I wonder if the life is correlated with temps? As in the ECU uses the rear brakes more heavily in cold climates, presumably to ensure you won't over-do front braking forces. The folks reporting the high miles on their brakes do seem to have been clustered in warmish climates....

 

I don't think so. If you ride a motorcycle with separate front and back brakes, you quickly learn that it takes little force to lock up the rear brake compared to the front. Which is a good thing, as I spent the night in a hospital after I managed to lock the front one. The point is that you can't do much stopping with the back compared to the front, and I suspect that is why rear brakes most often last twice as long as the front.

Excessive wear of the rear brakes might be caused by careless use of the parking brake, leaving it on, or partly on, or having it badly adjusted. That will take a toll on the rear brake pads and disks.

 

Don't believe that's possible - my 2008 Camry (and all G6 Camry, for that matter) uses a drum-in-hat parking brake -the disc pads aren't involved at all. AFAIK Toyota doesn't use the design where service disc brakes are used in the parking ("emergency" brake) design. The hat has ID of 170mm and more-or-less conventional drum brake setup, with the brake shoes activated by cable, and expanding against the drum contained in the rotor 'hat'. The rear calipers are hydraulic only, and not involved in an parking brake action.

Now, the older rear drums are were indeed different - but the TCH has 4 wheel disc, and the disc brake pads are not involved in parking brake action.

As to my reference - on the TCH, the computer does brake proportioning and manages the caliper apply pressures independently of direct driver input. My supposition was that the rears would be used more in cold temps and and related risk of front-wheel lockup. On the TCH, the rears are used to 'balance' the car while the regeneration mode of MG2 takes place. Limited by battery charge rate, up to .3G of braking torque is provided by MG2 on brake apply. The ECU also manages front caliper pressures as the car slows, or if the demanded stopping rate is more than the MG2 can provide. Really a cool piece of technology - and quite a piece of software that manages the whole shebang.

And, FWIW, 70K life on rear brake pads is pretty close to 'average' on a ICE-only car in a suburban setting. Since the bulk of light brake torque on the TCH is supplied by MG2 in regen mode, the fronts will last for darn near the life of the car, if driven conservatively. My concern about the brakes - and one I intend to remedy on my next service - is the quality of lube on the caliper pins. Since my car is pushing on 5 years, a clean-and-relube of the brake sliders is in order. In a salt-soaked environment, that frequency should be higher. When I inspected the brakes at the last service, the pads were less than 10% worn, after 45K miles of suburban commuting. The only annoyance is the occasional squeal when backing up....

 

Agree if it is a drum in disk type design for parking, you can't misuse the disk pads or wear the pads from mis adjustment.

Still I would expect less wear from the rear, just because they don't have that much traction before you lock them up. It is possible the braking system is smart enough to add front braking from regen to the actual front braking, and keep that in balance with the rear braking from the pads only. That would bias disk brake force more toward the rear. But still in a hybrid braking force needed for other than emergency stops should be pretty minimal. My biggest worry about the hybrid brakes is that they will seize up from under use. That causes problems of uneven wear; inside pad vs outside, or front to back of the pad, and early replacement.

Hybrid brakes may need a bit more cleaning and lubrication type maintenance, but with that should last the life of the car.

 

Ron,

The rear brakes are used ALL of the time when stopping the car and will more than likely last the same amount of time as normal brakes do for your driving style and route. The front brakes however are rarely used except in a hard braking situation or under 10 mph.

In my case with a 20+ mile interstate route to work and very few redlights once I am off of the interstate, my rear brakes typically lasted 150,000 in a full sized sport ute. Front brakes were replaced every 75,000 or so. With the Camry, the rears are showing some wear but should make 200,000 (due to a lot of traveling to job sites on the interstate). With me being careful, the fronts might last the lifetime of the car.

I plan on pulling mine and cleaniung/relubing where required as soon as I get a chance. I need to take a weekend and change out the water pump, thermostat, hybrid coolant and do a front end/strut/brake/bearings check.

 

Well this is really interesting. I was not aware of the front brakes were nearly all regenerative. So does this mean the maximum regeneration is from front braking and not the B mode? This would explain our lower mileage on our rear brake shoes.

 

Have a look at the link below and check out the diagram at the bottom of page 16. There has been a change in the braking system of the Toyota Hybrid System. While the early version on the Prius always used some hydralic braking, now with THS-II, you get significant braking from regeneration alone. I suspect that is due to the integration with ABS to prevent the front wheels from skidding.

THS-II

 

All regenerative braking comes from the front wheels. Only the front wheels are connected to the generators. B mode is a combination of engine braking and regenerative braking. Engine braking again is only the front wheels, as the engine is only connected to the front wheels. So B mode is all front wheels, and no brakes.

I'm not convinced all manual braking uses the rear brakes in the later Toyota Hybrid Systems, including the TCH. There is no real technical reason for it to be that way. The ABS will prevent the front wheels from locking up. See link in previous post.

 

Ron,

The rear brakes are used ALL of the time. The front brakes are either regenerative or hydraulic depending on speed and the amount of braking required. The front brakes have more of a bias than the rears but the car is braked front and rear every time you use the pedal.

 

Is their an indication of the transition from Regen to Hydrolic? For now I am just guessing.