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Marina Servo Diameter

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  • Marina Servo Diameter

    Does anyone know the diameter of the Marina servo? I'm looking to replace it with a Peugeot 205 servo but they come in three different sizes 7", 8" and 9"
    Mk2 SWB Marina Roadster with a 2.0L Pinto built in 1986

  • #2
    Re: Marina Servo Diameter

    Don't know the answer but I do know you need to be careful with boost ratios. Older servos had a pretty low boost. From experience the Metro was only 1.6. I guess the marina was similar. Newer ones have a far higher boost which could lead to rather sensitive brakes on a car as light as the Marlin.
    Cheers Robin

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    • #3
      Re: Marina Servo Diameter

      Marina servo appears to be 7 inch

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      • #4
        Re: Marina Servo Diameter

        @Martin, That's kind of what I'd like to achieve the peddle pressure on mine is very high and does not inspire confidence.
        Mk2 SWB Marina Roadster with a 2.0L Pinto built in 1986

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        • #5
          Re: Marina Servo Diameter

          Originally posted by danny_nelson View Post
          Marina servo appears to be 7 inch
          Thanks Danny
          Mk2 SWB Marina Roadster with a 2.0L Pinto built in 1986

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          • #6
            Re: Marina Servo Diameter

            Ok so how can you find out what the boost ratio is for a servo. I've found that a Triumph TR6 Servo will fit and the master cylinder has about the same bore but will I still have rock hard brakes. I'm guessing it will be no different to the Marlin example... Does anyone know?
            Mk2 SWB Marina Roadster with a 2.0L Pinto built in 1986

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            • #7
              Re: Marina Servo Diameter

              Believe the TR6 Servo ratio is 2.2:1 , Marina in the region of 1.9:1 so a small gain probably in terms of booster but will obviously depend on master cylinder bore as to total effect.

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              • #8
                Re: Marina Servo Diameter

                Hi Andy

                1) if the pedal is Rock hard are you certain you don't have a servo pipe /hose leak?

                2) I have noted on my Roadster that correctly adjusting the rear brakes makes the brake pedal lighter to press. I think the reason for this is that if the shoes have excess clearance then there is a possibility that the master cylinder piston has reached the end of it's travel and that could be why you have a hard pedal. This problem is magnified as the Marlin Pedals were shortened from the Marina originals. So your effort ratio results in less leverage.
                So my advice is adjust up the rear brakes first, it makes a big difference

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                • #9
                  Re: Marina Servo Diameter

                  I'm wondering if I have a dodgy servo as well. I'm going to try and test it at the weekend. I'm also going to inspect and adjust the rear brakes although I think that they are working OK as it only just passed its MoT. I am going to swap to a dual circuit system because I don't really like the idea of a single circuit setup after ripping a brake pipe out on a rally in the past. Fast approaching a milk float with the hand brake hard on is not an experience I would like to repeat . But before I go there I want to make sure that the current setup is working as well as it can and to ensure that if I go to the trouble of swapping the servo and master cylinder that I don't make things worse
                  Mk2 SWB Marina Roadster with a 2.0L Pinto built in 1986

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                  • #10
                    Re: Marina Servo Diameter

                    At one point, early in the rolling restoration after I fixed the leaky hose the brakes were so light they were lethal. The fronts would lock very easily. Now I don't think the servo is working, tried with the hose disconnected the brakes are heavy but OK. Why does a light car need the same braking power of a saloon car?

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                    • #11
                      Re: Marina Servo Diameter

                      @HairyDave maybe that is a test that I should do... I have considered a servo delete with a bias peddle adapter but that's more expensive I'm after dual circuit then addressing the poor front to rear bias.
                      Mk2 SWB Marina Roadster with a 2.0L Pinto built in 1986

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                      • #12
                        Re: Marina Servo Diameter

                        My Roadster initially had drum brakes all round and the only way to stop it was to throw an anchor out and hope it caught round a lamp post. I then put discs on the front which made a difference but still needed quite a push on the pedal. This was fine if you were used to driving cars from the '60s but with modern cars where you only need to breathe on the pedal and it slows it was always a bit of a wake up experience when you jumped into the Marlin. I then fitted a Lockheed remote servo in the single circuit braking system which seemed to give a good compromise between pedal pressure and braking ability.

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                        • #13
                          Re: Marina Servo Diameter

                          Andy: To test your servo . with the engine off pump the brake pedal about 4-8 times. That should expel any existing vacuum in the servo.
                          Then whilst pressing the brake pedal hard (you may need to use your left foot for this ) whilst using the throttle to start the car due to your carb set up.
                          If the servo is working you should feel the pedal go down as it now should have vacuum back in it.

                          The Mini's from the 70's had the addition of a brake limiting pressure valve that fits in the brake line near the rear axle because the coopers in particular had a habit of locking the rear wheels on a wet road. You could eventually try one of those from eg minispares or ebay.

                          Hairy Dave: When I first put my Roadster back on the road, I too noticed the eagerness for the fronts to lock up.

                          However regular adjusting of the rear brakes , means they must be touching now over most of the surface area of the drum and seem to be vastly improved ie fairly even front & rear braking.

                          Regular , correctly adjusting of the rear shoes is important so that the shoes don't wear effectively oval.

                          My A60 (the Marina's predecessor) had drums all round and no servo & correctly adjusted could stop quickly and lock all 4 wheels on a dry road if you pressed too hard on the pedal.

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                          • #14
                            Re: Marina Servo Diameter

                            Back in the 80's my friends Marlin was far too front brake biased - not surprising really

                            His solution was to fit a remote servo in the back brake line only
                            Made a massive difference - the brakes felt excellent

                            I'm busy building MY Marlin - I threw the Marina pedal box away and I'm fitting two master cylinders and a balance bar

                            I don't expect to need a servo

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                            • #15
                              Re: Marina Servo Diameter

                              Possibly my idea of good braking comes from my Series1 Landrover, it is not servoed and needs a good shove to stop it!

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