bought a used 2021 Prime LE about a year ago. loving it. was an upstate NY car I believe and had a good bit of rust on various components. I took rear brakes apart and re-lubed set everything - but noticed my mpg is a little below our 2021 Prime limited bought new and without the northern winters/salt, and we put on all the miles so we "know where it has been". Loving my 2021 LE - but feel that rear brakes are rubbing a bit too much. The wheels do not complete more than one or 1.5 revolutions when spun hard by hand. Is this likely corrosion in calipers/pins/etc.? What is it that causes brakes to "release" after they are applied? I disconnected 12v and was careful with brake pads dimple lining up with piston X face. Feel like the rotor "braking shiny area" is a little narrow - so something is a little off or warped or asymmetric. I re-lubed everything but maybe they're just not "releasing" properly back to neutral positon. (when you want a tiny bit of pad to rotor contact - a little "swish sound" when spun and from Mendel's videos a good 2-3 revolutions when you give em a hard spin by hand - but mine stop after 1 turn - a bit too much pad rubbing. should I just buy new rotors and pads - or new glide pins or all of it? Any good aftermarket brands - like "power stop" etc. to upgrade/replace and make a fresh start ? - I've had good success with Rock Auto in the past for various car parts. Thanks for your thoughts. If I could just "loosen the position they are at in 'neutral'" a little I'd do that. Maybe just the springs that help pull the pads off the rotors are weakened or mis-aligned/bent, etc. and so the pads don't "pull back" completely? When i put it in neutral at low speed to listen to rear brakes (without regen braking) i can definitely hear the rear brakes rub/grind a bit when I apply the brakes - not the smoothest sound. thanks in advance for any thoughts/ideas.
See this post. (Apologies for the length, it covers more than just that.) It also links to a 15-minute-ish pretty sensitive brake drag test I use.
Some have taken to using a spring piece too pull the pad off the rotor. Could be a separate piece or built into the metal clip the pad slides on. What does Toyota do for the parking brake? For a period of time, a mini drum brake was in the rear disc for that.
Thanks Chapman. Will look at that link for some ideas. Parking brake - I think is just the manual extension of the piston using the same pads by the foot pedal - with the piston rotating if not impeded by the dimple on the brake pad. (yes my older sequoia has the parking brake drum inside of rotor configuration). perhaps something allowed parking brake to be a little too tight/rubbing when it should be fully disengaged. I seem to remember rotating the piston manually to spin/retract it further when re-assembling the brakes - maybe I didn't get it retracted enough? Assume these are same rear disc brakes as regular gen 4 prius of similar years.
Thanks Mendel/all - yes a protruding bump on back of brake pads, not dimple. well it seems the rear brakes have two metal plates/anti squeel/contact plates but no "offset spring" that 'pulls' pads away from rotor. what does pull the pads back - just a well lubricated slide pin and 'bounce back' of the pads after brakes are pushed/piston squeezes inner and outer pads against rotor? am going to clean thoroughly - put some sil glyde on pins - and spin the piston in 90 or 180 degrees in hopes of less rubbing in 'neutral' non braking rotation.
My understanding was that disc brakes made poor parking brakes without some type of assistance; they could loosen to the point of car rolling. Does the gen4 have an electric parking brake? How did the pins look? When I clean them, I'll use a spray tube on the brake cleaner to get all the gunk out of their well on the bracket.
I know that this post is kind of long and covers other things, but if you scroll down (or Find in Page) to "When a caliper works right, what makes it let go when you're not braking?", you will find out.
