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Edward · Alfa 33 Joined: 21 Sep 2003 Posts: 307 Location: Bristol

Hi All,

On the car the brake pedal goes soft. It seems to have initial bite, but when the pedal is held down it starts slowly to feel as if it going to the floor. My guess it that it it the master cylinder and that the seals are going and fluid is getting past them. Is this the best area to look at - or should I look elsewhere first? Knowing my car if I change the master cylinder and then bleed the brakes the first thing that will happen is that I will snap one of the bleed nipples off!!

Any suggestions....

Edward.
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The faster the better.

bobbber · Posted: Tue Mar 21, 2006 10:13 pm Post subject:

Hi Edward,

It's a brake fluid leak somewhere???

Bob
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Fiat Bravo 165 Sport

Edward · Alfa 33 Joined: 21 Sep 2003 Posts: 307 Location: Bristol

Bob,

I can't see any leaks anywhere - and the reservoir level stays constant. Someone did suggest that it could be a hole in the diaphragm. I think they may have been guessing.
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The faster the better.

bobbber · Posted: Tue Mar 21, 2006 10:18 pm Post subject:

Here's something for you to look at then :

http://www.babcox.com/editorial/tr/tr502b.htm
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Fiat Bravo 165 Sport

Edward · Alfa 33 Joined: 21 Sep 2003 Posts: 307 Location: Bristol

That's pretty impressive Bob,

Did you have that all ready waiting for someone to ask the question??

Are you going to spring alfa day?
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The faster the better.

bobbber · Posted: Tue Mar 21, 2006 10:24 pm Post subject:

Yes - I'll be there with my cross of St. George!

Bob
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Fiat Bravo 165 Sport

Guest · Posted: Sun Apr 16, 2006 11:11 pm Post subject:

Bob,

I changed the master cylinder which solved the sinking feeling - but now the pedal is just soft and lacks any bite what so ever. Even trying an emergency brake there is no lock up. I put new pads in and cleaned the rotors but still after some prolonged braking there is no decent braking to be had. So as the article suggest is sounds as if the master cylinder needs bench bleading as suggested in the article. Do you have the link perhaps a further part in the article that might suggest how this is done?

Edward.

tvatavuk · Posted: Mon Apr 17, 2006 12:08 am Post subject:

Wne you put new pads, you surely need some 500miles or so before brake start to get their best.
But bleeding whole brake system is of corse 1st thing you do, after replacing anypart on it.
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Tino Vatavuk
Little black dress which replaced Alfa Romeo 33 S 16v Permanent 4 GMo

Edward · Alfa 33 Joined: 21 Sep 2003 Posts: 307 Location: Bristol

Tino,

Finally sorted out the problem today, it was basically down to bad bleading. I read some sites about priming the master cylinder to remove any trapped air within it. According to the sites when changing the master cylinder air can get lodged at the top of the cylinder chambers and needs to be removed by bleeding the master cylinder when it is level. So, I disconnected the 3 lines from the master cylinder and routed all three back into the reservoir, with some make up pieces. I then raised the back of the car until the master cylinder was almost level with the ground. It helps is you start on bit of a slope to begin with. Once I had bled the master by cycling the (clean & new) fluid around many times - all of the air and small bubbles had come out into the reservoir.

I then reconnected all of the lines and bled them normally. After that all was fine. This may sound a little extreme - but I felt pretty sure that I had done a decent bleeding first time.

I thought I had short circuited by driving a fair way with one foot on the brake as I was driving along.

I am off to the Nurburgring at the end of the month with Alfaowner guys - so I thought it would be good if the brakes worked. Should also get that 500 miles in anyway before I get there now.

Thanks for your advice.

Edward.
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The faster the better.