LexLeezard

Well, you sound pretty sure nothing I suggested makes sense. But you haven't said why you have that view. How about providing reasons we could all understand to back up your opinion? Don't know about you, but usually if somebody says they don't agree or if they claim that something is so, that isn't good enough without explanation. Your question about ISs and no squeal is reasonable because it raises the general question: what models over the years have had a brake squeal problem? Knowing about that could lead to a definitive fix for models where the problem exists.

Diesel350

It doesn't make sense because this happens in 95 degree heat in the middle of the day. It happens in the morning when I back out, it happens during lunch when I back out and it happens at night after dinner when I back out to go to the gym. It happened when I had all stock rotors and pads, and it happened when I had BRAND NEW AFTERMARKET rotors and pads.

Yes it happens EVERYTIME I back out NO MATTER WHAT!! I'm pretty sure nothing you suggested makes sense to me.

LexLeezard

Yeah, I can appreciate how frustrating it would be to have the squealing happen every time you back up, in all conditions, no matter what.

The squealing on my GS460 doesn't happen all the time. Only happens after the car has been sitting for an extended period of time. It seems worse / louder if it has been pretty cold out.

So, it happens first thing in the morning (guaranteed), and every once in a blue moon if I have a long day at work and it's late evening before I head for home.

But it's always in reverse, just like you. Never going forwards.

If I take my foot off the brake while backing up, and then hit the brakes pretty hard to bring the car to a sudden stop, and then keep on backing up as usual, there is no more squeal at all, no matter how light my foot touches the brakes.

From what I understand, squealing like this is just a high-frequency vibration. For example, the 2004 Volvo V70R we used to have just prior to our GS460 had the very common (for that model) "rain squeal".

At regular operating temperature while driving along, the exhaust pipe could be very suddenly cooled down by driving in heavy rain, or through standing water or snow on the road. As a result, the pipe would slightly twist with the sudden temperature drop, and it would very lightly touch the rotating driveshaft. The tiny contact point would create a very loud high-frequency squealing as the pipe scraped the rotating driveshaft. Very troubling, especially if you weren't expecting it. But it happened only when driving in heavy rain or through snow or quite deep standing water.

When the Volvo was on the lift, you could see the slight scoring on the driveshaft and the matching contact point on the exhaust pipe, only a very short distance away. The scoring was just a very thin, shiny line all the way around the circumference of the shaft. This annoyance was reported by almost all V70R owners. It was a design fault because the exhaust pipe was installed between two suspension points that allowed it to flex just enough under sudden temperature changes so it lightly touched the driveshaft, kind of like a needle on a phonograph. The problem could be cured with a two-cent shim to limit how far the pipe could flex.

So, in the GS460 either with OEM discs and pads or aftermarket gear, I am wondering if there is something about the pad / disc geometry that causes the vibration, but only with light brake application, and only in reverse. Could it be that when the disc is slowly rotating backwards (in reverse) the edge of the pad (which would be the trailing edge when the car is going forward) "chatters" at just the right frequency to create the squeal? Going forward doesn't do that maybe because of a small difference in "angle of approach" (which might be measurable only in tiny fractions of a degree). It might also have something to do with the repeated and much more frequent wear on the actual leading edge of the pad versus the trailing edge. Maybe what is normally the trailing edge "grabs" the disc differently when it is temporarily transformed into the leading edge, so it only happens in reverse.

I am not an engineer and I'm really speculating here, but -- could the squeal be a high frequency vibration generated by the pads which have that particular frequency just on account of how far apart their mounting points are in the calipers? If this was so, maybe it would be possible to install some kind of shim under the pads inside the caliper to change how they would vibrate. But I have no idea if such a thing is possible.

What do you think?

Anyone else out there have experience with this?

RSVP / Cheers / LexLeezard

ThomasGS4

iTrader: (19)

Seems as though everyone is reporting squealing in reverse, although my GS will only squeal when pressing on the brakes for the first time (after a cold evening) moving forward.

LexLeezard

Well, it will be interesting to hear from additional GS460 owners about whether they get squealing mainly in reverse, or going forward (or both?). And more from those who get no squealing whatsoever under any circumstance at all.

Makes me wonder if maybe it just so happens that the majority of us GS460 owners have a "default" factory configuration of pads (whether OEM or not) in stock calipers that makes the noise mainly in reverse, usually when cool.

And by "cool", I mean "operational cool", where they haven't been used for many hours. I am not meaning cool as in weather -- although "colder" weather could conceivably accentuate the noise before the brakes heat up to normal operational temperature from regular braking.

I am also thinking that maybe one of the reasons why owners of other models (at least to my knowledge) haven't commented much about brake squeal is that the "default" configurations in their vehicles could be sufficiently different from the GS460 that they just don't make much of a squealing noise, even in identical driving circumstances.

As far as a potential solution goes, I'd be very interested to hear about anyone's knowledge of, or experience with shims under the pads.

Cheers / LexLeezard

XxGoKoUxX

Guys, did you use the braking grease they provide when you installed the new brakes? I have ZERO squeal, forwards OR backwards. Rears are OEM, fronts are Rotora+EBC Green stuff.

LMK, if a shop's done your braking job, I'd go to your local auto parts store, buy the 2$ in grease, and go to your brake shop and make'em put it on (watch them while they do it too to make sure!).

GL!

LexLeezard

Hey XxGoKoUxX -- am going to the dealer tomorrow for this. Will observe (and take pics if possible -- usually is, so should be no problem). Thanks for the suggestion! Cheers from -37C (with wind chill, just a bit chilly this evening!) / LexLeezard

XxGoKoUxX

GL LexLeezard!

I don't know if the dealer will let you observe, but hopefully you will be able to!

That is ICE cold where you're at! We have a nice warm 30C over here in FL!

whlkev

'08 here and the only time it squealed on me (the rear brakes when backing out 100% of the time)

I took it to the dealer and they told me the pads were extremely low, so after replacing it, it was perfect

for 75k miles, that was the only period of time it squeal.

good luck

worker

I need to move there. Temp here can't go pass zero celcius.

I remember something about a metal put in to squeal when the pad is too low. Like a warning system.

XxGoKoUxX

Yup it's to tell you that you need your pads changed.

The rear pads take almost FOREVER to go out before the fronts do. I'm at about half my pad life left in the fronts and my rears still have life on them . I'd like to change'em out to slotted+drilled soon lol.

xRYD3Rx

my GS350 also makes brake squeak when going ONLY in reverse.
Took dealer and told them my issue they changed my pads and machined rotors picked up the car still makes noise....... THE F....?

RYKR

I'm running oem rotors and pads for the GS460, no squealing or squeak going forward or reverse ... aside from the infamous brake dust build-up, the GS has fairly grippy brakes to begin with, so I don't really think there will be a major difference using aftermarket performance pads on oe rotors or vice versa ... but the only setup that would really interest me are some serious carbon ceramic BBK's

dellexus

My V8 only squeeks when im reversing first thing on a cold morning but after driving for about a minute or so it goes away.

Got Pagid Pads and Discs.

LexLeezard

Dear all: So, I didn't get to the dealer as planned. Discussing and asking about the "braking grease" as suggested by XxGoKoUxX will have to wait until this week, or maybe even next week. Flexible time for this kind of stuff is hard to come by! Anyway, for those who like weather reports, it's still really cold here in S Alberta. This morning, when my wife and I were having coffee, it was -35C with a heavy ice fog and a wind chill of -43C. Don't worry -- it wasn't "iced coffee"!!! Right now as I write this in the evening, the outside temp is a verifiable -25C with a wind chill of -33C. Weird, but this part of Alberta very often has the coldest temperatures in Canada, and sometimes even on the planet! Regardless, the GS460 does extremely well even in these really cold conditions. Good to know. Cheers / Lexleezard