ausmini :: View topic - Fitting dual circuit brakes to a mini.

Hi All,
OK so my engineer wants dual circuit brakes for the mini due to the supercharger addition. I know Morbo has had to do the same with his build too (same engineer) and I wanted to know what I have to do re plumbing. I know which M/C i need to buy with the brake fluid switch in the top and add a light on the dash. But what plumbing do I need?
Can I keep the bias valve in the rear there?
I read something about rear wheel cylinder sizes, It was converted to discs when i got the car but probably nothing has changed in the rear brake department apart from spaced drums.
I think I can get some lines made up at a brake shop like the very rough drawing shows. Would this work?
The car is a UK built mini 1000 if it makes a difference.

Thanks

Author:	hpal [ Tue Feb 25, 2020 4:44 am ]
Post subject:	Fitting dual circuit brakes to a mini.
Hi All, OK so my engineer wants dual circuit brakes for the mini due to the supercharger addition. I know Morbo has had to do the same with his build too (same engineer) and I wanted to know what I have to do re plumbing. I know which M/C i need to buy with the brake fluid switch in the top and add a light on the dash. But what plumbing do I need? Can I keep the bias valve in the rear there? I read something about rear wheel cylinder sizes, It was converted to discs when i got the car but probably nothing has changed in the rear brake department apart from spaced drums. I think I can get some lines made up at a brake shop like the very rough drawing shows. Would this work? The car is a UK built mini 1000 if it makes a difference. Thanks

Author:	Gambo [ Tue Feb 25, 2020 9:13 am ]
Post subject:	Re: Fitting dual circuit brakes to a mini.
hpal wrote: Hi All, OK so my engineer wants dual circuit brakes for the mini due to the supercharger addition. I know Morbo has had to do the same with his build too (same engineer) and I wanted to know what I have to do re plumbing. I know which M/C i need to buy with the brake fluid switch in the top and add a light on the dash. But what plumbing do I need? Can I keep the bias valve in the rear there? I read something about rear wheel cylinder sizes, It was converted to discs when i got the car but probably nothing has changed in the rear brake department apart from spaced drums. I think I can get some lines made up at a brake shop like the very rough drawing shows. Would this work? The car is a UK built mini 1000 if it makes a difference. Thanks I had to do the same for my engineer. From memory, this is what I had to do: Change master cylinder to later model metro, hooking up a warning light on the dash (same as you) - https://minispares.com/product/Classic/ ... MC227.aspx You will need to change the bias valve on the firewall to this one - https://minispares.com/product/Classic/ ... M7821.aspx Grab this as well - https://minispares.com/product/Classic/ ... 654MS.aspx , brake pipe set to go from the new master cylinder to the new bias valve (they have different size nuts depending on which pipe goes front/rear). Everything else i just re-used existing lines. The t-piece that is currently in the front gets relocated to replace the proportioning valve on the rear subframe as this one is no longer needed. You just need to make sure you hook up the lines from the new master cylinder to the new front valve properly (you should get instructions with the master cylinder). I didn't have any issues with the rear wheel cylinders, but yes you may need to change them if the rears bite/lock up before the front. Shout out if you need any more info!

Author:	hpal [ Tue Feb 25, 2020 8:37 pm ]
Post subject:	Re: Fitting dual circuit brakes to a mini.
Thanks for that, I though we weren't supposed to use copper brake lines here or something like that? Anyway, I was hoping to not use that new bulkhead valve but retain the rear valve, I'll do some more digging. Cheers for the info

Author:	Gambo [ Tue Feb 25, 2020 8:46 pm ]
Post subject:	Re: Fitting dual circuit brakes to a mini.
hpal wrote: Thanks for that, I though we weren't supposed to use copper brake lines here or something like that? Anyway, I was hoping to not use that new bulkhead valve but retain the rear valve, I'll do some more digging. Cheers for the info The copper line in the pic is for the oil pressure gauge. You will need to use the different bulkhead valve, it’s part of what makes it a dual circuit system. It splits/separates the lines going to the front and rear. Just using the master cylinder won’t do it, even though it has 2 outlets. If you retain the rear proportioning valve it messes things up, so you just replace it with the t-piece from the front.

Author:	hpal [ Tue Mar 03, 2020 9:25 pm ]
Post subject:	Re: Fitting dual circuit brakes to a mini.
Thanks, theres an interesting thread here http://www.theminiforum.co.uk/forums/topic/336812-dual-circuit-brakes-please-explain-something/page-2?hl=%20dual%20%20circuit%20%20brakes which says I can also use a shutoff valve 13H7757 as a simpler solution to the PDWA valve. With either route removing the rear bias valve seems the go as if you have a front failure and stomp on the pedal then your back brakes wont work because of the bias valve (i think). Is the reservour in the dual circuit M/C split so the fluid stays in it's rear or front circuit? what does the pdwa valve do (apart from pressure limiting the rear circuit)? Surely the two circuits are separate as they have separate outlets and separate fluid compartments, sort of. Just trying to get my head around it all, sorry for all the questions.

ausmini https://www.ausmini.com/forums/

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Author:	Gambo [ Tue Mar 03, 2020 10:16 pm ]
Post subject:	Re: Fitting dual circuit brakes to a mini.
From memory the master cylinder is a stepped bore-bottom piston does rear brakes - upper piston does front brakes. The reservoir itself is not split from what I can tell. If you take a look at this, it has some fitting instructions, which is how I have mine set up -https://www.minimania.com/part/GMC227/Classic-Mini-Dual-Brake-Master-Cylinder-Pre-92-Non-Servo-Stepped-Bore May do a better job of explaining the setup instead of me guessing! I'm not sure about that other valve you mentioned - it may work, but it's not something I looked into. I set mine up as per the article above and the engineer was happy with that,using the valve I fitted ensures that if either the front or the rear fails, the other should work....or so I'm told! And ask all the questions you need to, happy to help.

Author:	hpal [ Thu Mar 05, 2020 12:24 am ]
Post subject:	Re: Fitting dual circuit brakes to a mini.
OK, so I can use this setup I think, either with the hard lines or the copper/nickel bendable ones (if they're acceptable in Australia) fron the bottom of the PDWA valve to the front brake banjo I can use the HMV013 pipe or have one made in steel to suit. But, how can I get the imperial union of the rear brake pipe into the metric thread of the pdwa valve?

Author:	Gambo [ Thu Mar 05, 2020 7:21 am ]
Post subject:	Re: Fitting dual circuit brakes to a mini.
You need to use this https://minispares.com/product/Classic/ ... 654MS.aspx It has the metric on the master cylinder end and the imperial on the other.

Author:	hpal [ Fri Mar 06, 2020 3:37 am ]
Post subject:	Re: Fitting dual circuit brakes to a mini.
Just wanting to know how to connect the imperial threaded rear brake pipe into the metric thread of the rear brake port on the valve

Author:	Gambo [ Fri Mar 06, 2020 8:12 am ]
Post subject:	Re: Fitting dual circuit brakes to a mini.
Ah ok - my bad. You should be able to use your existing imperial connection pipes from the valve to the front/rear. The valve outlets should be imperial. The front on mine needed some tweaking/bending as I have the booster fitted, but the rear pretty much fit right up. The metric fitting is on the master cylinder end of the brake pipes from the valve to the m/c - the conversion kit pipes have metric on the m/c end and imperial on the valve end.

Author:	slacko [ Fri Mar 06, 2020 2:02 pm ]
Post subject:	Re: Fitting dual circuit brakes to a mini.
The PDWA is all metric

Author:	Gambo [ Fri Mar 06, 2020 3:15 pm ]
Post subject:	Re: Fitting dual circuit brakes to a mini.
Pretty sure the valve is imperial - my existing lines (that go to the front and rear) fitted straight up to it. Only ones I needed to buy where the ones from the cylinder to to the valve/booster.

Author:	slacko [ Fri Mar 06, 2020 10:31 pm ]
Post subject:	Re: Fitting dual circuit brakes to a mini.
yes Gambo imperial 3/8 24 tpi will go into 10mm m1 metric , very loosely imperial and metric flares are different if you have screwed your single system front to back pipe into the front mounted pdwa valve you are running a risk pm me if you wish Mark

Author:	slacko [ Fri Mar 06, 2020 10:37 pm ]
Post subject:	Re: Fitting dual circuit brakes to a mini.
hpal pm me with a phone number

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Author:	Gambo [ Sat Mar 07, 2020 10:13 am ]
Post subject:	Re: Fitting dual circuit brakes to a mini.
slacko wrote: yes Gambo imperial 3/8 24 tpi will go into 10mm m1 metric , very loosely imperial and metric flares are different if you have screwed your single system front to back pipe into the front mounted pdwa valve you are running a risk pm me if you wish Mark Strange. Mine fitted up perfectly. No leaks etc.