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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