Brake disc wear

well done. are they scored or anything? how are the pads?

 

40 to 43% still seems an awful lot of wear for 58,000 miles. Mine seemed to be down by about 65% at 210,000 miles, after machining ... and I turned out to have some sticky caliper conditions speeding up the wear. So it's probably worth taking things apart to make sure they all move nicely.

How about runout - spinning the rotors by hand with a dial indicator resting on the surface near the rim, do they measure flat and straight?

-Chap

 

Brakes are brakes. While the Prius has shown less wear and less problems than most, they still require maintenance and monitoring. The ONLY other car I have ever owned that has had the same or less problems with brakes is my 2006 TDI Beetle...although the this specific vehicle has had many other maintenance nightmares.

 

Maybe OP's discs have been turned?

 

without his knowledge?

 

Might be embedded in a brake job invoice? Some dealerships are pretty trigger happy, machining rotors routinely. I think part of it is their need for fast, quantifiable results.

The other side of the coin: my rear rotors were pretty knackered, due to misalignment between pad and piston I think. The rotors were scored, and inside faces had a lot of rust.

I put in new pads, was careful with aligning and seating them. And it sounded like crap for a week or two: it took a while for everything to get back into equilibrium.

It did, the rotors look great now, but it took a while. But maybe a dealership doesn't want to go this route: they just machine them, no phone calls.

 

Never trust a dealer, ever.

 

sounds reasonable. i don't think i could get a written resonse like that from any dealer i've ever been to. i guess you'll have to have a look at the pads.

 

You hear a lot of talk about replacing rotors with new pads. I've never subscribed to that, just replaced pads, over the years. Works out fine every time.

I've only once had rotors get down to minimum thickness, and in that case the car seemed to be "eating" pads, every 30k km's or so, pads not releasing properly, for reason I never resolved. Sticking piston? Anyway, one disc finally cracked.

The car felt like it had a broken back every time you stepped on the brakes. I checked the discs and found the crack. Brought it in, reporting that I'd seen a crack. They called back half hour or so later, saying it was all fine, and no crack. I told them to check again, and then they found it. It was at that point I lost all faith in that dealership.

They had a very good service manager at the time, very knowledgable, helpful showing you the options when there were repairs needed. Anyway, we talked on the phone that day, he acknowledged they'd completely dropped the ball on the cracked rotor.

He didn't last long there though: I heard he's teaching in a local community college now, a better fit.

 

agreed, there must be a spec on when discs need smoothing or replacing, but i would just eyeball it. from the dealers point of view, it's the perfect scenario. he takes no chances, presents you with brand new brakes so to speak, with less chance of problems, and makes money in the process.

 

Pardon the sidebar question, but wouldn't rotaries (you call them roundabouts) make for less rather than more brake and tire wear???

Americans are rather poor drivers.
We have trouble even with binary intersections, let alone something that actually requires one to put down the phone and drive......but I always thought that rotaries would make for fewer stops and with a little forethought, better mileage and smoother traffic flow.

I still think that something is amiss.....unless you deliver the post or are in practice for a for an upcoming Formula-1 race.
Sorry,
I'm not seeing a 3-year old, 60,000 mile, adult-driven Prius as a candidate for new brakes.

 

From the 2010 Repair Manual:
Brake Pads
New - 10mm
Minimum - 1 mm

Discs
New - 25mm
Minimum - 22mm

The manual says to measure the pads with a ruler, the discs with a micrometer. A "Visual Safety Report" is just that.
Get a second opinion and have them let you watch when they measure.

 

If either of the above measurements are nearing the lower limit I would replace sooner than later. Especially the pads: if I open up a caliper to find pads at say 3mm, I'd leave it open, make a verification phone call and walk to the dealership ( blessedly nearby), for new pads. And likely replace the shims as well. The end clips seem to last forever, maybe stainless?

 

Assuming the rotors are in spec and not gouged or heavily grooved, you can just change the pads. Some recommend ""lightly"" scuffing or sanding them to cut the glaze or rust before installation, but either way you will be just fine. It's a good idea if you do this to hit an empty parking lot to bed or cut pads in though. This also gives you a good excuse/opportunity to flush the brake fluid while your at it.