Soft brakes

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Old 07-07-2010, 12:46 PM
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Soft brakes

New pads and rotors on the front (the carquest pads/rotors mentioned on here), rears are good. Brake fluid is original but full. When I apply the brakes its a really soft pedal, but if I slam them the ABS kicks in really well. I am only concerned of the soft brakes because we will be towing our travel trailer through the mountains of Canada beginning next week. Should I bleed and pump in new fluid and check the soft line or what? FWIW the truck has 88k miles on it.
 
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Old 07-07-2010, 01:45 PM
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Did this start after the front brake job? Are the rear brakes adjusted properly?
 
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Old 07-07-2010, 01:55 PM
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Just in case I will check the rear discs today.
 
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Old 07-07-2010, 01:59 PM
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Sorry, I was assuming rear drums. I have seen soft brakes on an explorer that were caused by rusty rear rotors. New pads and rotors fixed the problem.
Again, did this issue start immediately after the front brake job?
 
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Old 07-07-2010, 03:14 PM
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I honestly don't remember because the front discs were warped so that's all I could feel until after I replaced them.
 
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Old 07-07-2010, 07:10 PM
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Hmmm... Assuming the pads and rotors are ok... Bleeding the brakes wouldn't be a bad idea, but it will only help your issue if there is air currently in the lines. Try pumping up your brake pedal with the engine off and see how hard it feels. If it is working correctly it will go down a little bit, but then feel very hard. If it still feels overly soft, try bleeding the system.
Another possible cause is the brake booster. If that is leaking it would feel like a soft pedal. To check the booster wait for several minutes after the truck is shut off. Pull the check valve off of the brake booster (this is the piece the main hose connects to). If there is a rush of air then you know it is holding a vacuum and working properly.
Make sure you do these tests separately, because when you pump up the pedal with the engine off, you are relieving the vacuum in the booster.
Hope this helps!
 
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Old 07-08-2010, 11:31 AM
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Just for the heck of it I replaced the rear pads and bled the lines. It is just as you describe...when you push on the pedal it get firm after you push a little.
 
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Old 07-08-2010, 11:55 AM
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Any change in the soft brake issue?
 
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Old 07-08-2010, 11:56 AM
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Originally Posted by ford norseman
Try pumping up your brake pedal with the engine off and see how hard it feels. If it is working correctly it will go down a little bit, but then feel very hard. If it still feels overly soft, try bleeding the system.
Pumping the brake with the engine off will ALWAYS make the pedal feel hard... unless you have a bad leak in the MC.

Pumping the brake depletes the vacuum and the pedal will get really hard.

Originally Posted by ford norseman
Another possible cause is the brake booster. If that is leaking it would feel like a soft pedal.
NOPE. A leak in the booster will reduce the vacuum and make the pedal harder.
 
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Old 07-08-2010, 12:02 PM
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Originally Posted by mkosu04
Pumping the brake with the engine off will ALWAYS make the pedal feel hard... unless you have a bad leak in the MC.
Or if there is air in the lines. If there is air you will be compressing that air every time you step on the pedal, so it will feel soft.


Originally Posted by mkosu04
NOPE. A leak in the booster will reduce the vacuum and make the pedal harder.
It will also make you press the brake harder when driving,some people describe this as a SOFT pedal. I'm trying to cover all the bases.
 
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Old 07-08-2010, 12:13 PM
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The rear pads were really thin. So when I pushed the pistons in the brakes did frim up a bit, I guess I will have to wait until after our road trip to check the MC, too damn hot to work on the truck.

One more thing... When I press on the brake pedal is sounds like I am compressing air.
Oh and I do have the adjustable pedals.
 
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Old 07-08-2010, 12:22 PM
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The adjustable pedals shouldn't make a difference. If you are hearing the "compressing air" noise when the engine is off, that is normal. The air I'm referring to in the lines you won't be able to hear.
If you replaced the rear pads and left the old rotors on, it may take a little time for the pads to break in. Once they do, you will probably feel an improvement in the brakes.
Also, typically if the MC is bad, the pedal will slowly go to the floor as the fluid leaks out. If this isn't the case, I would bet it is fine.
Remember to keep it in low gears when going down mountains and have a good trip!
 
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Old 07-08-2010, 01:06 PM
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Thanks for all your help!
 
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Old 07-09-2010, 12:15 PM
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Originally Posted by jdub96
One more thing... When I press on the brake pedal is sounds like I am compressing air.
You are probably hearing the sound of the air entering the booster around the brake pedal. This is normal.

Originally Posted by ford norseman
It will also make you press the brake harder when driving,some people describe this as a SOFT pedal. I'm trying to cover all the bases.
if somebody describes pressing "harder" as "soft" then that person is an idiot and beyond help.
 
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Old 07-09-2010, 03:23 PM
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Originally Posted by mkosu04
if somebody describes pressing "harder" as "soft" then that person is an idiot and beyond help.
I'll remember that next time a customer comes to me with an unclear description of the problem. I'm sure calling them an "idiot" and "beyond help" will make me tons of money.
 

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