Bias Valve And Hydraulic Handbrake Plumbing

[cybernck 400 1 Cars]

it's clear that the bias valve goes in before the hydraulic handbrake cylinder,

but what's not clear to me is what the inlets and outlets are on them.

 

 

i've got a Tilton bias valve which doesn't seem to have any IN/OUT marks

(perhaps they are on the other side), but looking at some pics it looks like

IN is the upper and OUT is the lower connection. that should make sense

as in this case the lever will give more pressure to the rear brakes when

the lever is pointing in their direction, but i've seen some contradicting pics.

 

 

 

as for the hydraulic handrbake cylinder it doesn't have any marks on it

either and i've also found some completely condraticting information

(here on the forum). on slave clutch cylinders the rear hole (the one

on the left in the pic) has a bleeding screw while the other is the IN,

so i guess that the rear hole is OUT in this case. however, these two

mentioned cylinders work in an opposite way, so i'm not sure.

 

 

 

oh and by the way, what's the best place on the standard lever to attach

the pin to in order to get the best ratio between lever travel and braking

force? ideally i'd like it to have the same feel as a cable handbrake .

 

 

thanks.

[jonah 1]

Yes you're right about the bias valve, upper port is IN and lower port is OUT (makes bleeding it interesting as air bubbles don't like to go down! ) Here's the installation instructions:

http://www.tiltonracing.com/pdfs/29.pdf

 

(actually that shows the lever working in the opposite direction, i.e. towards IN for more pressure, but I'm still sure the lower port is OUT on yours as this seems to be the same on all the bias valves I've seen, I guess they all use the same basic mechanism inside.)

 

For the master cylinder, the rear port is IN and the middle (angled) port is OUT. This nearly caught me out too, I only realised that they were this way round when I saw a picture in a catalogue of the same master cylinder but with an integral reservoir - the reservoir goes in place of the rear port.

[cybernck 400 1 Cars]

thanks for the reply and the link to the guide.

 

 

 

so orientation is easily adjustable depending on how do you mount the valve

and if you plan to use it for the front or the rear brakes and mine is the way

i want it, which is good.

 

 

however, how could they give out contradictory information in the official guide?!

 

 

 

however, i'm now positive that the upper connection is IN, as suspected.

 

 

one more question regarding the valve itself. mine seems to be flapping around

in the first two "clicks" while i nearly can't engage the last two clicks . is it

supposed to be working like this? i expect it to change it's behaviour once it is

actually plumbed in, as it has been working fine on sean's old red track mi16.

 

 

thanks for the info re the master cylinder. i also recall seeing the integral versions

and they've had the reservoir on the rear hole. i thought that different manufacturers

may have used a different way of plumbing, so though i'd check.

 

 

thanks.

[cybernck 400 1 Cars]

well it seems the the rear connection on the m/c is outlet afterall

(and the angled one inlet) as that's what happens when the rod

is pushed in with a little bit of oil in the cylinder?!

 

however, there's a problem - it doesn't work! rear brakes work ok,

but when i pull a handbrake there's no resistance and no braking

action at all! we've tried swapping the connections just in case,

but it still doesn't work - faulty cylinder or something else?

 

thanks.

[boombang 2]

I've sent you a PM with friends details for pics of the installation.

 

If its all connected right then I cannot work out where the fluid is going when the bar pushed it!

 

Only thing I could think are seals were gone but then it would come out beneath the rubber gaitor

[jonah 1]

I can assure you that the rear port is the inlet! During the first couple of mm of travel, the movement of the valves inside may force a small amount of fluid out of the inlet port, but after that the pressure will build up on the angled (outlet) port.

 

Here's a photo of my install showing the plumbing - works perfectly and the master cylinder is an identical shape to yours.

 

The M/C may be faulty, but could it just be that you haven't got enough travel on the master cylinder piston? How is it attached to the handbrake lever - got any pics?

[cybernck 400 1 Cars]

an update - we got the m/c refurbed with new seals and a longer piston made.

 

now it's better but still something isn't right, as the hanbrake seems to brake lightly

and return a bit of oil back to the reservoir. however, if the foot brake is applied

(only just) then it locks the wheels good and proper.

 

what the heck is the problem, surely that's not the way it works .

 

p.s. yeah, we made sure the rear connection is inlet as it appears to be right.

 

any ideas?

 

thanks.

[Butler 0]

now it's better but still something isn't right, as the hanbrake seems to brake lightly

and return a bit of oil back to the reservoir.

 

That sounds like the pipes are the wrong way round. I can't see any other explanation.

[Craigb 2]

now it's better but still something isn't right, as the hanbrake seems to brake lightly

and return a bit of oil back to the reservoir. however, if the foot brake is applied

(only just) then it locks the wheels good and proper.

 

 

 

what the heck is the problem, surely that's not the way it works .

 

p.s. yeah, we made sure the rear connection is inlet as it appears to be right.

 

any ideas?

 

thanks.

 

Its sounds about right to me ..

 

try this , are you getting full travel on the handbrake cylinder .

 

The pressure you can generate with the handbrake type you have is far less than the foot brake can generate .

 

If you have a look at jonah's photo , he has the better version of the hydraulic hand brake that has a longer lever . therefore it is easier to generate the pressure.

 

I hav eteh type that you have , and have only ever been able to lock the rear wheels when i fitted std rear pads, that were a bit softer than the 1155's iI used to have .

 

I would look at the travel leverage and also re bleed the system using the hand brake instead of the foot brake ..

[boombang 2]

This is puzzling!

 

Its a standard Girling MC used in pretty much every hydraulic handbrake on the market so:

if its not leaking

its being pushed the right direction on pulling the handbrake

the distance to operate is sufficient (normally not much at all)

 

I cannot work out why it wouldn't work?

 

If you remove the handbrake lever and operate it manually does it lock up? i.e. check that the handbrake linkage is pushing it back far enough.

 

If you hold on the handbrake does the amount of breaking force remain the same or does it get weaker with time - just can only think something internal isn't sealing?

[jerseypug 1]

i have the same set up on my car and have problems locking up the rear wheels in the dry. more people seem to be going for the longer lever for more leverage.

[jonah 1]

Still sounds like a lack of travel of the piston. Can you post a photo of how it's attached to the handbrake lever?

 

Here's what's (probably) happening. When the braking system is at rest, the non-return valve in both master cylinders (handbrake and footbrake) are open. When you first start to move the handbrake cylinder piston, the volume inside the cylinder decreases so fluid is forced out, but since the valve is still open it takes the path of least resistance which is out of the inlet port, through the open valve in the footbrake M/C, and into the reservoir. Only when the piston has moved 1 or 2 mm, the valve will close so that any further piston movement now has to force fluid out of the outlet port and to the rear brakes.

 

If you press the footbrake a small distance, this closes the valve in the footbrake M/C. So any movement of the handbrake M/C piston will immediately generate pressure in the brake system, even before its own valve is closed. That's why it works so much better with your foot lightly on the brake pedal.