John,
Having had experience with the Girling MkIA 5", 7", MkIB 7" and various Lockheed
units, as well as seeing the Midland-Ross '55 T-Bird installation, I can offer
these personnel observations.
The MkIIB was a far superior design to the MkIA, using a flexible diaphgram,
rather than a Large tin can with a sheet-metal disc piston, for actuation. This
is the method durrently used by all major power brake builders. Unfortunately,
Lucas/Girling no longer make any rebuild kits, and the ONE I located was over
$350 for the kit.
The MkIIA kit is available, at a semi-reasonable price, but you really need to
know how too do this job right, or you are in trouble. Assembley and
dis-assembly are triky, though documented. Checking the Tomato Soup Can bore
for scores is easy, but the design sucks, as it is not corrosion protected. A
good plating (hard chrome if you can afford it), will pay off in the long run.
Powder coating all the sheet metal steel parts (except the seal area of the
sheet metal piston) looks good, and will pay off in cleanliness, Watch out for
the condition of all the hydraulic bores (multiple sets) within the hydraulice,
and make sure htey are honed and still within tolereance. This unit could badly
use a brass or stainless sleeving. There are a few outfits that will do brass,
but I aven't found any who speak stainless. The weakest seal is the on on the
actuating rod where it passes through to the vacuum chamber. Weak design, major
cause of "eating hydraulics" and could benefit form hard crome plating for
reducing ear, and getting the diameter right for the seal, if it's worn. The
later 7" model is a much stronger boost than the early 5", but fits the engine
compartment with out room for a playing card between the firewall, on one side,
and the fender on the other. The vertical bracket is bent, rather than
straight, to connec the horizontal brace to the hydraulics. The band is not
used, as there is no room for it. This makes the attachment of the hydraulic
line fittings one of the Mad dogs and Englishmen's revenge. CAD (or chrome,
depending on taste) of the end plate and screws is a good idea.
Warning. Very few brake rebuilders know beans about the Girling units, unless
they are named "Paul", " Dan" or "Dale", plus a few others.
I have a Lockeed unit that was removed after a week on my son's Series V
Alpine. The model he got, from VB, could be installed, although their very
expensive "installation kit" can be made by you with a few cuts of sheet metal
and some bends. Only need an "L" with holes for the case studs and holes for
the firewall on the Tiger. The plumbing is all in different locations, so be
prepared to re-do your inlet and outlet lines. Make sure you use English
"bubble" flares, not American "Double" flares. Rick, at Sunbeam specialties,
has straight lengths of these. Haven't seen a "home" flare making kit in US,
but they are used in England and New Zealand a lot.
This unit only had a 2:1 boost. The MkIIB had a 3:1 boost, and the MkIA is near
the same. Jay took off the Lockheed because a C.A.T. "emergency" braided hose
connector replacement quickly convinced him the there wasn't enough difference
without a booster. Rick's Lockheed replacement is 2.25:1, I think. Hey, it's
your foot pressure feel that matters. There are many boost ratios available
from Lockheed with the same outer dimensions and look. A quick call to
Lucas/Girling (800 number) will give you their recommended Lockheed
replacement. Lockheed, or Lucas, my even be able to supply boost ratio. Be
sure you get the unit part number, not the kit number.
BE SURE youve got the correct master cylinder bore, or you will not get the
desired results, and may even run out of travel, if not achieve th boost level
you want. The nes ones are cheap enough, but keep the old center clevis. The
replacement unit "Universal" one won't fit, and you need to replace the threade
rod with the original welded clevis.
The Midland-Ross is a neat unit, and I believe you can still get one in
re-buildable condition, and with kits and brake shop expertise to re-build.
Here you will have bubble flares at the Mster an remote block, and double flares
at the booster. You can get most competent shops to make a double flare, or buy
the attachment kit yourself. Not easy.
Last word. Get that C.A.T. "Emergency Brake Booster" stainless line for about
$10 and throw it in your trunk with some wrenches and fluid (sealed can, LMA
Girling).
-- "
Steve Laifman < One first kiss, >
B9472289 < one first love, and >
< one first win, is all >
< you get in this life. >
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