brake pedal soft
Thread Starter
|
Senior User
Joined: Mar 2003
Posts: 191
Likes: 1
brake pedal soft
I am just finishing the conversion to disc brakes in the front of my 74 250. I bleed the system and the pedal is still very soft and when the truck is on with the boster the pedal goes to the floor. I put a new mater cyclinder and calipers and line and been bleeding them a few times any sugestions.
Post Fiend
Joined: Jul 2003
Posts: 11,945
Likes: 3
From: Spokane, WA
I'm not an expert on the matter but read this thread: https://www.ford-trucks.com/forums/s...d.php?t=170248 Don't know if you did the bench bleed on the new master cylinder before installation but that may be your trouble.
Last edited by ivanribic; Sep 11, 2004 at 06:45 PM.
Posting Guru
Joined: Feb 2004
Posts: 1,388
Likes: 0
From: Saratoga, NY
I had problem with bench bleeding a new/rebuilt master cyl, that sucker just wouldn't shoot out any fluid from the front, plenty to the rear, so what I did was take an old fitting and screwed it in the front hole, hooked up a hand vacuum pump and in no time i got fluid coming out, and then after I was all done the brakes were rock hard.
Just because you bled the system doesn't mean you got all the air out. Sometimes the good old 2 man method is the only way it works.
The booster is good if it sinks a bit when you start it and gets hard when it's off after 3 pumps.
Also make sure the calipers, and wheel cyls and any hoses and lines are not leaking, just because any part is new don't mean it's good.
Just because you bled the system doesn't mean you got all the air out. Sometimes the good old 2 man method is the only way it works.
The booster is good if it sinks a bit when you start it and gets hard when it's off after 3 pumps.
Also make sure the calipers, and wheel cyls and any hoses and lines are not leaking, just because any part is new don't mean it's good.
Last edited by Phinxter; Sep 12, 2004 at 12:21 AM.
Thread Starter
|
Senior User
Joined: Mar 2003
Posts: 191
Likes: 1
I think the booster is bad. It will makes a hising sound every time i step on the pedal and the pedal feels good when the truck is off but as soon as I start it the pedal sinks to the floor. The booster is from the junk yard.
Posting Guru
Joined: Feb 2004
Posts: 1,388
Likes: 0
From: Saratoga, NY
Whether or not you have a bad booster has nothing to do with why the pedal is going to the floor. It is very possible it is bad but it does nothing more than give you an assist to make it easier to apply the brakes thats it! Sure it will be hard when it's not running, there is no vacuum when the engine isn't running, and it will get hard after about 3 pumps because any reserve vacuum get used, and the your left trying to push this big spring inside along with the MC piston. How to test a booster is easy, pump the brakes 3 times hold the pedal, start the engine, it should sink slightly, once the pressure builds in the hydraulic system it stops sinking. It seems you have no pressure, so you have air in the lines, a leak someplace, or a ballooning hose, or a bad MC.
Is the master cyl new? If not it could have an internal leak
did you check the pushrod on the booster to make sure its adjusted properly? (if it's adjustable)
Is the master cyl new? If not it could have an internal leak
did you check the pushrod on the booster to make sure its adjusted properly? (if it's adjustable)
Last edited by Phinxter; Sep 12, 2004 at 08:02 PM.
Thread
Thread Starter
Forum
Replies
Last Post
93Sunplex
1987 - 1996 F150 & Larger F-Series Trucks
6
Apr 6, 2007 04:38 PM
jackcassid
1973 - 1979 F-100 & Larger F-Series Trucks
15
Mar 3, 2007 09:25 PM
