Brake System Nightmare - 99 4runner ltd 4wd

I posted a thread recently about a front end problem I was having. The
front end would start to shimmy at higher speeds. The problem became more
and more frequent. Then the brakes started lock down as if the calipers
weren't releasing. I gave up diagnosing myself and took it to a shop. Tell
me if this sounds right. I was told that some time back, something other
than brake fluid had been added to my brake system. Over time, all the
rubber components in the brake system have started to deteriorate and break
down. This would cause the calipers to hold on while the rear wheeles were
still trying to accelerate causing the shimmy in the front end. The shop
says I need to replace every component that has any rubber in it. This
includes all hoses, both calipers, master cylinder and reservior, rear wheel
cylinders, and replcing pads and rotors. This seems excessive to me. Not
to mention, about a $1,300 job by their estimates. Now while I don't like
to "half-ass" anything, shouldn't I just be able to replace the master
cylinder, flush the entire system, replace the pads and turn the rotors?
That could be done for a quarter of the price. I understand these guys work
on commission so I see why they suggest a total overhaul, but is this
completely necessary. Thanks.

Bryan Taylor wrote:[color=blue]
> I posted a thread recently about a front end problem I was having. The
> front end would start to shimmy at higher speeds. The problem
> became more and more frequent. Then the brakes started lock down as
> if the calipers weren't releasing. I gave up diagnosing myself and
> took it to a shop. Tell me if this sounds right. I was told that
> some time back, something other than brake fluid had been added to my
> brake system. Over time, all the rubber components in the brake
> system have started to deteriorate and break down. This would cause
> the calipers to hold on while the rear wheeles were still trying to
> accelerate causing the shimmy in the front end. The shop says I need
> to replace every component that has any rubber in it. This includes
> all hoses, both calipers, master cylinder and reservior, rear wheel
> cylinders, and replcing pads and rotors. This seems excessive to me.
> Not to mention, about a $1,300 job by their estimates. Now while I
> don't like to "half-ass" anything, shouldn't I just be able to
> replace the master cylinder, flush the entire system, replace the
> pads and turn the rotors? That could be done for a quarter of the
> price. I understand these guys work on commission so I see why they
> suggest a total overhaul, but is this completely necessary. Thanks.[/color]

All the parts you mentioned have rubber grommets/bushings/o-rings and etc.,
or any combination of them. There is also a proportioning valve and possibly
rear anti-lock valve that possibly have rubber in them as well. They are
correct, all parts that have rubber need to be replaced if the fluid is
contaminated, anything less is "half-assing" it.
There are quite a few things that could have contaminated the fluid, the
most likely would be moisture or water. Brake fluid is hydroscopic (sp), IOW
it will absorb moisture over time and that is why it needs to be changed on
a regular basis. Also, brake fluid will usually start to turn milky or
cloudy if it's starting to saturate with moisture.
It's also possible someone added synthetic, DOT 5, fluid which would
contaminate as it isn't compatible with DOT 4. It's also possible anything
could have been added.
Not trying to second-guess them but, I would get a second estimate or
negotiate for a discount on parts prices from the original shop, they may
feel sorry for you a little.
HTH, Dave

On Wed, 03 May 2006 19:06:21 GMT, "Bryan Taylor"
<bryan1856@sbcglobal.net> wrote:
[color=blue]
> I was told that some time back, something other
>than brake fluid had been added to my brake system. Over time, all the
>rubber components in the brake system have started to deteriorate and break
>down. This would cause the calipers to hold on while the rear wheeles were
>still trying to accelerate causing the shimmy in the front end.[/color]

I'll bet somebody was "helping! I'm Helping!", and put motor oil or
power steering fluid (or god knows what) in the brake master cylinder
reservoir. The only way to tell for sure would be to drain all the
brake fluid and send it to a laboratory, and run it through a mass
spectrometer to see what the contaminant was - which will cost almost
as much as the repairs...
[color=blue]
> The shop
>says I need to replace every component that has any rubber in it. This
>includes all hoses, both calipers, master cylinder and reservior, rear wheel
>cylinders, and replcing pads and rotors. This seems excessive to me.[/color]

Sorry, when they say 'every rubber component', they speak the truth.
They use a special rubber for the seals in all those brake parts that
swells and goes bad when petroleum products get inside them. Wheel
hoses, axle hoses, caliper and cylinder seals. And they didn't
mention the Load Sensing Proportioning Valve (poor man's Rear
Antilock) on the rear axle or the Brake Failure Sensing valve.

Replacing pads and shoes is optional, unless they are worn out and
need replacing anyway. Rotors or drums need replacement only if
they're worn past safe tolerances. It's a good idea to do them while
they have the rest of the brake system apart, but these are still
optional items you could very easily (and safely) skip for now and
save a few bucks.

The power booster assembly should be fine, it doesn't contact the
brake fluid unless the seals on the master cylinder have leaked in it.

And even if the power booster goes bad the worst that happens is you
lose the power assist - If you can put your back into it and brake
hard with both feet this is not a big problem, if you're an 88-pound
weakling it could be. ;-P
[color=blue]
> Not to mention, about a $1,300 job by their estimates.[/color]

Actually, after you add it all up that doesn't sound that far out of
line.
[color=blue]
> Now while I don't like
>to "half-ass" anything, shouldn't I just be able to replace the master
>cylinder, flush the entire system, replace the pads and turn the rotors?
>That could be done for a quarter of the price. I understand these guys work
>on commission so I see why they suggest a total overhaul, but is this
>completely necessary. Thanks.[/color]

I said this a few weeks ago to someone else, but it bears repeating
- do you REALLY want to find out what those "Runaway Truck Escape
Ramps" are for, and exactly how they work? Or worse, lose your brakes
in a bad place that /doesn't/ have a way to save yourself?

Repeat after me: Never Screw Around With The Brakes. They are the
one system that Has To Work, Every Time. Or bad stuff happens.

--<< Bruce >>--

--
Bruce L. Bergman, Woodland Hills (Los Angeles) CA - Desktop
Electrician for Westend Electric - CA726700
5737 Kanan Rd. #359, Agoura CA 91301 (818) 889-9545
Spamtrapped address: Remove the python and the invalid, and use a net.

They're right. My shop has the same policy due to safety and liability
concerns. The contaminated fluid can seep into the rubber parts and
can't just be flushed out.

"Bryan Taylor" <bryan1856@sbcglobal.net> wrote in message news:Na76g.64840$_S7.26625@newssvr14.news.prodigy.com...[color=blue]
>I posted a thread recently about a front end problem I was having. The front end would start to shimmy at higher speeds. The
>problem became more and more frequent. Then the brakes started lock down as if the calipers weren't releasing. I gave up
>diagnosing myself and took it to a shop. Tell me if this sounds right. I was told that some time back, something other than brake
>fluid had been added to my brake system. Over time, all the rubber components in the brake system have started to deteriorate and
>break down. This would cause the calipers to hold on while the rear wheeles were still trying to accelerate causing the shimmy in
>the front end. The shop says I need to replace every component that has any rubber in it. This includes all hoses, both calipers,
>master cylinder and reservior, rear wheel cylinders, and replcing pads and rotors. This seems excessive to me. Not to mention,
>about a $1,300 job by their estimates. Now while I don't like to "half-ass" anything, shouldn't I just be able to replace the
>master cylinder, flush the entire system, replace the pads and turn the rotors? That could be done for a quarter of the price. I
>understand these guys work on commission so I see why they suggest a total overhaul, but is this completely necessary. Thanks.
>[/color]

If your lucky some of the componets might just need new rubber. But I doubt it.



"calipers to hold on while the rear wheeles were still trying to accelerate causing the shimmy in the front end"

One thing that seems odd about this is there is no mention of the rotors condition.
I would expect to see rotors that got so hot they were blue and warped (shimmy source maybe) big time.
The pads would also be so hot that when you stopped they be pumping out that stinky smoke.


Dan