brake pedal feels low

turborich

turborich

Dedicated LVC Member
Joined
Dec 16, 2005
Messages
1,945
Reaction score
0
Location
las vegas
My brake booster went bad, I replaced it ( what a PITA job) No more vacuum leak & the booster seems to be working right, but my pedal feels lower then it used to. I never undid any of the master cylinder lines so that shouldn't be the issue.

The car stops but you can feel the pedal almost bottom out & you really have to put all of your weight on it to activate the anti lock.


Any ideas? :confused:
 
Bleeding the brakes and putting nice fresh fluid in would be the first thing to do, as it is good to change it every few years or so anyways as it asorbs water and will make for a spongy pedal.
Recheck your work to make sure vacuum lines are working to it etc.
Could be a bum master cylinder as well (leak internally) or a minor leak somewhere else...
 
As soon as you do extensive break work, you should bleed the brakes, always the first closest to the master.

It's going to leave air in the lines, thus you having to push further on the break pedal, thus you posting.

-Rick
 
How would there be air in the lines if I never opened them? I simply moved the master cylinder out of the way while the lines were still connected.

I am kinda leading towards the bad or not so good brake booster, I picked it up at autozone & now it's bitting me in the butt! When I push on the brakes the idle fluxuates a little bit. I think the new part is junk!

If I do need to return it I will get my money back & just pay 3 times more at Ford for a good part!
 
I got an original from Max for around 260 last year. (made by ATE) I wonder if the Autozone one is junk? Is the push rod length even the same?
 
Just a weird theory. But the new booster is working better, and thus assisting you better. You have been used to a weak pedal for a while and now its just easier to operate. Using the same force though, your bottoming out a pedal. This could mean you had air in the lines all along and never noticed. Just a guess though!
 
Brake

First thing bleed the master and all 4 brakes, even if you did not remove any lines from the master. If you rotated or changed the level of the master cylinder more then 40 degrees you can introduce air into the master cylinder.
 
+1 for bleeding the brakes, regardless if you removed any of the lines or not.
 
I will go ahead & bleed the brakes, The fact that when the brake pedal is depressed & the idle lopes around a little bit bothers me! That says there is a vacuum leak somewhere within the new booster. The old booster was good one day & bad the next. It just started leaking all of a sudden & you could clearly hear it in the car. A loud hissing under the dash. That noise is gone with the autozne replacement, however it shouldn't lope around when depressed. I have a feeling that I will be changing it out again. I'm not looking forward to it though! Kinda hard to reach all of those nuts under the dash.
 
Check the vaccum lines to the booster and others to see if it's low. Vacuum should be above 12 in-Hg at idle. It may sound silly, but check your front wheel bearings for play too as it can knock the pads outwards further and make for more pedal travel.

Is the ABS and Traction Control working normally?

Here's some things to check & read from the manual if you can get a MityVac pump or similar:

Brake Booster Operation Check

1. Check the hydraulic brake system for leaks or insufficient fluid.

2. With the transmission/transaxle (7002) in PARK, stop the engine. Depress the brake pedal several times to exhaust all vacuum in the system.

3. With the engine turned off and all vacuum in the system exhausted, depress the brake pedal and hold it in the applied position. Start the engine. If the vacuum system is operating, the brake pedal will move downward under constant foot pressure. If no motion is felt, the power brake booster system is not functioning. If slight motion is noted, the master cylinder o-ring is missing or out of position. Replace or reposition and perform tests.

4. Remove the vacuum hose from the power brake booster check valve. Manifold vacuum should be available at the check valve end of the hose with the engine at idle speed and the transmission/transaxle in NEUTRAL. Ensure that all unused vacuum outlets are properly capped, hose connectors are properly secured, and vacuum hoses are in good condition.

When it is established that manifold vacuum is available to the power brake booster, connect the vacuum hose to the power brake booster and repeat Step 3. If no downward movement of the brake pedal is felt, replace the power brake booster.

5. Operate the engine a minimum of 10 seconds at fast idle. Stop the engine and let the vehicle stand for 10 minutes. Then depress the brake pedal with approximately 89 N (20 lb) of force. The brake pedal feel (brake application) should be the same as that noted with the engine operating. If the brake pedal feels hard (no power assist), replace the check valve then repeat the test. If the brake pedal feels hard, replace the power brake booster.

If the brake pedal movement feels spongy, bleed the hydraulic system to remove air from the system. Refer to Hydraulic System Bleeding in «Section 06-06»
Click to expand...

The vacuum booster push rod (output rod) is not adjustable. The push rod length is set during assembly. A properly set push rod that remains within the power brake booster after it was assembled in production should never require service.

A power brake booster that is suspected of having an improper set push rod length will indicate either of the following:

l A push rod which is too long will prevent the brake master cylinder piston from completely releasing hydraulic pressure and cause brakes to drag.

l A push rod which is too short will increase brake pedal travel and cause a clunk or groaning noise from the power brake booster.

If necessary, booster push rod length can be verified with a depth micrometer using the following procedure:

1. With engine OFF, depress brake pedal several times to deplete vacuum in brake power brake booster.

2. Without disconnecting the brake tubes, disassemble the brake master cylinder from the booster.

CAUTION:
The brake master cylinder must be supported to prevent damage to the brake tubes.

3. Measure the push rod length while a force of approximately 22N (5 lb) is applied to push rod end. The correct push rod dimension is 28.3mm ± 0.3mm (1.11 inch ± 0.01 inch) as measured from brake master cylinder mounting surface.

4. If the push rod dimension is correct, assemble brake master cylinder to power brake booster. Alternate the tightening of the retaining nuts to 21-29 N-m (16-21 lb-ft).

5. If the push rod dimension is incorrect, replace the power brake booster. The push rod length is not adjustable.
Click to expand...
 
Is the ABS and Traction Control working normally?

I would asume it is? There is no brake light coming on.

Thanks for the great info you posted. I have checked most of that allready except for the rod length. I have verified that the only vacuum leak is within the remaned power booster. It seems to come & go though? Kinda weird. I even changed out the check valve. I will give it a few days to see if it seals itself up before I tear into it again. I will also bleed the brakes, it's just been too dang hot here lately! I might do it tomorrow night.

Again, thanks guys! I appreaciate the input. Sometimes you think you know it all & you find out you actually don't & need some help.
 
Well, it's the piece of crap power booster from autozone!!! The darn thing is still leaking vacumm internaly.

I know it has been talked about many of times before, Besides fluids, belts, hoses, spark plugs & stuff like that stay the hell away from that horrible store! I will never buy any actuall car part from that crap hole again!

I'll see if 5 star or team ford has a better price on a new ford unit.
 
Why is it when I read something on here that same thing goes on mine :( Now my brake pedal is feeling lower than normal. May be time to replace the master cylinder, lines, etc.... fun.
 
You must log in or register to reply here.

Members online

No members online now.
Total: 1,099 (members: 0, guests: 1,099)
Back
Top