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Brake Bias valve which one?
https://www.ausmini.com/forums/viewtopic.php?f=2&t=94436		 Page 1 of 2
Author:  Jenk [ Sat Dec 17, 2016 7:15 pm ]
Post subject:  Brake Bias valve which one?
I need to replace the brake bias valve mounted in the rear sub frame and it was suggested that I should fit an adjustable one but they're not cheap nor easy to find $195 from minisport . They're cheaper in the UK but they're out of stock and have been for a while now, then I came across this:

http://www.ebay.com.au/itm/like/Wilwood ... RTM2010730

its $85 delivered and the quality of the Wilwood one would be better wouldn't it, would have to re route the lines and the thread is NPT but no biggy right? what you think?
Author:  drmini in aust [ Sat Dec 17, 2016 7:35 pm ]
Post subject:  Re: Brake Bias valve which one?
Some people in USA have used the Wilwood, it's a proportional valve not a limiting one. But works in a Mini when adjusted correctly.
Can't be adjustable inside car for road use.
Author:  Stev0 [ Sun Dec 18, 2016 10:34 am ]
Post subject:  Re: Brake Bias valve which one?
If your brakes are standard you shouldn't need an adjustable one (one would hope they got it right at the factory).

But you can make the standard one adjustable according to david vizard. The mini spares one seems to use a screw pushing a plunger..but I've not pulled it apart to find out what they've done.
Author:  drmini in aust [ Sun Dec 18, 2016 10:54 am ]
Post subject:  Re: Brake Bias valve which one?
Problem with the standard one now is repair kits are NLA. They were made by Lockheed.
Edit, typo
Author:  simon k [ Sun Dec 18, 2016 1:43 pm ]
Post subject:  Re: Brake Bias valve which one?
Jenk wrote:
its $85 delivered and the quality of the Wilwood one would be better wouldn't it, would have to re route the lines and the thread is NPT but no biggy right? what you think?


looks like they give you a pair of 3/8 24 adapters anyway...

you'll just need to replace the existing valve with a T piece, one the same as on the firewall if you have a spare
Author:  mickmini [ Sun Dec 18, 2016 3:53 pm ]
Post subject:  Re: Brake Bias valve which one?
Jenk wrote:
I need to replace the brake bias valve mounted in the rear sub frame and it was suggested that I should fit an adjustable one but they're not cheap nor easy to find $195 from minisport . They're cheaper in the UK but they're out of stock and have been for a while now, then I came across this:

http://www.ebay.com.au/itm/like/Wilwood ... RTM2010730

its $85 delivered and the quality of the Wilwood one would be better wouldn't it, would have to re route the lines and the thread is NPT but no biggy right? what you think?


I and others including Miniminded in the Netherlands have found that one does not have enough adjustment and/or the spring is too stiff so it does not limit the rear presssure enough. Changing mine back to a standard Mini limiting valve until i have time to make a Vizard style one.

Both the Vizard and Wilwood ones work on the same principal for adjustment - spring rate and length. The stiffer the spring, the higher the pressure in the line needs to be to close the limiting valve and the adjustment of the length of the spring is by winding the screw in and out. But as Doc says, the Wilwood one only gives a proportion of the of the output of the master cylinder pressure based on the adjustment. So if you press the brake really hard, the rears will always get x% of the pressure, as you go harder, they get Y% and so on, which means that you need to have the abosolute minimum proportion with the delivered spring and it still locks up.

The standard Mini ones will increase the rear pressure to a hard limit based on the spring rate and the length. After it reaches that limit, no matter how much harder you press on the brake, the rears get no more pressure, and if you have your sums right, then they won't lock.

Remember that the main reason you have rear brakes in a Mini is to keep the rear of the car from trying to overtake the front. So you only need just enough retardation and not to lock them up.

cheers
michael
Author:  Bill B [ Sun Dec 18, 2016 9:50 pm ]
Post subject:  Re: Brake Bias valve which one?
Karcraft list a new non-adjustable unit (fitting on rear subframe) but at $235.
What is wrong with your old one? They can be cleaned if that is all that is wrong.
I've seen some that are ok after a very long life down under there.
Author:  Jenk [ Mon Dec 19, 2016 4:11 pm ]
Post subject:  Re: Brake Bias valve which one?
thanks to all for your input

Bill B the valve sat around for a year after I stripped the car down for resto... thought I would put a seal kit through it before re installing but no seals are available unfortunately.
Author:  Bill B [ Mon Dec 19, 2016 7:41 pm ]
Post subject:  Re: Brake Bias valve which one?
The main seal is swaged onto the piston so a kit must include the piston. It isn't a slip-on type seal like everywhere else in a mini. I have removed a piston assembly from a cylinder which from memory appears to be in reusable condition. The body was slightly pitted, making it unserviceable. You are welcome to use it to get you out of trouble.
The original repair kit was p/n GRK6002. Might be available from eBay NOS listings.
Author:  winabbey [ Mon Dec 19, 2016 8:42 pm ]
Post subject:  Re: Brake Bias valve which one?
If all else fails in getting a repair kit the limit valve is available new. Cooper S is different to standard Mini.

http://minikingdomonline.com.au/product ... -cooper-s/

http://minikingdomonline.com.au/product ... -cooper-s/
Author:  mickmini [ Mon Dec 19, 2016 9:34 pm ]
Post subject:  Re: Brake Bias valve which one?
winabbey wrote:
If all else fails in getting a repair kit the limit valve is available new. Cooper S is different to standard Mini.

http://minikingdomonline.com.au/product ... -cooper-s/

http://minikingdomonline.com.au/product ... -cooper-s/

and the difference is the spring stiffness AFAIK.
Author:  drmini in aust [ Tue Dec 20, 2016 6:02 am ]
Post subject:  Re: Brake Bias valve which one?
Cooper S tax on the spring. It must be made of unobtainium... :)
Author:  Bill B [ Tue Dec 20, 2016 8:14 pm ]
Post subject:  Re: Brake Bias valve which one?
drmini in aust wrote:
Cooper S tax on the spring. It must be made of unobtainium... :)


There is a big difference in the price of the complete limiting valve assembly for Cooper S vs normal mini.
But Mini Spares lists the original spring on its own (27H6620) for 75 pence ("last the AP stock").
Buy the standard valve and the S spring. Easy swap.
Author:  John Smidt [ Wed Dec 21, 2016 8:26 am ]
Post subject:  Re: Brake Bias valve which one?
drmini in aust wrote:
Cooper S tax on the spring. It must be made of unobtainium... :)


"Cooper S TAX" I always find this a little amusing.
I am not 100 % sure what the other Mini parts dealers do, but as far as I know they operate the same way as we do, that is cost plus a minimum mark up,
which does not change because it is a Cooper S part.

However what does not seem to be understood is that we the suppliers pay more for Cooper S parts, and this is often because the Market for " Cooper S specific parts " is less than the general Mini Parts so the production run is smaller so the cost is higher.
Author:  Irish Yobbo [ Thu Dec 22, 2016 8:57 am ]
Post subject:  Re: Brake Bias valve which one?
John Smidt wrote:
drmini in aust wrote:
Cooper S tax on the spring. It must be made of unobtainium... :)


"Cooper S TAX" I always find this a little amusing.
I am not 100 % sure what the other Mini parts dealers do, but as far as I know they operate the same way as we do, that is cost plus a minimum mark up,
which does not change because it is a Cooper S part.

However what does not seem to be understood is that we the suppliers pay more for Cooper S parts, and this is often because the Market for " Cooper S specific parts " is less than the general Mini Parts so the production run is smaller so the cost is higher.


I don't think anyone is accusing suppliers of inflating the prices of Cooper S parts. It's as you say, and simple supply and demand.

On top of that, a great number on mini drivers will buy to just make things work - very few leyland 998 drivers are going to spend big on OEM or heritage parts when there are other parts around that will work just as well. But if you have a Cooper S, most will do whatever they can to keep it original, which means spending the extra on the original parts instead of generic parts that work.
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