Results 1 to 17 of 17

Thread: Disc brakes for Morris Minor

  1. #1
    Banned
    watchdog's Avatar
    Join Date
    Jan 2008
    Posts
    2,966
    Thanks
    136
    Thanked 869 Times in 514 Posts
    Rep Power
    0
    Reputation
    8320

    Cool Disc brakes for Morris Minor

    Anyone here put disc brakes on a morris minor. Mine currently has HB torana discs with a remote vacuum booster but they are still whoeful. I am in panic mode when I reverse down my driveway because they just do not work in reverse , not too bad going forwards. Any ideas?



Look Here ->
  • #2
    Senior Member global88's Avatar
    Join Date
    Jan 2008
    Location
    Melbourne
    Age
    59
    Posts
    1,157
    Thanks
    4
    Thanked 7 Times in 3 Posts
    Rep Power
    237
    Reputation
    53

    Default

    Couple of things come to mind.
    So they work well forward but not in reverse?

    The master cylinder your useing is for a car with disk front drum rear? Hope its not one from a car with 4 wheel disks because your back brakes wont work. One of the outlets, the one going to your drums must have a one way valve fitted to it. It usually on the master cly just under the drum brake pipe fitting, inside the master. This is to stop the drum brake springs bringing in the shoes too far in, the valve hydrolicly locks the slave cly in your drums. If you dont have one, when you press your pedal the front works but the back will not contact with the drum because they have returned too far. If you have it fitted to your front the disk brakes will drag because they cant return.

    Your rear brake shoes are fitted the right way around? One is usually a lead shoe and the other a trail on most cars. It will effect the way the brakes work forward compared to reverse.

    The last that i learned the hard way after converting a car to disks front and larger drum rear (at high speed i must add), is that your brake proportioning may need to be adjusted. Its a valve that can be added to limit the amount of braking to the rear.
    A good test is to brake HARD a couple of times to see if the front or rear locks first and then play with the proportioning to get even braking in an emergency.

  • #3
    Banned
    watchdog's Avatar
    Join Date
    Jan 2008
    Posts
    2,966
    Thanks
    136
    Thanked 869 Times in 514 Posts
    Rep Power
    0
    Reputation
    8320

    Cool

    The master cyl is the original MM that sits in down in the chassis u channel. The rear are from a datsun stanza cause the complete stanza rear end is in there. I never said they work fantastic in forward but they have managed to pass rego & I dont drive it that often. But I am at the stage were I have a bit of time , so I 'm going into rebuild mode and I'm looking for better breaking. Most other things I'm happy with although I'll probably change to an auto g/box.

  • #4
    Senior Member global88's Avatar
    Join Date
    Jan 2008
    Location
    Melbourne
    Age
    59
    Posts
    1,157
    Thanks
    4
    Thanked 7 Times in 3 Posts
    Rep Power
    237
    Reputation
    53

    Default

    Stanza rear end in a Morris, go watchdog! lol.
    Sounds like you need a larger dia master clyinder with a rear one way internal valve and a proportioning valve.
    You may be able to adapt a master from a disk front, drum rear wreaked car. If the rear starts locking after this you could then add a proportioning valve. Stanzas have pretty largish drums from memory.

    Havent seen a morris master cly, maybe a stag/truimph 2500/ rover one could be looked at.

  • #5
    Banned
    watchdog's Avatar
    Join Date
    Jan 2008
    Posts
    2,966
    Thanks
    136
    Thanked 869 Times in 514 Posts
    Rep Power
    0
    Reputation
    8320

    Cool

    yeah , I'm thinking that the master cyl is letting me down. The trouble is that I will have major peddle rework to do if I change the master cyl because it hinges up out of the floor. Anything that hangs off the firewall will result in the need to strengthen the fire wall. This is why I haven't moved from the original master cyl previously. Also I am a bit short of room with a 2 ltr motor stuffed in there.

  • #6
    Senior Member global88's Avatar
    Join Date
    Jan 2008
    Location
    Melbourne
    Age
    59
    Posts
    1,157
    Thanks
    4
    Thanked 7 Times in 3 Posts
    Rep Power
    237
    Reputation
    53

    Default

    Do you have anything solid near the master like the chassis?
    If so what you can do is build a master clyinder stopper.
    What it is, is a bracket mounted to a solid part of the car infront of the master clyinder. It has a theaded screw doing through it which you undo and adjust until its in contact with the front of your master.
    When you press your pedal, the force is transmitted thought the firewall, through the master onto the stopper which wont move.
    Im about to build on for my GTR for my track days, it gives better, firmer pedal feel because the firewall wont flex.

    See here for an example

  • #7
    Banned
    watchdog's Avatar
    Join Date
    Jan 2008
    Posts
    2,966
    Thanks
    136
    Thanked 869 Times in 514 Posts
    Rep Power
    0
    Reputation
    8320

    Cool

    I may have to think about this without the beers. While there may not be any flex where the master cyl bolts on , surely there will be flex at the pivot point of the pedal at the firewall ?

  • #8
    Member streeter75's Avatar
    Join Date
    Jan 2008
    Posts
    291
    Thanks
    0
    Thanked 11 Times in 6 Posts
    Rep Power
    0
    Reputation
    62

    Default

    maybe a big besser block with a length of rope might be the easiest solution......


    Sorry couldnt help myself...

  • #9
    Senior Member global88's Avatar
    Join Date
    Jan 2008
    Location
    Melbourne
    Age
    59
    Posts
    1,157
    Thanks
    4
    Thanked 7 Times in 3 Posts
    Rep Power
    237
    Reputation
    53

    Default

    Point is with a bigger master you wont be pressing the pedal so hard.
    One way or the other, yes sit down and have a long hard look and think, dont know if too many beers will help though. Take your time, its your brakes.
    You could possibly reinforce the firewall from inside if your really worried, something to think about.....

    Streeter, your a killer

  • #10
    Senior Member global88's Avatar
    Join Date
    Jan 2008
    Location
    Melbourne
    Age
    59
    Posts
    1,157
    Thanks
    4
    Thanked 7 Times in 3 Posts
    Rep Power
    237
    Reputation
    53

    Default

    Some points ive been thinking about.
    You said you fitted a remote booster, its working ok? Have you tested it with and without the vacuum line connected to compare? You have fitted a one way valve to it? The valve is the right way around?

    When i said you may need a larger master the correct term would be one with a small diameter piston, this gives your system more hydrolic leverage.

    More leverage via pedal pressure can also be achived by the pivot point to master connection on the pedal. The closer you place the master to the pedal pivot point, the more leverage you have, the less pedal pressure you need.

  • #11
    Junior Member
    Join Date
    Feb 2010
    Posts
    3
    Thanks
    0
    Thanked 0 Times in 0 Posts
    Rep Power
    0
    Reputation
    10

    Default

    Hi there,in reference to your brake problem,I know that it may sound simple but have you checked the venting cap on the floor mounted master cylinder?If this vent is not clear the brakes often do not work well at all.I am in the process of fitting toyota KE70 disc brakes to the front of my morrie,I have installed the booster and dash bracing and now have to do the lines,I am currently keeping the standard rear end until later when I may fit a rear end from a toyota KE55,this width is acceptable by the engineer.My project still has a long way to go as I have not even started to fit the 1.3 ltr engine yet but I will get there.Good luck and hope you sort your brakes out..

  • #12
    Senior Member tagg's Avatar
    Join Date
    Jan 2008
    Location
    In a Tin Can
    Posts
    2,203
    Thanks
    872
    Thanked 378 Times in 221 Posts
    Rep Power
    308
    Reputation
    1897

    Default

    Hmm as most people have pointed out, your master cylinder has to match your front disc's or they won't work correctly its the same if you use a master cylinder that is bigger then the disc that you are using you will get a hard peddle but no stopping power.
    try to match things up if you can, seeing that you have big front and rear brakes but a small under powered master cylinder start there if you can ??

    Cheers
    Tagg

  • #13
    Administrator
    admin's Avatar
    Join Date
    Jan 2008
    Location
    Victoria
    Age
    56
    Posts
    31,150
    Thanks
    2,238
    Thanked 13,731 Times in 5,823 Posts
    Rep Power
    4552
    Reputation
    165805

    Default

    Quote Originally Posted by scorpious View Post
    Good luck and hope you sort your brakes out..
    Post date is over 2 years ago so if he hasnt sorted it out he is either very lazy or a stunt driver.

  • #14
    Senior Member
    Godzilla's Avatar
    Join Date
    Jul 2008
    Location
    Melbourne
    Age
    59
    Posts
    12,740
    Thanks
    16,580
    Thanked 7,201 Times in 3,648 Posts
    Rep Power
    2198
    Reputation
    79113

    Default

    What a many people seem to be missing is you cannot just take a master from car X, connect it to front disk calipers Y and a rear disk or drum brake assembly Z.

    There are different types of master cylinders, some are designed to work with rear drum assemblies and have a one way check valve to stop the drum assembly from compressing inwards in the drums.
    Having this check valve missing would lead to the rear drum brakes not working because the clearances in the drum would be too wide due to the compression of the drum shoes brought on by the compression springs.
    Having this valve in place with disc calipers causes the brakes to remain applied and overheat or jamb the brakes on.

    Then there is the matter of hydro leverage, you need to calculate the master piston size in relation to the front caliper pistons and rear drum slave cylinders or rear caliper pistons.

    The distribution force calculated also need to take into consideration the weight distribution of the vehicle.

    Point is under hard and sharp braking the car should not be inclined to lock either the front or rear brakes individually, it should be well balanced.

    Fine tuning is possible with a brake distribution valve.

    I was building a LJ Torana coupe with a worked 265 Hemi for a friend years ago, the owner of the car had just converted the rear diff assembly to a Ford 9" with the whole rear original Ford drum assembly and did not warn me.

    First time out when tuning it, i opened it up for a squirt, hit over 170 in a blink of an eye, when i went to brake and wash off some speed it completely locked the rear end.
    The 9" brakes were too powerful for the rest of the braking system, it totally threw out the proportion for braking force.
    Last edited by Godzilla; 06-02-10 at 05:49 PM.

  • #15
    Senior Member tagg's Avatar
    Join Date
    Jan 2008
    Location
    In a Tin Can
    Posts
    2,203
    Thanks
    872
    Thanked 378 Times in 221 Posts
    Rep Power
    308
    Reputation
    1897

    Default

    Yea what he said

    Tagg

  • #16
    Junior Member
    Join Date
    Feb 2010
    Location
    Brisbane 4051
    Age
    71
    Posts
    3
    Thanks
    0
    Thanked 0 Times in 0 Posts
    Rep Power
    0
    Reputation
    10

    Default

    Morry's .... plenty of info one here



    cheers

  • #17
    Banned
    watchdog's Avatar
    Join Date
    Jan 2008
    Posts
    2,966
    Thanks
    136
    Thanked 869 Times in 514 Posts
    Rep Power
    0
    Reputation
    8320

    Cool

    Frosty - good to see your expandong your horizons ( omce per year)

    the Toss

  • Bookmarks

    Posting Permissions

    • You may not post new threads
    • You may not post replies
    • You may not post attachments
    • You may not edit your posts
    •