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Brake Pressure Differential Warning Activator (PDWA)
https://ausmini.com/forums/viewtopic.php?f=2&t=100849		 Page 1 of 1
Author:  michaelb [ Mon Mar 22, 2021 1:43 pm ]
Post subject:  Brake Pressure Differential Warning Activator (PDWA)
So! I need to get my brake modifications engineered in NSW. :(
My Mini was a late model 1275LS and is now very modified including the brakes.
I have a set of Minisport 4 pot calipers with ventilated discs for the front and drum brakes on the rear.

From what I can find, is that no one has an ADR31 compliant brake system in a mini.
The 1978 Master cylinders are no longer available as are the proportioning valve so I have a modified setup with the GMC227 Yellow tag master cylinder, which is a split system, but I don't have the 5 way valve as it was non serviceable and no longer available. I am using the old style rear subframe proportioning valve which is working fine.
To comply with the ADR rules the testing will involve disconnecting the rear brakes and ensuring the front still work and visa versa. From what I can see, the GMC227 does not provide that isolation between front and rear? Or is my Master cylinder faulty?
And I haven't been able to find a working 5 way valve. But not sure if this is what provided the PDWA functionality or it was the old master cylinder, which did have a switch on it, also no longer available?
I think I need to add a PDWA in between the master cylinder and the wheels?

So far I am not having much luck with finding what I need from any of the mini parts suppliers?

Any assistance greatly appreciated.
Author:  Gambo [ Mon Mar 22, 2021 1:48 pm ]
Post subject:  Re: Brake Pressure Differential Warning Activator (PDWA)
michaelb wrote:
So! I need to get my brake modifications engineered in NSW. :(
My Mini was a late model 1275LS and is now very modified including the brakes.
I have a set of Minisport 4 pot calipers with ventilated discs for the front and drum brakes on the rear.

From what I can find, is that no one has an ADR31 compliant brake system in a mini.
The 1978 Master cylinders are no longer available as are the proportioning valve so I have a modified setup with the GMC227 Yellow tag master cylinder, which is a split system, but I don't have the 5 way valve as it was non serviceable and no longer available. I am using the old style rear subframe proportioning valve which is working fine.
To comply with the ADR rules the testing will involve disconnecting the rear brakes and ensuring the front still work and visa versa. From what I can see, the GMC227 does not provide that isolation between front and rear? Or is my Master cylinder faulty?
And I haven't been able to find a working 5 way valve. But not sure if this is what provided the PDWA functionality or it was the old master cylinder, which did have a switch on it, also no longer available?
I think I need to add a PDWA in between the master cylinder and the wheels?

So far I am not having much luck with finding what I need from any of the mini parts suppliers?

Any assistance greatly appreciated.





Is this the valve you are referring to?

https://minispares.com/product/Classic/ ... M7821.aspx

I had to go to dual circuit master cylinder as well for my engineer .I had to fit one to mine - but had to remove the proportioning valve from the rear subframe and replaced it with the t-piece that was on the front. I'm running the same GMC227 Yellow tag master cylinder as you.

Attachment:
IMG_8194.JPG
Author:  michaelb [ Mon Mar 22, 2021 2:03 pm ]
Post subject:  Re: Brake Pressure Differential Warning Activator (PDWA)
Hi Gambo, Do you know if the front or rear brakes were disconnected to conduct the testing? Or did he just pass it with out any testing?
Author:  Gambo [ Mon Mar 22, 2021 2:11 pm ]
Post subject:  Re: Brake Pressure Differential Warning Activator (PDWA)
michaelb wrote:
Hi Gambo, Do you know if the front or rear brakes were disconnected to conduct the testing? Or did he just pass it with out any testing?


Hi Michael

The engineer I used (Troy Brody - Fink Engineering) didn't disconnect anything - he basically took it for a drive at certain speeds, and repeatedly jumped on the brakes to make sure that the rears didn't lock up before the front, and he was happy with that. He did use one of those brake force meter things they use for rego checks.

I had to get it engineered for a few things, front disc conversion being one of them.

He did specify I had to have the dual circuit master cylinder and different proportioning valve so that in the event of a circuit failure at least one end of the car had braking capability. With the yellow tag master cylinder, you do need to make sure you have them hooked up correctly (Top connection for front, bottom for rear), as well as removing the proportioning valve from the rear.
Author:  michaelb [ Mon Mar 22, 2021 2:27 pm ]
Post subject:  Re: Brake Pressure Differential Warning Activator (PDWA)
Sounds like what I am going through. Maybe I need to give Troy a call? My engineer is talking about my car needing to follow the whole ADR31 approval process which includes continual stops from 100kmh until the brakes fade..
Author:  Gambo [ Mon Mar 22, 2021 2:38 pm ]
Post subject:  Re: Brake Pressure Differential Warning Activator (PDWA)
michaelb wrote:
Sounds like what I am going through. Maybe I need to give Troy a call? My engineer is talking about my car needing to follow the whole ADR31 approval process which includes continual stops from 100kmh until the brakes fade..



I can highly recommend Troy - very helpful. My mods were engine swap, brake conversion and different seats. He told me exactly what I needed to do for the brake conversion to make it safe/legal.

This is the brake section from my engineering/compliance report which may be helpful.

Attachment:
Brakes.JPG
Author:  michaelb [ Mon Mar 22, 2021 2:45 pm ]
Post subject:  Re: Brake Pressure Differential Warning Activator (PDWA)
Thanks Gambo.
My brakes a Minisport 4 pot alloy calipers and I don’t have a booster but brakes work fine. Harder pedal pressure than my Cooper S but to be expected with no booster.
Author:  Gambo [ Mon Mar 22, 2021 2:48 pm ]
Post subject:  Re: Brake Pressure Differential Warning Activator (PDWA)
I don't think the booster was a "must have", but the dual circuit set up was.

Give Troy a call - he will let you know what's needed.
Author:  Harley [ Mon Mar 22, 2021 9:36 pm ]
Post subject:  Re: Brake Pressure Differential Warning Activator (PDWA)
It's funny how the engineers work. I had to do the test where you simulate a leak in the front to see if there's pressure available to the back, and all the engineer did was stick his foot on the pedal after opening a front bleed screw and feeling how much weight was in the brakes. No resistance would have been a fail, but there was still enough of an amount there to satisfy him - That said - My car runs all factory spec components (late model master cylinder on booster, proportioning valve on firewall, standard drums at back and 4 pots up front).
Author:  Gambo [ Tue Mar 23, 2021 7:49 am ]
Post subject:  Re: Brake Pressure Differential Warning Activator (PDWA)
You would think they all had a standard they need to adhere to.... oh wait....
Author:  michaelb [ Sat Apr 17, 2021 6:26 pm ]
Post subject:  Re: Brake Pressure Differential Warning Activator (PDWA)
Hi Gambo, FYI the new yellow tag dual master cylinder will provide braking to the other axle when either front or rear brakes fail. This is not done by the proportioning valve mounted on the rear of the firewall. At the moment I have the latest Split master cylinder and the early style proportioning valve on the rear subframe. Basic brake testing has been done on a workshop brake testing machine. So far passed all low speed testing. Next is high speed brake testing at a yet to be decided location.
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