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Discussion Starter · #1 ·
I have little to no breaking power until the pedal is about 75% depressed. Occasionally I can feel the brakes start to grab when the pedal is initially pushed but then it goes to that 75% mark before any real stopping happens.

I just replaced the drums, shoes, and hardware in the back and the rotors, pads, calipers, hoses, and hardware in the front. I bled the front only (did the rear a few weeks ago.) It stops much better, but this problem was there before I replaced all that.
 

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Assuming you don't have any hydraulic leaks elsewhere in the system, the system is properly bled and no air exists in the system and the rear brake shoes are properly adjusted, then it could very well be a faulty master cylinder. You may want to double-check the rear adjustment and then bleed the whole system, again, making sure you follow the factory service manual procedure just to be sure. I attached a copy of the 2003 Frontier FSM "Brake" chapter below; it should be the same for all 01-04 Frontiers, if not all 1st Gens.
 

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Discussion Starter · #4 ·
Assuming you don't have any hydraulic leaks elsewhere in the system, the system is properly bled and no air exists in the system and the rear brake shoes are properly adjusted, then it could very well be a faulty master cylinder. You may want to double-check the rear adjustment and then bleed the whole system, again, making sure you follow the factory service manual procedure just to be sure. I attached a copy of the 2003 Frontier FSM "Brake" chapter below; it should be the same for all 01-04 Frontiers, if not all 1st Gens.

No leaks.When you say the rear brake shoes are properly adjusted, you are referring to the shoe clearance adjustment talked about in the fsm? I believe I have that right. I just replaced the shoes drums and hardware. If anything I would suspect air.

I have bled all wheels but I'm nervous about opening lines to bleed the master cylinder because I'm not familiar with how to bleed the abs module right after the MC, is there a bleeder on that or do you have to take the lines off? I guess I need to look at it more.

Thanks for posting that section of the manual. I have the whole thing downloaded but I need to get it off an old computer.
 

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Yes, I'm referring to the drum to shoe clearance. You shouldn't need to bleed the master or the ABS unit unless one of them has been replaced or the whole system was ran dry when the calipers/hoses were replaced.
 

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Discussion Starter · #6 ·
Yes, I'm referring to the drum to shoe clearance. You shouldn't need to bleed the master or the ABS unit unless one of them has been replaced or the whole system was ran dry when the calipers/hoses were replaced.

I don't believe I ran it dry. The reservoir may have gotten low but I tried to keep a good eye on it. Is it worth trying to bleed the mc just to be sure?

I'll note that with the truck off, after pumping the pedal a few times, you can still push the pedal in a little way (maybe up to half) and hear a fluid like sound.
 

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Are you sure it's fluid and not the power brake booster that you are hearing? Usually a mad master cylinder will start allowing the brake pedal to gradually sink to the floor once pressure has been put on it. If you can pump up the brakes and then keep constant pressure applied to the brakes without it sinking, it's probably not the master cylinder. Bleeding the master cylinder wouldn't hurt if the lines aren't to bad to break loose.
 

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Discussion Starter · #8 ·
Are you sure it's fluid and not the power brake booster that you are hearing? Usually a mad master cylinder will start allowing the brake pedal to gradually sink to the floor once pressure has been put on it. If you can pump up the brakes and then keep constant pressure applied to the brakes without it sinking, it's probably not the master cylinder. Bleeding the master cylinder wouldn't hurt if the lines aren't to bad to break loose.

Could be, it just sounds to me like fluid rushing.

The lines and fittings look to be in fine shape. Is it best to totally remove them when bleeding it? I see the fsm refers to holding your fingers over the ports while bleeding. If I cap the lines to prevent any fluid from coming out of them do I need to bleed the ABS module and everything else downstream as well?
 

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Don't think you would hear fluid rushing through

The booster is probably leaking internally and the noise is a vacuum leak (air rushing through, you'll only hear it when you press the brake pedal and you'll probably hear it down by the brake pedal inside the cab when the truck is running)

But a slight air leak in the booster won't cause your problem of no brakes until you press it all the way

Did you adjust the star wheels inside the drums when you did rear brakes?
 

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Discussion Starter · #10 ·
Don't think you would hear fluid rushing through

The booster is probably leaking internally and the noise is a vacuum leak (air rushing through, you'll only hear it when you press the brake pedal and you'll probably hear it down by the brake pedal inside the cab when the truck is running)

But a slight air leak in the booster won't cause your problem of no brakes until you press it all the way

Did you adjust the star wheels inside the drums when you did rear brakes?

Well I hear the noise when the truck is off. Like when I was bleeding the wheels and my helper would step on the brake.

Yes, I adjusted the star wheels after I put the drums on. I went until there was moderate to high resistance while still being able to turn the wheel by hand. I don't have anything to measure how much weight it takes to turn them.
 

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Did you bleed all 4 wheels? It still sounds like you have air, in the lines somehow.
 

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Discussion Starter · #12 · (Edited)
Did you bleed all 4 wheels? It still sounds like you have air, in the lines somehow.

Yes all 4 wheels are bled. I didn't actually break into the system in the rear, since I didn't replace the wheel cylinders back there. But I bled the back a few weeks ago.

This weekend I'm going to try to bleed the mc and the abs module.
 
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