Brakes Issue.

Hi to all Bimmerfest members and thank you for these forums.

Initially, my brakes were going out. The pedal was sinking to the floor, and I was continuously having to pump the brakes to have it stop. (1)My first step was to replace the master cylinder and bleed the brakes. After completion, while I was driving the following day to school I noticed a heavy vibration. Soon after, me and my dad proceeded to step two. (2)Replacing the front calipers, rotors, and brake hoses (from calipers). After finishing up and bleeding the brakes, we noticed how difficult it was to turn the rotors. I have read several threads, but nothing that involved the use of new Girling calipers, which are not releasing from the rotor. We have been troubleshooting to find another culprit that would be causing the issue. My initial response would be possible Guide pins (since we lubricated them initially), possible bad caliper(s), possible metal brake line issue, brake booster problem (vacuum), or a brake proportioning valve (Brake pressure regulator?). After spending about 300$ so far, since I work at a carquest, I am still unable to troubleshoot the correct issue. Any help is appreciative.

I am beginning to feel like taking my issue to a mechanic may be an easier method. I am stretched low on cash due to gas, and college, etc. So anything that is DIY is great.

sounds like the booster to me. howd you bleed the brakes?

Well, my car has ABS. I started at the master cylinder, bleeding all of the lines there. Then I did all of the line going into, and out of the ABS Module. Then I just did the normal rounds where I started at the rear right, the rear left, front right, then front left, while doing 12 pumps to attempt to bleed any extra air that may be trapped in the ABS (According to the BMW Manual). I noticed that the Brake Proportioning Valve has a single line running to it, but I did not attempt to bleed it.

i would first try to take out any leftover pressure in the lines, like do the corner to corner bleed just without the pumping. if it still happens, then i would go after the booster. i would upgrade it too since its gunna be out anyway

I will see about doing this. I have decided to first off; replace the newly installed master cylinder since it is approximately where the issues first started. It is new, but I work in a parts store, and I know that parts can become defective from time to time. My logic is in that before I replaced anything my brakes were reaching the floor, and I was losing braking. Once I replaced the master cylinder the locking up of the calipers began. I will attempt a thorough bleeding this time around, even though we did a proper bench bleed. We did have to remove the reservoir during installation, perhaps causing air into the cylinder.

they wouldnt stick if air was in the lines. everytime i get air within my brake lines (bike) it doesnt have the clamping power like it should.

I see what you are saying. Today I took off the master cylinder for replacement tomorrow morning, and as I was taking it off I noticed that the piston from the booster was coming out with it. I am not very experienced with brakes, but to me it seems like there may definitely be a brake booster issue, if the piston basically falls out of the booster. My dad is going to spend some time with it tomorrow to see if he can diagnose the issue with the booster. If I do replace it, it will more than likely be Friday before I can get the part. It is in Texas at the moment.

look at some of the m50 swaps. they used a different booster. itll be a nice little upgrade

Not that I couldn't learn how to modify an e50 booster swap, but that may have to wait until I graduate and have a little more savings in the bank. I was looking at the treehouse swap and $329 dollars is a little hefty versus my $62 reman. I plan on doing a lot in the future, but that will have to wait in the mean time. Those M3 and M5 engine swaps sure do look appealing, as well as, the 540hp achievement. In time perhaps, I still have much to learn about BMWs.

By the way, Any information or links you could come up with would be appreciated.

search for fcsteves bronzit ftl thread. he did the full swap plus some