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RE: Girling Hydraulics

To: tigers@autox.team.net
Subject: RE: Girling Hydraulics
From: "Dobrowski, Robert S" <Robert.Dobrowski@JSF.Boeing.com>
Date: Thu, 6 May 1999 12:41:02 -0700
The silicone fluids have additives to cause the proper seal swell

> ----------
> From:         Bob Palmer[SMTP:rpalmer@ames.ucsd.edu]
> Reply To:     Bob Palmer
> Sent:         Thursday, May 06, 1999 12:37 PM
> To:   Roland Dudley; laifman@flash.net
> Cc:   tigers@autox.team.net
> Subject:      Re: Girling Hydraulics
> 
> Roland, Steve, et Listers,
> 
> A few months back I had my buddy in the shop at UCSD (it always pays to
> have a "buddy" in the shop) sleeve my clutch slave cylinder in stainless
> steel. So far it has worked fine; i.e., no leakage. I was concerned about
> the interference fit and thermal expansion too. This is particularly
> important with the slave cylinder since it sits right over the exhaust
> collector. I considered having Randal install the sleeve using Locktite to
> both keep the sleeve in place and prevent fluid seepage. However, I never
> did more than think about it and it doesn't appear to have been necessary.
> I'm sure that surface finish is a factor as well as the amount of
> interference. If there is no sealant between the sleeve and cylinder body,
> then I do not see any reason why silicone should be any more prone to leak
> than glycol based fluids. It should only depend on viscosity I think. One
> reason not to use silicone is because you need some exposure to glycol to
> get the rubber to swell and seal (see, for example, Ton Hall's post a few
> months back). I would suggest using Castrol or equivalent for a while and
> then replace with silicone if you like.
> 
> TTFN,
> 
> Bob
> 
> 
> At 11:02 AM 5/6/99 -0700, you wrote:
> >Roland Dudley wrote:
> >
> >> Steve,
> >>
> >> I can't speak for the servo rebuild, but you might want to do some
> >> research regarding re-sleeving of master cylinders with stainless.
> >> I've heard, but not personally verified the following:
> >>
> >> 1. That silicone brake fluid will seep past a stainless sleeve/cylinder
> >>    interface.
> >>
> >> 2. That stainless sleeves must be interference fit into the master
> >>    cylinder and that the aluminum they are made of is not strong enough
> >>    for this purpose.  Another possible issue is the different thermal
> >>    expansion rates for stainless and aluminum.
> >>
> >> Roland
> >
> >
> >
> >
> >A good thought, Roland.  Although the original user of one firm seems to
> >have had no problem.  Besides, not sure about the synthetic in the brakes
> >yet.  Using it in the clutch to see what happens.  Easier to replace.
> >
> >Most sleevers use brass, which has an even higher thermal expansion, but
> >probably not as high as the aluminum, so maybe it keeps outer contact
> >better.  These are made with a friction/press fit, so some expansion
> still
> >leaves compression between the sleeves and the cylinder.
> >
> >--
> >Steve Laifman         < Find out what is most     >
> >B9472289              < important in your life    >
> >                      < and don't let it get away!>
> 
> Robert L. Palmer
> Dept. of AMES, Univ. of Calif., San Diego
> rpalmer@ames.ucsd.edu
> rpalmer@cts.com
> 

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