Brakes Squealing!

Neil Choi · January 04, 2014, 10:36:00 PM

Ummm, on reflection, guess the tray does several things as all have discussed.

Keeping nasties out of the engine bay (theoretical).

Aerodynamic effects, it does work (at speed).

And collecting or trapping any oil leaked from your motor, which is probably the main requirement for environmental reasons. All new cars seem to have them.

And back on OP, have changed pads and discs on several different cars many times, disc brands include OEM (Ford, SAAB and Alfa), RDA, Brembo; pad brands OEM, Hawk, EBC, QFM, Racebrakes. Never had squealing. But have cooked some pads so much they broke off in chunks. Also gouge out a set of Brembo's because the pads were too hard but the car did stop. Have used EBC greens and reds for years and all are fine, they have a chamfered edge and a bedding in compound. Also a soft backing layer on the backing plate where the piston pushes in to create a good indentation, to stop squealing as I understand it to be.

Off topic: on recent brake and bearing replacements, was surprised how cheap EBC pads and Ford parts are compared to others.

Quattroporte · January 05, 2014, 12:12:07 AM

I haven't cooked the brakes at all, but it seems they are faintly squealing on occasion towards the end of slow braking. Not sure how I can resolve this particular issue? Surely they shouldn't squeal? I'm pretty sure the rumbling is the gravel tray wobbling underneath on the left side of the car. It's most audible when I go over a bump. Do you reckon this could be the cause of the noise?

colcol · January 05, 2014, 10:50:53 AM

The rumbling may be the gravel tray being loose, just get under the car, and see if its hanging down somewhere or if you can grab it and move it by hand, it will need refastening or fixing, do it before it gets anymore damaged.
The brakes are noisy most likely because they are a bit hard and don't have enough friction, the top brands of brake pad have a chamfer on the leading edge of the pad, does your pads have this and what brand of brake do you have?, some brake pads have a shim / spacer between the piston and the brake pad, Colin.

Quattroporte · January 05, 2014, 02:31:44 PM

My discs and pads are all genuine Alfa Romeo as far as I'm aware. I also believe they are soft compound pads.

Neil Choi · January 05, 2014, 04:06:45 PM

Solution:

Install a sports exhaust.

Turn up volume of your favourite driving music.

I just listen to my V6's rumble and 1026 newsradio. Not kidding.

colcol · January 05, 2014, 06:14:14 PM

I had Genuine Alfa Romeo brake pads on my 156 and they didn't make any noise, but they dusted up the rims quickly, the easiest thing to fix, would be the gravel tray, silence that and then think about the brakes.
1026 AM News radio, only for old people, may even put you to sleep, Colin.

Quattroporte · January 06, 2014, 11:36:07 AM

I'll have the gravel tray replaced ASAP. I'm genuinely tipped off now, though, because the brakes are squealing! I didn't glaze them, I know that for sure! What can be done to resolve this issue? Would machining them help?

colcol · January 06, 2014, 08:35:54 PM

If the gravel tray is broken, then have it repaired or replaced, if it is just loose, fix it, sometimes the nut rivets strip, you can also use large mudgaurd washers to hold the gravel tray on, [like i do].
Take the pads out and give them a deglaze on some rough concrete, in a figure 8, to break the glaze, also chamfer the leading edges of the pads, by rubbing brake pad at 45 degrees to the rough concret, this may help to avoid 'push off', that is the leading edge of the pad pushing away, due to the direction of the rotor travel, and the back part of the pad doing the braking, Colin.

Quattroporte · January 08, 2014, 03:18:10 PM

The gravel tray was fine! It turns out that it's just the unlubricated part of the suspension that is making that noise. It's nothing major! It's not making it all the time either! As for the breaks, my mechanic told me that chemicals that are used to clean the tyres/wheels can cause some squealing. The brakes are not glazed and he said once they fully bedded in they should stop squealing. It's a matter of the the residual chemicals fading away.

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colcol · January 08, 2014, 09:04:19 PM

All the suspension is unlubricated, grease nipples in front suspensions went out with pushrod engines and rear wheel drive, it is most likely the top control arms are rattling.
You won't be able to tell if they are glazed unless you pull them out, they will appear all shiny with low friction.
Whenever you put in new pads, you should have the rotors machined, but they are so cheap now, put in new ones, so there is no grooves or ridges.
Usually when you put in new pads, you clean up the calipers, and put copperslip on the guide pins for smooth operation, Colin.

Quattroporte · January 12, 2014, 02:23:33 PM

I'm stressing out! I don't believe it's the suspension making this rubbing/vibrating noise! I can feel it through the acceleration pedal. It's not when I go over bumps all the time either! May cost a lot to access the right part though! Also the brakes are still squealing! I've done over 1000 kilometres in them. They're also kinda rusty as I hosed them down as per my mechanics advice to try get rid of the so called cleaning chemicals. Not sure what to do!

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colcol · January 12, 2014, 03:24:08 PM

Take the car to an Alfa Romeo service provider and find out what is making all the noise, my Magnetti Marrelli brake pads don't make any noise, but dust up the wheels badly, as did the previous Genuine Alfa Romeo pads.
The tops arms usually start knocking around 80,000 - 100,000klms, there are millions for sale on Ebay, Colin.

Quattroporte · January 12, 2014, 04:37:24 PM

My car is only about to hit 39,000 kilometres. When I took it last he could not make the car make the sound! Also is there any way I can remove rust?

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colcol · January 12, 2014, 05:35:50 PM

The brake rotors and calipers are steel, so they will rust when exposed to water, the rust on the rotors will go after a few brake applications, the calipers are permanently covered in dust, which will stop the caliper rusting anyway.
May need to take it to an Alfa Romeo service provider to trace that noise, but with such low distance covered, the suspension should be ok, some might be loose somewhere, Colin.

Domenic · January 13, 2014, 08:38:40 AM

Quote from: Quattroporte on January 12, 2014, 04:37:24 PM
My car is only about to hit 39,000 kilometres. When I took it last he could not make the car make the sound! Also is there any way I can remove rust?

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We at Italian Automotive Spares stock Textar brake discs that come with an anti corrosion coating on them (silver), so even if you hose them down, they won't rust like yours have. I know it' s a bit late now, but if you ever need to replace them in the future you have that option.

Also, Col mentioned a general rule of thumb when replacing pads to machine the discs, just make sure the person doing the job machines the complete disc, some of those guys that do disc machining on the car can't always machine the full disc as they're machine has clearance issues, this leaves the disc not fully machined and a lip on it and could be the cause of brake squealing as well.
Seen it a couple of times and the machining guy can't do anything about it as the machine won't fully fit in the wheel well to machine it all. So you're left with either a non fully machined disc(may cause squealing), or you have to take the disc off the car and send it away to get machined, thus costing you more than just replacing the discs with a new ones. Just so it's done correctly.