At 08:14 AM 4/8/97 +0100, Keith Bedford wrote:
>A little problem with my 77 BGT (servo) brakes...
>
>When idling applying the brakes causes a gentle but persistent rise in RPM,
>up to 2000 and still going.
>
>Today the edge has gone from the brakes - they work but I have to push harder
>and they don't inspire confidence.
>There is still pressure in the system - switching off with the pedal pressed
>I feel the pressure drop.
>
>I thought (and hope) its a vacuum leak - the manifold to servo hose looks
>old but isnt obviously perished. Do I need a special hose to replace it?
>Could the 'one-way' valve in the manifold be stuck?
>Would renewing the servo filter help or is the servo itself likely to be on
>the way out?
>
>Any advice gratefully recieved - the suns shining and I don't want it off
>the road!
>--
>Cheers,
> Keith
It sure sounds like your brake booster is in need of rebuilding. Please
check the obvious things as you mentioned above. If you have one of those
Mityvac's, or just a vacuum gauge, connect it to your vacuum hose to your
servo assist and see if it holds a vacuum. If it doesn't, it's shot. I had
the same problem with the vacuum assist on my '78 B and it turned out that
the rubber seal inside the servo had a tear in it and ergo would not hold a
vacuum. The pedal was extremely hard(required a lot of force to stop the
car). I could have done without the servo assist, but my idle was
constantly being dragged down every time I hit the brakes. It seems that
when the servo goes out, you lose vacuum and I think you may richen the
mixture. Since it hurt my idle, I decided to replace the servo rubber
piece. It only takes a few hours, and you don't have to remove the master
cylinder(I think; check your booster; I haven't been under the hood of my
'78 in a while).
Question: why are the brakes excellent on my '70 B, yet there is no need
for a booster? Why did later models come with boosters? The pedal box
design seems to be the same for all years, so I see no reason why later
year cars would need a booster.
Jay
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