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brake pedal going to floor

2K views 10 replies 9 participants last post by  mobil1syn 
#1 ·
I have fairly new brake calipers, rotors, pads, and lines on my truck.. replaced them in the fall.. Anyways as of recent.. every so often my brake pedal will go to the floor and feels like there is no pressure there. Once I pump it a few times, it's fine and i can stop.. just seems strange, was wondering if anyone knew what this is?! master cylinder? brake booster? :confused:
 
#3 ·
i had the same problem.... look around the master cylinder and you will probably see a little bit of rust cause the brake fluid is leakin from the master and it is eating the paint on the booster.... takes about 35 minutes to replace....
 
#6 ·
ROKTOY said:
Are you losing any fluid?

You need to know if it is a leak letting fluid leave the closed system or some other problem internally......
Jay

I'm not losing fluid.. well as far as coming out the lines.. I will check for a leak around the master cylinder/brake booster.. The brake fluid was at max when I did my brakes a few months ago.. and now it's at the halfway point between min and max.. which that doesnt take much fluid to get to that point..

if it ends up being my mastemr cylinder should I upgrade to another one??
 
#7 ·
Yea you should check out the flintstone line of brake systems I hear they have a great M/C.You could also swap in a M/C from an FJ60 series its larger in size but you might have to change a few lines or possibly fittings.
 
#8 ·
obex26 said:
Yea you should check out the flintstone line of brake systems I hear they have a great M/C
Genious :shaking:

You could also swap in a M/C from an FJ60 series its larger in size but you might have to change a few lines or possibly fittings.
Then, he would have to swap in other components to match it. If he has the stock size calipers and an oversized M/C then he will have a shorter pedal throw and less pressure applied :eek:

Check and make sure the wheel hub is not lose. I had the same problem a couple weeks ago. peddle would go to the floor sometimes and kept getting mroe frequent. Then, it started leaking diff fluid all over the inside of the tire. Turns out that the spindle nuts had come lose and my wheel was about to fall off. Fixed that problem and my brakes were fine.
 
#9 ·
Benny,

Then explain to me why my setup has not failed me. I have stock 85 calipers up front(I learned that they were from an 85 when it came time to replace the front brake pads.) stock rear proportioning valve, gm metric rear calipers and an LC M/C. My braking appears to be fine? Tell me what my setup has that defies your explaination.
 
#10 ·
your primary piston seal in your master cyl. is going out so your master needs to be replaced. The seal is not holding the pressure its suppose to therefore causing your pedal to bottom out. You can try to rebuild it but id just say upgrade to the nicer fj80 master from marlin since you need to replace it anyway.
 
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