I just checked the pads, and all are fine. I replaced the front pads about 6 months ago, so no surprise there. The rear pads were at about 4/32-5/32 in., which is a lot of pad, and the car would have no problem passing inspection.
However, especially in the morning when backing out of the driveway, the brakes sound like metal on metal. Not the grinding sound you might hear when the rotors are being destroyed by a low pad, but a high pitched sound that you can’t help but notice.
I have been chalking it up to the rust that forms overnight on the rotors (car is outside), and the brakes rarely sqeak when I get to the end of my neighborhood. However, this weekend I was in a parking lot after about a 20 minute drive, and when I was driving around to find a spot, the loud sound was there again, just as if I was pulling out of the driveway.
Anyone have any ideas of what I should check? I just pulled all the wheels, and checked the pads and rotors, and all were fine… I did that right before this post, so is there something else I should be checking?
I had this problem last year before I changed the front pads, and it went away for a while. I thought it may have been because I put ceramic pads on the front, and I wondered if the old pads were made of something else that caused the sound. But it never went away completely… I did not replace the rear pads because they have plenty of pad on them, and I am not even sure that is the problem. Before I change the rear pads, I thought I’d ask you all if there is something I am clearly overlooking.
You can minimize the chance for disc brake annoyance noise by using premium pads designed for that purpose. One example is Wagner ThermoQuiet. Back in the old days the rotor finish was a significant factor but with these types of pads I haven’t had any noise problems and on most of the brake jobs I do the rotors are re-used as is.
It’s also helpful to lubricate the pads’ metal-to-metal contact points (pad backing steel to shims, clips, brackets, etc.) and the caliper slide components.
You can eliminate the first-thing-in-the-morning noise by moving to Arizona.
I thought a warped rotor would be able to be felt by the driver through thr brake pedal? I have felt a pulsating beat when I’ve had a warped rotor, but maybe that is just a really badly warped rotor…
If you are talking about the anti-vibration clips, yes… i installed those. I am not sure what you mean by shims, if you are referring to something different.
Arizona sounds just fine with me.
And I can’t recall the name of the pads I bought, but they were definitely ceramic, because I thought ceramic pads don’t make the sounds that semi-metallic pads sometimes do… But again, maybe I am mis-informed. Wouldn’t be the first time… Something is squealing, and it isn’t going away.
They might not have greased the back of the pads properly.
I did my own brakes but forgot to apply molybdenum grease to the pad on the first two wheels (the pads came with little packets of the grease). They worked fine for a few thousand miles, but eventually started squealing. I suspect there was a trace of grease left, which eventually dried out.
This is possible. I did the brake job myself, and I didn’t apply any grease to the back of the pads, but I also didn’t grt any packet of grease in the box with the pads.
Thanks for clearing this up for me.
Now that I am looking at these pictures, I don’t recall seeing these or putting them on. I will have to look again and see if the shims were on the brake pad when I installed them. If they were stuck on the pads and I installed them without knowing, that is possible. But it is also possible that I didn’t get them and didn’t install them. I am sure I didn’t take shims off the caliper or the old pads before installing new pads, so either the old shims fused to the old pad, or they were never there. I just don’t know.
Thanks for the link.
I am confident in the car’s stopping ability, so the issue is the noise. If installing shims would help, I can certainly do that.
As for the grease on the back of the pads, i can also do this. Either job is going to require me pulling off the brake pads again and reinstalling.
Where are the points to put a touch of grease on the rear of the pads, and what type of grease should be used?
I can also trade the car in, but until I do that (or move to Arizona) I will look for a solution for the short term.
Anyone know if the ceramic pads reduce noise, or am I incorrect with that belief? If I have to buy something like the Wagner ThermoQuiet product, fine. I don’t want to replace the pads because they hace less than 5K miles on them, but I also a,msick of the noise. So if I cannot solve this quickly with andab of grease or shims, new pads are next…
While some brands may include a grease packet, it’s not a universal practice. Generally you’re expected to provide your own.
This is a case where “back” and “rear” don’t mean the same thing. The back of the pad is the large surface of the pad’s metal backing plate. The other side is the friction material that contacts the rotor. The rear of the pad is whichever side faces the rear of the vehicle – this is essentially a useless concept.
The place to put grease is wherever the pad’s metal backing touches something. This includes the anti-rattle clips, the slots in the bracket that the pads fit into, the parts of the caliper that the pads abut, and where the piston contacts the pad.
It needs to be a high-temperature grease or it will soon be useless. Silicone grease works; synthetic brake grease works better.
No, and you don’t want full metallic pads on a passenger vehicle.
The best choice is generally to use the type of pad supplied at the factory. Do not use semi-metallic where organic was the original, and do not use organic where semi-metallic was the original – either substitution will cause problems. As far I know, ceramic can be used in either of those cases. Use only ceramic if ceramic was the original.
Can you explain why? I have never heard this, and couldn’t find anything on the web (I am sure I wasn’t searching correctly, because I don’t know what exactly to google.)
I am referring to the substitution problems you mention. What kind of problems, and do you know this from experience or from reading up on brakes?
I have a copy of an article from a trade journal from some years back. I cannot find it online. I’ll summarize, using “org” and “met” as abbreviations.
Org pads work best in the 90-300ºF range, fading at higher temps. Met pads work best at 300-600ºF range, working poorly and wearing quickly at lower temps. Front brakes do most of the work, and brakes essentially change kinetic energy into heat energy – in other words they get hot, and the more work they do to stop the car the hotter they get.
To illustrate using a car that happens to take the same size/shape pad front and rear, it calls for mets on the front and orgs in the rear. Put orgs on both front and rear and the front pads are likely to fade due to being overheated, which will overwork the rears and wear them out prematurely. Put mets on front and rear and the rears won’t get hot enough to be effective, overworking the fronts (possibly to the point of fade) and wearing them out faster.
The article didn’t mention putting orgs on the front and mets on the rear, but it seems clear that the braking would be quite lousy.
The point is, the parts store shouldn’t ask whether you want orgs or mets, and they shouldn’t suggest substituting one for the other for what are essentially trivial reasons (quieter, lasts longer, brakes better [it won’t]). What you want is what the factory specifies. Professional engineers who know about this stuff far better than any laymen have already figured out what works properly. Second guessing them won’t yield a better result, it will yield a worse result.
This article was written before ceramic pads appeared, and I don’t know the specifics of substituting them. I think they’re effective over a wider heat range. I’ll try to find out.
I just talked to someone at Wagner Brakes. My guess was wrong. He said in some cases ceramics can be substituted, but they come in a variety of formulations and there is no dependable rule. He affirmed that it’s always best to stick with what the catalog calls for – make sure it specifies OEM or OEM compatible, not simply something that will fit. The brake pad manufacturer will know which of their products are suitable for a given application.
When I purchased the ceramic pads, I didn’t go for the cheapest solution. They were listed as “meeting or exceeding OEM specifications”, and since I thought ceramic pads were quieter, that is the direction I went. However, I don’t know what the OEM pads were… I suspect semi-metallic, but I’ll have to do some research and see if I can find out.
With that said, I don’t think the original pads were on the car anyway. If I can’t fix the noise problem this week, I may just buy new rotors and pads and start from scratch, making sure I get a set that is compatible with the OEM specs.
As to the sound… I looked at the pads, and they did come with shims, pre-installed, which is why I didn’t recall them. It turns out, the pads also were supposed to come with a little pack of lubricant, which I either missed or it wasn’t in my box. (Don’t know how I could have missed it, but oh well…) I am pretty sure that putting the lube on the back of the pads and the other metal on metal touch points will reduce my noise, so I am going to do that asap.
I’ll return to the thread to post my results just for closure. Hopefully, the solution is near!
