Early ID19 brake systems
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Thread: Early ID19 brake systems

  1. #1
    Fellow Frogger!
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    Default Early ID19 brake systems

    As befits the poverty model the early ID19 didnít get the full high pressure hydraulic braking system afforded the DS19. In fact, the very first ID19s had a simple single-circuit master cylinder system carried over from the Traction. Few, if any, ID19s exist with this system, and it was quickly replaced with a hybrid powered arrangement.
    In this second ID19 braking system, the master cylinder had a hydraulic spool valve added. The intention was that during normal braking the conventional single circuit/master cylinder operation would occur, but in an emergency stop where the master cylinder piston was fully extended it would actuate the spool valve and introduce main pressure hydraulic fluid to the brakes. Good idea in theory but not in practice. The system was prone to difficulty in achieving a hard pedal, and if the high pressure was initiated it could blow back through the master cylinder and spew brake fluid all over the bodywork.
    In September 1961 Citroen modified the ID19 braking system.

    The master cylinder was replaced with a brake control valve, still operated with a conventional brake pedal. The front brake circuit pressure was supplied from the main accumulator, and the rear brakes were supplied from the rear suspension feed. There were a number of other changes including replacing the pressure distribution block with a security valve.
    The system changes are described in Slough Technical Note 752, dated Jan 1962, which is a translation of the French bulletin, dated 14 Nov 1961.
    It is possible to convert a pre-1961 car to the later system. It requires access to a number of parts including a pedal box, brake valve, and a security valve. There is also a lot of plumbing involved, so itís not for the faint-hearted. However, if anyone is interested I am happy to advise/assist.
    roger


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  2. #2
    Fellow Frogger!
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    Roger, I agree with all of the above. In the early 60s the master cylinder cars were produced in Melbourne, and as you say had extremely high pedal pressures, and also as you rightly add were prone to losing that solid pedal. As an 18 yo I did the master cylinder to brake BUTTON conversion. The floor pressings changed ( along with the muffler on second nose cars ) as did the accellerator pedal. Powered systems using an organ type bottom hinged pedal and the master cyl. cars had a cable pulling pendant pedal .. thus to fit the button system into a master cyl car naturally required the rod operated gas pedal. That car was always nose heavy in braking application ( the rears would barely work, but seized wheel cylinders from under use was typical )... I was told the actual pistons in the discs were a different size on powered brake cars, are you able to confirm ???? These I did not exchange so that was probably the reason for the nose dipping .... mind nothing matches the braking action of the genuine DS truck system where the fulcrum point between front and rear valves is variable. That system could really see the rear end tuck down under braking instead of floating skywards. My mother once got a Morris Minor wedged between the boot wall and the rear bumper...The Morris had progressed too far forward and the over riders got caught as the car was a touch high at the rear from braking action... fun days !!!

  3. #3
    Fellow Frogger!
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    Hi Fritzelhund,
    thanks for the comments. A change to a button brake valve would have been quite complex - well done!
    For the ID19 the front caliper piston diameter changed from 38mm to 42mm around July 1959, prior to the change to the powered system. At the change to the powered system the rear cylinder diameter was increased from 16.5mm to 18mm. Also the main accumulator pressure was changed to 570 psi.
    roger

  4. #4
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    What more can I say ?
    Science has baffled a teenager's enthusiasm !!!

    I recall my mother's ID19 ( a "62 ) with the pedalo power brakes, the clutch cable moved a different mechanism ... equally cobbled up looking. The floor ridge to accommodate the throttle rod was an unfortunate legacy for all later Ds and demanding an unnatural foot action to the clutch pedal. The cable operated carby had a flat floor more like a traction.

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