Really unenjoyable brakes. Help :( (ALB?)

[NafemanNathan]

have a look at the caliper and see how many brake lines you have going to it?

Just the one.

[mercutio]

have a look at the caliper and see how many brake lines you have going to it?

Just the one.

so the fluid must be mixed

[jjmartin349571]

I can't see from the manual if the fluids from the 2 systems ever mix so I can't say if they are closed from each other or not, although to be fair I'm just looking at the bleeding section The manual definitely states that the modulator is bled from nipples A, B and C as part of the main brake hydraulic bleeding process though.

For reference here's a schematic of the 2 systems, there's 5 bleed screws on the modulator and only 3 are used for the main hydraulic system so maybe the 2 systems are closed and interact through some mechanism in the modulator.

[Vtecmec]

I'm pretty sure the fluids do not mix, and the abs system acts as a second 'pedal' (using its own fluid to operate), it affects the brakes via the 2 lines going to the master cylinder.

[NafemanNathan]

Becca, you know there's a cel light on the ALB ECU itself right? You can see if it's throwing any codes.

[becca]

yeah when they say fail they mean electrically fail like a dodgy sensor or ecu the calipers will only have one fluid system which means the fluid from one system will have to mix with the other.
have a look at the caliper and see how many brake lines you have going to it?

Ok. There is one line.

I could be completely wrong here then as I'm definitely no mechanic and my mechanic (Bruce) has given up... but if both systems have separate reservoirs (if that is indeed correct, and there are definitely two in the engine bay) then if one is now disconnected will it be unable to release it's fluid into the system of the other via some kind of cut off valve? Therefore rendering the bleeding of it irrelevant to the functioning of the brakes-minus ALB system?

I've had a quick look on the manual and it says that there is an inlet and outlet valve, the ALB system (when it kicks in) closes one and opens the other which would indeed result in mixing of the fluids.

But if the ALB system is not operating (due to being disconnected), then am I right in saying there is no chance of the fluids now being able to mix because it won't open the valve to do so? Meaning bleeding of the ALB system would not be relevant to the functioning of the brakes as a lone function (without ALB) as if there was air in the ALB system it couldn't reach the other system without ALB kicking in?

Sorry if I'm not making much sense, I am super tired and this is definitely not my forte! Thanks for bearing with me

[Thebusofwoe]

If there is air in the alb modulator it will cause the brakes to feel spongy. The equipment req to bleed the alb is the 4W-ALB Checker, and the ALB high pressure pump T wrench. Regardless as to weather it has separate reservoirs or not, it will all be one complete system. I do know on the 3rd gen prelude I had to sort the alb out on (cant remember username) you have to use the alb checker to activate the high pressure pump and the modulator solenoids to be able to bleed the system properly. The T wrench is used to bleed the high pressure pump and the accumulator side of things. Both the alb checker and the T wrench are something that I can use at home from my workplace. Not many Honda dealers have those kits around anymore!!

[wurlycorner]

Yep, I've been reading up more on the ALB today as well.

I think the systems have 2 completely separate fluid systems by design and they should not mix.

The master cylinder acts directly onto the brake calipers, which is why the manual tells you to bleed that system via the brake calipers and not from the ALB modulator.

The ALB hydraulic system acts only within the ALB modulator unit, which is why it only tells you to bleed the ALB system from the modulator valve itself (using the ALB checker) and not from the brake calipers.


So, the ALB works by altering the pressure to each caliper, which it does by changing the volume in the circuit of each caliper, by using an actuator to move a piston in a chamber within the modulator unit. Moving the piston alters the volume in the circuit between the master cylinder/brake cylinder and 'interrupts'/alters the pressure acting on each of those.

To move the piston, the ALB modulator operates an solenoid, which allows pressurised hydraulic (brake) fluid to flow onto the other side of the piston. To do this, the ALB modulator needs an active (constantly pressurised) hydraulic system (whereas the brake circuit is a passive system, only pressurised when you operate the brake pedal/master cylinder) hence it has its own reservoir and takes its pressure from the pump ("power unit") and the accumulator .


If the ALB system is electrically isolated, in theory the solenoids won't operate and hence the piston in the ALB chambers shouldn't move and therefore it shouldn't interrupt the normal braking system at all - it behaves the same as an ordinary brake proportioning valve (which is what the ALB modulator replaces on an ALB equipped car).
And even if you get air in the ALB hydraulic circuit, it shouldn't (in theory) cause any change, because the actuator won't be allowing that fluid to act on the piston.
However, if the ALB system is trying to operate and it does have air in its hydraulic system and that air gets into the pistons inside the ALB modulator, then when you apply pressure through the normal braking system onto the other side of the pistons in the modulator, then the pistons could move (you're applying pressure via fluid on one side of the piston, while the other side has fluid containing air on the other side, so regardless of what the actuator is telling the piston to do, the piston would be able to move/compress the air in the ALB fluid).
In this scenario it would also be susceptible to heat (the air in the ALB fluid would expand/contract as the engine bay temperature changed) which would alter the piston position and therefore affect the braking force sent to the calipers.

I don't think there's any realistic scenario where seal failure of the piston could allow the 2 fluids to mix.


None of this theory of operation is actually explained in the bloody manual, but that's what I take from looking through the exploded parts diagrams explaining how to overhaul the valves etc.

So my advice would be;
- Re-bleed the normal braking system, according to the manual, making sure you flush through all the old fluid to replace with new (in case of any age/heat related deterioration in the fluid)
- Check all the ALB lines from the pump, accumulator and modulator to check there are no leaks that could induce air (the low pressure return line from the modulator to the pump is probably a hose rather than a pipe???)
- Bleed the ALB modulator properly, using the ALB checker
And then see how it feels.
I'd also sort out the ALB system fault light and see if there are any fault codes logged in the ALB system.


Failing which, if you don't want ALB at all...
- Disconnect the 6 hydraulic lines from the ALB modulator (2 from the master cylinder, 4 that go to the brake cylinders)
- Get a normal brake proportioning valve, fit that to the car and connect the lines up to that instead
- Re-bleed the brake system


And regardless of all that... Change any drokked brake calipers! It's not worth risking driving around with dodgy brakes.

[Thebusofwoe]

Wow, that's a pretty awsome description of all that alb rubbish . Spot on

[becca]

Yep, I've been reading up more on the ALB today as well.

You are an absolute star for actually researching that, if I had a gold star or a merit certificate it would be heading your way haha! that's what I thought I read too but I always doubt myself when it comes to anything super technical

This morning it completely failed again, so I limped it to the workshop and left it there, this evening we completely bled the normal brake system. Bruce blasted both rear callipers and rebuilt them - the dodgy one still isn't 'great' but it's just a little sticky rather than actually seized. So I'll be ordering up two new/remanufactured rear callipers this week to fit.

Fully flushed the standard system anyway and they seem spot on now! The fluid was pretty rank tbf, and I think the ALB fault was probably due to the calliper sticking and confusing it thinking it needed to kick in. It's disconnected for now via relays, fuses etc. but the actual thing is still in there for now - just unable to work. Will see how it goes for now but the brakes seem great now, in fact better than ever If the ALB doesn't seem to cause any future issues given that it's now unable to work and the fluids do not mix then we'll just leave it in there.

Happy that we have a car again now though!


Ordered overfenders for the bloody thing at the weekend so we could fit some Extreme Offset Wheels (to replace the stupid buckled set on it - yep this car is nothing but trouble apparently!!!), bought it a present and it decided to break on me - typical