Why Would ABS Problem Require Replacing Control Arms?

I have an old 1995 Honda Civic and the ABS light started coming on. I
took it to a mechanic who diagnosed it as a faulty left rear wheel
sensor. OK, fine, replace the sensor; sounds simple enough.

Then I get another call from my mechanic some time later: He rattled
off some gobbledygook that "the sensor runs down where the rear control
arms are" and that the control arms had become frozen by rust or
corrosion over the years, would not come off, and needed to be replaced
too. And something about bushings needing replacement too.

I have absolutely no idea what he's talking about, so I could use a
sanity check. Does any of this make any sense at all? Why would
replacing an ABS rear wheel sensor have anything to do with control
arms, bushings, etc.?

 

It is coincidental. While inspecting the ABS he has been up close and
personal with other components which have aged and suggests you replace them
before disaster strikes.

Huw

 

In order to get to and replace the sensor the hub has to be separated from
the control arm. If it is all rusted together they will be damaged in
removing and will have to replace. Expect these problems in 12 year old
cars. Steel rusts and has to be replaced..

 

There are indeed lines, going to each rear wheel's ABS
sensor, that run along the rear control arms. Small bolts (6
mm nominal diameter) and brackets attach the lines to the
control arm. This appears on the bottom drawing on the first
page at
http://media.honda.co.uk/car/owner/media/manuals/CivicManual/pdf/19-144.pdf .

The control arm is the member that extends from inboard at
the wheel hub to outboard, with the coil spring attaching
in between.

I would be surprised if the mechanic had any serious
problems with those small bolts connecting sensor lines to
the control arm. Worst case, maybe they have to be drilled
out IF they need replacement. If he's only doing the sensor,
I am doubtful the lines have to be unbolted at all.

The control arm bolts with bushings around them are the much
larger ones (10 mm diameter) that take an enormous load and
so tend to freeze to the inner sleeves of the bushings.

He means the control arm bolts are likely frozen to their
respective bushings, meaning they typically have to be cut
out or torched out. This is very common not only in Hondas,
but many other makes of cars. Frozen control arm bolts have
received a lot of attention at this newsgroup over the
years, mostly described in four-letter words.

The bushings of a Honda over 10 years/100k miles very likely
could stand replacement. Doing so will likely improve
handling. OTOH, if you're not having tire wear problems, and
do not have a lot of money, and are fine with the way the
car currently handles, you can put this off, IMO. To have a
shop do all the suspension bushings would probably run
around $700 to $1000.

The bolts being seized to the bushing sleeves is also not
per design, of course. They're supposed to rotate somewhat
within the bushings.

I suspect he's saying that, while diagnosing the wheel
sensor problem, he noticed the control arm bushings looked
very worn and also suspects frozen control arm bolts. If he
did not mention this, I think he would be remiss. He may be
trying to make more money off you, but it's more than likely
a legitimate recommendation.

Ask him to clarify whether he feels he has to remove the
control arms to replace the wheel sensor. My take so far
from the drawing and working extensively on my (non-ABS)
Civic's rear control arms is that this should not be
necessary.

 

---------------------------------------------------

The ABS sensor is cylindrical, and almost exactly the same size as the
hole in the control arm, and when it gets rusty in there, there ain't
now way of getting the sensor out without destroying the sensor.
HOWEVER, there's no reason to destroy the arm. The newer sensors are a
bit smaller (and tapered) so they won't rust in place. I went through
this with our '95 Odyssey.

'Curly'

 

Now that I was armed (no pun intended) with your description, I was able
to get more clarification. The mechanic said the control arms don't
have to be replaced; it's the bolts and bushings that have gotten worn
and rusted frozen in place. And he's only going to service those bolts
and bushings on the control arm for the wheel sensor that needs
replacement; not any other control arms. Finally, he assured me that
the rest of the suspension is in good shape.

So it does sound like he knows what he's talking about.

But based on what you said, I will ask him if at some future point it
might be worthwhile to inspect and service the bushings on the other
control arms too.

Thank you, and thanks also to everyone else who responded!

 

[Obvious post-o: The bushings rotate somewhat around the
bolts, which are fixed to the car chassis.]

He sounds honest, too.

If you ever find out whether the arms actually have to come
off to replace the sensor (I can't quite tell from what you
quote him saying), I'd be interested to know. Seems those
sensors are not an uncommon failure item. If the control
arms have to come off, wow, that's potentially one expensive
fix.

FWIW, and not to drag this out, but I suggest trying to
ensure the mechanic uses OEM ( = genuine Honda) bushings.
Non-OEM rubber parts on Hondas have a reputation for a much
shorter life. They might be fine, but I personally don't
risk it anymore. I pay the extra money up front for the OEM
parts, and I'm pretty frugal.

You're right on target, AFAIC.

Good luck.

 

Well, if they are rubber, the inner sleeves should not be rotating on
the bolts - the twisting of the bushing as the suspension works is all
done through the compliance of the rubber. This is fairly common for
most vehicles. So, it's not a matter of "if" the stuff will seize up
but "when" if you live in the right climate...

nate

 

Not sure what you are trying to say, but the bushing inner
sleeves are not rubber. They are very hard steel. The
sleeves (inner and outer) are like a shell that hold the
rubber part. See photos under "Bushing Removal" at
http://home.earthlink.net/~honda.lioness/id15.html .

No, you're messed up. The control arm is supposed to rotate
by design (as the car goes over bumps etc.) to some extent
about the long axes of its bolts, these axes being
concentric with those of the bolts' respective bushings.

No rotation, and the passengers are in for one harsh ride.

If properly installed, the bushing rubber should not
normally twist. The rubber should normally be somewhat
compressed, because of the weight of the car and the way the
suspension system works.

Fact: Control arm bolt metal typically 'cold welds' or rusts
or similar to control arm bushing sleeve metal.