Disc Wear Survey

[Wooster]

I'm trying to find out what is 'normal' wear for the front disc rotors on the Gen 3 Prius.   Have any of you had your front disc rotors replaced due to normal wear - and if so, what was the mileage covered by the car at the time?

[PeteB]

When I traded my Gen 3 (2012 post facelift T3) for a Gen 4 it had done 60,000 miles with 6mm pad remaining and disc reported as "good" (whatever that means!).

See also my post here:

 

[Mick F]

Brakes wear the more you use them.

Comparing mileages from one person's use to another's, is pointless.  If you live in Norfolk or the flat lands of mid-USA and compare the mileages achieved by them to someone's car in The Pyrenees or Cornwall, you will find that hills need brakes and flat places rarely do.

Mick.

[kithmo]

Or in some cases, with the Prius and its regen braking, they wear faster because they don't get used enough. 

[PeteB]

I agree it's true type of usage (terrain, weather and driving style) will have a large bearing on brake life, it's not completely wasted to have this discussion, particularly with cars that have partial regenerative braking, as it can give an indication of what's possible.

One thing I've found (even before I lived in Norfolk) that using the car almost every day and without any special tricks like reverse braking or braking in N to rub the discs, the brakes do seem to last better than ordinary petrol/diesel cars with no regenerative braking.  And that despite the fact my Hybrids have not been garaged.  Infrequent use will have a detrimental effect.  Even in some of the more aggressive Hybrid driving I've observed in others, part of the braking will be handled by the regen system so that the brake wear will be reduced compared to conventional braking (except on some Hybrids like the Mitsubishi Outlander PHEV if the driver selects 0 regen out of the 6 available settings).

One thing that surprised me in a couple of 2,000/2,500 mile tours of Scotland and some trips in hilly parts of Devon, was that going down 20% 6 mile long gradients was possible on regen braking alone if one resisted the temptation to use B mode (unless necessary to aid control or safety) until after the HV Battery was completely full (with took a surprising amount of time after the last HV gauge bar was lit).

 

[Wooster]

Thanks for your replies.  I agree with everything you've said!  Perhaps I'd better explain my curiosity.  I have a 2010 Prius, 67000 miles, bought second hand from a Toyota Main Agent about 2 years ago.  Full Toyota Main Agent service history.  According to the 'customer portal' on the toyota.co.uk website - where I can see my car's service record - the front disc rotors were replaced 21,000 miles ago.  I had my car MoT'd last week and an 'Advisory' said "Front Brake disc worn, pitted or scored, but not seriously weakened" I think I'm gentle on cars - I regularly get 62 to 65 mpg and I sold my Gen 2 Prius (2 years ago) with 72,000 miles on it - and with the original rotors and pads. 

My thought are:  1)  Gen 3 rotors could be much, much softer than those fitted to the Gen 2.   2)  The Toyota main agent who changed the rotors fitted non Toyota parts.  3) The Toyota main agent did NOT replace the rotors at all.    As the previous owner was UK Power Networks, I'm guessing the driver didn't pay the service bill, nor did he care what was done to it.  So, No 3) is my favourite option!

I guess what I'm asking is:  Is it as outrageous as I think it is (or even totally impossible) - to have the rotors wear out in 21,000 miles?

[PeteB]

16 hours ago, Wooster said:

...what I'm asking is:  Is it as outrageous as I think it is (or even totally impossible) - to have the rotors wear out in 21,000 miles?

It's absolutely possible.

As I explained in a post link above, a Gen 1 Prius I once owned and kept until it was 9 years old with 163,000 miles on the clock "had minimal wear showing as the car reached 70k, but then for a year I used a company Prius and mine only got driven once every week or two, and then usually for short journeys.  The rust was the killer, and the brakes were very noisy with grinding sounds and all the discs/pads needed replacing within the next 10k miles.  The car was then used daily until I sold it at 9 years old with 163k and the discs/pads were still well under half used.  This car was not garaged either."

Although a lot of other factors can influence disc life, infrequent use seems to be a major enemy due to the cycle or rust while standing and brake wear on the occasions the car is driven.  I've heard of lots of other reports of brake rust and subsequent demise due to low usage.

Both my Gen 3 and 4 Prius were used almost every day it and looked like the brakes (discs and pads) would be good for nearly a quarter of a million miles if the wear continued at a linear rate.

I was a bit disappointed that Toyota didn't improve the mix of metals used in OEM discs to counter the tendency to rust with low use.  For the Gen 1 Prius they were prepared to replace discs that rusted prematurely, but after this they changed the wording of the warranty so they didn't have to do this any more - a cheapskate alternative!

[FROSTYBALLS]

As the car was previously a company vehicle, the owner, UK Power Networks, may have stipulated that cheaper parts were fitted to keep their costs down.

[TonyHSD]

That is normal, the discs were rusted not worn out, lack of use and the weather conditions. I changed all my discs and pads when I had the car because of the same reason, mileage was 42000 5 years old car, now I am getting close to 130k all brakes more than a half life remains, but I do clean and lube them once or twice a year, this is very important to keep them nice and clean and prevent rust issues. 
Regards 

[Wooster]

The discs are necessarily rusted.  The Mot mechanic has to click on a fault code. The words "Front Brake disc worn, pitted or scored " is the catch all phrase for anything wrong with the disc.  All I'm saying is that I had a Gen 2 and now a Gen 3.  Both have been run in virtually identical conditions.  Both about 12,000 miles a year, garaged in the same area.  Both molly coddled by me.  The Gen 2 had the same discs & pads after 70+k miles.  The Gen 3 has  "Front Brake disc worn..." after 21k miles.  Can  this be a true reflection of the difference in quality? 

 

 

[Stivino]

It's more likely to be a reflection of the guy who is looking at them.

[QuantumFireball]

A common problem with the rear brakes on the Gen 3 is the caliper slide pins (guide pins? I forget which is Yank English) seize and cause uneven wear, leading to corroded discs. Mine were not in a good state when I got it at around 40k miles, but replacing the pins and lubricating properly seemed to sort things out. The rear discs still seem a bit discoloured but not rusty (except lip around the edge), and seem to perform OK.

I haven't seen this happen with the front brakes, but they get used more.

Mine's at about 73k miles now, I've since replaced the rear pads (uneven wear was also the cause of that) but nothing else. I don't know if the discs are the originals, but the service history suggests they were never changed.

[BJ Ingwersen]

2011 Prius Hybrid Gen 3. Purchased 2015 with 38, 000 miles. 61, 000 miles-rear brakes and rotors, 2017. 92,000 miles- front brakes and rotors, frozen rear brake caliper, left side, replaced, 2020. 118, 000 miles- rear brakes and rotors, Nov. 2022. 126,000 miles-all brakes and rotors, frozen rear caliper replaced, Nov. 2023. I trust the guy doing the work, but this last one is a mystery, as we drive the car more than earlier. Rust has always been present, and rotors have always pulsed before replacement. Salt is an issue in N Michigan where I live. I am gentle on the brakes, as is my wife. Any suggestions?

[TonyHSD]

Hi, 

more regular service on brakes and more progressive braking to keep discs clean and pads and callipers warmed up so any moisture can evaporate. 
Salt and water are real enemies to all cars. 

[on the rivet]

Hi BJ,

Owners in cold/salty conditions need to tell the mechanic to clean & lube the caliper slide pins (front & rear) at least once a year. This isn't included in the Toyota service, although it certainly should be. Plenty of discussion on the US Prius Chat forum about the Gen 3 slide pins including the unusual silicone grease they need. I've got to the point where I insist on a video from the workshop of the mechanic pushing the pins to demonstrate they've been done. If you're unlucky you'll present with rusty discs or binding/poor braking performance and the garage will change the pads & rotors without servicing the pins. I honestly wonder if they do this on purpose to keep up the number of rotor/pad changes they get to charge, or if they genuinely don't know the core issue.

[Auris James]

A few weeks ago I replaced the front disks and pads on my 2015 Auris Hybrid estate. Serviced at Toyota and red advisory for front disks/pads. Bought new disks and pads from online main dealer.

Toyota dealer was right. Disks heavily scored with heat lines around disk, corrosion and slider pins seized. Fitted new disks and pads and new slider pin kit/grease. Cost £206.00. Calipers were fine. Mot in December and will get them to do the rears as amber 6 months advisory/recheck.

James