First check to make sure you are getting vacuum at the servo from the manifold.
The hose should be good with no leaks or blockages. The manifold should
be able to produce a good vacuum. Poor tuning can leave you with too little
vacuum to operate the servo.
Second check to make sure the servo can hold a vacuum. Either use one of the
vacuum gauge/pumps or just try sucking on the end of the hose and then blocking
it with your thumb. I recommend the gauge/pump operation myself.
Third check your anti-return valve. Some versions had it mounted on
the manifold in others it is mounted directly on the servo. It is almost never
mentioned
in the mantenance manuals but it is very important and pretty simple to test
and replace.
It should only allow air to flow from the servo to the manifold.... Not the
other way.
Pull it out and put it on a vacuum pump to make sure it is working correctly.
Fourth Check to make sure that you have the right brake master cylinder
installed.
The volume/pressure of Brake Master Cylinders is very finely tuned to the slave
cylinders and the incorrect unit will not work correctly. There must be
sufficient
volume to properly fill the slave cylinders and there must also be sufficient
pressure
to clamp the brake pads/shoes either one being incorrect will result in poor
stopping
power. It is amazing how many vehicles I have bought with the wrong unit
installed.
Usually because the owner or mechanic installed the cheapest unit they could
find
and bolt up. No one bothered to make sure it was the same unit that belongs
with
the car.
Sometimes even the parts books are wrong . Transition
years are especially bad because the vehicle is listed as one year
but the brake parts are from another. Some companies are also worse
about this than others. I owned a car once where the parts counter people
cringed
every time I walked in the door. It had all kinds of strange parts from
different years
installed in it. It got to the point were I would just bring the part in and we
would
match it visually.
Good Luck and be carefull!
Bad brakes should always be the first thing fixed on a car.
> >> The brakes don't seem to be very good at the moment. I am sure the vacuum
> >> servo isn't working. I can lock the wheels, but the brakes just don't seem
> >> to grab on. The pedal needs to be pressed pretty hard to stop.
>
> >> Scott
|