Master Cylinder repair question

1959 - 1978, M151, M151A1, M151A2, Technical questions and discussions, regarding anything related to the M151.
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steveperryman
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Master Cylinder repair question

Post by steveperryman » Sun Aug 27, 2017 6:35 pm

Does anyone have the exploded view of the inside of the m151a1 master cylinder? My old one popped apart so fast I couldn't see what came out first and in what order.


The photo shows the way I think it should be attached, but I dont know..

Thanks, Steve
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artificer
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Re: Master Cylinder repair question

Post by artificer » Sun Aug 27, 2017 8:44 pm

The spring & check valve are wrong way round & the primary cup lip goes toward the spring/fluid. The check valve goes to the body out....the piston, spacer & circlip are correctly positioned.
John GIBBINS Member Institute of Automotive Mechanical Engineers [Ret], ASE Master Medium/Heavy Truck & Auto Technician USA -2002 Licensed Motor Mech NSW MVIC 49593 Current 2015
TO DIAGNOSE, TROUBLESHOOT OR FAULT FIND ANY AUTO SYSTEM....
Understand how system parts interact with one another. GOOD parts can then be established & the NOT GOOD problem/s part/s isolated for repair or replacement.

steveperryman
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Re: Master Cylinder repair question

Post by steveperryman » Mon Aug 28, 2017 4:08 am

Thank you for your reply! I attached another photo to make sure I understand what to change. I reverse the spring (A), I reverse the position of the check valve (B, B is just the rubber unit, not the steel piece), I place the primary cup (C) like I'm pouring water into it from the spring side, as I drew above the cup.

Thanks again.

-Steve
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artificer
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Re: Master Cylinder repair question

Post by artificer » Mon Aug 28, 2017 11:30 am

A [the spring & residual check valve] are turned around, as you say.
B [the piston & secondary cup] are right without altering.
C [the primary cup] is put in front of B orientated as you have drawn up against the spring A.
John GIBBINS Member Institute of Automotive Mechanical Engineers [Ret], ASE Master Medium/Heavy Truck & Auto Technician USA -2002 Licensed Motor Mech NSW MVIC 49593 Current 2015
TO DIAGNOSE, TROUBLESHOOT OR FAULT FIND ANY AUTO SYSTEM....
Understand how system parts interact with one another. GOOD parts can then be established & the NOT GOOD problem/s part/s isolated for repair or replacement.

steveperryman
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G-Staff Sergeant
Posts: 55
Joined: Sun May 14, 2017 4:06 am

Re: Master Cylinder repair question

Post by steveperryman » Mon Aug 28, 2017 11:42 am

Thanks so much! I'm going to assemble tonight and bleed the brakes..

One more question please. The rubber seal directly below the B I wrote, that has a raised lip, does it make a difference which way the lip is directed?

Thanks


-Steve


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artificer
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Re: Master Cylinder repair question

Post by artificer » Mon Aug 28, 2017 12:00 pm

If you have had off....I recommend both B & C are replaced....Both lips MUST go to the inside.
If C is reversed the brakes will be extremely dangerous & the pedal go to quickly or sink to the floor boards.
If B is reversed on the piston fluid will leak out the rear of the master cylinder & eventually drain the reservoir.
Bench bleed the master cylinder before installing.
This may help you:
http://jeepdraw.com/images/HOW%20to%20B ... LEEDER.pdf
John GIBBINS Member Institute of Automotive Mechanical Engineers [Ret], ASE Master Medium/Heavy Truck & Auto Technician USA -2002 Licensed Motor Mech NSW MVIC 49593 Current 2015
TO DIAGNOSE, TROUBLESHOOT OR FAULT FIND ANY AUTO SYSTEM....
Understand how system parts interact with one another. GOOD parts can then be established & the NOT GOOD problem/s part/s isolated for repair or replacement.

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