REFLECTOR: Master Brake Cylinder Bleeding

[Brian Michalk]

Now that's a novel idea.  Yes, they are both facing the same direction.  
I can apply some o-ring grease and there's practically no chance of air 
getting in.

On 10/8/2012 10:46 AM, steve korney wrote:
> Are both the cup seals facing the same way..?   Maybe you can turn one 
> around so they seal in both directions...
>
>
>
> Steve
>
> > Date: Mon, 8 Oct 2012 10:34:47 -0500
> > From: michalk at awpi.com
> > To: reflector at tvbf.org
> > Subject: REFLECTOR: Master Brake Cylinder Bleeding
> >
> > Two weeks ago I did some high speed taxiing and blew a brake line. This
> > weekend, I replaced the lines and added inserts in the compression
> > fittings, and then proceeded to bleed the brakes.
> >
> > The left side bled fine and is firm. The right side continues to pull
> > bubbles in from that I assume is the primary cup seals on the 
> retraction
> > stroke.
> >
> > I pulled the cylinder and took it apart. There is a very strong spring
> > that on the reservoir end pushed a rubber disc against a hole to the
> > reservoir. Pushing against the opposite end are two cup seals. Now,
> > this spring is very strong. I think what is happening is that after a
> > power stroke, the cup seals have been pushed towards the reservoir
> > seal. Releasing the pedal causes the cup seals to make a vacuum in the
> > cylinder until enough force is generated to overcome the spring and
> > allow fluid to flow past the reservoir seal. Unfortunately, the spring
> > is too strong, causing excessive vacuum, drawing in air across the cup
> > seals.
> >
> > I plan on calling the manufacturer today, but don't have high hopes 
> that
> > I'll talk to anyone useful. To fix the problem, I can reduce the spring
> > tension, or increase the cup seal force. It's a run of the mill 5/8
> > bore, so I should be able to find a lot of various seals. Any
> > experience with this problem here on the reflector?
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