RawBenz

The car is RHD.
When braking at very low speed (walking speed) you can hear a Bird/Chirping Noise.

It goes away when you remove your foot off the brake. It seems to only happen with slight application on the brake pedal engaging the brakes. It's coming from the driver's side front. (Right Hand Side)

Only started doing it recently, any ideas?

zibby43

Sounds like it could be a glazed brake pad.

RawBenz

That's what i was thinking.
Rotors were changed recently and original pads retained.

What's an easy fix?

zibby43

That could help explain it. Easiest fix would be to take a look at that pad and then have it replaced.

If all of the pads are in bad shape you could have them replaced with Porterfield R4S pads, which are outstanding.

http://porterfield-brakes.com/manufa...akes/R4-S.html

Alternatively, you can run through this checklist:

#1: Make sure you have straight and true surfaces on your rotors and pads. Turn rotors as necessary (or replace a rotor if one is defective) - do the same with the pads.

#2: Inspect calipers, caliper sliders, and all other mounting surfaces and metal-to-metal contact areas. (This includes the rotor to hub mounting surface which commonly becomes contaminated by rust and other debris!) Lubricate all metal-to-metal contact areas with moly grease or lube. Inspect complete system and make sure that rotors and pads are lining up 'true' when brakes are being applied.

#3: Apply anti-squeal moly lube or similar to backing plate of the pads - or use an anti-squeal shim between the pad and the piston contact areas. This will change (dampen) the frequency of the vibration and will help reduce the noise.

#4: Chamfering of the leading and trailing edge of the pads will also help to reduce noise levels.

#5: Inspect related suspension components to make sure worn components are not placing undue stresses on the braking system, calipers, and pads.

RawBenz

Thanks

zibby43

No problem man. Good luck.

Those are all fairly easy things to accomplish. I'm confident that one of those options will take care of your issue.

sinape62

#3 fixed the issue I had on our C230 that recently had the install of new rotors and pads. GL

Diabolis

#6: Find a stretch of road where you can open up the car and do a couple of panic stops from high speeds (and coast aftwerwards to cool the brakes down). A lot cheaper and easier than options 1 - 5 if all it is is glazing on the pads/rotors.

zibby43

The rotors were all brand new (per the OP).

Correct me if I'm wrong but if the pad is already glazed, isn't it done for? This was always the case with my BMWs.

Isn't that why initial bedding-in is so important?

bhamg

As per what Diabolis said, this is courtesy of Tire Rack. The procedure as outlined under "Hawk" is what I've always done. Even if you didn't have any noise I'd advise you to do this.

All brake pads must be bedded-in with the rotor they will be used against to maximize brake performance. The bedding-in process involves a gradual build up of heat in the rotors and pad compound. This process will lay down a thin layer of transfer film on to the rotor surface. Following the bed-in procedures provided by the manufacturer will assure a smooth, even layer of transfer film on the rotor and will minimize brake judder. Here are a few things to keep in mind when installing new rotors and pads:

When installing new pads, the rotors should be new or at least resurfaced to remove any transfer film from the previous set of brake pads.

It is critical that the installer clean any rust, scale, or debris from the hub mounting surface thoroughly and check it for excessive run-out with a dial indicator gauge before installing the rotor.

The new rotor should also be checked for excessive run-out using a dial indicator gauge before the caliper and pads are installed. If a rotor has excessive run-out of over .004" (.10mm) it should be replaced.

If your new rotor has excessive run-out, please contact our customer service department for a replacement rotor. Do not install and drive using the rotor! Rotor manufacturers will not warranty a used rotor for excessive run-out. Running with excessive run-out on the hub or rotor will cause vibration issues.

Failure to follow these procedures may result in brake judder, excessive noise, or other difficulties in bedding-in the new brake pads. The pads need a fresh surface to lay down an even transfer film. Residue from the previous pad compound on the surface or an irregular surface on a used rotor will cause the pads to grip-slip-grip-slip as they pass over the rotor surface under pressure. The resulting vibration will cause noise and telegraph vibrations through the suspension and steering wheel. This vibration is known as brake judder or brake shimmy. This is typically caused by an uneven transfer film on the rotor surface or an uneven surface on the rotor not allowing that transfer film to develop evenly. This is often misdiagnosed as a warped rotor.

Bedding-in new pads and rotors should be done carefully and slowly. Rapid heat build up in the brake system can lead to warped rotors and or glazed brake pads. Most brake pad compounds will take up to 300-400 miles to fully develop an even transfer film on the rotors. Following are the recommended bed-in procedures from each manufacturer:

AKEBONO

400 to 500 miles of moderate driving is recommended. Consumer should avoid heavy braking during this period.

ATE

400 to 500 miles of moderate driving is recommended. Consumer should avoid heavy braking during this period.

BREMBO Gran Turismo

In a safe area, apply brakes moderately from 60mph to 30mph and then drive approximately 1/2 mile to allow the brakes to cool. Repeat this procedure approximately 30 times.

HAWK

After installing new pads make 6 to 10 stops from approximately 35 mph with moderate pressure. Make an additional two to three hard stops from approximately 40 to 45 mph. Do not allow the vehicle to come to a complete stop.When completed with this process, park the vehicle and allow the brakes to cool completely before driving on them again. Do not engage the parking brake until after this cooling process is compete.

NOTE: Hawk racing pads (Blue, Black, HT-10, HT-12) may require a different bed-in procedure. Contact your sales specialists at the Tire Rack for racing application information.

POWER SLOT

Follow the brake pad manufacturer's recommended break-in procedure taking care not to produce excessive heat in the system. Avoid heavy braking for the first 400-500 miles.

zibby43

This procedure is for when you are breaking in new pads/new braking systems in general. One of the reasons to perform a bedding-in procedure is to avoid glazing on the pads.

The section I put in bold is why I said that doing a bedding-in with new rotors and old pads is probably futile. OP has brand new rotors but the same, old pads.

Once a pad has been glazed, it is hard to "bring it back," so to speak. Ideally, you'd want new pads mating/applying transfer material to the new rotors.

bhamg

In an ideal world everything goes in new. In principle while I agree with your point, I've swapped out one or the other a number of times and never had a problem after performing the bedding-in procedure, and I've always done that. We're talking about quite a few such changes so the sample size in my case starts to be meaningful. And practically speaking, whether it's been old or new rotors paired with new or old pads respectively, this bedding-in procedure seems like a all-win, no-lose proposition. I don't see any downside.

RawBenz

The OEM pads were still brand new.
But i got my wife aftermarket rotors. The rotors are brand new and she retained the OEM pads because they had a lot of life left in them.

The noise happens at very slow speed when you apply the brake slightly and come to a stop you hear a bird chirping/whistling noise. It's a similar sound to birds of a morning.

The other conclusion is she's hit a bird and it's stuck in there somewhere lol.

Diabolis

Like bhamg, I used to swap brake pads before track events every other weekend - the street pads came off and the track pads went on. Sometimes new pads went on old rotors, sometimes previously used pads went on "new" (unused at the track with those pads) rotors, and most of the time they were both used. I've never had a problem in 15 years.

There's a great article and video at http://www.essexparts.com/learning-c.../swapping_pads that among other things explains why and how you can swap pads, but most importantly, that you need to worry about keeping the rotors clean, not the pad. Used pads are just fine with new rotors for as long as you bed them in. As I said, two or three panic stops from high speed (with enough "coasting" time afterwards to properly cool them off - or if you're using an arggressive track pad, never heat them up top the point of material transfer) is more than enough to (re)bed them in.

If the brake pads have been severely overheated and are crystallized throughout, you will have to replace them. However, if the glazing is only on the surface, a couple of panic stops - followed by coasting to cool everythign off properly - is usually enough to burn and/or scrape off the glazed pad surface without completely destroying the pad material. Try it out. If they still squeal, you may have to resort to suggestions 1 through 5, or you just may have to replace the set.

Part 1 of that article / video is also quite informative for bedding in new pads and rotors - URL is http://www.essexparts.com/learning-c...ds/post/Bed-in. Those two pages contain some of the most useful information on the subject I have ever seen.

Diabolis

They just need to be bedded in. See part 1 (second URL) in the previous post.

Two HARD stops from 80-90 mph to 20 and then driving for the next four or five minutes without touching the brakes ought to clear the problem. Make sure you don't do in places where it's not safe or the police hide - this is exactly how I got in serious trouble with the law last time.

Diabolis

P.S. If the pad is glazed throughout, as in cooked due to severe and sustained overheating to the point where the resins in the entire pad melt and crystallize, then yes, they are garbage. However, unless you've been tracking the car with street pads and have severely overheated them (we're talking heat soak here to the point at which you start to boil your brake fluid), the "glazing" is usually just on the surface.

What the OP is describing though doesn't sound like cooked pads at all, but rather slightly uneven contact area between used pad and new rotor (hence some possible surface glazing on the small portions of the pads that actually contact the new rotors), and/or rotors that have no material transfer build-up on them yet.

builthatch

pull the e-brake...drive against it a little...NOT A LOT, LIKE A FEW INCHES. release the e-brake. see if the sound is gone.

i had something very similar happen to me a one point the summer before last and that fixed it.

RawBenz

I'll give that a go.
How far in should i kick it in. It's a footbrake.

builthatch

oh, yeah, haha - sorry, that's what i meant. push it in like normal and try to move the car a little, then release it.

builthatch

any updates

RawBenz

Yes, the noise just went away on its own.