I might just suck at bleeding the brakes this much but i dont have brake pressure. I had to pump the breaks a few times to stop during my test run with the new car. I did put in different booster and disconected and put in a different MC, where could i have gone wrong with this so i loose compresion. When i push in the brakes i hear air escaping, i dont thin this is good, did i need to seal the MC to the booster along with the 2 bolts? The booster should be good since it worked perfect a few weeks ago from my red car.
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There should be a rubber O-ring between the Master cylinder and the booster. Did you Bench bleed the Master cylinder before installing it?85 325e 2.7 ITB'd stroker
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i will need to find that o-ring, i dont remember seeing one. I did what i thought was bench but i dont know if i executed it right, i am going to look up the procedure. thanksComment
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Can i get away with getting the air out of the brakes without bench bleeding the MC?Comment
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not easily85 325e 2.7 ITB'd stroker
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does it just take a whole lot of bleeding?Comment
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yup
Originally posted by DaveCNComment
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the o-ring sits right in the back of the master cylinder, it should only come off the master cylinder if you take it off I think. I am going through this right now on my swap project. Frickin' brakes take one full pump to get anything. The master cylinder works well, the rotors are good, the pads are good, there are no leaks from vacuum or brake lines anywhere. I think the calipers might need a rebuild as the pistons have a little rust on them, but I'm not sure that explains why I have to give it a full pump to get good brake pressure. There is absolutely zero air in the brake lines (confirmed by the local shop I had do the alignment for me) and I'm just about baffled. i have m3 brakes on my car and a spare set of rebuilt calipers I'm going to install tomorrow and see if that helps at all. If not, it's gotta be the booster but damn if I have to replace that. I'll have to remove half my s50 just to get it out of there I think.
let us know how yours turns out, I'm looking for ideas as well. i swapped in a new master cylinder today and re-bled and still have the same exact problem. It's quite annoying...after one full pump they feel awesome, but it shouldn't take a full pump to get there...sounds like you have the same problem. Is it possible that the adjustment rod the brake booster is not set up properly, does it need to come out more?
keep us posted, I'll post how mine turns out as well
DaveComment
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Whoosh!
If the booster is leaking it would require extra pedal effort but bgrake pressure is directly related to pedal movement - assuming correct alignment. Air in the system is the usual culprit. Also a bulging brake hose. If the calipers are bigger from an upgrade you may need a different size master cylinder for the extra volume of fluid.
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