Brake bias knob - wrong type ?

[GJUK]

Yeah I agree. But if you have time you can twizzel the nob

Yeah...if you run that slow....

They're only 1 turn or so, fully open to close.

Line lock would be better for jamming on the brakes.

But then this guy wants something to sort out his locking rear brakes, if you used a line lock for that you would end up in a Bananarama! hedge.

[Pete]

That's better than the usual American proportioning valves - like Morgan probably needs - mine took many turns to make a difference...

[Pete]

Morgan, take a look at the attached, including the technical material that you can access:

http://www.wilwood.com/MasterCylinders/ ... alves.aspx

Cheers

Pete

[GJUK]

for burn outs you need one of these.

[autofetish]

I get it


Up to 180psi you set your brakes bias up as you want

The difference between inlet and out pressure is linear 1:1

Flow is restricted as you adjust but the pressure stays the same

More you twist less rear brakes

Which is what you expected.


When you go pass the 180psi mark

Eg Standing on the brakes !

The inlet to out let pressed curve changes to 3:1

Meaning that 180psi pressure is to much for the rear brakes

Due to the high forces with the axle loaded up you don't need 180psi to the rear brakes as they might lockup

So the valve reduces this pressure ( giving you more front brakes )

Flow is still set at what you set it at only the pressure changes

Eg: a good hard brake while out for a hack or Bananarama! your self and standing on the brakes


I think this type is a much better idea and makes sence

I will buy it off ya

[Dave999]

Yes


Dave

[morgan]

OK valve fans - the update you have been waiting for.
Reading Wils theory, I like that - and it makes sense. But I couldnet get to that conclusion from the instructions alone.

I contacted the vendor trying to explain my question - which was really difficult - given that the brain-trust on this forum couldnt be 100% sure me on my own had no chance Anyway, they have now amended the description and offered me a full refund immediately.

I do get the feeling this might just be the path of least resistance (i.e. make me stop asking questions and go away) but thats OK. I can understand that ! So, Valve can be returned, Petes Wilwood link can be followed, and I still have no idea if this item is actually fine for my purposes. I have the nagging feeling that Wil is correct and it may actually be even better than what I set out to do...

Wil - If you do want it, let me know. May as well post to you as post to them. No worries though, can easily return. Unless the devil gets the better of me and I keep it and fit out of curiosity - its only a pipe and a brake bleed to try it...

Thanks all -

(transcript below)

Hi Morgan,

thank you for your detailed e-mail. I am very sorry to report that the instructions are correct and the description is actually not very clear. We do not intend to mislead any customer, this has surprisingly never been picked up. I would like to offer you a full refund and my most sincere apologies. We offer brake bias adjusters but these can only be used with vehicles with double cylinders, one for rear, one for front.

Thank you for pointing out this discrepancy in the description, this will be changed immediately.

Best Regards

---------------
Hi. Will do, although the picture of the item is exactly right (the picture in the description).
The bit which is causing my concern is the instructions supplied which describe a sudden 3:1 pressure reduction rather than a variable brake balance control - which is not mentioned in the ebay description.

I was expecting functionality to be 'variable restriction of rear brakes' to allow me to cure the rear lockup. In short an functional equivalent of this (link) http://www.wilwood.com/MasterCylinders/ ... alves.aspx

My requirements are simple, and it may be that I am simply reading too much into your instructions. I just need confirmation that this will, as advertised, allow me to adjust my brake bias on a variable basis.
To be clear, the ebay description sounds perfect. The photocopied instructions supplied have caused concern as they talk about fixed point pressure loss rather than variable reduction.
I hope that is clear enough - its difficult on email.

Thanks in advance,

Morgan.
----------------------+


Hi Morgan

Could you please attach a picture to your reply to see exactly what we have sent you as we would love to resolve this as soon as possible for you

Kind Regards
--------------------
Hi - Thanks for the fast delivery - excellent.

Unfortunately I dont think the item sent matches what I thought I had ordered. I was expecting a variable brake proportioning valve, but what I have appears from the instructions to be a 'fixed 3:1' valve with an adjustable set point ? (of which there is no mention in the ebay description)

I have an old yank car with rear brakes that lock before fronts - I simply wanted a valve to allow me to change the balance by restricting flow to the rear. I dont think a 'set point 3:1' will do that - I need it variable flow restriction. Of course I may just have been sent the wrong instructions and the item may be fine for my purpose.

Before I return it could you please clarify ? Its a shame as it looks perfect.

Many thanks -

Morgan

[Dave999]

granted you didn't get what you throught you were getting but

I have a feeling that whatever you buy works exactly the same way

you can not alter the braking force at the rear wheel cylinder by any method other than isolating that circuit from the master cylinder and using the princepal of levers to adjust the force you apply to the peddle to a lesser force into a the rear circuit

none of the brake bias valves do that.

all of them provide some restriction to flow.

and you can work that out becasue with a bias valve in place you can still put brake fluid in the the master cylinder and have it flow out of the bleed on the wheel cylinder. i.e they are not isolating the rear from the master cylinder at all.

therfore all there can be in the bias device is a variable sized restrictor

a restrictor restricts flow that is all

hence all they can do is extend the length of time it takes the rear brakes to rise to full on.

a none compressible fluid takes longer to pass through a smaller hole than a bigger hole

the longer this time is

the slower you will be going when ultimatly the rears get to the point where they would lock.

(jab the peddle in an emregency and you won't lock up)

but by that stage the centre of mass of the car and the nose dive assocaited with heavy braking is past so the chances of locking up are greatly reduced.

I think you are swapping 1 device for another that does the same thing and possibly is less usuful becasue it will act all the time.


There is an alternative all though installation is probably quite costly
you can get the parts off a 90s Day van

1 small ECU
1 reluctance pickup
and an electronic brake control for the rear circuit of your brakes

provides true anti lock for the rear

ECU under Dash
wire to the solenoid adapter for the rear brakes that mounts on master cylinder outlet
2 wires out to a pickup that you bolt into your rear end pointing at a tone wheel built onto the ring gear flange

tone = no anti lock normal brakes
when the ring gear slows dramatically alters speed or stops moveing, the tone picked up by the ECU is a lower note (low frequency) or silent. then the ECU pulses the rear circuit to avoid lockup by activating the valve in the solenoid adapter on the rear circuit.

I can photocopy the details if you want.

Dave

[autofetish]

Dave to much you have smoked my brain



Yes i will have it if the devil does not get the better of you


which i reckon it will


I will send you addres via PM then send me an all in total and paypal info


If it dont turn up i know why

[morgan]

Dave. I dont know where to start on that. How about "Dave. You are special". ( but its too much for my small brain/capability!!)

Wil. PM received. Ill be in touch.

[Dave999]

speckled?





Dave