1999 CR-V with 70k miles. Just noticed a slight constant scraping sound when car is in motion. I had a friend drive the car in a tight circle around me while I stood in a parking lot and was able to isolate the sound to the front right wheel. Sounds like a caliper dragging on the brake disk. Brake pads have plenty of meat left on them. I’ll take it into the shop on Monday, but first I want to think through all the possible causes and remedies. Would appreciate any expert insight into what to look for. So far, these are the possible causes I can think of:
- caliper piston sticking in bore
- caliper not sliding freely on caliper pins
- brake hose restriction not allowing piston to retract
I had never heard of a brake hose restriction not allowing a piston to retract, but I just read an online forum comment where someone was having a similar problem, and someone else said it was possible for an old brake hose to look fine on the outside but be swelled on the inside, thus restricting fluid flow. Any other ideas? And can something like a stuck piston be remedied with grease, or does the whole caliper have to be replaced?
The first thing I would check for is if the caliper slide is sticking from rust. A lot of people will do a brake job but never remove, clean, and re-lubricate the caliper slides. So the caliper piston comes out , pushes the inner brake pad onto the rotor, which then causes the caliper to slide the outer brake pad onto the rotor. And then when the brake pedal is released, the piston retracts back into the caliper releasing the inner brake pad from the rotor, but caliper slides stick and the outer brake pad is still held against the rotor.
If it is the caliper, you can rebuild them by rehoning it. Harbor Freight actually sells a tool that you mount on a drill and does a good job.
I think tester is on point, though. A caliper slide pin that needs to be regreased is far more likely.
Those slider pins have these little accordion rubber boots around them. Replace them if they are torn.
I’ll go with Tester and ask the shop to lube the slide pins, and hope that does the trick. Thanks.
I would actually hope for something simpler - like a bent dust shield. It depends on what kind of scraping sound it it, but in general I wouldn’t describe the sound of a pad on a rotor as scraping.
I tend to agree with a rotor shield problem but you say the pads have plenty of meat on them. Does this mean you checked the inside pad too? Many people often look through a hole in the wheel, see the outer pad is good, and then assume the inner is good also.
Just pointing this out in case the above was the method used.
OK is correct; I checked only the outer pad. I didn’t think of a bent shield, but I like that idea best cause it’s the easiest fix. Will report back Monday with the verdict.