Brake disc replacement period

 My 2004 Prius has just gone in for a 60,000 km service (38,000 miles). Told
the front discs and pads need replacing by the Toyota dealer as they cant be
reshaved. Seems too short a time to have to replace the discs. My last car a
Ford Falcon wagon 92 model did about 150,000 km before it needed disc
reshaving. Anyone else have this dilemma?

 
That is unusual - more typical life for the front brakes is at least 100K
miles (nearly 200K km). Rust may affect that.

Our two 2002 models have 95K and 120K miles on them and the front brakes are
like new. Something is wrong.

Mike

 

Dealership told us the front brake pads had worn down to bare metal gouging
the discs beyond repair. Didnt get a service on the car before buying it is
why ...lesson learnt.

 
That explains a lot! The type of damage, that is. There are two possible
explanations that come to mind: loss of lubrication on the front caliper
slide pins or buildup of pressure in the hydraulic system.

The first would be a mistake in construction, because the silicone grease
Toyota uses is good for many years. If the pins are dry they bind and don't
allow the caliper to release. Once I forgot to grease the slide pins on my
Volvo when replacing the pads and rotors, and within a month the pads and
rotors were unsalvageable. A hallmark of this type of failure is uneven
wear, especially comparing inner and outer pads on the same side.

The second cause is typically an adjustment problem (except in cars with a
lot of years on them, where failures in the rubber brake hoses can create
check valves). In conventional systems with vacuum boosters and no
regeneration it is caused by the brake pushrod - between the brake pedal and
the booster - being misadjusted so it is as though you are keeping the brake
slightly depressed. I don't know if the same applies to the Prius system.

By all means ask to have a look at the damage, but it seems the best
approach is to have the replacements done and verify they will check for the
brakes not dragging and other potential causes. Sounds like the previous
owner was fond of very hard braking, which brings the hydraulics into
action... although riding the brakes may have the same effect. Dunno about
that.

Mike

 

Thanks for the input Mike. Picked up the Prius from the dealer who told me
that the steering wheel isnt sitting dead center, which I already knew
of..and that they wouldnt set it straight until the car got a wheel
alignment first..and they couldnt align it for me because their aligning
eqiupment was being replaced. I said well its obvious alignment isnt
necessary as your report states tyres are good, but sales guy still insisted
that they wouldnt touch the steering until an alignment is made. Car drives
well I can live with the wheel offcenter..just wonder why it got that way??