16 replies to this topic

[minimk1]

I have a plastic type master cylinder with the twin exit. However when I said this to minispares they said I needed some sort of valve on the bulkhead. When I looked back at a picture I had no such valve and so he said that it would not work and so I couldn't get all of my brake lines p. this is the best picture I have and clearly the brakes did work as we drove it home with mot any help would be great as to what system I have or what I could do many thanks harry

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[minimk1]

If you click the picture it will be bigger, sorry

[minimk1]

They think I should have something like this. http://www.minispare...|Back to search

Edited by minimk1, 02 February 2014 - 10:38 PM.

[cookie4343]

Not sure if yours was fitted with one out the factory but I have a 1979 Austin Morris mini with a brake valve limiter compensater fitted exactly where your t piece brake fitting is, not sure if yours had one out the factory so I'm not much help but I have a pic below of the compensater fitted to mine.

[tiger99]

No, that is a rear subframe mounted valve, and is unsuitable for your system. You need the PRV, item 29 in the link below, and the matching pipes.

 

The car is unsafe and illegal without that valve, as the rear wheels will be grossly overbraked. If you use the other type of valve, again it will be unsafe and illegal, because the rear brake effors will be limited always, even if the front brakes fail. The correct valve limuts rear pressure to prevent wheel locking if the fronts are working, but lets full pressure through to give you the best chance of stopping, if the fronts fail.

 

http://www.somerford...page=page&id=65

 

Edit: same as Cookie4343's picture.

Edited by tiger99, 02 February 2014 - 10:46 PM.

[cookie4343]

Also states on somerford mini website below

This system is applicable to right hand drive 1978 on Models and left hand drive 1980 on models

Think mini mk1 mini is a 1977

[tiger99]

Well, if your master cylinder is dual circuit, you need the appropriate PRV, regardless of actual year of manufacture. Some previous owner may have upgraded it. Few Minis are in original condition nowadays. It is a good thing to upgrade anyway.

 

If there is doubt, you also need to check the rear wheel cylinder diameter, and that there is not a rear pressure limiting valve fitted, just a plain T piece on the subframe. Mixing bits of differently configured brake systems is a very bad idea.

[minimk1]

Yeah cookie's picture is the valve I was trying to show. So thoughts are I should put the valve in place and rum my lines from there

[minimk1]

Thank you everyone I should be okay now, when I go to minispares I can now get all my brake lines and carry on with the car

[cookie4343]

Have you got one of those valves I pictured, just asking as I have a few lyeing around.

[minimk1]

No I don't could you send me a pm ? Many thanks hardy

[dklawson]

I assumed from your login name that the car was going to be a Mk1.  The wiring, master cylinder, fuse box, and air filter assembly indicate that this is not a Mk1.  Having recently been working on a similar looking car... I am going to guess this car is vintage 1977-1978. 

 

Trace the brake lines (CAREFULLY) leaving the master cylinder ports.  I suspect you will find each line has a "T" fitting, one on the left side of the car, one on the right.  Behind the manifolds there will probably be brake lines traversing left to right from the "T" fittings.  If that is what you find, this would be the brake setup I have recently been working on.  It is stock for the 1977-78 model years, has no proportioning/limiting valve, and is a dual-diagonal setup, with the master cylinder being GMC167.  GMC167 is not in production but I think Somerford had them in stock when I looked.  There are also rebuild kits available for it.

 

I will not weigh in on the discussion of the limiting/proportioning valve.  I am sure it will be a good thing to add but doing so will require sourcing the valve and replacing several hard pipes to accomodate it.  I have no experience making that change.

[minimender]

Could stick one of these in at the back

 

http://www.ebay.co.u...=item19e83aea49

 

Or second hand adjustable ones are pretty cheap :)

 

.

[dklawson]

The link above is for the single line brake system used on early cars and may not be appropriate for this particular car without additional changes. 

[tiger99]

Doug, that is a good point about the diagonally split system, which mercifully is quite rare, as it was not a great success and was used for only a very short time. If I had one of these, I would convert it to the later dual line system, because the safety of the diagonally split system is highly questionable. As the Mini does not have zero scrub radius at the front, I suspect that it may be seriously uncontrollable in the event of a failure of half the diagonally split system. Also, the rear braking must be excessive, because although the very smallest bore of rear cylinders were eventuall fitted, 0.5", without any pressure limiting there seems to still be an excess. But the first diagonally split systems used 11/16" rear cylinders, which seems positively lethal. You can tell that Issigonis had moved on and was not involved in Mini mods at that stage, as a general lack of competence had crept in.

 

The GMC160 master cylinder for the diagonally split system is unique and no longer available, which will eventually force everyone to upgrade anyway. The GMC159, even if still available, must not be used because it has a different sub-division of stroke length between front and rear circuits, and would have insufficient volume displacement if a failure happened in the part of the system with the longer piston travel.