Vaccuum issue affecting brakes?

[John]

I’m just trying to figure out of I have a brake issue or vaccuum leak. If I let go of the brake pedal as slow as I possibly can when i’m in drive. I can feel some shaking. There is not shaking or pulsating when braking. Any hits would be nice.
This is on a 2005 dodge ram with new pads, rotors and calipers. It was doing the shaking before new parts were installed.

Topic

[Its me]

Shaking can be caused by other issues. Is your engine shaking or the vehicle…Vehicle shaking can be tires, suspension parts, a tire balancing issue and u joints as well. How fast are you going when the problem occurs. Does it go away at certain speeds?

Karl

[John]

This is when i’m parked and i’m slowly releaseing the brakes, not applying the brakes.
It’s like engine starts shaking a little but the rpm gauge does not change. Sorry for the missing info, this is when i put it in drive and slowly start releasing brake.

[Gumpy Guss]

It could be a momentary vacuum leak in the brake servo.

If you hold it just right there can be position where the valves are just so, so it’s trying to both vent the chamber to atmosphere AND hold the manifold vacuum valve open to recharge the chamber with vacuum, which can somewhat lower the manifold vacuum and introduce an air leak of sorts, maybe.

I would not worry about it unless that bad spot gets rather wide, or if it really bothers you.

[college man]

check the hose and fitting to the brake booster. You could
cap the brake booster line and see if the symptom goes away.
Your brakes will become really hard to push. Do this in an
area of space.

[Bill]

When you apply the brake it’s using the vacuum stored in the booster. When you release the brake the booster has to restore the vacuum that it used to apply the brake. Under normal driving you would never notice it.

If you play with your truck long enough, I’m sure you will find all sorts of weird stuff happening.

[EricTheCarGuy]

I don’t think a vacuum leak at the brake booster would cause that. You may have some other issue that’s effecting the engine idle. Remember that the brake lights also activate when you depress the pedal. You could have a voltage supply problem that’s robbing the engine of voltage when you use the brakes. This can effect the idle. You might try checking system voltage to see if it’s above 12v. Not a bad idea to check the battery as well. Once you’ve ruled out an electrical issue, then you might start looking for vacuum leaks or other issues that could effect performance.

[Author]

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