Tomtwtwtw

So occasionally my car will make some extra brake noise when slowing down from highway speeds. Almost sounds like a loud rubbing noise, not quite grinding, definitely not squealing. The harder I brake, the louder the noise, whereas light braking is fine. I've checked the pads and rotors and all look good. I know others have had axle / CV shaft issues, but I almost wonder if this could be bearing noise as well. Car also has a light vibration in the steering that starts up around 65-70 mph. In trying to vary the corner loads the vibration doesn't seem to be affected, so I'm stumped. Just had the tires rotated so wheels should be balanced (vibration in question was there before and after the recent rotation). Looking to see if anyone has any feedback as to where I should start first, or of any additional tests I might do to help narrow down the source. Thanks in advance!

mrgold35

New brakes recently? I was getting something similar when I put new pads/rotors on my MDX. It took about month for it to really go away. That sound stayed until I came to a complete stop (didn't hear as much a high speed because it was too noisy outside).

If not, you can check out the pads to see if they are wearing evenly. Maybe some pad material is not transferred evenly and you don't hear it unless you are traveling at XX mph and brake.

Tomtwtwtw

No, brakes are definitely not new...might be original based on where they were 20k ago and where they are now. Not sure what the typical mileage is for OE pads on this car. Last I checked the appeared to have 20-30% life left on all corners (inner and outer).

KenB350z

I had my brakes for 80k when I went with the BBK up front and 100k went I had to replace the OEM rear pads and resurface rear rotors.

Tomtwtwtw

Cool, thanks for the info. I'm due for an oil change here in the next month or so, so I'll get under there in detail sooner than later.

KenB350z

Get it!!!!!

Tomtwtwtw

So yesterday while driving I heard what I'm pretty sure is the brake wear indicator starting to drag on the rotor. Guess they've worn a lot over the last 10k...and I guess I'm definitely not waiting till my next oil change to get under there. Yay for maintenance expenses!

Tomtwtwtw

Those of you that have done your first brake job - did you also replace the front rotors or did they look good for another round at the time?

Kaputnik

My fronts were clean and fine at 46k when I replaced the pads.

My rear pads had 4-5 mm left but were making noise. The pads were a bit glazed and burnt looking, and the rotors had a fair amount of rust in the non-contact area. So I replaced the pads and took the rear rotors to a local machine shop and had them resurfaced for 25 bucks. Machinist said they were straight and still easily within spec.

Did a gravity bleed after and everything is smooth and quiet.

KenB350z

Upgrade them brakes, man!

Tomtwtwtw

Maybe next time around...would be nice to have but my money has to go elsewhere. I'm sure yours would stop in the air if you drove it off a cliff.

mrgold35

I just did OEM pads and kept the same rotors at around 90,000 miles. Still felt good braking at all speeds. I had a lot of hwy miles before 1st brake job, now the RDX just sees city commuter duty. I can see the brakes lasting 1/2 -3/4 as long the second time around.

Tomtwtwtw

So 75k isn't unreasonable then. I do mostly highway, but the car went through 3 separate owners before coming to me at 52k so who knows what type of driving was done then. I just know the local dealership had all the maintenance records and it was in pristine condition so I had no worries being the 4th owner.

KenB350z

You are probably right.

Tomtwtwtw

A couple more questions for those that have done their brakes. I checked my pads and my passenger inner pad is done. Driver's inner pad is getting low, but not in the danger zone yet. Both outer pads had a ton of material left. I know this can happen on floating calipers, but the difference on my passenger side seems a little extreme. If they were wearing more evenly I would get another 25k out of these. So...

1. Anyone else experience this type of uneven pad wear?
2. Is there a way to lubricate the sliding pins of the caliper to help the pads wear more evenly once replaced?

This was a common issue (and solution) for the rear brakes on my old Cobalt (fronts were 4-piston fixed...no wear issues there). I had the rears replaced under warranty at less than 20k miles, but after that they wore perfectly even and they were still at 50% when I sold it with 85k miles. Once I actually pull the brakes I'll get pics of the pads to better show the wear.

Tomtwtwtw

Pads replaced, will get pics up tomorrow...ish. I did notice some fluid bled from the master cylinder when I compressed the pistons. Not much - it was a tiny puddle maybe 6" across. I assume that the brake fluid was probably topped off at some point during a dealer maintenance visit, but can someone else chime in and let me know if I should be wary? If for peace of mind if nothing else.

Kaputnik

My inboard rear pads were a bit more worn. I did pull the caliper pins and regreased them thoroughly while the pads were out. They still seemed pretty clean and well greased in the first place, so not sure it will help. I don't think you can lubricate them any other way.

Was the level ok once the pistons were pushed back? I'm sure it's fine. I bled mine while the pistons were compressed to really clean out the old brake fluid.

Tomtwtwtw did you use OEM pads? My new set of OEM pads came with shims and an anti-rattle clip. The originals didn't have these installed. They are very quiet now.

Tomtwtwtw

I honestly didn't check the level prior, but the brakes feel great and there is no excess pedal movement. I did use OEM pads, and both the old and new brakes had the shims and clips. It does appear that the driver's inner pad was also pretty worn, just not quite as bad as the passenger. All together, I'd say each outer pad was around 25% life and each inner maybe 3-5%. Not terrible I guess, but it could be better. I did not separate the caliper, but maybe I should have...

Kaputnik

Since my RDX formerly lived in Chicago, the calipers were pretty rusty and needed extra cleaning where the pads live. It was quick and easy to separate them.

Tomtwtwtw

Both did seem to move fairly easily. I'll inspect them once I get some miles on them and see if they're wearing evenly. If not I might take the calipers off and lube them up a bit. I assume you just pop the pads out and pull the sliding piece out as far as it will go and apply grease? Or did you completely disassemble it?

Kaputnik

^^Once you remove the floating caliper, you actually don't even have to pull out the pads. The sliding pins are held in place only by the boots at this point, in the caliper support. You remove them by carefully unseating the boots (they are tougher than they look, fortunately), then the pins slide out. One pin is different and has a flat side to it. Clean them up and grease the hell out 'em. It wasn't hard to get the boots to pop back in place. I cleaned them up too so I didn't get crud all over the fresh grease on the pins.

Tomtwtwtw

Awesome, thank you. Any specific type of grease you use or just some general high-temp stuff?

Kaputnik

I used CRC Industries - Brake Caliper Synthetic Grease, a high temp grease. No particular reason other than my local auto shop sold it, and it had good reviews. I imagine unless you are tracking and need something extreme, most any good quality stuff should do.

Even without pulling the sliding pins out, you can get a good feel for their ease of movement, once you get the caliper off. Just by tugging on them a bit.