Ken:
You pose an interesting theory - I've been looking at the servo section of
the workshop manual and reading through the description of how it operates.
Bob makes a good point of the input pressure being needed at the master cyl.
without the mechanical advantage of the pedal assembly.
I honestly don't know if it would be worth the effort. You would have to
replicate the car's hydraulic system in some way - the servos' control
piston and the output piston are interlinked hydraulically. I'm not sure
that simply getting the control piston to move would give an adequate test
Supplying vaccuum would not be a problem - connecting the servo to an idling
engine would do it.
I still think that the best test would be on the car, then both the output
hydraulic pressure to the wheels and the master cyl. would correctly
modulate the pressure to the control piston - ie: as in the real life
condition - not sure if you could reliably replicate that on the bench.
If you decide to give it a try, we'd all be curious as to your findings.
Cheers, ------------------- Earl
----- Original Message -----
From: "Freese, Ken" <Ken.Freese@Aerojet.com>
To: "'Earl Kagna'" <kags@shaw.ca>; "Bob Spidell" <bspidell@pacbell.net>;
"Healey List" <healeys@autox.team.net>
Sent: Wednesday, May 12, 2004 8:59 AM
Subject: RE: brake booster test
Maybe I can hook up an old master cylinder that has a little built in
reservoir.
Ken
-----Original Message-----
From: owner-healeys@autox.team.net
[mailto:owner-healeys@autox.team.net]On Behalf Of Earl Kagna
Sent: Tuesday, May 11, 2004 10:48 AM
To: Bob Spidell; Healey List
Subject: Re: brake booster test
Ken:
I agree with Bob - the air valves are activated by the movement of the brake
fluid itself, which in turn activate the vaccuum piston. It's been my
experience that the whole deal tends to be pretty delicate.
My advice would be to bite the bullet, stick it on the car, and hope that
the Girling Servo Gods are smiling on you!
Cheers, ----------- Earl
----- Original Message -----
From: "Bob Spidell" <bspidell@pacbell.net>
To: "Healey List" <healeys@autox.team.net>
Sent: Tuesday, May 11, 2004 9:27 AM
Subject: Re: brake booster test
Ken,
In its "normal" state the vacuum/air valve (I think) will apply vacuum
to both sides of the vacuum piston. The only way to "cycle" the vacuum
would be to remove the cover on the vacuum/air valve (on the side of
the servo body) and manually move it. You will probably need
a new gasket afterwards, although if you're lucky you might be able to
re-use the old one. BTW, you can't buy that gasket alone--at least I've
never seen one--and rebuild kits run about $80.
I've just rebuilt two of these, and I can't think of any way to test one on
the bench. You just have to hope the rebuilder knew what she was doing.
bs
********************************************
Bob Spidell San Jose, CA bspidell@pacbell.net
'67 Austin-Healey 3000 '56 Austin-Healey 100M
********************************************
----- Original Message -----
From: "Freese, Ken" <Ken.Freese@Aerojet.com>
To: "'Earl Kagna'" <kags@shaw.ca>; "Freese, Ken" <Ken.Freese@Aerojet.com>;
"Healey List" <healeys@autox.team.net>
Sent: Tuesday, May 11, 2004 8:37 AM
Subject: RE: brake booster test
> Thanks, Earl, I guess I will hook up the unit to engine vacuum and cycle
it
> a bunch of times manually. Assuming I can figure out how to do that.
> Ken
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