Date: Sun, 15 Apr 2007 08:21:11 -0400
Reply-To: Mike <mbucchino@CHARTER.NET>
Sender: Vanagon Mailing List <vanagon@gerry.vanagon.com>
From: Mike <mbucchino@CHARTER.NET>
Subject: Re: Lower bleeder screw question (searched archives)
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Neil,
The lower screw should be bled also, to rid the internals of contaminants;
water and dirt like to lay down there. Obviously, air will rise, but be sure
and bleed from both. Pumping the pedal quickly, will cause turbulance and
force more air bubbles to come out from thier little hiding places than slow
pumping. Also, holding the last push down hard while someone opens the
bleed screw, makes a difference, too. A pressure bleeder is great, and way
better than a vaccum bleeder, if you can't enlist some help. A vacuum
bleeder sucks air in from the bleed screw threads, requiring heavy grease
applied to seal the threads while they're open. It also can and does suck
dirt in past the wheel cylinder cup seal lip. It's beveled one way to seal
pressure from the inside; the bevelled cup will collapse due to strong
suction inside, bringing in contaminants that are laying just outside the
seals. A pressure bleeder is the best way, because it most closely
simulates the actual designed use of the system. I bit the bullet and
bought a Motive unit for european cars, and I was so impressed, that I'll
never bleed the pump way again! Superior, fast and a good, solid pedal the
first time. And no need to enlist help, grease bleed screws, or go round
and round and round, trying to get a better pedal. Invest in one, if you
plan to do all the work on all your cars, like I do. They're not very
expensive, and you can avoid taking the car to a shop and paying them to use
thier pressure bleeder on your car. It'll pay for itself on the first use.
HTH,
Mike B.
----- Original Message -----
From: "neil" <musomuso@GMAIL.COM>
To: <vanagon@GERRY.VANAGON.COM>
Sent: Sunday, April 15, 2007 2:17 AM
Subject: Lower bleeder screw question (searched archives)
> Hi all.
>
> Amongst other things, I've installed a new MC. I bench bled it til
> fluid came out, installed. bled at MC, then gravity bled brakes. They
> felt ok, but not really efficient. I started to bleed them again with
> a one man one way valve hose but it popped off the RR so I went with
> straight hose on the rest. I would pump about 10x's per wheel then on
> last stroke, kept pedal down with piece of wood braced against seat,
> then shut bleeder screw. Regardless, no improvement. In fact worse.
> Pedal travels too far. Rears were adjusted not long ago.
>
> I'm making a power bleeder and using that before taking to a brake
> shop to have them bleed my brakes.
>
> I have read that the lower bleeder screw on each caliper is for
> draining only . I have also read that on the early two piston type
> calipers, that one needs to bleed upper and lower bleeder screw on
> each caliper.
>
> Frankly I do not know for sure if I have the two piston model, but I
> DO have two screws per caliper.
>
> Do I bleed at upper AND lower screws on calipers?
>
> Even if lower for drain (as per Bentley) will bleeding it help?
>
> Thanks for any help, and sorry for long post.
>
> Neil.
>
> --
> Neil Nicholson. 1981 Air Cooled Westfalia.
>
> http://web.mac.com/tubaneil
>
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