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+--- Thread: Help me fix my brakes (/showthread.php?tid=5770)
Help me fix my brakes - Hunter - 04-08-2007
So I just changed brake lines in the bmw and a funny thing happened while I was bleeding them afterwards, the master cylinder ran dry. :x Basically it was a miscommunication between me and the guy I had pumping the pedal. He thought I said to keep pumping while I went inside to grab another bottle of fluid when I really wanted him to stop.
So now when I pump the brakes it's not sucking in fluid and I'm sure it sucked in a ton of air. Anyone know how I could fix this? Am I going to see a new master cylinder in my future?
This sucks.
- Ginger - 04-08-2007
Would a bench bleed and then a full flush help this?
- .RJ - 04-08-2007
Gravity bleed all 4 corners at once... it will take a while.
- Hunter - 04-08-2007
RJ, do you have any idea how long it might take? I'm trying to deciding if I need to pull the master cylinder out tonight or not, but I'd rather give the gravity bleed a shot first.
- .RJ - 04-08-2007
Shouldnt need to pull the master. Put the car on jacks, hook up bleeder lines/bottles to all 4 wheels and pop all 4 bleeders. Let it gravity bleed for 20-30 minutes then pump a bottle or so of fluid through it (bleeders stay open, just pump the pedal).
- BLINGMW - 04-08-2007
You can also crack the lines at the master to bench bleed it on the car. Pretty easy way to get it full, then you can work from there. Same thing at ABS pump. Just pump, hold, crack line, close, repeat just like doing it at a caliper. Obviously you can't connect a hose, just use a rag to catch it.
*edit* RJ's idea sounds easier if that works!
- Hunter - 04-08-2007
Yea I'm going to do RJ's first. I'm all about low effort.
- .RJ - 04-08-2007
You can drink beer while you gravity bleed!
- Hunter - 04-08-2007
I actually started the drinking well before I started the bleeding. I came back to the computer to tell you that if this works, I'm buying you a beer next time I see you.
- Maengelito - 04-08-2007
RJ's been preaching the gravity bleed for awhile, but i've tried it without success. it never made anything worse, but it definitely didnt get rid of any air bubbles. YMMV though, so give it a shot.
- xvxax - 04-08-2007
Let us know if it works.
- PDenbigh - 04-09-2007
Since the MC went dry, you need to prime the MC. (Just like any pump that runs dry.) If you have a mityvac it does it for you. What RJ's suggestion does is force the pump to prime, hopefully. I usually either pressurize the MC or put a vacuum on a caliper and it gets it going.
There are other ways but they are messy and a last resort. Try the gravity bleed for a while first.
- white_2kgt - 04-09-2007
bench bleed (you can do it in the car), then gravity bleed or if you can pressurize it that will probably be the quickest, start at the MC and work your way down.
- Hunter - 04-09-2007
So RJ's method worked.
Last night I let the car gravity bleed for about 2 hours and I eventually started seeing fresh fluid at all 4 corners. Then I just went ahead and pumped about half a bottle of fluid through the system with all the valves open. I did a normal partner bleed during lunch today and now the brakes feel great. I'm glad I didn't have to pull the MC and bench bleed it, really just because I'm lazy. RJ I will buy you a beer next time I see you.
Also, there is a dramatic difference between old rubber lines with 170k miles on them and a new set of braided stainless steel lines. The brakes have never felt this good.
- Sijray21 - 04-09-2007
Hunter Wrote:Also, there is a dramatic difference between old rubber lines with 170k miles on them and a new set of braided stainless steel lines. The brakes have never felt this good.
which lines did you replace? front and back or just front? I thought about putting some SS lines on the bike and on the integra.
- white_2kgt - 04-09-2007
Hunter Wrote:Also, there is a dramatic difference between old rubber lines with 170k miles on them and a new set of braided stainless steel lines. The brakes have never felt this good.
Keep a close eye on those SS lines, I suggest you get some wire wrap (the spiral kind you can get at Radio Shack) and wrap the SS lines in it, then inspect the wrap, if you see any wear spots on it, try and correct the problem then rewrap. I've worn down the spiral wrap on mine several times but the lines look brand new. Ask pete what he found on his SS lines...
- .RJ - 04-09-2007
IMHO, most SS lines are junk with junk crimped fittings. I'll trust an OEM brake line for a long time before I'll replace it with some junk aftermarket chinese made SS line. The notion that they are "safer for track use" boggles my mind. The useless DOT spec that mandates all lines have to be crimped bothers me a bit too, but thats not the point here.
I used Stoptech lines on the racecar - and they sure werent cheap. One of them did not fit properly and after a few weekends on track the protective plastic coating had become worn off (I assume tire rubbing on it). Stoptech replaced the line for me.
- Andy - 04-09-2007
white_2kgt Wrote:Hunter Wrote:Also, there is a dramatic difference between old rubber lines with 170k miles on them and a new set of braided stainless steel lines. The brakes have never felt this good.
Keep a close eye on those SS lines, I suggest you get some wire wrap (the spiral kind you can get at Radio Shack) and wrap the SS lines in it, then inspect the wrap, if you see any wear spots on it, try and correct the problem then rewrap. I've worn down the spiral wrap on mine several times but the lines look brand new. Ask pete what he found on his SS lines...
SS lines come in wrapped in poly now so you have that rubbing problem anymore. Earl's is the only company that I know of that still doesn't wrap their SS lines.
- Hunter - 04-09-2007
Yea the lines I picked up have a poly outer layer so theres no exposed braided metal. I'm pretty sure I would have felt a dramatic improvement with the oem lines too, just because the lines on the car were pretty damn old.