RE: [T3] Hydraulics, what does pumping do?

["Stephen Jackson" <stevejax61@hotmail.com>]

<x-flowed>
It is a sealed system.  Pumping with bleed valve open/closed/ releases fluid 
which hopefully also takes the air out with it.  Otherwise, you would have 
air bubbles in the system which degrade performance because air is 
compressible and fluid is not.  Worse, still, compressing air produces heat, 
which has its own problems to add to the mess!
As far as a rigid line goes, I think perhaps there is too much motion and 
vibration involved...perhaps the throw of the clutch is not properly 
adjusted.  I'd like to add hydraulic clutch to my T3 fastback after I get 
her on the road again!
Regards, Steve Jackson
stevejax61@hotmail.com
71 FB (in drydock)
Houston, TX USA
> From: fess <fess-vwtype3.org@fess.org>
> Reply-To: type3@vwtype3.org
> To: T3 List <type3@vwtype3.org>
> Subject: [T3] Hydraulics,  what does pumping do?
> Date: Fri, 13 May 2005 11:34:39 -0700
>
>
>
> Actually I have two questions:
>
> question 1.
>
> When you pump your brakes, or in my case a hydraulic clutch,  what does 
> that do exactly?
>
> does more fluid flow into the system from the resovoir, which then flows 
> back out later?
>
> if it were a sealed system, then pumping wouldn't do anything.
> but then you wouldn't be able to bleed it, without manually opening
> a bleeder valve on both ends.
>
> If it had one way only valves then you would "pump" up the system, and the 
> slave cylinders would never return.
>
>
> This all relates to my hydraulic clutch issues.  [ I've been very busy at 
> work, so haven't made any progress ]
>
> I was observing, that sometimes, when I didn't have enough throw to get it 
> in gear, I could pump it and
> it would go in gear.   A friend suggested that that was proof that there 
> was air in the line.
> but it's been well bleed.  And I don't think that extra action from pumping 
> guarantees that there is air
> in the line.
>
>
> question 2.
>
> does anyone have any data on how much volume can be lost per foot on a 
> steel braided hydraulic line
> vs. a solid hydraulic line?   One of the suggestions for my clutch problem 
> was to run
> a solid line, rather than the steel braided line that came with the kit. 
> I'lld like to do
> a rough calculation of how much this might gain in clutch travel.
>
> --fess
>
> ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> List info at http://www.vwtype3.org/list | mailto:gregm@vwtype3.org
> ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~


</x-flowed>