june 2011

GETTING YOUR BRAKES’ HYDRAULIC SYSTEM IN SHAPE
OR
STOPPING IS MORE IMPORTANT THAN GOING
By Art Gardner
Many of you are aware of the tendency these days to "update" the car's brakes with disk brakes in an effort to make the car
safer. In my opinion, the biggest danger with the original 1949 Cadillac brakes is the lack of a second circuit, not raw stopping
power. Up through 1961, I think, the brakes were all single circuit. Certainly in 1949 they were single circuit. That means
that if you pop a line or hose or wheel cylinder anywhere on the car, you will lose ALL brakes all at once. Dual circuit brakes,
which I think started with the 1962 Cads, eliminate that risk and leave you with either front or rear brakes in the event of a
calamity. Many people will say, but "hey, I have never had a problem, so why change anything." But when you do have a
problem, this is a BIG problem.
So, the most important thing, in my opinion is to make sure the original parts are PERFECT, especially the metal lines. Brake
fluid is hydrophilic, meaning it attracts moisture (right out of the air). The water that gets in the lines in this way rusts the
metal lines from the inside out. They can look perfectly normal in a visual inspection, but be rusting away on the inside. One
day a pinhole pops though and you lose all brake pressure. This happens more regularly than you might think, which is why
the government eventually outlawed single circuit brakes. This fluid-borne rust is also how your wheel cylinders and master
cylinder get pitted. The fix is to replace the plain metal lines with stainless steel lines. Put on all new hoses. Sleeve the wheel
cylinders and the master cylinder with brass or stainless steel. Flush out the brake fluid and replace it with new fluid every 2-3
years. Do that and the original drum brakes should be safe for a long time!
If you want to make them even safer, you can put in a dual circuit master cylinder. It takes some extra work and plumbing, but
to me it is worth it for the additional peace of mind. This is what I did with my last „49 6107 Club Coupe and am doing it to
my new „49 coupe. I developed a nice kit for installing such in the original mounting place on the frame, so everything looks
great and works correctly. I haven't worked out how to do this on my 1956 Series 60 Fleetwood, but I am still noodling on it
(as there is precious little room at the front of the 56 power brake booster for a dual circuit master).
I tried a disk brake "kit" on my last 49 and it was a disaster. I never did get it to work right, so I gave up and went back to the
reliable drum brakes (augmented by my dual circuit master kit using a modern Wilwood dual circuit master).
I drive my old Cadillac's as daily transportation. Right now, I use the '49 fastback in the cold months (it is black and has no air
conditioning) and use the '56 60S in the warm months (its factory air works great). So I am relying on my good old drum
brakes every day to stop my cars and keep me safe.
If you use the car only occasionally, such as for club events a few times per year, you might feel less motivated to be so finicky
about brakes and might be tempted to do the minimum, instead of the maximum, in restoring the brakes. I can understand that
tendency. But keep in mind that, as the song says, rust never sleeps and the corrosion inside the lines and the cylinders
continues whether you use the car or not. So you can still have a safety issue with the brakes, even if you only use the car a
few times per year.
If you keep the single master, but make the entire system perfect, you should be okay. A dual circuit master is a nice peace of
mind as an extra safety measure, but you should be okay without it if everything else is right.
TECH TIP: ’49 CADILLAC SPARK PLUGS
Early ‟49 Cadillacs used AC 48 spark plugs, a very “hot” plug. The difference between hot and cold spark plugs is how
quickly the plug body dissipates heat. Hot spark plugs dissipate heat slowly, keeping its temperature higher, which allows the
plug to burn off harmful carbon deposits quickly. They are used in cars that are usually driven slowly and in stop and go
traffic, whose motors frequently don‟t get fully warmed up. When designating the spark plug for the new „49, Cadillac
engineers thought most of them would be used under such conditions, but apparently this turned out not to be the case as the
following 1949 Cadillac factory “Serviceman‟s Supplement” explains: