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    Front Brakes Bind-up When Hot

    My Stag's brakes needed a new master cylinder as it lost pressure during use. New MC fitted by mechanic and car got MOT'd.
    On return he thought brakes were binding slightly so fitted new pads and eased the caliper pistons to full retract, didn't do a test drive.
    I collected my car, drove home only to encounter a laboured engine due to front brakes binding.

    It must be the PDWA - so I duly stripped and rebuild with new seal kit. System fully bled.

    Two mile drive and front brakes still binding.

    It must be the servo adjustable rod too long - so spaced the MC off it using 3mm washers.

    Two mile drive and front brakes still binding.

    It must be the servo - which was duly replaced by a recon unit.

    Two mile drive and front brakes still binding.

    Could be air / water in the brake fluid - hydraulic system bled all four corners, all good.

    Two mile drive and front brakes still binding.

    It must be duff new MC not venting back - proceeded to strip / rebuild original MC, but just cannot budge the large nylon ring, not even 150psi moves it. Give in...

    So this is where I am now. Almost whole braking system replaced and front brakes still binding.

    Any thoughts please before I waste any more time and money. Don't ask how utterly p....d off I am.
    Last edited by Stag74; 12th July 2019, 11:44.
    1974 STAG

    #2
    The flexible hoses can fail internally so that a flap of rubber becomes loose inside and behaves like a one-way valve. This will cause brake binding issues.

    Probably not what you wanted to hear!

    Best of luck.

    Comment


      #3
      Originally posted by mallardstag View Post
      The flexible hoses can fail internally so that a flap of rubber becomes loose inside and behaves like a one-way valve. This will cause brake binding issues.

      Probably not what you wanted to hear!

      Best of luck.
      This was the cause of a front brake binding issue on a Jeep Cherokee i once had.
      Chris TV8 O/D Carmine, Scirocco TDI 180 R Line

      Comment


        #4
        My friend over here repairs old British cars for a living (but no Stags!) he has had a load of brand new master cylinders that simply do not work in recent years, maybe your new master is indeed the culprit?

        I'll ask him in a couple of hours (its still early here!) see what kind of symptoms he usually sees.

        Terry
        Terry Hunt, Wilmington Delaware

        www.terryhunt.co.uk

        Comment


          #5
          We had a member who’s rear brakes were same, and it was the flexi hose acting as described above,

          David

          Comment


            #6
            Originally posted by mallardstag View Post
            The flexible hoses can fail internally so that a flap of rubber becomes loose inside and behaves like a one-way valve. This will cause brake binding issues.

            Probably not what you wanted to hear!

            Best of luck.
            New Goodridge brakes hoses were fitted at same time as new master cylinder
            1974 STAG

            Comment


              #7
              Originally posted by trunt View Post
              My friend over here repairs old British cars for a living (but no Stags!) he has had a load of brand new master cylinders that simply do not work in recent years, maybe your new master is indeed the culprit?

              I'll ask him in a couple of hours (its still early here!) see what kind of symptoms he usually sees.

              Terry
              I'd be keen to hear what happened there
              1974 STAG

              Comment


                #8
                Ironically, before starting all this work pre and post the MOT, the car drove well other than having brake pedal pressure loss
                1974 STAG

                Comment


                  #9
                  Piston sticking in one or more caliper?
                  Paul - 3 projects, 1 breaker - garage built and housing 2 white Stags. One runs, one doesn't

                  Comment


                    #10
                    That's a point, both calipers binding or just one?

                    Terry
                    Terry Hunt, Wilmington Delaware

                    www.terryhunt.co.uk

                    Comment


                      #11
                      Agreed ref calipers possibly sticking, although mechanic was adamant they were fine. However, recon seal kits for these arrived today so I'll try that next to hopefully eliminate them from the issue
                      1974 STAG

                      Comment


                        #12
                        We recently had to change a brake master cylinder which was under warranty for not bleeding front brakes

                        Dave
                        73 mk 1/2 now gone to the dark side BLUE

                        Comment


                          #13
                          Originally posted by new to this View Post
                          We recently had to change a brake master cylinder which was under warranty for not bleeding front brakes

                          Dave
                          Can you say who the supplier was please, msg me if prefer not to do so plublicly. Would help me if from same supplier as mine
                          1974 STAG

                          Comment


                            #14
                            Originally posted by Stag74 View Post

                            I'd be keen to hear what happened there
                            He said that a number of TR6 masters would not bleed, but recently they have been OK.

                            Terry
                            Terry Hunt, Wilmington Delaware

                            www.terryhunt.co.uk

                            Comment


                              #15
                              I had a similar problem on my MG when I fitted a new master cylinder, occasionally all the brakes would lock and remain so until pressure was released.

                              In my case the issue came down to the piston in the MC not always retracting far enough to expose the fluid transfer hole from the fluid reservoir, which allows the pressure to neutralize. In that application, the lever connecting rod is adjustable and I had set it too tight so it occasionally exhibited the problem. A miniscule adjustment solved the problem.

                              John.
                              Your wife is right, size matters. 3.9RV8

                              Comment

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