I rebuilt a servo with smooth and clean cylinder bores a couple months
(and 1,500 miles) ago. I'll be interested to see how long it goes (SFSG).
BTW, another problem with rebuilders: I had a cylinder sleeved on my
backup servo and they sandblasted the h*ll out of it. This--besides removing
too much material from the body, IMO--left a rough finish where the air/vacuum
"switch" seals bed (which should be a machined finish). Recommend you ask your
re-builder/sleever to not media blast the cylinder body.
bs
********************************************
Bob Spidell San Jose, CA bspidell@pacbell.net
'67 Austin-Healey 3000 '56 Austin-Healey 100M
********************************************
----- Original Message -----
From: "Michael Salter" <msalter@precisionsportscar.com>
To: <healeys@autox.team.net>; <owner-healeys@autox.team.net>
Sent: Wednesday, April 21, 2004 1:36 AM
Subject: RE: Brake help needed
> I think a little clarification is required here.
> The bores of aluminium (aluminum) brake and clutch cylinders are
> anodized. This hard layer is very thin and although not usually damaged
> by the normal action of the seals moving back and forth it is very
> quickly destroyed when any sort of cylinder hone is used. Many
> rebuilders are unaware of this and will routinely hone the surface
> without realizing that they are destroying the cylinder. In my
> experience the bores of the original booster cylinders do not suffer too
> badly from corrosion as they usually and protected from water because of
their location in the middle of the hydraulic system.
>
>
> Michael Salter
> www.precisionsportscar.com
>
>
>
> -----Original Message-----
> From: owner-healeys@autox.team.net [mailto:owner-healeys@autox.team.net]
> On Behalf Of Blue One Hundred
> Sent: Wednesday, April 21, 2004 12:38 AM
> To: Bob Spidell; Peter Ryner; healeys@autox.team.net;
> owner-healeys@autox.team.net
> Subject: Re: Brake help needed
>
> Bob -
>
> Micheal Salter posted on the list a while back that
> these aluminum cylinders are specially treated - the
> cylinder surfaces are treated & hardened at the
> factory. That's why a new unit will last for 15
> years, but a rebuilt unit will wear out in a year...
> the hardened surface wears out and then on rebuild the
> bare aluminum is too soft and wears too fast.
>
> If you can believe it, any brake master cylinder or
> booster that goes bad... it goes bad most likely not
> because of the rubber seals wearing out, but because
> the inside cylinder surface has lost its factory
> treated hardening layer. It can't be rebuilt with new
> rubber seals alone!
>
> 15-16 years ago I went through 3 rebuilds on my
> booster, 2 rebuilds on my brake master, 1 rebuild on
> my clutch master, and two rebuilds on my clutch slave
> cylinder... all to no avail. I replaced them all with
> new units 15 years ago and haven't had a problem
> since... I definitely learned my lesson (I didn't
> sleeve any of these rebuilds, hence my problems).
>
> Regards,
>
> Alan
>
> '53 BN1 '64 BJ8
>
> --- Bob Spidell <bspidell@pacbell.net> wrote:
> > Alan,
> >
> > re:
> >
> > > Any rebuilt brake booster MUST be resleeved... if
> > it
> > > hasn't been resleeved it will only last about a
> > year
> > > or 10,000 miles before it breaks again
> >
> >
> > If the cylinders are not pitted or scored at all,
> > why would this be necessary?
> >
> >
> > bs
> > ********************************************
> > Bob Spidell San Jose, CA
> > bspidell@pacbell.net
> > '67 Austin-Healey 3000 '56 Austin-Healey
> > 100M
> > ********************************************
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