Master cylinder?

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trmorrisminor
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Master cylinder?

Postby trmorrisminor » Wed Mar 13, 2019 11:57 pm

Hi all, I have a couple of questions I was hoping somebody maybe able to help me with please. I have recently had some work done on my morris minor van, its had new everything on the brakes eg master cylinder, shoes and drums, pipes, brake switch etc etc. Last year I bought a job lot of bits of morris minor stuff and amongst the stuff was a new lockheed master cylinder. It looked new, shinny and unused. Rightfully or wrongfully I decided to take pot luck and ask the garage to fit it, along with all the other new bits I had bought to replace the old braking system. On the way back from the garage the van felt like something was holding it back (literally like the brakes were on) having finally arrived at my house, i left the engine running, jumped out of the seat , wondered round the back and noticed that the brake lights of the van were on (even though there was nobody in the van). Smelling the intense smell of brake dust , i stupidly felt one of the minilight wheels, which was baking hot! I am not in touch with the garage having collected the van and have no plans on going back to him. Can anyone tell me if they have had a similar experience please. My gut feeling is that there is an issue with the master cylinder? Would anyone else agree?
Second question is the rod that goes into the mastercylinder, how far in should it go when the brake pedal is not in use? I am wondering whether the rod needs to be adjusted back towards the pedal, is it possible its been set to far into the mastercylinder? I have also noticed that once the van has been left overnight and then you start it , the brake lights dosent come on straight away, you need to drive the van for a bit and then the same thing happens, brakes seem to stay on, making it very difficult to drive, and when you get out of the van, the brake lights are on? Any ideas please.
My father in law and i plan to replace the existing master cylinder with a brand Lockheed master cylinder and bleed the brakes etc but really want some advice before we do it? Many thanks

kennatt
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Re: Master cylinder?

Postby kennatt » Thu Mar 14, 2019 7:20 am

wait till brake light is on then check the free play on the pedal,if non then probably rod too tight or pedal stuck on shaft,if penty of free play at pedal then problem in master.

trmorrisminor
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Re: Master cylinder?

Postby trmorrisminor » Thu Mar 14, 2019 7:56 am

Many thanks for the info, that all makes sense. I currently have the master cylinder cover off,obviously everything is connected,how much play should i have? Do you wiggle the red side ways to see and push the pedal down? When i am pushing the brake pedal down by hand, how will i know when the rod is actually working the mastercylinder, how far roughly should the rod be in when its static and the footpedal is not in use? Thanks again for your reply.

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Nickol
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Re: Master cylinder?

Postby Nickol » Thu Mar 14, 2019 8:53 am

Were all the wheels hot when you touched them or only the one? Perhaps you did not feel the others after the first "hot" shock. Before you jump to the conclusion that the MC is at fault, jack the car up so that the wheels are off the ground ( or at least in turn the front and the back) then apply the brake as normal and release. Both or all wheels then jammed? If so definately MC. If only one then another fault. Collapsed old brake hoses are prone allowing the brake to work but not allowing them to back off. But there are other things as well.

The adjustment of the rod length operating the MC from the foot pedal is a bit fiddely. If you do have to take the MC out, then check the pedal for free and easy movement. Otherwise adjust the rod length to get the specified free movement of the pedal. This free movement can be ( I have not checked but I seem to remember 20 mm ) proven by Hand because no pressure is needed. Once the free movement is used up and the rod strikes the Piston in the MC, you should not be able to push it by Hand any more.

Without the free movement, the Brakes will jam on. Ask me how I know!
Gott schütze mich vorm Sturm und Wind und Autos, die aus England sind.
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philthehill
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Re: Master cylinder?

Postby philthehill » Thu Mar 14, 2019 9:33 am

The master cylinder piston should be right back against the circlip before starting to adjust the pedal clearance.

The pedal should be able to depress for 3/4" (19mm) before the push rod starts to contact and move the piston.

The clearance is adjusted by turning the pushrod which is threaded onto the pedal yoke.

The pedal return spring must be in place and effective otherwise the clearance will be nil at all times.

See BMC wksp man section M illustration M2 for assembly details.


trmorrisminor
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Re: Master cylinder?

Postby trmorrisminor » Fri Mar 15, 2019 11:24 pm

Many thanks to you all for the info. Much appreciated.


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