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

Brake pressure limiting valve
https://www.ausmini.com/forums/viewtopic.php?f=2&t=96877		 Page 1 of 1
Author:  deluxe67 [ Fri Feb 23, 2018 8:22 pm ]
Post subject:  Brake pressure limiting valve
that's supposed to be mounted on the front of the rear subframe. Simply put, my '67 Deluxe only has a brass T piece (looks 50 years old and original)...
Is this just wrong, has a previous owner put in a T piece for whatever reason or could it be like that from new??
I have Cooper S discs up front and Cooper S drums and brake cylinders at the rear. The rear wheels have never locked up (did some high speed emergency braking to test, years ago) and I think the brakes work well. I'm confused as apparently all Mk 1's had the limiting valve fitted as standard according to a discussion on another Mini website (UK)...
Appreciate your thoughts,

Cheers

Michael
Author:  mickmini [ Fri Feb 23, 2018 8:29 pm ]
Post subject:  Re: Brake pressure limiting valve
Yes should have the limiting valve, even with Cooper S set up. I think i remember that the spring is different in the Cooper S vs drum brakes.

But if a later model twin circuit master cylinder is fitted, the rear mounted limiting valve is not used. Depending on which twin master set up there is a distribution block mounted to the bulkhead (per Clubman) or not (Later Rover etc). [all from memory and i have just finished off a growler of fancy Derbyshire beer :-)]
Author:  deluxe67 [ Fri Feb 23, 2018 8:43 pm ]
Post subject:  Re: Brake pressure limiting valve
Ye gods! More confusing..

All the brake system/ lines/ master cylinder is definitely original 1967 stuff (actually, thinking about it, maybe Mini K master cylinder?) except for the Cooper S stuff. Since the brakes are good as they are, with a simple T piece, should I source a pressure limiting valve? What would I have to gain and how would I set it up? And why do I only have a 50 year old lookingT piece? :shock: :?
Author:  Scoop [ Fri Feb 23, 2018 9:40 pm ]
Post subject:  Re: Brake pressure limiting valve
The tee piece is likely to be from a late model leyland mini. Even a complete subframe may have been used in another life of your car, as its rubber cone. Just a thought
Author:  2lateagain [ Sat Feb 24, 2018 6:57 am ]
Post subject:  Re: Brake pressure limiting valve
I purchased a Cooper new in 1963, at the time I was employed as a brake mechanic. The car was hard to stop under any conditions so a brake booster was fitted under the front mudguard. I was then able to stop the car easier, but the rear wheels would lock up very quickly so trial and error was applied with different pads and shoes and as a last resort the inside of the limiting valve was removed, this was done after consultation with the top guru's within the business. It overcame the initial rear wheel lockup, but they still locked, but at a later stage in the braking and normally only under hard braking, usually the left rear would lock first so you had to be ready to compensate, was not real good in wet weather, but at least the car stopped much better than when it was new. This was with Better brakes, so maybe it was spoken about within the company and applied as a fix if there were problems, I have no idea if that would be the case.

Graham
Author:  Bill B [ Sat Feb 24, 2018 4:02 pm ]
Post subject:  Re: Brake pressure limiting valve
2lateagain wrote:
I purchased a Cooper new in 1963, at the time I was employed as a brake mechanic. The car was hard to stop under any conditions so a brake booster was fitted under the front mudguard. I was then able to stop the car easier, but the rear wheels would lock up very quickly so trial and error was applied with different pads and shoes and as a last resort the inside of the limiting valve was removed, this was done after consultation with the top guru's within the business. It overcame the initial rear wheel lockup, but they still locked, but at a later stage in the braking and normally only under hard braking, usually the left rear would lock first so you had to be ready to compensate, was not real good in wet weather, but at least the car stopped much better than when it was new. This was with Better brakes, so maybe it was spoken about within the company and applied as a fix if there were problems, I have no idea if that would be the case.

Graham


There is a technical bulletin on here that details some of the history/problems with Cooper brake evolution.
Author:  winabbey [ Sat Feb 24, 2018 5:24 pm ]
Post subject:  Re: Brake pressure limiting valve
Bill B wrote:
There is a technical bulletin on here that details some of the history/problems with Cooper brake evolution.

http://www.ausmini.com/forums/viewtopic ... 49&t=92146
Author:  Bill B [ Mon Feb 26, 2018 2:08 pm ]
Post subject:  Re: Brake pressure limiting valve
winabbey wrote:
Bill B wrote:
There is a technical bulletin on here that details some of the history/problems with Cooper brake evolution.

http://www.ausmini.com/forums/viewtopic ... 49&t=92146

Thanks winabbey.
As for the original question, as others say, there should be a pressure limiting valve on the rear subframe, but if it works without one, who knows. Every mini is an individual! Wheel/tyre can influence lock-up greatly.

The limiting valves were in short supply recently but seem to be coming back. If you check on the Mini Spares UK website, there is an explanation of which valve fitted which cars in the UK at least.

21A1774 was the valve for UK mk 1 & 2 minis and Cooper S (5/8 inch cylinders)
21A2031 was for most minis with 3/4 inch wheel cylinders.
They are around $200 mark, but generally lasted well.
The only difference was the internal spring and both springs seem to be available too.
Page 1 of 1 All times are UTC + 10 hours
Powered by phpBB® Forum Software © phpBB Group
http://www.phpbb.com/