Less brake pedal feel

[quang]

Hi everyone,
I've just changed my front brake pads from OEM to some QFM HPX pads,
the pedal is still firm but its lighter in the first bit of pressing the brake as compared to the OEM pads.
Is this normal? i still stop like crazy now, just i don't have that initial firmness that i'm use to. I pretty much followed ecu-man's DIY (thanks ECU-MAN)

Also i had my discs machined, but after putting the pads on, there are lines coming up on the disc, is this due to dirt or debris being stuck on the pad that i may have forgot to remove or does this normally occur?
i got the discs machined to get rid of the lines that were already on them from the OEM pads.

Any info would be appreciated.

Thanks

[Limbo]

did u bed in the pads?


Bedding in advantages:

1. Gradually heat treats the rotor and eliminates any thermal shock in the rotor

2. Burn off volatiles and moisture from the resin that is near pad surface. This will eliminate "green fade."

3. Establish a layer of transfer film about a few microns thick on the rotor surface. Shearing of the film during friction is an effective source of friction force. Otherwise, when using a freshly ground rotor without the transfer layer, the main friction force would come from cutting, plowing, or scoring the asperities on the rotor surface. This leads to inconsistent braking effectiveness.

4. Mate the two surfaces to a near perfect geometrical match, so that the contact area is high, and therefore the friction force is increased.

5. The performance of a fresh rotor/fresh pad system would be inconsistent. This is due to ever-changing structures and properties of the two mating materials. Bed-in of pads and rotor will form a stable transfer film.

6. If bedding in procedure is not applied, a stable transfer film may not be established for a long time. In other words, the rotor surface would have to be constantly regenerating a film that is not quite stable for a long time. This effect would reduce the performance and increase the wear.
Procedure

Always consider the Brake pad manufacturers bedding in recommendations.
1. After installing new disc rotors &/or brake pads, perform 8 to 10 slow downs applying moderate pressure from approximately 50 - 60 kph without coming to a stop.

2. Make an additional 2 to 3 slow downs applying heavy pressure from approximately 60 - 70 kph without coming to a stop.

3. DO NOT DRAG BRAKES!

4. Allow at least 15 minutes for brake system to cool down.
After step 4 your new disc rotors &/or pads are ready for normal use. Be aware that the full bedding in process can take up to 300 - 500 Kms depending on driving style. During this period try and avoid any high speed hard braking to a dead stop.

from http://www.repcotrade.com.au/go/news/dba-bulletin-basic-initial-brake-bedding-in

[bennjamin]

Did you bleed your brake lines as well ?

[quang]

yep i bedded in the pads, about 8 slow downs from 50-60kmh. although i may have been a bit hard on them during the bed in.

ah no, i didn't bleed the brakes, i didn't think i needed to as i had bleeded my brakes about a month ago during a 200,000Kms service, so it was still pretty fresh.

any ideas about the lines?

[OMG.JAI xD]

Those lines are probably scoring from the previous pads.

My best guess, is you have a thinner disc (due to the machining) along with a set softer compound brake pads.

If you still stop, it shouldnt be a worry.
Though i would try bleeding the brakes again. I had sort of the same problem with my old eg. Except it happend when i bled the brakes. I used a different brake fluid, and probably that was what was causing it. It still grabbed and no spongyness, so i left it as it is.

[quang]

bled the brakes, back to normal now guys, thanks for all your help. although, now i'm wondering if i should have done it, sorta liked that slight spongy feeling :). but def more confident in braking now, back to old driving style :thumbsup: