Brake job

I've logged 129,000 miles and decided to take the car in for a brake job today because I had a coupon for $200 for the service. I get a call back saying I"ve got 75% left on the front and that I didn't need new brakes and that I would owe $50 for having my brakes checked. I was in shock. Anyways I decided I might as well replace the brake pads as it will need to be done sooner or later rather than being out $50 and having to do the brakes eventually.

 

Sweet! I may *never* need a brake job!

 

I know. By my calculation, 75% left after 129,000 miles would mean I could probably drive 500,000 miles before even needing a brake job. I told them to keep the old brake pad. I'll take a pic and post if possible.

 

How are San Francisco drivers doing with their brakes? I simply cannot imagine my brakes will last 100,000 miles while I'm constantly braking due to hills, traffic, and lights or stop signs every block. Our city is so unique that I don't think other people's conditions give me an indication of how well my brakes will do.

My last car was a 97 Mustang and I had to change the brakes every 25-30K miles, btw.

 

At 26,000 miles my '06 failed my state's annual vehicle safety inspection today, at the selling dealer's service/inspection facility. The cause was rust on one surface of one brake disk. There was no measurable wear on any brake part, front or rear. The observation was that one pad was wiping the rotor in such a way as to indicate that only the inner half of the pad area was contacting the rotor. The service mgr. insisted that this was a definite cause for failing the inspection due to loss of breaking power and potentially pulling the steering under hard braking. Further the service mgr. contended that the cause was galvanic corrosion between the rotor and the metallic pad material -- I'm somewhat unconvinced. Repair involved cutting/facing the rotors and sanding the pads.

I think that more aggressive routine braking on the part of this driver may have prevented the problem. I thought I was being good to my car by braking gently, but perhaps not.

Keep an eye on those rotors!

 

i'm still kind of skeptical of the long mileage claims on brakes or the actual way the toyota dealershoips measure the brakes. it makes sense to me that the rears on a prius would probably wear before the front brakes do, and in order to really prevent wear you need a motor on each axle or wheel, ill believe others claims when i have my brakes actually done, which i have no idea when!!!!

heres some measurements done by toyota dealers

mileage front rear
------------------------------------
10,000 9mm 5mm
20,000 8mm 3mm left 5mm right
24,963 11mm 4mm left 4mm right
30,000 9mm 3mm left 3mm right


art's automotive in berkeley, a hybrid repair shop, had a cool article about the brakes

The fake brake! When you step on your brake pedal in a conventional system, you're pushing a piston that is pushing fluid out of a cylinder (think bicycle pump), through brake lines, to a hydraulic caliper that squeezes stationary brake pads against a rotor that spins along with the wheel. When you step on the brake in a Prius, your still pushing fluid with a piston, but instead of going to the calipers, the fluid goes to a "dead end" chamber with a piston that pushes on one or two springs. The only purpose of the chamber is to provide a pedal feel for the driver. When the brake is pressed with moderate pressure, the piston is only touches the softer of the 2 springs, providing a little give in the brake pedal. This simulates line and caliper flex normally felt on a conventional system. When brake pedal is pressed harder, the piston comes in contact with the second, stiffer, spring, providing a harder brake pedal, simulating the feel of a conventional brake system once the "slack" has been removed. The real braking work is controlled by a brake control computer, which monitors the brake pedal position with two redundant sensors. The brake computer then uses the electric motor / generator MG2 to slow the car and charge the battery or applies pressure to the calipers using pressure stored in the ABS accumulator. If there were a serious brake control problem, two solenoids open, by-passing the dead end chamber and computer control, allowing the brake system to function just like a conventional system.

 

Here is a schematic of the Prius brake system. Note the Stroke Simulator, not to be confused with the Stroke Stimulator .... oops, wrong topic

 

206,456 Miles on my of Prius and Its time to do a brake job..Yep over 206,000 miles on the originals !!

 

Clubford00 nice

mine has now 161,000 km's on the clock 100,400 Miles 2 years ago mechanic was crying trying to tell me that I will kill myself with bad brakes, 1 year ago same story, 6 months ago again (this is each time I did an oil changes)...

Yesterday I changed two tires and rotated the other two, we noticed so little use on the rear discs that they have now corroded and covered with funny rust inside where they corroded.

Question:

Is there any not too much invasive way to clean that rust?

Please don't tell me to reverse downhill with N gear on and my foot on the brakes...

Any easier tips?

 

That rust isn't anything to worry about. It shows up all the time, especially after rain. The next time your brakes hit the disc, they'll knock it off.

If you're really worried, just use a little medium-grit sandpaper with light pressure. It's not really invasive... some folks actually lightly sand their discs when replacing pads to remove the glaze, increasing friction.

 

A good number of European owners who live in relatively wet climates have complained of rear disc rust. The simplest approach is to gently brake from 40-50 mph or so, while in N so that the friction brakes are applied; repeat a few times; and see if that makes any difference.

However if that does not help then you may need to have the rear discs replaced. Since your mechanic has noted and pointed this rust out to you repeatedly, the condition may be more than light surface rust.

 

Try this with forward motion, not reverse.

 

I was just kidding.

Anyway as Patrick mentioned, the condition is worse than just light surface rust.

I will try the N technique but have a feeling that most of the braking power goes to the front (my feeling is based on the condition of the rear discs).

Thanks a lot lads.

 

If you need new rear discs check out Jolly Good Car spars (Ebay) a good guy to deal with. I bought some a short while ago for the same reasons as you. £17 for the pair really good quality made by National Brake Discs (British company) part no NBD1095. Even with delivery to Ireland they will still be very cheap.

John.

 

You are right. However if you try very light braking while in N, you may find that the rear brakes will sufficiently engage so that the pads can work on the rust.

 

Then why not take the discs off, take them to a shop and have them turned down a few mils? This will make them good as new for much less than the price of buying a new set...

 

You have to remember that the OP is in Ireland the other side of the pond from you. Over hear it is much cheaper and quicker to replace discs than have them machined even if you can find a shop to do it. I am lucky that I have access to a workshop but even then I would not do it.

The rear discs are only 9mm thick when new and the minimum thickness is 7mm if the discs have lost 1/2mm off each side due to ware and rust this only leaves 1/2mm or under 20thousands of an inch left to machine of each side to reach minimum thickness at that point the car would fail our MOT (ministry of transport yearly vehicle test).

 

20 thousandths of an inch = 20 mils

You only need to remove a few mils to reface the disc...

Sounds like you could make a small fortune just turning brake discs in your workshop... you should give it a whirl! It really isn't rocket science.

 

A mil in Europe is 39 thousandths of an inch, mil being short for millimeter 25.4 mm=1inch

 

Hmm, I was taught differently in shop class. Then again, this could be one of those cultural things...

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