2018 Prius Brake problem 35K miles

I experienced strange braking behavior on a recent trip, similar descriptions on this thread. I've had warped rotors on an F150 in the past but I haven't driven my prius in any similar conditions which would have caused warping.

Last month I was driving a long downhill section of highway with tight turns. I was stuck behind a car which was taking the turns very slowly, so we would speed up then hit the brakes pretty hard. Conditions were cold and dry, but there had been snow in the area the week before. At first, the brakes performed normally, but then about 1/2 way down the hill the car would shake violently when I applied the brakes. This is the one and only time I've experienced this. It cleared up and even with hard braking on highway or city I haven't felt it repeat.

The feeling was very similar to when I had warped rotors on the F150, but my dealer explained it as just ABS kicking in. I will admit that compared to my 2012 prius with Michelins, this 2018 with stock tires will engage ABS much more frequently - particularly in city driving. But when the shaking occurred I was too preoccupied with driving to notice whether the ABS light on the dash was turned on. Looking forward to getting new tires as these stock shoes are pretty awful.

I'm going to just monitor this and see if it repeats, but thought I'd add to this thread in case others experience similar behavior.

 

I believe what you experienced is called brake fade--the reduction in stopping power that can occur after repeated or sustained application of the brakes. The pads and rotors heat up and rather than grabbing, they just slide, kind of like butter sliding around a hot pan. Perhaps this didn't affect both sides equally, and caused the ABS to kick in (which pulses the brakes) when one wheel sped up compared to the other. This explains why the condition cleared up after the brakes cooled down to normal temp. This sounds like a situation to use the B mode to add engine braking when running downhill. The only other "cure" is to pull over and let the brakes cool down. Pikes Peak Highway in Colorado has a brake check station on the way down to make sure brakes don't overheat and become dangerously useless on the way down. They also warn about using a lower gear (B mode in the Prius).

 

Interesting - thanks for that input. It does sound consistent with the symptoms. I'll keep an eye on it, and definitely agree the B mode is really helpful. Cheers.

 

Sounds normal to me, if braking hard. On regen braking the ABS doesn't apply until the hydraulic brakes kick in, if one wheel lets go then it feels like the car is surging forward, you then brake hard and the hydraulic brakes and the ABS kick in quite violently.

 

I am also going through the same thing with my 2018 Prius! I'll slightly push on the brakes and I'll immediately start feeling the pulsating. Also when I tap on the brakes, it makes a creaking noise after it comes to a complete stop. As I hold on to the brakes, it sounds and feels like clicking. Not sure if it's something electrical from the brakes but it's acting weird. I want to know if is something to worry about since I only have 32,000 mi on it.

 

Have you ever had an in-depth brake inspection, where the calipers are pulled off the rotors, pads/shims/caliper pins inspected, cleaned and relubed?

Not guarenteed to fix, but a good first step, if that's been neglected.

 

MendelLeisk: I understand your post, and the possible need for an in-depth brake disassembly/inspection to isolate a problem. I assume, at 32-35k miles, that this these issues are the exception and not the rule.
Is it possible that, since we're discussing brakes on a hybrid, that these parts might be more susceptible to corrosion/rusting, since they're not being exercised as vigorously as on a pure ICE auto?
My 2014 Avalon hybrid is at 111k miles, and brake wear is about 50%. Everything is functioning as designed. I'm wondering if there will be issues with disassembly of some of these parts if they're not serviced?
I chose to remove and replace spark plugs on the Avalon around 75k miles, not because they were worn out, but because I was concerned they might be seized to the aluminum head. They came out w/o issue.
For sure, I'm OCD about these things, always want to be proactive with maintenance rather then reactive!!!

 

Toyota is "vague" to put it mildly, but they have two mentions of brake maintenance in the US schedule. First, every 5K miles or 6 months they call for a cursory visual inspection:



Then every 30K miles or tri-yearly they say this:



And:



The Repair Manual has an extensive section on brakes, but unlike Honda Manual, which will have a spection section titled "Brake Inspection" (or similar), the Toyota document just lumps everything together, including a complete calliper overhaul (which likely would never be done).

You're pretty much on your own interpreting what needs doing at a brake inspection. I fall back on the Honda guidelines:

1. Pull off the caliper and clean and lube it's contact points with the pads.
2. Remove pads, separate the shims, clean and relube all contact surfaces.
3. Pull the caliper glide pins, clean and lube.
4. If there's any evidence of pulsing or the car's getting on, check the rotor thickness and runout.
5. Check and record pad thickiness.

 

I would love it if any UK car dealers' service department did this, but unfortunately they don't, they just inspect and don't dismantle unless replacing parts. They would rather your calipers and or pads stick, that way they get new pads, calipers or both out of you more often.

 

kithmo: I agree. We have annual safety inspection, which is entirely visual. As I said above, in 6 years, 111k miles, my brakes have never been touched.

Should I/we be disassembling/lubing brakes every "X" number of miles? I'm not dealing with road salt, so undercarriages are usually free of rust.

 

@pianewman when I was younger and fitter (and drove many more miles) I used to dismantle and lube the brakes on my cars every year before our annual inspection (MOT), but since I've been buying newer cars and using dealer servicing I've just resigned myself to the fact that it doesn't get done and hope they don't stick before I trade the car at 5-6 years old.

 

...ditto. On my 2005 Tundra, caliper pins needed to be driven out with a drift punch, corroded in place. However, that was after 3 years in Michigan (serious road salt), 4 years in Northern VA (some road salt).

 

Caliper pins cannot be driven out with drift pin on Prius; they're in blind holes. I like to do a full inspection every 3~4 years. DIY, It's a couple of hours for the front or rear, costs nothing. Four years now, cus our usage is getting SO low.

 

I just fitted my snows for their breakin. So between the new set of 4 just installed than removed to fit the new snows, I'm noticing both fronts look a bit off. Both rears are ok with a silly mm on the outside outer edge of the rotors I can catch my fingernail on. I haven't seen the backside of any of the rotors yet. And I know there's not much I can do to fix the current front rotors unfortunitly.


Still, I'm glad I noticed them at this point before they wore even more.

edit: Before I'd noticed thses front rotors, I mentioned in another thread related to my current EV range, that I can hear my brake pads rubbing on the rotors a lot longer than I remember hearing that noise in previous EV trips. It's really hard to notice stuff like that when driving any car the same way day after day as the difference isn't noticable between trips.

 

Looks like significant portion of the rotor is not making good contact, rusting up. Maybe @ChapmanF can comment?

 

thanks Mendel. My first thought is to pull the calipers, check the backsides of the front rotors, pull rotors and do a rube goldburg on the outer edges of the rotors since I can't find anyone that still turns rotors, check the pads for uneven wear and reassemble. I actually thought first to just replace the front rotors and pads, but I'm not sure the wear is that unusual yet. Besides, I have other more pressing vehicle chores ATM ....

 

Close to 300 miles ago, I think, the caliper pins loosened up enough in heavy traffic and hard braking that I heard and felt some ugly brake behavior. The pads were, I think, grabbing those outside edges for about 200 miles. The noise and grabbing has settled down again and I think the pads are back to the shiny parts of the rotors, but the right front pad(s) is (are) still rubbing on the rotor.

yuck
maybe next spring- if I live that long.

 

I'm still open to suggestions about why my front brakes are wearing so quickly.
removed the 4 anti-rattle clips 04947-42050 from the caliper mount bracket 47721-47060 and the 2 wear clips from the pads with gloved finger pressure.
Although one rattle clip was a LOT tighter than the other 3.
Inside pad was worn-out, a few mm's from bare and outside pad was barely-worn. hope that sentence is not a mirror image, upside down and inside out... There was virtually no runout on passenger or driver side. The runout gauge jumped around as I ran it across the outer rusted edges, the gauge showed no movement on the inner shinny area. The caliper slide pins were tight but not bound.

Could a bit of precision filing of the caliper mounting bracket so the rattle clip slides into place evenly like the other three be all I'm looking at?



it got dark and started to rain, of course.
Saw the brake light on the dash for a half a sec as I touched the brake pedal the first time after going into (Ready), even after I pumped the pedal a few times before turning the car on.

 

Do you live near the ocean? Our ocean-side residents have rust issues like that.

 

The brake calipers need a good and complete rebuild; new pins for sure. To save some costs and labor, check out rebuilt calipers if available. A stuck pad that rapidly spent itself against the rotor probably means rotors are worn out too or at the least very uneven wear now.

GOOD LUCK!