David:
Just went through all of this when re-boostering several local BJ8's. We
decided on PBR (Australian) boosters. They are (or were) made in a couple
of vacuum chamber sizes, and 3 or 4 body bore sizes to match them to
whatever braking system the car has.
For instance, on Healeys there is a different recommended booster for the
BJ7 (and BN7 / BT7) and the BJ8, just as the original Girlings were
different - boosters are sized according to calliper (wheel cyl.) size,
master cyl. bore size, etc.
I was advised by the supplier that the original BJ8 Girling boost ratio was
3:81. We chose a PBR VH40 booster that has an appropriately sized vacuum
canister and has a boost ratio of 3:25. The cars already switched over feel
very close to the original boost - excellent braking feel. The use of DOT 5
silicone brake fluid, which everyone around here seems to use, will slightly
affect the braking feel on any booster. We are very happy with these
boosters - Kilmartin in Australia even supplied mounting brackets for them
so that they bolted right up to the cars, (with 2 new brake pipes being bent
to connect to the hydraulic system). The booster even has a bleed screw on
it's body, which is really nice for bleeding.
Your boost ratio of 3:00 shouldn't feel much different, and you probably
saved a lot of $$$.
Earl Kagna
Victoria, B.C.
BT7 tri-carb
BJ8
----- Original Message -----
From: "David Masucci" <drmasucci@comcast.net>
To: <healeys@autox.team.net>
Sent: Thursday, August 20, 2009 6:19 AM
Subject: [Healeys] Girling brake boost ratio
Hi all,
Does anyone know the boost ratio of the stock Girling brake servo in a BJ8?
Last night I replaced my original unit with the 8 inch Powertune unit (PN
LE10117). The boost ratio is 3.00:1 which I thought was supposed to closely
match the original. I am getting assist, just not quite as much as original,
and I am curious as to why.
Thanks,
Dave
BJ8
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