1969 boosters and brakes

["Watry, Andrew (LNG-MBC)" <Andrew.Watry@domain.elided>]

Following from Dana's question:

I can't say for certain without checking my references, which I don't have
with me (so I'm going out on a limb), but I think non-US LHD cars never got
the dual-booster setup with floor pedals.  US (all LHD) cars got the
dual-booster setup in response to a US federal requirement for dual brake
circuits, and I imagine the dual-booster setup we saw in 1969 only was the
expedient way to do it with the brake MC under the floor.  I don't think any
non-US cars adopted it, did they? Perhaps Canada?  There's simply not enough
room to fit a single booster between the pedal and the floor MC in one of
these cars, though VW did it for one or more years with the bay-window van
around 1971.  So if you fit the booster downstream in the hydraulic circuit,
as Alfa did, you have to fit one for each circuit, hence the dual setup.
Rover did a similar thing on the 2000 TC.  Same Lockheed boosters too, at
least by appearance.

As an aside, the 1969 and earlier LHD boosters and RHD boosters (Benditalia,
Bendix, Bonaldi, Lockheed) have hydraulics running through them. 1971 and
later LHD boosters have no hydraulics, and are purely pneumatic, working
against the brake MC directly, based on brake pedal movement.

By 1970/1971, Alfa moved the brake MC and clutch MC out from under the floor
and onto a common pedal box high up on the firewall (which took some
reengineering). I assume the main point of this was to give room for an
integral booster between the pedal and the MC (probably to more easily meet
the US requirements), like most "normal" cars, and hence the need for only
one booster.  All LHD cars for all LHD markets, I believe, got this setup
thereafter.  Maybe some Juniors or other oddities were different.

The brake MC and clutch MC on RHD cars never got moved out from under the
floor, because Alfa never engineered a RHD firewall pedal box setup.  So RHD
cars, which I gather got dual circuits in 1969/1970, continued to need the
dual boosters for the same reason the US cars did in 1969.  There are
conversion RHD Spiders, which I believe have the pedal box on the left, but
have pedals on the right and a cross-over bar to actuate the MC.  But that
was a UK conversion (perhaps factory sanctioned), not an Alfa project.  I
assume Alfa didn't put the effort into the RHD cars because they didn't sell
enough of them for it to make sense, and/or because there wasn't room on the
intake side of the engine for all the hardware, especially once the steering
got moved over there too.  Alfa didn't even make any later series RHD
Spiders, right? They're all UK conversions, if I remember Chris Rees' book
correctly.

I wouldn't expect a single-circuit LHD floor MC setup to be difficult to
deal with, regardless of year.  And as has been said, the dual-booster setup
does not have fundamental flaws, and can be made to work fine, but it is
admittedly more hassle and more money.  To address one other point, Duettos
with no booster had a different diameter MC, don't they?  That changes the
forces involved and pedal effort.  Some/all GTAs didn't have boosters
either, at least the one on the cover of the Centerline catalog doesn't.

Andrew Watry
Berlina Register
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