By - jamesc023
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A few things can cause uneven pad wear. Usually corrosion builds up on the caliper bracket causing the brake pads to not move freely. Sometimes caliper pins seize. It’s pretty common for RAV4 rear pads to wear unevenly. I’m not sure what state you’re in but in PA, pads need to be UNDER 2/32”, which is roughly 1mm, to fail inspection.
Thanks for the info - makes sense on the uneven wear I suppose, and probably something we'll need doing in the future at some point.
I'm in Ontario, Canada, so maybe things are a bit different, but in general, where do those official pass/fail numbers live? Is that provided by Toyota or set by the local government/authority?
As NoFlow said, it's a state thing. At least in the US. Not every state has safety inspections, those that do have different criteria the state decides on. So what's fine in Texas may not be in California. I'm in Mo, the brake pad thickness for failure is 2/32" for bonded pads, 6/32" for riveted. Need to be thicker on riveted to account for the rivets which leaves around 2/32" above the rivets same as 2/32" bonded. If unable to verify (see) that they're clearly riveted pads, it's assumed they're bonded (friction material glued/bonded to the backing).
Could be seized slide pins, could be a caliper piston getting hung up, could be a flex hose on that side internally damaged. Sometimes the soft rubber flex lines to the caliper will deteriorate internally and a flap of rubber can form. Like a piece peeled up internally acting as a one way 'valve'. Fluid pushes past it to activate the caliper but when releasing the flap lifts up blocking fluid from flowing back. You can end up with a brake on one side that's not fully locked up but partially dragging causing abnormal wear vs the other side.
Usually if the outboard pad is more heavily worn it's the slide pins, if it's the inboard it's the caliper piston sticking.
It’s a state thing so every state is probably different. Here’s Toyota’s spec:
10.5 mm (0.413 in.)
1.0 mm (0.0394 in.)
Makes sense - in general, does the state say that 1mm is the minimum, or are they just deferring to whatever Toyota says in their spec?
Also, where can I find that spec? Is there any way I can find a copy of whereever it says that?
It sounds like the mechanic is failing my car unnecessarily, so having some evidence might be useful.
The state decides what fails and a lot of times it’s up to the inspector to interpret. “Pads wearing unevenly, brake pads not moving freely causing decreased brake performance.” Or “Seized brake pads causing brake fade.” A lot of it is how thorough the inspector and how anal they want to be. Inspectors can be challenged by calling a State Trooper. You could also just change your brakes and bring it back to them for inspection.
I get charged for a second inspection ($100ish) if I bring it back, so hoping to avoid that - definitely need to replace them at some point, but if it's good enough to pass, then I shouldn't be paying for another inspection.
Best you find someone good for replacement. TLC.