Hydraulic handbrake is not working

[Hyfly]

Hey Guys,

I have installed an hydraulic handbrake last week, and it is not locking...
Started with the 0.75 cilinder, didnt work.
Ordered the 0.625 cilinder, worked a bit better, but is not locking.

Is there anyone who experienced the same thing after installing?
The brakes work as they should, I took them apart after the 0.75 cilinder
was not working and checked them.

Regards, Stefan

[Reub_e30]

So I take it that u are running a dual caliper setup. Did you bleed the line properly? You did add brake fluid right? Checking just in case lol

[TobyB]

It's a matter of leverage or travel. Or maybe coefficient of friction?

But the details are hazy- we'd need more pix to figure it out using this poor tool called
'the internets'...

A long time ago, I wanted a .500 x 5" master cylinder for my clutch. Sadly, no luck...

t

[Hyfly]

I'll try to take a picture later today.
But to be ahead of the game:
- I bleeded the lines with a garage vacuum bleeder so should be fine.
- It is a single line into T-peice for both OEM calipers, not a dual caliper setup

It is an in-line hydraulic handbrake.

[TobyB]

So you've disabled the stock rear brake?

It gets interesting to try to keep stock rear brakes with an additional hydraulic handbrake...

t

[Reub_e30]

So you should have installed like this correct?

[czkb]

Put this
before e-brake not after, or it wont lock, had same problem with my 0.70.

[Hyfly]

@ Reub E30, Yes excactly like that.

@ czbk: What is that? A brake pressure limiter? And where can I find this on my E30 316?

[jpod999]

Look underneath the fusebox in a LHD E30.

[AndrewBird]

You probably want to go with a BIGGER master cylinder, not smaller. I bet you aren't moving enough fluid to fully actuate the calipers. Larger bore will flow more fluid for the same amount of throw. It will be harder to pull though.

[Hyfly]

I checked the travel of the calipers, they are more then sufficient. I had a 0.75 cilinder before this one and was even worse. (On brakeforce that is)

And the pressure restrictor is before the handbrake, because I tied in under the drivers seat.

I will try bleeding it manually next week once more...

[Madhatter]

smaller cylinder = more force. Not the other way around.

[Hyfly]

Correct, but what Andrew says is also correct.
Smaller cilinder could mean less liquid to move the pistons.

[pazi88]

Are you sure the rear brakes are really working? Maybe stuck pistons because corrosion? With that setup you should be able to lock the rear tires easily. With both cylinder sizes.

[Hyfly]

I will check everything again this weekend.
It is just so weird that it is working so badly, and others say they can pull with one finger to lock them up....