[Mgs] B master cylinder [now veering OT but still LBC-related]

[Max Heim]

Marginally related to this topic, I thought I'd share a "unique" braking
solution that a friend of mine encountered.

He had recently purchased a Sunbeam Alpine that had been converted to a GM
FI V6 and 5-speed, with a Ford rear axle and various other upgrades and
modifications. Typically for a drivetrain swap, it was not quite sorted out,
but it was drivable.

He was attempting to fix an asymmetrical stiffness in the steering, when he
found that (among other problems), the tie rod was rubbing against a custom
bracket welded to the frame near the base of the passenger-side firewall.
Investigating the purpose of this unusual excresence (being quite familiar
with stock Alpines), he discovered a highly unorthodox and "original" master
cylinder arrangement.

It turns out that the PO had desired power brakes, but the particular
booster which he wanted to use would not fit in the normal position attached
to the master cylinder, due to the width of the V6 engine. Apparently he had
never heard of remote boosters, even though they were fitted to some
Alpines, so his rather dubious solution was to install a single line,
unboosted master cylinder in the standard location, operated by the brake
pedal, with a hard line running across the firewall to a slave cylinder
located in the passenger footwell, which in turn operated the push rod of a
dual master cylinder with vacuum booster, protruding through a hole cut into
the firewall, and supported by the aforementioned bracket; and this second
master cylinder actually operated the brakes.

Need I add that this PO was a high-end engineering consultant?

Very ingenious, but as my friend pointed out, this system introduced
multiple points of failure, many of which had the potential of introducing
brake fluid into the interior. He is currently engaged in removing the
entire setup, replacing it with a "single" dual MC, unboosted, in the
standard location.

I suppose this should be filed under "DPO Tales"...

--

Max Heim
'66 MGB GHN3L76149
If you're near Mountain View, CA,
it's the primer red one with chrome wires


on 7/23/07 4:01 PM, James Kleemeyer at jkk at adams.net wrote:

> ----- Original Message -----
> From: "Keith G." <kger at plex.com>
> 
> 
>> In trying to bleed my 79 B's brakes, I found nothing was happening at
>> the rear brakes.  I checked each connection back toward the master
>> cylinder and found the same thing.  Finally, I disconnected the line
>> from the master cylinder and found that no fluid comes out of that
>> port on the master cylinder.  Well, that would explain it.
> 
> I had the same thing happen to me not long ago. I dissasembled the master
> cylinder only to discover the link that connects the front and rear pistons
> was broken and no part is available to repair it. I'm was going to make one,
> but can't really determine the correct length so that's on the back burner
> for now.
> 
> Jim