is that they need to be replaced. admittedly, my driving
style, based on previous conversations, is a little different from
yours, but with bad bushings, i find the car wallows around at the back
and leads to unpredictable [dangerous] handling when cornering hard.
this may not be how you drive generally, but i know i sure don't want it
to bucket about unpredictably because i hit a bump on a corner just when
i'm in the middle of an evasive manuever because the guy up in front has
just... you get the idea.

more predicatable braking for similar reasons.

can't help you on that one. i'm lucky enough to just have california
cars at the moment, so have no issues with taking apart 15 year old cars.

the rubber still cracks & fatigues. i very much regret throwing out the
last set i replaced without photographing them for you. both bushings
were completely torn through, top & bottom.

again, i'd replace as a safety issue. it's only 5 bolts & a trip to the
dude with a bearing press. makes a massive [safety] improvement to
handling & control.

 

Looks a little different from my 91 Civic's, so I assume this is not a 91
Civic...

On my 91 Civic, I can see just about the whole front bushing pretty easily;
it's not filled with dirt(?) like the one pictured is. It has some huge
cracks in it. I don't know how deep they go. I'll have to bounce the car
around by hand and see if I can tell more.

I'll get in there and take a closer look in a few weeks. I don't notice any
handling problems. I see your point about how one torn up bushing isn't as
big a concern as all three support points being pretty shot.

Jim, I'll also see if I can find a shop that will press out/in bushings for
me.

Depending on the condition of all the bushings, I'll either pursue this or
let it go for another 4-5 years.

I drove the mountain again yesterday. The brakes still seem fine. So I
suppose some dirt etc. got into that right rear drum and prevented its
floating properly for a little while.

Thanks, Tegger and Jim.

 

these bushings are two-point - top & bottom.

i take mine to a motorcycle machine shop. imo, the m/c guys are much
more precision oriented than car guys - with m/c's, mistakes are easily
fatal and i believe mechanics who ride are /way/ more switched on to
getting it right as a result.

if this was a front bushing affecting steering, you'd be all over it.
because deterioration is gradual, you lose perspective on how the car
used to drive, but i assure you, when you replace them, you'll be
astonished home much more stable & safe the car feels. as i say, you
may not think you need to bother until there's an emergency, and then
you do. which is how i first discovered how important replacement was
on my first civic.

 

Sounds good. I do have motorcycle shops in my area and will start making
inquiries there.

Yes, I was thinking this...

Okay. To be looked at again when the warmer weather hits in a few months.

 

i got a couple of blank stares from m/c shops - m/c /machine/ shops
otoh, particularly those that work on japanese componentry, seem to be
staffed by hardcore race fanatics that are obsessed with accuracy &
perfection!