Date: Mon, 20 Jan 97 10:23:32 -0800
Sender: Vanagon Mailing List <vanagon@vanagon.com>
From: vince_pappalardo@om.cv.hp.com
Subject: Re: Brake Cylinder Rebuilding??
Item Subject: Brake Cylinder Rebuilding??
Jim,
I have done many rebuilds and have always honed the cylinders at
least five or ten strokes to break any surface imperfections and
slightly rough up the surface to get the new seals to seat. I have not
ever "screwed it up with a hone" and I have had my share of the hones
slipping out and stones coming off. The purpose of the honing is
mostly to remove surface imperfections that will cause premature
failure of the new seals--it does not come close to resembling a
boring process. If you elect not to hone, I would highly recommend
running your finger over the entire surface of the bore to verify that
there are no imperfections.
As for what type of hone to use. I have used two and three blade
hones. Mostly this is dictated by the size of the cylinder you are
doing and the size of the hone that will fit inside it. The three
stone type I feel are more stable but I don't have much a problem with
the two blade ones either. Good technique is more important than the
hone itself. Strive for keeping the hone shaft concentric to the bore
and use a in out motion that is continuos that will produce a 45
degree angle hone mark pattern.
I also think you should wait on doing the rebuild on these until you
need them. If you do them now you will need to store them with brake
fluid in them to protect the surfaces from rusting. This is risky
because, unless you seal all the open ports well, the brake fluid will
absorb water from the air and cause the very pitting they don't have
now. Moreover, the seals will start to relax and break down while
not in use therefore reducing there life once installed.
I would simple clean and dry them. Then coat the bores with a heavy
grease or oil that will stick to the walls to prevent rusting.
Well, that's about all I can add to this discussion.
Vince,
'85 Westy, GL
'90. . .some other foreign car that now seems pretty refined (but not as
utilitarian) compared to the Westy.
______________________________ Reply Separator _________________________________
Subject: Brake Cylinder Rebuilding??
Author: Non-HP-vanagon (vanagon@lenti.med.umn.edu) at HP-Corvallis,shargw1
Date: 1/20/97 9:08 AM
Hi all,
I've recently replaced (with new) both the rear wheel cylinders on our 88
Vanagon - one was leaking. Also, recently I had the clutch slave cylinder
replaced on my 87 Syncro.
I'd like to rebuild the old cylinders and keep them as spares. The bore of
all of the cylinders is very smooth and shows no signs of pitting. It seems
like the leaks were like caused by old and stiff rubber seals. The seals in
the rebuild kits are much more flexible and the outer sealing "skirt" is a
bit larger in diameter than the old ones. I theorize that the seals, after
being held inside the cylinders for 9-10 years, have assumed the diameter of
the cylinders and no longer exert much force on the walls on the cylinder
wall.
My question is about honing the cylinders. Since they are smooth inside,
does this realy need to be done? I'm a bit worried about taking a cylinder
with a nice smooth bore and screwing it up with a hone. Also, any
suggestions on the brand or type of hone required?
Thanks,
Jim Davis
87 GL Syncro
88 GL Wolfsburg