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Dual Cylinder - Master Brake Cylinder

Discussion in 'Rootes Racing' started by alpineracer, Sep 6, 2018.

  1. alpineracer

    alpineracer Diamond Level Sponsor

    Has anyone used this:


    I know it is longer than any of the stock cylinders, but came across it when researching for the aluminum rear brake drums the early Z cars used which can be adapted to the Alpine axle hubs.
  2. 260Alpine

    260Alpine Silver Level Sponsor

    The earlier one is 7/8", the later 15/16" bore. You want 11/16" to 13/16" with 3/4" ideal. Another issue is the bottom fittings hit the steering box of the Alpine. May work fine for the Tiger with larger than stock brakes.

    PROCRAFT Gold Level Sponsor

    Rock auto 7/8" PN 13-1658 39 bucks$ 260/280Z
  4. Barry

    Barry Bronze Level Sponsor

    Series Alpines without a brake booster had 0.700" (Series I / II) or 0.750" (Series 3 / IV / V) master cylinders.

    Series Alpines with a brake booster had 0.875" (7/8") master cylinders.

    There is no practical way to use a tandem master cylinder with a brake booster.

    A 0.875" (7/8") master cylinder (tandem or not) on a Series Alpine with stock calipers and without a brake booster will give a very heavy brake pedal.
  5. 260Alpine

    260Alpine Silver Level Sponsor

    Plus, the fittings interfere with the steering box. The Tiger, the master is moved over.
  6. DanR

    DanR Diamond Level Sponsor

    Barry, do you mean when the brake cylinder and the booster are hooked together ? or seperate?
  7. DanR

    DanR Diamond Level Sponsor

    I recently obtained a master cylinder very similar to the 64-103 that has the 3/4" bore. I believe it is possible to make it work in one of my 2.8 V6 Mustang II conversions.


    I also recently was able to get a Master Brake Cylinder 3/4" bore with the pressure connections on the engine side that I believe also will work. I may have to either remove the brake lines to the master cylinder when and if the valve covers should need to be removed.
  8. Barry

    Barry Bronze Level Sponsor

    Sorry, but I don't understand your question.

    A tandem MC has two "separate but equal" hydraulic outputs. If you plumb only one of the outputs to a booster, then the series Alpine brake system would be wildly unbalanced. Plumbing the two "separate but equal" hydraulic outputs from a tandem MC to two "separate but equal" boosters would theoretically work, but it is certainly not practical.
    Last edited: Sep 11, 2018
  9. DanR

    DanR Diamond Level Sponsor

    Barry, I made the question not understanding if the units were linked together inline as in some American cars. I now understand what you said:)

    Anyway, missed you Saturday in Norcross. Had a good showing of the Sunbeams.
  10. Barry

    Barry Bronze Level Sponsor


    I understand your question now. As you noted, American cars with power brakes mostly used a vacuum powered mechanical booster between the brake pedal and the master cylinder (in an integrated unit). For the series Alpines, Rootes used a normal (un-boosted) master cylinder and then used a separate vacuum powered hydraulic booster between the master cylinder and the calipers / wheel cylinders. Both systems lower the pedal effort to achieve a given hydraulic pressure to the brakes. I assume (yes, I know) that Rootes used the normal MC + separate vacuum powered hydraulic booster because there was not enough room for an integrated mechanical booster + MC in the series Alpine engine bay. Not a matter of better / worse, just a practical solution to the constraints of the very cramped series Alpine engine bay.

    Planned on being at Norcross, but out-of-town family issues got in the way. Maybe Hilton Head on 3 NOV???
    Last edited: Sep 11, 2018

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