Brakes - "Certified PBR Automotive Engineer - not!"
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The braking system on a standard 1600 is not all that spectacular.
It consists of solid discs up front with a sliding single spot calliper,
and rear single cylinder drum brakes. The system also boasts an exceptionally
useful under-dash ratchet hand-brake and unassisted braking. Pretty
standard for that type of car and year.
The unassisted braking isn't so much of an issue. Many people don't like power-assisted brakes because they provide less feedback. It is not true that power assisted brakes will make you stop quicker. Stopping distance is simply a matter of friction on the discs and wheel traction. The booster remained simply because it was the easiest method of mounting the master cylinder to the firewall. These is the front disc/calliper setup. Quite heavy, but appears to work quite well... |
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We've changed the master cylinder over for a larger bore dual circuit
240K item. This is extremely important, because even though
the age of the car ('68) will let it race with a single circuit system, it is
far safer to have a dual (in fact some clubs actually enforce it by
adding the rule to the race sup-regs). You really tend to notice
this when you loose entire rear-wheel assemblies (brakes and all) and then
find you have no foot or hand-brake to stop with!
The servo comes from a donor 180B and the master cylinder bolts straight up. You'll also need the proportioning valve (to get some sort of front-rear brake bias), if you can't afford to pay $300 for an after-market item. It's a relatively simple matter to bend/flare the pipes out of some existing brake-line and fabricate the under-bonnet system from scratch. |
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When the rear brake conversion happened, we planned on installing a
hydraulic handbrake. This gizmo is the clutch master cylinder off
a Land-Rover, and it allows both operation of the foot-brake and the hand-brake.
Note that when the foot-brake is applied, the hand-brake piston will extend
to it's limit (and further if allowed - don't allow it!). You really
need a plate over the front of the cylinder to stop this occurring (this
is one of our to-do items!).
The cylinder is just plumbed directly in-line with the existing rear brake line. Note that the mounting bracket could possibly be about twice as long as the one pictured here. The amount of force supplied by the hand-brake is quite high and this setup does move a bit more than is necessary. |
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In an effort to get this car to pull up a bit faster, we've changed
the front discs and callipers over for those found on a 200B. Both
the disc and pad areas are larger, however it's not a great improvement.
We do find however, that it's quite easy to lock up the front end most
of the time. Thus, due to the surfaces we run on, the 200B setup
is probably quite adequate. If we plan on doing any black-track work
then the front brake package might become more of an issue.
The rear drum brakes were replaced with Skyline solid discs and Commodore VN rear callipers. The advantage of this setup is the low cost and relatively easy installation of the components. All that is needed is a new mounting plate for the calliper; simply welded onto the existing drum backing plate mount. The entire conversion doesn't change the rim offset at all, however the disc/calliper arrangement means larger rims (>13 inch) will have to be fitted to the car. Oh, and bleeding is a bit difficult with the calliper mounted horizontally... |
One note of warning... the brake booster on a stock Mazda is separated from the inlet manifold vacuum by a rather lengthy section of hose/pipe. This is because brake booster's don't like ingesting petrol. If you don't put this pipe in, the booster's rubber diaphragm will deteriorate at some in-opportune time.
