New pads and discs after 20k miles?

122,000 miles on my '04. Had an issue with grabbing on the right rear at 120,000. It was an accumulation of brake pad dust in the springs. Cleaned it up and it's good as new.

The verdict on pad wear: 50% left on the front pads, 60% left on the rear.

 

Huh? What and how do the "Super Capacitors" work?

My brakes rust up almost every night it is raining or snowing. First time I press them in the morning they grind like crazy. It goes away almost immediately and is common on my other cars also. I just ignore it and have never had serious problems with brake wear.

Steve

 

Perhaps your brake pad linings have delaminated and are floating loose between the pad and the rotor. This happened to me around 90,000 mi (although I still had at least 40% of my pad life remaining). If the loose lining is rubbing against the rotor while you drive, it can make noise.

Log into Yahoo's Prius_Technical_Stuff group and check the file
http://autos.groups.yahoo.com/group/Prius_Technical_Stuff/files/brake_pad_replacement_procedure.pdf
for details of what this looked like and how I replaced the pads.

Douglas (2002 Prius)

 

Pad de-lamination at 90K is one thing; at 20K, it is entirely different. While possible, I tend to doubt that pad de-lamination is occurring. Something else is happening for there to be a requirement to replace a rotor and pads at 20K.

 

It is interesting how when there isn't much wear, the extent to which brake dust can build up and cause 'hiccups'. In a prior lifetime, I had the same grabbing on the right rear drum of a 1978 Diesel Rabbit that I managed to put 250+K miles on before the engine overheated and cracked the block. The grabbing first presented itself at 70K and the cause was brake dust build up to the point where the shoes would not retract.

 

They are referring to the capacitors in the Prius's electric braking system. They are there so the braking system has its own independent supply of backup power to last long enough for you to stop the car in the event of a loss of electrical power.

I'm not so sure about the location of the brake system computer, but had assumed it was underhood or underdash.

 

Returning to the OP thread, here in the NE of England we have always had problems with brake disc (rotor) corrosion on all our cars. Neither I or my wife brake hard enough to clean them and its worse on the Prius because the mechanical brakes hardly ever come into operation. Our 2005 had intermittent severe squeal at around 10k miles - whether braking, just driving or accelerating - and both front discs and pads were replaced.

No problems since.

 

The skid control ECU (aka brake system ECU) is located near the steering column. The brake control power supply (containing the large capacitors previously discussed) is located adjacent to the 12V auxiliary battery in the right rear corner of the hatch.

 

i have a customer right now that's on his 3rd set of pads, we replaced the caliper and the slides, pads and machined his rotors under warranty. But apparently his US car has been consuming more gas than normal (less than 30 mpg), and his 3rd set of pads after 40 k miles. He does not know what's wrong with the car and same with the tech that worked on his car, we are both stumped as we are going to call Toyota Canada and see if they have heard another case where the regenerative braking system failed to be utilized. Although personally I haven't driven the car to comment if it was really the car or the driving style of the customer, but the customer claims he has another prius and it works fine. He's just so shocked that he's on his 3rd pads and his normal cars usually last longer than that.

No check engine light or anything for that matter

 

That sort of mileage without any codes almost certainly means the brakes are dragging. I suspect the pads are failing to retract when not in use.

Tom

 

Hi Phil,

Regarding the regen braking system not working, if there are no warning lights, no DTC, and you can hear the inverter whine when you are pressing on the brake pedal, then that should not be an issue.

Regarding the front brakes dragging, how about using an IR thermometer to assess the front brake temperature after driving a given distance and speed, and compare to another Prius known to be in good condition.

 

Easiest way to check would be to drive the car on the flat somewhere, a strip that you know well--cruise control would seem the best bet. The MFD is going to show really poor mileage if the brakes are hanging. If it doesn't show poor mileage in the test then repeat while the customer is driving and you are watching.

With less than 30 mpg the brakes must be hanging, unless the ICE is idling in park much of the day or the customer is doing something that forces friction braking while cruising.

 

yeah i never followed the update to what happened to the customer, but i will take all suggestions to heart when i have future prius owners with the same problem! Next time i'll just test drive with the customer to try all the above.

 

Say Hobbs, tell me: when you lightly press on the pedal, do you notice an ever so slight pulse in the pedal? If you do, you likely overheated the rotors from braking way too hard - and braking hard will cause premature wear of the pads.

 

"Claims" he has another Prius? Doesn't he bring that one to you for service? If he can't prove he has another one that is working correctly we have to suspect driver error.