Scraping noise coming from new front pads/rotors....

I recently replaced my front pads and rotors and caliper bolts/bushings and the brakes work well. But soon after I noticed a scraping noise. Its not a constant scraping, but as the wheel rotates faster the noise becomes faster.

I put the car on stands and put it in gear but the noise did not come. The wheels were off during this test. It seems like sometimes the noise goes away for a little but it comes back. Any suggestions?

ps the car does not slow down at all when it is making the scraping, it still cruises well when I let off the gas pedal.

Did you bed the pads in at all?

this advice is at your own risk: You might want to remove and reinstall the pads and rotors.

Reason: I learned that the clearances on the Riv's brake system are REALLY small. The pad only backs off the rotor about a thickness of a trash bag. So a layer of rust on the hubs is enough to cause problems. Also I bet your new brake pads were a pretty tight fit. If you scraped off enough of the silicone brake lube when you put them back together, that also will cause problems because the pads will not necessarily back off the rotor when you let go the brakes - again, they pads do not move very far.

Get the picture? when everything is perfect they work OK. And it is possible t ge things perfect. But even one small error or omission will get things out of their designed alignment, and if you happen to make a number of small errors the effect is interesting - the errors magnify each other.

So I think you should take it apart & put it back together but this time...
- make sure it's all clean *when you dis-assemble* and keep all the parts clean as you work. Clean means no loose dust or rust. If you don't have a workshop with clean counter, use newspapers to put your parts on. Also helps to have a couple cheapie plastic food containers (you can reuse for gerage or throw away) to hold small items. Or maybe a stainless steel bowl from the dollar store you can also use to wash parts and trap solvents...

- when you take everything apart, clean off the hubs down to shiny metal. This is a little tricky due to tight spaces. ATE sells a kit - in Europe - just for this. Google on '1340.4 760110 brake' to see it in their catalog, on pages 4-8 and 4-9 (.pdf pages 44 and 45). I use a 3M rust remover wheel on a drill, about $7.00 from walmart, to do it, but it is *really* tough to get between the studs.

- when you install them in the calipers, make sure the new metal guides are completely seated. Some people clean off an old brake pad adn use that to push in the new guides, then lube the face of the guides using silicone lube on a q-tip.

- when reinstalling, make sure the calipers go on the spindles straight and flat. One way to do this is to put the bolts in finger-tight and wiggle the caliper a little to make sure it's seated flat. And be sure to use loctite on the bolts, or they may back out by themsleves (which is one possible cause of scraping noise), and be sure to set them to the right torque with a torque wrench (you already knew that).

I sincerely hope this helps you, but again it's at your own risk. .

Tell you a funny story, I'll try to keep it short. I still take my car to the dealer for some service, but not all. A couple years ago I did a brake job on the car - however I had an iffy hub sensor on a rear wheel. Had cheapie rotors on the rear, they rusted onto the hubs. Could not find my puller - big problem - so I eased the rear rotor off with a 6-pound sledgehammer with a short handle... and killed the sensor. So the next day I took the car to the dealer and told the mechanic ("Mooch" - known him for almost 10 years) what I did & please replace the hub, I was out of time to do it because I had several (driving) business trips coming up. The dealer charged me *a lot* (almost 10 benjies: 1 benjie = $100) for that. When the lot attendant came to get me from work, she asked me a bunch of questions about the brakes on her Suburban. I answered a couple and then said 'hey Dawn, you got all those mechanics swarming around the shop and they can't tell you about brakes? What's up with that?' and she said, 'yeah, but when they were replacing your hub I heard them say you really knew what you were doing.' I said 'you must be joking, my car's in because I screwed up the job' and she said 'oh, no, that happens to them sometimes but what they will do is get a good used hub from the boneyard to replace it and not put it on the customer's work order. Sometimes they send me to get them. No, they even pulled the fronts to see what you did up there' (I had put on the factory drilled/slotted rotors for the Camaro).[/b]

Good advice posted above. In addition, I use a brake pad lube called "molli-lube" on any surface the inside pad makes contact with the piston, also where the outside pad contacts the caliper. The grease helps to quiet squeals, and also makes the pads stick to the parts that move them.

I've also found ceramics to be very quiet, though it doesn't sound like that's the cause of your problem. Best of luck.

that is some good advice. Only thing is I did take the calipers off again. I made sure to lube them well with silicon compound. But its strange that the car won't do it when it is on jack stands with the wheels off. It also hasn't done it in the last day or 2 because its been raining and wet here.

I am going to bleed the brakes and put in some nice new synthetic brake fluid. DOT 3 & 4 compatible of course.

One thing that did ont occur to me - when were your wheel hubs last replaced? You could just have a bad wheel bearing. If over 100K miles on original hubs, this might be a problem. Have to shop around for replacements tho - they can be pricey. (yeah, just ask me...) Bearnigs may not make noise unless wheels are on ground - when wheel is up the bearing pre-load (you have to bolt them onthe spindles and the tightnes is the preload) can hold them straight & they won't scrape. Also due to pre-load this one is tough to diagnose (won't always wiggle when of ground) - by the way ANY play means time to replace.

lotsa luck.

If hub/bearing assembly is making a scraping sound, it's in really bad shape. Does the sound come from both sides, or just one? If it's the bearing, it will only come from one side, as they rarely fail at the same time. Usually you'll hear a low-pitch rumble on a bad bearing when you shift weight on to the failing side (in a hard turn). The sound will get louder over time, until it's really loud... or the hub melts and your wheel falls off.

When mine went at around 105K, I was able to reproduce the noise during a hard right turn (driver side bearing). I was not able to wiggle the wheel at all with the car off the ground. New hub was $120 from NAPA, and noise went away. I did not replace the passenger side... still good at 140K+.