Re: Pressure Bleeding experience + questions

[alex.fadeev@xxxxxxxxxxx]

"Michel Drainville" <MDrainville@domain.elided> wrote:
> OK.  Let's put a caliper rebuild on the TO DO list.
>
> For the ABS. Do you know a source where I could read in details how
> the internal of the ABS works? I mean, what the pump does, it takes
> fluid and send it where? And the solenoids, do they retract a kind
> of piston to lower the pressure in the line etc.

Michel,
That info is proprietary to BMW and/or whomever builds their ABS system for
them.
Good luck digging up those specs.

> I'm asking that because I'm an electronic technician and would like
> to design something to manually activate the ABS during bleeding.
> I'm pretty sure I can figure out what the connections are, but I
> need to know the sequence of activation, what needs to be activate
> in the same time or not at the same time etc.

I think it's pretty safe to say that if the problem was with finding how to
flip the switches it would have been solved long time ago. In fact, there
are posts on the net with details on which ABS relay contacts to jump to
activate the pump. The problem is that it activates the solenoids in no
particular order resulting in net fluid flow of zero.
The trick is engaging the solenoids in the right sequence to expel the
old/suck in the new fluid into the ABS pump.
The only solution that I am aware of is the $25?K MODIC black box.

> Also,  I used around 32 fluid once of brake fluid to flush the lines.

You did not mean 32 cans of fluid, did you?
It takes about 1.2 quarts of fluid to flush the whole system. Less than 1
quart if you do not bleed the clutch.

> It was hard to see the color change. Is this too little for a fluid
> change?  I think next time I will buy ATE blue, so I can see the
> difference.

That's exactly what I do: iterate ATE Blue with Type 200 fluids (blue and
gold respectively) so that you can easily spot the color of the old vs. the
new fluid.

alex f

------------------------------