Author Topic: bleeding brakes, soda stream brake fluid  (Read 14924 times)

Offline Neo Badness

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bleeding brakes, soda stream brake fluid
« on: 09 April 2011, 22:12 »
Right I've upgraded the brakes on my mk2 16v to 280mm ones, thought I'd be a wise guy and upgrade to DOT5.1 fluid when I renewed all the brake lines/ master cylinder as I am hoping to do the odd track day.

Anyway, I bled the system with an assistant, no air bubbles. Loosened the spring underneath and pushed the arm up, retightened after bleeding. Now the brakes work but I get a sort of weezey noise when I depress the pedal and there is alot more travel before they bite.

It failed MOT due to "spongy brake pedal".

Is this because I have DOT 5.1 Fluid? Should I go back and redo it with DOT4?

I've put at least 1ltr through and am getting firm pedal intially then seems to go soft after sitting, yet no sign of leakage or reducution in fluid.

Anyone help please?

 it's doing my nut in and retest is on Monday :undecided:
« Last Edit: 04 May 2011, 10:28 by Neo Badness »

You don't own a Mk2, you support it.

Offline Lewy

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Re: bleeding brakes, think I've done something daft
« Reply #1 on: 09 April 2011, 23:58 »
Loosened what spring, the pedal or the sense valve under the car?

Offline Neo Badness

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Re: bleeding brakes, think I've done something daft
« Reply #2 on: 10 April 2011, 00:11 »
Under car one, that stops rears locking up before the fronts .

You don't own a Mk2, you support it.

Offline Lewy

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Re: bleeding brakes, think I've done something daft
« Reply #3 on: 10 April 2011, 09:57 »
You shouldn't push the arm anywhere when bleeding the brakes. No need to touch it at all.

Offline emery1990

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Re: bleeding brakes, think I've done something daft
« Reply #4 on: 10 April 2011, 10:11 »
I'm doing mine soon, got some 4 dot waiting, remember reading something about a bias valve and pinching it.

Offline cняis

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Re: bleeding brakes, think I've done something daft
« Reply #5 on: 10 April 2011, 10:35 »
surely you need to move the spring so the bias valve opens up, otherwise it restricts the flow of brake fluid going to the rear brakes!


I don't think a semi will give the same results

Offline Lewy

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Re: bleeding brakes, think I've done something daft
« Reply #6 on: 10 April 2011, 10:43 »
Why, when all you are looking for is fresh, air-free fluid?

The valve acts like a load sense valve, it measures the amount of weight in the back and applies the force to the rear brakes accordingly.  If your car is lowered you will need to adjust it to suit the new height of the beam to arm, but other than that you don't need to mess with it.

Offline clipperjay

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Re: bleeding brakes, think I've done something daft
« Reply #7 on: 10 April 2011, 10:48 »
Sounds like air to me  :rolleyes:
Devil has uses for idle fingers  :evil:

Offline emery1990

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Re: bleeding brakes, think I've done something daft
« Reply #8 on: 10 April 2011, 10:49 »
ok, I wont touch it then.

Offline Neo Badness

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Re: bleeding brakes, think I've done something daft
« Reply #9 on: 10 April 2011, 11:31 »
Was told by an experienced local dubber to open the valve.  :rolleyes:

This is the first time I've "done" brakes and it's doing my head in.

Squishy pedal is air in the system and nothing to do with DOT5.1?

Considering seeing if I can borrow a power bleeder but time is so against me.

Gotta lay a bathroom floor too :cry:

You don't own a Mk2, you support it.