Feels like brake drag but mechanics can find no evidence of that

2014 Mazda3 Sedan

Ongoing issue for more than a year.

Much worse during the winter.

Intermittent.

Symptoms:

  • Brake pedal is stiff at the top; first two inches of travel have a lot of tension and do very little.
  • In general, brake pedal requires extra force to stop car.
  • Nearly impossible to come to a smooth stop, no matter how much I feather the pedal.
  • Car requires a lot more throttle to get going, and frequently needs wide-open-throttle (floored) just for normal city driving.
  • I need to rev higher before shifting to the next gear.
  • At highway speeds, it’s very difficult to maintain speed without constantly pulsing the throttle.
  • Car feels shifty and unbalanced at highway speeds (but it’s subtle)
  • When I release the throttle I can feel the car subtly decelerating in my butt (also subtle).

It doesn’t happen all the time, but it almost ALWAYS happen when I follow this pattern:

  • Normal city driving for 10-15 minutes (car feels totally fine during this phase; all of the above are not happening).
  • Stop and engage e-brake for 10-15 minutes (this is me waiting to pick up my kid from school).
  • Symptoms begin when I disengage e-brake and drive home.
  • Generally speaking, car is fine again the next day.

Before you point out I now have a passenger so the car has to work harder, two points:

  • He’s only 65 lbs.
  • If I skip the e-brake and just put the car in 1st gear (and turn off), it doesn’t happen.
  • If I skip the e-brake and instead hold the pedal for the entire time, it does happen sometimes.

When it happens, the following does not work, and often makes it worse:

  • Aggressive pumping of the brake at red light.
  • Generous yanking of the e-brake handle.

When it happens, the following sometimes fixes it:

  • Find a hill and let the anti-rollback thing release the brake for me.
  • Get the car rolling gently then slam on the brakes (if I hear “ERRRR”, it’s good).

Both rear calipers replaced in the last three years.

Other observations:

  • General vibrations in the car feel “waxy”, if that makes any sense.
  • Even blipping the throttle while out of gear it seems to have less response, but that might be my imagination.
  • The car does roll gently in neutral.
  • The rotors are not excessively hot after a normal drive, but I have some evidence of one rear rotor being about 20C hotter after a long drive (60C vs. 40C, not crazy).

So, are the brakes dragging? The mechanics at my dealership say no. They’ve found no evidence of it; the rotors are fine. No discoloration or warping. Also, the wheels spin freely when they lift it up. They say even if it was dragging a little, sometimes, they’d be able to see evidence. Also, the e-brake spring/levers seem fine.

I’m at my wit’s end because the car is an absolute nightmare to drive when it’s happening (mostly because the throttle seems muted, but the jerky braking is also annoying).

I’m wondering if it has something to do with how long the pads are glued to the hot rotors. More than 15 minutes and it’s cooled down. Less than that (stop sign), and it’s not a problem.

I’m considering selling it (since they’ve said it passes safety with flying colors), but that feels unethical to me.

Thoughts?

That sounds like a brake booster problem and/or master cylinder. Has the brake fluid ever been changed?

I’d also suggest that each of the rubber brake hoses is likely due for replacement. When they fail, they act like check valves and act like a dragging brake, although you can generally can test for that by checking the rotor temps. Yours seem a touch high at 60 and 40C. They are cheap and if you are getting a brake fluid change, I’d do the hoses at the same time.

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I’ve had the car for 5-6 years. Lots of brake work in that time, but not a full flush. I’ll request that the next time I take it in.

Are they correct in saying they would see some evidence of this, though? Even really subtle dragging would show up on the rotor?

I don’t know how the mechanics tested this.

Brake companies would drive a course that would not require braking at all after pushing the pedal a couple times before driving. Once coasting to a stop, the rotor temp is taken. A zero drag corner will be the same temp as ambient. That is the goal of modern fuel efficient cars. It is easy to do this yourself with a non contacting temp gun and a large parking lot.

In 5 to 6 years you should have changed brake fluid twice by now. Every 3 years is recommended or required, depending on the car.

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Thanks, perhaps they did change the fluid then. I’m up to date on all maintenance (and they are quite vocal about it when I am not).

I have a non-contact (IR) thermometer that I’ve been using to get a sense of what’s happening.

My understanding is that there is always a bit of friction on modern-day disc brakes, so the temp will always be elevated, even without braking, but I’ll try your suggestion.

For the past three days the car has been 100% perfect, with the only change being that I have not been using the e-brake while waiting to pick up my kid from school. I continue to use it in my driveway and when I make longer stops. The amount of time the pad is in contact with the rotor seems to be playing a part…

Don’t assume that it was done unless you have hard copy documentation to prove it. A surprising number of people–including at least one member of this forum–claim that it’s not necessary.

Back in 1976, I bought a genuine Grandma car, a 1960 Ford Falcon, with ~17k miles on the odometer. While I was able to confirm that the oil had been changed once each year, there was no proof of brake fluid flushes, so on day two I took it to my mechanic. When the mechanic drained the brake fluid, he stated that the fluid was “more water than brake fluid”. :unamused:

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So maybe there’s some particulate matter in the line, and when I release the pedal, some pressure remains and a sliver of the pad stays in contact with the rotor? And then overnight it manages to relax fully? Is that a working theory?

Yes, that is possible. It is also possible your master cylinder seals are shot.

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I really appreciate your engagement on this.

Last question for now: I know the e-brake system is essentially mechanical and not related to the hydraulics, but when the caliper is engaged that way, does it still force movement of the fluid through the lines? The difference being a pull versus a push? Do you figure that’s how/why the e-brake is implicated?

That is correct. The piston extends and is backfilled by fluid. If there was crud in the lines, that could affect it.

Also keep in mind the master has little holes, the ABS unit also has little holes and all are connected.

You need a brake fluid flush and change anyway, so prove or disprove the theory by getting it done.

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Excellent. Thank you.

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You can use brake fluid test strips to check the condition of the brake fluid…
Some shops (bigger ones anyway) use them and would probably check it for free of you asked…

+1 for Mustanmans advise on checking for drag…
I have also, after the vehicle has been sitting for a while, maybe over night, then push the vehicle (on a flat level surface like a garage) and see how far it rolls before stopping… Then drive it for a little while to get everything up to operating temp then check it again in the same spot, see if it is harder to push or stops shorter then before…

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Thanks, I may try that.

There are lots of little things I’ve noticed that indicate it’s happening. For instance, there’s a steep hill I need to drive down regularly. When it’s doing it’s thing, I can coast down it in 5th gear and the car won’t accelerate past 60kph, which is fine, but considering the grade and high gear, it should be a runaway. When the car is operating normally, I need to use 4th or stay in 5th and apply the brakes a bit.

Just wish it was more obvious to the techs. Feel like they’re gaslighting me when I go in, lol. But I’m happy to pay for the flush and new hoses to start ruling things out.

The pads are supposed to retract slightly when you release the brake. This is accomplished by two actions; runout of the rotor and the piston seals in the caliper. The brake piston seals rotate in their groove when the piston is pushed out during braking. This results in tension in the seals and their elasticity is what causes the piston to retract when hydraulic pressure on the piston is relieved. If these are older calipers, the rubber seals may be aging and not as elastic as they once were. All rotors have some runout and that often helps retract the pads from the rotor surface as well. Of course, crud accumulating in the piston bore can also impede retraction. Maybe some other things to think about when the other options are exhausted…

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Interesting…

Regarding age: Both rear calipers were replaced in the past 2.5 years (along with new rotors). Both calipers had “seized”. I brought the car in…because the brakes were dragging. :slight_smile:

Plus 1 for Mustangmans advice. also, would replace the rubber brake hoses like he mentioned. they can collapse or deteriorate from the inside.

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At a time you are noticing this problem, pull over to somewhere safe, out of traffic, and jack up each wheel, one at a time. Do they spin freely? The front wheels won’t spin as freely as the rear b/c car is FWD, but even the front’s should still rotate by hand easily. May be easier to do using a small bottle jack than messing with the screw jack that came w/the car. If any of the tires are really difficult to hand -spin, you now have the evidence. (This might not work on the front unless both front’s are jacked at same time.)

If there really is a brake-drag, most likely causes

  • faulty rubber brake hose
  • faulty power booster
  • faulty wheel bearing
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I jacked up the rear with the tiny emergency unit one day. Both rear wheels spun freely, but the car had also been at rest for awhile. This theory of bad brake hose ± bad fluid is starting to make a lot of sense. It sorts itself out, just takes time. I will say that over the winter, it basically never fixed itself. It was bad the entire season (so I rarely drove). First hot spring day it was magically better.