I fixed a somewhat perplexing thing with the Limo's brakes this weekend.
From day one, the front hydraulic/friction brakes were making an odd creaking/clicking sound as pressure was increased and decreased (but not when it was held steady). On both sides of the car.
Just listen to this! (With apologies for the crappy old cell phone video)...
(Exaggerated volume since the phone was so close to the source.)
This would be annoying on any car, but it's even worse on a hybrid.
Why? Because under light/moderate braking, the car slows via regenerative braking. The friction brakes are only called into action when the car is nearly stopped, or just moving slowly. So when I would brake, at first the only sound was the quiet, cool Jetson's whine of the hybrid system doing the regen thing, but as the car transitioned to friction braking as the speed dropped, the front friction brakes would come on with this awful creaking/clicking noise. On top of that, remember the car typically shuts off the engine when coming to a stop, which made the noise even more noticeable.
Annoying! And... as of this weekend:
fixed!
I assumed it was dry/sticky caliper slider pins, but I discovered they were all free & slidy.
No, it turned out it was something else that was -- surprise, surprise! --
rust related!
There was a generous layer of caked/half pulverized rust on all the anti-rattle/squeak shims and on the backs of all 4 brake pads. I removed the rust, greased the shims & the backs of the pads, put it all back together and now it's as quiet as can be.
The car brakes quietly to a stop -- the regen/friction transition is waaaay less obvious.
Much nicer to drive.
I'm going to make a dedicated thread on the topic so other Prius owners will be able to find it easily.