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Discussion Starter #1
hi every body

my question is.... I have a swiss 404 and have a very soft pedal for the brakes. if i step on the brake pedal it is real soft, step on it again right away and it firms up like how it was when i first got it, any ideas? I thought it might be the manual brake adjustment, i did the adjust ment to the best i can but no real differance. ?????

thanks for any help or ideas

derek
 

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You need to bleed your brakes. You have air in the brake lines. Check http://www.bmw-m.net/TechProc/bleeder.htm This site shows how to make a homemade pressure bleeder. You then attach this to the cap on your master cylinder and open the brake bleeders on each wheel one at a time starting furthest from the master cylinder. You need an extra cap for your master cylinder to use with the pressure bleeder. The pressure will force the air out and new fluid in. On an offroad vehicle you should be flushing the system more often than an on road vehicle, at least once a year if you go in water. You can also buy a commercial bleeder or do it the old fashioned way, with your wife pumping the pedal while you open the bleeders one at a time. You will have her pump the pedal until it is hard then you open the bleeder while you have a clear hose attached to the end going into a bottle with a little brake fluid in it the pedal will go the the floor and expell air and brake fluid. Have her hold the pedal down and tighten the bleeder, then pump up the brakes again and repeat until nice new clear brake fluid flows with no air bubbles out of each wheel cylinder. Use DOT rated #3 or #4 brake fluid, do not use #5 silicone.
 

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I too have this problem, but bleeding the brakes hasn't seemed to work yet. Here is what led up to my loss of braking: My master cylinder was leaking so I rebuilt it with a kit. I figured since I had it apart, I would replace the flex lines. I also checked over the individual wheel cylinders, and they looked dry. I bled the brakes, nice and clean and no more air bubbles. I pulled it out of the driveway and had about 50% of the braking power I had before. I too have to double pump the brakes to stop. I have had an independent mechanic check the brakes, he also spent time bleeding them. I am at a loss, maybe there is air in the line, I just can't believe that is the problem. Is it possible that the Master cylinder is badly worn? I simply removed some light rust or build up in the cylinder with some light emery cloth and used a new kit. The truck does not leak any fluid, the reservoir is not changing levels and I know fluid makes it to each wheel because I get a good flow when I bleed the cylinders.

Dave
 

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After pumping up the pedal to where it feels better, hold your foot on it maintaining the same firm pressure (engine off- no boost). If it is a failed master it will slowly drop back to the level at which it feels low, otherwise it is probably air.

When manualy bleeding, sometimes it helps to pump the pedal three or so times then hold it down while an assistant releases the bleeder. This just can help by compressing the air, moves it along a bit better.
 

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You may need to bench bleed the master cylinder. A new master cylinder should be bled while held in a vice before instalation by pushing in the actuator until fluid flows freely then install the master cylinder and bleed the brakes. You may need to bleed them a few times after driving to get all the air out.
 

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Discussion Starter #7
well seems like everybody thinks air in the system
i have vac assist brakes, i'll try bleeding the brakes again and see if that helps

derek
 
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