time for new brakes

[rooby]

The sound I refer to as squeal is usually a longer squeal type noise instead of short sharp squeak squeak squeaks. This noise is from the brake pad on rotor contact and is related to the brake pad compound (and apparently incorrect bed in procedure can also be a factor). That's why you see on brake pad brochures information about noise. Often high performance brakes can be a bit noisy.
This noise should only happen when you are braking and has nothing to do with bumps.
It usually only happens when you are very lightly applying your brakes, usually at low speed, like when you are stuck in traffic and creeping forwards, or coming to a stop at traffic lights.
It is much less likely at high speeds and you shouldn't get it under normal and hard brake pressure (unless your pads are worn out or you have something stuck between your disc and pads like dirt or rocks).

And how do fix this one in particular??

Depending on the pads it might just be the pads and you have to live with it or get different pads. Mine squeal a little but pretty rarely, but I kind of expect that from race pads that are high dust. I would think most street pads shouldn't have a noise problem.

Or if you didn't put new rotors on at the same time were the rotors skimmed to remove previous pad matter or else machined?

There is also some discussion on bedding in and squeal here viewtopic.php?f=38&t=7822&start=30#p139105

[LBR37Y]

They are new DBA slotted rotors and the pads are the exact same ones Jacks-GTB is selling on here, and I was going to put the anti squeal stuff on but the bloody mechanics forgot to put the locking nut key for the wheels back in the car for me so I'm current putting about with no locking nut key!!!!

So I'll have to attempt to put the anti squeal on at another date...

[LBR37Y]

This noise should only happen when you are braking and has nothing to do with bumps.
It usually only happens when you are very lightly applying your brakes, usually at low speed, like when you are stuck in traffic and creeping forwards, or coming to a stop at traffic lights.
It is much less likely at high speeds and you shouldn't get it under normal and hard brake pressure (unless your pads are worn out or you have something stuck between your disc and pads like dirt or rocks).

After doing a few road tests just then and the above happens when I'm crawling at low speed and with a slight pressure on the pedal..

So with the anti squeal stuff work on this situation or do I just need to go out there floor it then jump on the anchors???
As I want to get rid of this squeal because its very loud and embarrassing for me...

The pads that I have are these: http://forum.liberty.asn.au/viewtopic.php?f=25&t=17265

[rooby]

In my opinion grease / crc stop squeal won't help your problem.

Those pads are supposed to be pretty low noise I think, although I've seen some posts about them being noisy (seems like you get some posts like that for pretty much all pads though).

I would lean towards maybe the fitting/bedding process not being done right? But I don't really know.

I would ask your supplier for advice first. They probably have heaps of other customers using the same pads and could tell you if it is normal for those pads or not and maybe suggest a solution.

[LBR37Y]

I didn't bed them, the person who changed the pads on Friday said that he drove up n down the street a few times going from 60kmh to 20kmh a few times..

Not sure if thts right or not..


So what options am I left with a change of pads??

[rooby]

Jacks-GTB might have some ideas.

This might work viewtopic.php?f=38&t=7822&start=30#p139246

As far as I know bed in usually involves 5 or 6 moderate brakes from 70-80k to around 10k, without stopping completely and without dragging the brakes (no light pedal pressure, just brake then stop braking).

Then do 2 or 3 reasonably hard brakes from about 100k to 10k or so, again without dragging the brakes.

Then let the brakes cool down to ambient temp or as close to as possible. Drag brakes as little as possible when returning home or wherever you are letting them cool.

The idea is to get the pads up to temp an then get a good smearing of pad material onto the rotors and then let it cool and stick there. Then it is pad material on pad material when you brake, which = grippiness.

If you have high temp pads like track pads the bed in procedure should have more stops and if possible higher speeds to get the pads up to the higher operating temp.

Then there is this viewtopic.php?f=38&t=7822&start=30#p139198 which says certain types of pads do not require this type of bed in at all.

[LBR37Y]

I'll give it a go tomorrow maybe, but my driveway isn't straight and its a fairly steep hill and I usually go down it pretty slowly..

But I'll do what was previously stated 80kmh to 10kmh moderately then 100+ to a low speed with a hard pedal...


See how we go, I'll still put the anti squeal stuff on the shims but

[senator]

The idea is to get the pads up to temp an then get a good smearing of pad material onto the rotors and then let it cool and stick there. Then it is pad material on pad material when you brake, which = grippiness.
.

that's technically warping the rotors……. Any pad material left on the face of the rotors is only going to lead to reduced life of the pad and rotor.

Unless you’re using a track specific pad and rotors combo rated to 1000ºC + you don’t need to bother with a bedding process……. Drive normally with light braking applications for a few days….. this has worked for me running rotor and pad sets up rated the 800ºC+ for daily driving.

The squealing comes from the glazing of the pad surface, due to the gases and residue burn off from the sintered adhesive used to adhere the pad material. By so-called bedding in, your heat cycling the pads too quickly hence the residue is not burning off and forming a harder layer over the pads face….. the quick and easy way to fix this, is too rub down the surface of the pad with sandpaper, this will only be a short term fix as the brake medium would be already f#$ked from the initial bedding process.

Shims are used to reduce the vibration between the pad and calipar mating faces……. Which can result in squealing as the pad wears

[rooby]

The idea is to get the pads up to temp an then get a good smearing of pad material onto the rotors and then let it cool and stick there. Then it is pad material on pad material when you brake, which = grippiness.
.

that's technically warping the rotors……. Any pad material left on the face of the rotors is only going to lead to reduced life of the pad and rotor.

Unless you’re using a track specific pad and rotors combo rated to 1000ºC + you don’t need to bother with a bedding process……. Drive normally with light braking applications for a few days….. this has worked for me running rotor and pad sets up rated the 800ºC+ for daily driving.

The squealing comes from the glazing of the pad surface, due to the gases and residue burn off from the sintered adhesive used to adhere the pad material. By so-called bedding in, your heat cycling the pads too quickly hence the residue is not burning off and forming a harder layer over the pads face….. the quick and easy way to fix this, is too rub down the surface of the pad with sandpaper, this will only be a short term fix as the brake medium would be already f#$ked from the initial bedding process.

Shims are used to reduce the vibration between the pad and calipar mating faces……. Which can result in squealing as the pad wears

Really?

I get the part about the glazed surface & squealing, but almost all brake pad retailers / manufacturers recommend said bedding process to get a transfer of pad material to the rotor (at least that's what the evil internet would have you believe).
And they say that uneven transfer of pad material can give the impression of warped discs.

I guess with lower temp pads such a bed in process would risk getting the pads too hot, leading to glazing, whereas with really high temp pads regular driving might not be enough to get a good transfer?

In essence, normal driving should do the same as the bed in process, just over a longer period and with less risk of overheating lower temp pads.

[rooby]

Also, I'm not trying to argue about it Tony, I just like to try to learn as much as possible from people who know more than I.

[t.renshaw34]

It's the rear that creates all the kerfuffles. The front is easy.

Which way were you going with the handbrake? DBA's custom made rear rotor to suit the normal soes or modified handbrake shoes to suit the STi rotors?

How do you modify the handbrake to suit the std rear brembo rotor?

[LBR37Y]

It's the rear that creates all the kerfuffles. The front is easy.

Which way were you going with the handbrake? DBA's custom made rear rotor to suit the normal soes or modified handbrake shoes to suit the STi rotors?

How do you modify the handbrake to suit the std rear brembo rotor?

If I was you I'd sell the STI rotor n buy a rotor to suit ours??

[3rspecb]

It's the rear that creates all the kerfuffles. The front is easy.
Which way were you going with the handbrake? DBA's custom made rear rotor to suit the normal soes or modified handbrake shoes to suit the STi rotors?

How do you modify the handbrake to suit the std rear brembo rotor?

Adding more friction material to the parkbrake shoes. Search HyRax's thread, from memory he has a pic of his modified p/brake shoes.

[HyRax]

How do you modify the handbrake to suit the std rear brembo rotor?

As mentioned already, you replace the friction pad on the handbrake shoes with fatter ones, allowing the pad to reach the larger STi rotor contact area.

In my case I went to a wrecker and got some spare handbrake shoes, had them modified by a brake specialist who stripped the original material and bonded on new material, and then I swapped them out with my existing handbrake shoes when I was ready to perform the caliper and disc upgrade.

You can see a pic of the modified shoes in my profile thread here. And a before and after shot when fitting.

[LBR37Y]

hey guys sorry to dig up and old post...

but i have changed pads (from the stoptech ceramics) to some Garage88 ones (dixcel type ES) just yesterday i might add
i also put on some anti squeal grease stuff on the shims and pads

still having same issue... all i can think of now is skimming the rotors and getting out some sand paper on the pads???

all this is in regards to the brembo set up on a GTB

any other ideas??