13 replies to this topic

[M I N I]

Hello all,

Need to replace the master cylinder for the brakes as have a leak. I was told to see what colour tag it has normally yellow. Mine had a black one (see picture) and I can’t seem to find a ‘black tag’ replacement. Yellow tag one (see pic 2) looks the same but I can’t be sure. Due to be doing a run in 1 week so need to get replacement ordered ASAP.

I noticed this plug is corroded very badly to the point where the wires came off the plug. Need to get a replacement plug but not sure what it’s called or whether it’s generic (pic 3).

Also, now have a major fuel leak on the fuel pump (aaah) does anybody have any experience changing these? Going to attempt it after I have sorted the brakes.

Thanks in advance for all your help!

Attached Files

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•  IMG_0244-min.jpeg   55.64K   4 downloads

[bpirie1000]

Are both top and bottom brake flares on the pipes the same diameter?

That is a tell tail sign...

Edited by bpirie1000, 30 August 2023 - 06:19 PM.

[M I N I]

Not 100% but fairly certain they are.

[Lplus]

As I understand it, on the basis that the car has front/rear split brakes, the yellow tag is the only available replacement but needs the  additional new pipes down to the PDWA valve on the bulkhead as the pipe arrangement and size is different.

 

Also the yellow tag has a fluid level sensor in the cap instead of the pressure differential shuttle of the black tag cylinders so the two wires need spade connectors fitting or a different plug, (though I'm not sure if the test switch wiring is exactly the same.)

 

If the brakes are diagonal split and have metric threads then a direct replacement cylinder appears to be available but a lot more expensive. (GMC167)

[Spider]

That's a GMC167. They are available;-

https://www.somerfor...ic-unions-76-80

 

http://www.minispare...|Back to search

 

The switch in the body as best I am aware is NLA, however, you can use a lid that has a float switch, which I've found to be way more effective;-

http://www.minispare...67.aspx|Back to

 

[[email protected]]

That's a GMC167. They are available;-

https://www.somerfor...ic-unions-76-80

 

http://www.minispare...|Back to search

 

The switch in the body as best I am aware is NLA, however, you can use a lid that has a float switch, which I've found to be way more effective;-

http://www.minispare...67.aspx|Back to

 

That is a front to rear split, not diagonal. Pipes are going into a compensator, rather than splitting to a t pieces on on either side.

[Spider]

 

That's a GMC167. They are available;-

https://www.somerfor...ic-unions-76-80

 

http://www.minispare...|Back to search

 

The switch in the body as best I am aware is NLA, however, you can use a lid that has a float switch, which I've found to be way more effective;-

http://www.minispare...67.aspx|Back to

 

That is a front to rear split, not diagonal. Pipes are going into a compensator, rather than splitting to a t pieces on on either side.

 

 

While the GMC167 was fitted in some markets for diagonal splits, in ours and several other markets, they were plumbed up with front / rear splits. We had them factory fitted to all Minis, from 1976 and Mini Vans and Mokes from 1978 on. They were all Front / Rear split to meet our local rules. Off hand, I can't recall the introductory date for the GMC227 (Yellow Tag), but they were never fitted here as they don't meet our local rules.

This is a description and diagram from our 1976 Factory Workshop Manual, 4th paragraph down n General Description, it refers to front and rear circuits;-

 

 

 

 

[[email protected]]

 

 

That's a GMC167. They are available;-

https://www.somerfor...ic-unions-76-80

 

http://www.minispare...|Back to search

 

The switch in the body as best I am aware is NLA, however, you can use a lid that has a float switch, which I've found to be way more effective;-

http://www.minispare...67.aspx|Back to

 

That is a front to rear split, not diagonal. Pipes are going into a compensator, rather than splitting to a t pieces on on either side.

 

 

While the GMC167 was fitted in some markets for diagonal splits, in ours and several other markets, they were plumbed up with front / rear splits. We had them factory fitted to all Minis, from 1976 and Mini Vans and Mokes from 1978 on. They were all Front / Rear split to meet our local rules. Off hand, I can't recall the introductory date for the GMC227 (Yellow Tag), but they were never fitted here as they don't meet our local rules.

This is a description and diagram from our 1976 Factory Workshop Manual, 4th paragraph down n General Description, it refers to front and rear circuits;-

 

 

 

 

Interesting. There were dual front to rear master cylinders under various numbers. GMC227 came in around 1984/5 to supercede the earlier front to rear masters.

 

From memory it went GMC173 front to rear imperial fittings (black failure switch)

 

GMC198 as above with metric fittings

 

GMC227, metric fittings, stepped bore with failure switch on the cap.

[Ethel]

You can see the FAM7821 in the bottom piccy.

 

I note Minispares states  theirs has metric unions, I thought they were originally UNF - something to verify before fitting.

 

A yellow band would also work, but you'd definitely need the conversion kit to plumb it to the regulator valve.

[mad4classics]

 

The switch in the body as best I am aware is NLA,

 

While we're on this subject can someone enlighten me as to the difference between the black AAU1752A the switch which is NLA and the white AAU2454 and AAU3821A switches fitted to many other classics including MGB.

 

Is it the metric vs UNF thread thing again?

 

There's an article here, but it doesn't explain the difference

 

https://www.moke.com...e-fail-switches

[Spider]

 

 

The switch in the body as best I am aware is NLA,

 

While we're on this subject can someone enlighten me as to the difference between the black AAU1752A the switch which is NLA and the white AAU2454 and AAU3821A switches fitted to many other classics including MGB.

 

Is it the metric vs UNF thread thing again?

 

There's an article here, but it doesn't explain the difference

 

https://www.moke.com...e-fail-switches

 

 

The two switches were used with different shuttles in the (in built) PDWA Valve.

The original type fitted to a Mini was a true (press) switch. The 'button' on them was held in by the PDWA Shuttle when in a healthy mode, but would release and lock the PDWA Valve on a pressure differential in the system.When repaired and bleed, the Switch needed to be removed, the pedal pressed hard to re-set the Valve Shuttle, though, more often than not, they needed help. I found them very unreliable.

The White 'Switch' was in fact, just a contact, it's not a switch at all. These worked with a different shaped Shuttle in the PDWA Valve. The Pins in them are on a common contact on the threaded end. When screwed in, it was in 'free space' but in a fail mode, the shuttle would move and touch the contact in the body of the 'Switch', making the circuit by Earthing it and bringing the Fail Lamp on. Best I can tell, this was a cost cutting exercise.

The way the Fail Lamps were wired up in our (Australian) Minis and Mokes, these two switch types can't readily be interchanged without wiring modifications.

[Ethel]

I can't quite recall the details, but the PDWA circuit could test the switch in master by pressing the rocker on the dash. The filler float switch circuit is simpler because it's possible to test it by just pressing the dibber in the middle of the cap.

[Verderad]

Replaced mine with a yellow tag and 2 new pipes.  
I have a 76 Clubman with PDWA. 
I tried refurbishing 2 blacktags that I had, could not get a satisfactory pedal. 

[Ethel]

A PDWA won't work with a stepped bore master, or rather it would every time you pressed the brakes.

 

Unless you meant the one built in to the master that will be removed with it.