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Re: servo problem?

To: doelakie@yahoo.com, healeys@autox.team.net
Subject: Re: servo problem?
From: Simonlachlan@aol.com
Date: Thu, 22 Jul 2004 07:54:46 EDT
In a message dated 21/07/2004 22:45:31 GMT Daylight Time,  doelakie@yahoo.com 
writes:

After several years of driving my 65 BJ8 without a
brake servo, I  finally got around to  rebuilding
(replacing all seals in)  my  PBR unit.  The main
cylinder looked excellent without any  noticeable
scratches or scoring, hence I did not have  it
resleeved.
After reinstalling the unit, I bled it, then  proceeded
to bleed all four wheels.  When I step on the brake
pedal  it goes right to the floor with no resistance
whatsoever.  However, if  I pump it rapidly with about
a half a dozen strokes, it builds up pressure  to what
I would consider about the right amount of "pedal". 
It has a  somewhat cushioned feel, as I would expect
with a servo. (previously a very  firm pedal without
the servo). If I hold it there, it doesn't seem  to
fade as long as I don't completely release the pedal.
But as soon as  I let it return completely to it's
fully released position, I lose ALL  pressure, and it
now goes right to the floor again! The master  cylinder
was working fine before introducing the servo????
Any suggstons  would be greatly appreciated.
Thanks, in advance,
John Lakie
65  BJ8
Ontario,  Canada       




I've had my share of trouble with rebuilds - in an original - and one  thing 
that cost me hours and was not the servo's fault was this:-
I'd bleed the brakes the old way...with pipe into bottle and willing(?)  
slave at the pedal.
I'd do each wheel starting from the furthest etc.
I'd get up and test it...worse than before.
I'd blame all on servo and curse some more.
Probably strip servo out and check over for the nth time..
etcetc...you get the idea.
Eventually, I discovered that the bleed screws are fairly coarse and  need to 
be tightened up while the pedal is down at the end of each stroke, or  - 
perhaps better yet - still moving down. I found that releasing the pedal was  
allowing air to draw back into the system. And, yes the end of the tube was  
immersed.
Try that before taking any drastic steps.
Simon.





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