Brake Bias Valve

[Guest Alan_builder]

Iain

 

Lol

 

 

The rear brakes need increasing by 30%!

 

I my

[Guest chris brown]

Now this has got stupid. The question was do I need to fit a bias valve. The answer is yes but only if the rear brakes lock up before the fronts and then it needs to be set so as not to make the rears virtually inoperative. I built my 2B with the Sierra one but set at a slightly steeper angle so as it worked later. In this position it passed SVA but I felt the rears could do with a little more power so I removed the valve and found it better with the fronts still locking up well before the rears. Later I changed the rears to discs and still find the fronts lock up first. So in my case the valve is defiantly not required. But you may find your car acts differently especially if you have gone for second market brakes

[Guest mower man]

Let's end this topic as chris says it's getting silly [that is the nice word ] if you feel you need a load sensing valve fit one !if the braking system works and satisfies the IVA or MOT testers OK ,if you like and are happy with it do it likewise if you don't want one and the above points are met dont bother .Istill stand by my orig statement for MY car and SYSTEM for ME bye for now mower man

[speedtripledan]

Dan, mine goes in the rollers.

But that has little to do thin Keith's question.

 

I my

"Calm down dear its just an internet forum"

[Guest jetskijase]

Confused.com!

 

Wheres Andi and his polls!

 

 

I never fitted it and never had a problem at sva and mot tests. And i've never locked up my front brakes! maybe i brake too early!

 

To be honest i never put too much though into it when i had it in my hand!!!, i just thought, nope, this isnt a heavy sierra estate , and the brake test is static so shouldnt be a problem so chucked it away!.

 

Cheers

Jase

[Mitch]

and i bet Keith starts all this again at thursdays meeting !!!!

 

 

Mitch

[Guest carl leonard]

and i bet Keith starts all this again at thursdays meeting !!!!

 

 

Mitch

 

 

50 /50 Choice - Either fit / not fit the bloody thing and then if it fails, just remove, pay the retest fee and look happy!

 

Job done.

 

carl.

[Guest kleighton]

Wow.....thanks for all your replies guys. I've not logged in for a few days, and I've come back to this now......I've not read any replies yet, but I'll go through it today when I can get time.

 

Again. thanks for all of your replies,

 

Keith

[Knock-on]

Hi Keith

 

Perhaps to save your sanity it might be easier to summarise this thread.

 

Take a spin down the road and test the brakes by jumping on the pedal. If you're not using Toyota ones, you should stop.

 

1 - If the rears lock before the fronts, you should look at why the fronts aren't working better.

 

2 - If the fronts lock shortly before the rears you're looking good.

 

3 - If the fronts lock miles before the rears, you might like to think about why the rears aren't working more effectively.

 

My experience is that put a fat b**tard and a tank of fuel in it with the brakes working properly and bedded in, then you will probably find #2 will happen which used to make Mr SVA happy and I'm sure his cousin, Mr IVA, will be content as well (unless the world has turned upside down in the last 12 months).

 

However, if the laws of physics are having an off day and you cant achieve #2, then you will have to consider a mechanism for adjusting the bias to correct it. My guess is you probably wont need to and should avoid it if at all possible.

 

As Alan says, K.I.S.S.

[Guest kleighton]

Thanks knock-on, saved me an hour there. I'll get out on the road and see what happens.

[Knock-on]

Do it quick before someone replies that I've got it all wrong

[megadodo]

Just off to the garage to remove my valve and re-plumb the rear pipe, again! Good thread folks!

[Peter Bell]

As there is a lot of discussion about this thing, here is something I wrote for the Boyz mag many years ago, it may help or otherwise

 

Brake Pressure Regulator.

This is often spoken about, sworn about and sometimes misunderstood. Here is a cross-section of it or a similar one and an attempt to describe how it works. It is fitted in the rear brake line and at low braking rates/speed, brake fluid is pumped through the inlet, past the ball, through the hole in the piston and on to the rear brake cylinders with no pressure limiting effect at all. When the braking retardation is high the ball rolls up the slope and blocks off the hole in the piston. Then the stepped piston comes into effect, and as the fluid flows into the valve it moves the piston acting on its smaller diameter end, the other end being larger exerts a lesser force on the fluid in the line to the rear brakes. The difference in pressure is proportional to the difference in the areas of the two ends of the piston. In a Sierra of course under heavy braking the front of the car will also dive considerably, changing the angle of the valve allowing the ball to move easier. In a Hood this attitude change is minimal so the movement of the ball will be due only to inertia, unless of course you are going down a steep hill! This shows I hope, that for the unit to work it has to be installed correctly, and even if it is installed at exactly the same angle as the donor it will not work quite the same. My car has the 1300/1600 brakes, standard linings and pads and I have had no problems with the rears locking. I have wondered as the front brakes are so well cooled on a hood and do far less work to do than a Sierra with 5 people and luggage, if hard pads are fitted they would rarely get hot enough to work properly, which may explain why the rears could lock up first.