Brake pedal goes deep when stopping

[Shane Mckinley]

A couple weeks ago I replaced front rotors and pads.

The pedal seems to go fairly deep when stopping.

The following is the rear brake shoes which I have parts intending to change if need be. However this looks like MAYBE 50% wear and it might be more beneficial to replace the master cylinder.

Ideas? I know I’ll have to do a complete bleed when I do this.


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2005 RHD TJ Sport
2010 BMW 528xi

 

[toximus]

What is the fluid level at?

 

[Shane Mckinley]

It’s full


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2005 RHD TJ Sport
2010 BMW 528xi

 

[jeepins]

IF you change the MC... I'd put the new shoes on as well.

 

[Shane Mckinley]

I only have the brake parts for the rear. I’m second guessing changing the rear pads and hardware as that doesn’t look THAT bad wear wise

I am asking if I should replace the master cylinder ?

I don’t feel like I’m in danger. The Jeep stops fine. I just think the pedal acts a little weird and that points to the MC

Opinions?


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2005 RHD TJ Sport
2010 BMW 528xi

 

[JEEPCJTJ]

Was the fluid level really low when the front needed done? Was the brake pedal ever pushed while the calipers and/or pads were "off" the Jeep? If both, or either answer is yes I'd try bleeding before changing the MC.

Actually I'd probably try bleeding even if the answer was no. Bleeding is somewhat easier that changing the MC and a heck of a lot cheaper.

 

[Shane Mckinley]

Was the fluid level really low when the front needed done?

Yes

Was the brake pedal ever pushed while the calipers and/or pads were "off" the Jeep? If both, or either answer is yes I'd try bleeding before changing the MC.

No

Actually I'd probably try bleeding even if the answer was no. Bleeding is somewhat easier that changing the MC and a heck of a lot cheaper.

Can you quickly explain how to bleed the MC?

I know the process wheel by wheel but not at the MC

Thanks




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2005 RHD TJ Sport
2010 BMW 528xi

 

[Farmergreg]

I'm not aware of bleeding the MC other than bleeding out at each wheel.

(I replaced all the calipers, rotors, pads on mine and bled the ever-loving shit out of it. Both by pushing pedal and releasing the bleeder and using a Midi Vac to draw two quarts of fluid thru....and I still feel like the brakes "aren't there" like they should be.)

 

[Shane Mckinley]

I'm not aware of bleeding the MC other than bleeding out at each wheel.

(I replaced all the calipers, rotors, pads on mine and bled the ever-loving shit out of it. Both by pushing pedal and releasing the bleeder and using a Midi Vac to draw two quarts of fluid thru....and I still feel like the brakes "aren't there" like they should be.)

That doesn’t make me feel better lol


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2005 RHD TJ Sport
2010 BMW 528xi

 

[Jorge Bolivar]

If after inspection, no leaks are found.
Bleed the lines this way,
Rear pass
Rear driver
Front pass
Front diver

Try to pull as much fluid you can. I do usually use 2 qts.
I do use my Mity Vac tool, the part i do like the most is the clear tubing, because allow me to see if fluid has air on it.
If fluid is foamy, air is been absorb somewhere.

Clear tubbing can be also use it with pedal push and bleeder realese method is preffered.

 

[Shane Mckinley]

Is there a need to close and pressurize repeatedly at each wheel

I just looked and I don’t have any clear tubing so I’m assuming so. My bottle needs to be clear at least


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2005 RHD TJ Sport
2010 BMW 528xi

 

[Jorge Bolivar]

Should ask,
Did you see any leak between the Master cylinder and the brake power booster?

 

[Jorge Bolivar]

Is there a need to close and pressurize repeatedly at each wheel

I just looked and I don’t have any clear tubing so I’m assuming so. My bottle needs to be clear at least


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2005 RHD TJ Sport
2010 BMW 528xi

I do usually does it 3 times per tire or untill air is not see it. Air is not good, this will be the deciding factor on how many times per wheel. I do guess that is a personal preference on this that may vary depending on the expert level.

Clear tubbing just help to see thru, a clear bottle will let you see the fluid. You will notice when the bleaded fluid has air on it and when is not.

 

[mrblaine]

Was the fluid level really low when the front needed done? Was the brake pedal ever pushed while the calipers and/or pads were "off" the Jeep? If both, or either answer is yes I'd try bleeding before changing the MC.

Really low may be an issue. Pushing the pedal with the caliper off is not an issue. There is not enough volume in a pedal stroke to fully extend the pistons or deplete the fluid level to where it needs bench bleeding again.

Actually I'd probably try bleeding even if the answer was no. Bleeding is somewhat easier that changing the MC and a heck of a lot cheaper.

Good advice. A bleed will tell you if the problem is air in the system.

 

[mrblaine]

I'm not aware of bleeding the MC other than bleeding out at each wheel.

(I replaced all the calipers, rotors, pads on mine and bled the ever-loving shit out of it. Both by pushing pedal and releasing the bleeder and using a Midi Vac to draw two quarts of fluid thru....and I still feel like the brakes "aren't there" like they should be.)

Throw the vac thing in the trash where it belongs. This is for you and the OP.
To bench bleed a master perfectly every time and at the same time diagnose its functionality.
Put master in a vise clamped by one of the mounting flanges only. Do not clamp around the bore.
Acquire two plugs for the ports.
Insert plugs finger tight.
Fill master with brake fluid from a sealed container. (that doesn't mean a fresh bottle, just one that has been stored with the cap tight)
Stroke push rod in and out a couple of times.
Open front plug like a bleeder and while open, push the rod in all the way and hold it. Close plug and let rod out slowly. The vacuum created will pull fluid from the reservoir into the bore.
Continue until you push in on the rod with the plug open and fluid comes out around the threads. Close plug while fluid is coming out and make sure it is tight enough to seal.
Move to back port and repeat.
Once you have fluid at both ports and sealed, continue stroking the pushrod in and out until you get to the point that it will only go in about 1/8-3/16". It is now ready to bolt onto the booster.

Now for the diagnostics part. A bad master will not bench bleed correctly. It won't get to the point where you can only push in the rod the small amount. It will bypass fluid around the seals and you can feel that happening. You can not tell this with any other bleeding method like the little hoses, vacuum bleeders, or power bleeders. You can only tell this by manually bleeding with the above method. It is no fun installing a bad master after bench bleeding and doing all that work to only have to do it again or chase your tail thinking it is something else because you new out of the box master is bad. BTDT and it sucks.

 

[mrblaine]

If after inspection, no leaks are found.
Bleed the lines this way,
Rear pass
Rear driver
Front pass
Front diver

Try to pull as much fluid you can. I do usually use 2 qts.
I do use my Mity Vac tool, the part i do like the most is the clear tubing, because allow me to see if fluid has air on it.
If fluid is foamy, air is been absorb somewhere.

Clear tubbing can be also use it with pedal push and bleeder realese method is preffered.

If you can not bleed the system using a half pint of fluid after the master is full, stop and find the problem, all you are doing is wasting fluid.

I should also mention that all bleed of the corners needs to be done with the key on so you can see if the dash light is being tripped by the safety valve being shifted.

You are correct on the clear tubing. It is a visual aid to watch for bubble free fluid and no other reason.

 

[mrblaine]

Is there a need to close and pressurize repeatedly at each wheel

I just looked and I don’t have any clear tubing so I’m assuming so. My bottle needs to be clear at least


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2005 RHD TJ Sport
2010 BMW 528xi

That is the only reliable 100% works every time method. Yes, you should use clear tubing to see what is going on.

However, you do not pressurize. You open the bleed screw first, have the pedal pushed down hard and fast, hold at the bottom, close bleeder, let pedal up. Repeat 3-8 times per corner.

 

[mrblaine]

Should ask,
Did you see any leak between the Master cylinder and the brake power booster?

Can't see that without pulling master and peeking in booster generally. If that has happened, buy a new booster because yours is either dead or about to die. The rubber in boosters is not brake fluid compatible.

 

[mrblaine]

I only have the brake parts for the rear. I’m second guessing changing the rear pads and hardware as that doesn’t look THAT bad wear wise

I am asking if I should replace the master cylinder ?

I don’t feel like I’m in danger. The Jeep stops fine. I just think the pedal acts a little weird and that points to the MC

Opinions?


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2005 RHD TJ Sport
2010 BMW 528xi

Pedal height in a drum disc system is highly affected by rear shoe adjustment. If you pay attention you will notice two things as the rear shoes wear down. The first is the parking brake sets higher in the stroke and the second is the brake pedal moves lower. The first thing to do is adjust the rear shoes in the drums until you get slight drag and see if that changes pedal height.

 

[Shane Mckinley]

Pedal height in a drum disc system is highly affected by rear shoe adjustment. If you pay attention you will notice two things as the rear shoes wear down. The first is the parking brake sets higher in the stroke and the second is the brake pedal moves lower. The first thing to do is adjust the rear shoes in the drums until you get slight drag and see if that changes pedal height.

Can I do this repeatedly backing up or should I take the wheel and drum off and adjust the screw manually?


Sent from my iPhone using Tapatalk
2005 RHD TJ Sport
2010 BMW 528xi