RexNuts Subaru Forums

Just changed the front brake pads on the car to QFM HPXs. Took it around the block for a quick drive and they squeal a fair bit when I brake probably cos they're still new. The odd thing is.. the squeal is still there for around 5 odd secs after I take my foot off :S.

I had to unscrew the cap on the brake fluid reservoir to push the pistons back in before I could fit the caliper back over the new pads. This caused the fluid to overflow from the top and some bubbles to form I cleaned it up promptly and it looked normal. Came back from the drive and there seemed to be a few more bubbles at the top .

So my question is, could I have somehow got some air into the system and thats what is causing the pistons to take a while to lift off the pads causing them to squeal even without brake pressure?

Thanks guys wave.gif

Only if the master cylinder resevoir was empty would you get air into your brakes.
Just bed your new pads in with the standard hard stops.

Cheers for clearing that up Pat

So the continued squeal after lifting off the pedal is normal do you think?

The squeal could be the pad not returning with the piston right away as the pads are not attached to the pistons, you can get a anti squeal goo that you put on the back of the pad so it returns with the piston but i wouldnt suggest this as it is a bit messy. also did the pads have a shamfer on the edges? like the ends of the pad surface was cut on an angle towards the back of the pad?

Did you re-use the shims.
I agree with using an anti squeal paste.
Ive heard the QFM pads are fairly quiet.
Just give them a day or two to settle down.
Let us know how you go.

I put some grease on the back of the pads and I re-used the shims. This is supposed to help stop them from squealing I believe. Didnt use a lot cos it was getting messy and I didnt want any grease on the inside of the pads obviously. Pretty sure the edges on the pads were cut at a slight angle.. so thats supposed to help stop them squealing?

Just need to give them a bit of time and bed them in properly I suppose. Atleast I know that theres nothing "wrong" with them now and that I didnt screw anything up! lol

Quick update.. did the bedding in excercise and the squeal "seemed" to get better for a bit. But that didnt last very long at all and they're squealing like mad everytime I touch the brakes . Also i think the pads/shims are rubbing somewhere cos I can hear it when I drive next to a barrier with the window down. Had this brake shudder issue before I put the new pads in and that hasnt gone away either

So anyway I'm over it now and just taking it in to my local subie guys to get the rotors machined to get rid of the shudder and hopefully they'll be able fix the continuos noise from the rubbing as well.

The shudder would always have been the discs needing machining or replacing. Is the shudder coming through the steering wheel or just brake pedal pulsations?

Not the brake pedal or steering wheel.. the whole front end of the car shudders as I pull up. The car jerks as it slows down under brakes.. a jerk every time a certain part of the rotor passes by the brake pad :S. Was just hoping putting new/better pads (which I needed anyway) and bedding them in would even the rotors out .

Ah well, hope it gets fixed on friday at the shop... so over all this squealing and shuddering!!

Definitely sounds like warped rotors to me..

get the, machined, or buy new ones?

Was thinking this is a great excuse to step up to some sexy slotted rotors. But guess what the DBA648s I was keen on are out of stock across the country for atleast 2-3 weeks

Anyway I managed to get the issue fixed today. A good machine was all that was required it seems. That and some Castrol Super Dot 4 fluid have the brakes feeling right once again!

Found some interesting (and somewhat offputting) info about QFM pads along the way though. Basically, they're not as wide or as thick as the stock pads. The difference is quite apparent once you put them next to a new Subaru pad. Because of this, the QFMs leave about a 2mm groove on the outside of the rotors as they dont cover the entire rotor out to the edge... lost braking capacity much

They dont have shamfers on the edges that Leon mentioned above ^. For some reason I thought they did.. so thats one of the causes of the squeal right there.

Anyway... guess I'm stuck with them for a while. Will look into getting both rotors & pads once these ones are worn out. On the whole though, it does seem like you get what you pay for in the end.

I wouldn't be too worried about the fact that it leaves a small lip, both them and Subaru pads will wear the discs down just the qfm ones won't wear all the way to the edge and braking efficiency lost won't be that noticeable I don't think. As for the shamfer, you can always put one on yourself but again that means less pad to rotor contact until the pad wear down to where the shamfer stops

I installed my new brakes on the weekend..

RDA rotors and QFM HPX pads.

Mine done squeak or squeal at all. I reused the shims, and greased them lightly.
I love mine.