Changed rotors/pads/fluid, brakes feel weak
 

I just swapped out my pads, rotors and fluid this past weekend because it was past due. I installed Hawk HPS pads, OEM rotors and DOT 3 brake fluid. I was expecting a night and day difference from before but it still feels weak. Don't get me wrong they work fine and are not a safety hazard but I was expecting them to really grab and response quickly. They sort of feel spongy and it takes more leg pressure than expected. I'm used to driving my parents F30 335i Sedan which has impeccable brake system and maybe I got a little spoiled by the response time.
I did the bedding process and its already been 100 miles but they still feel the same. I'm thinking maybe I didn't flush properly. I started from the front drivers (closet to the master cylinder) and went in reverse from closest to farthest. I really only flushed out about 1/4 of a bottle of water worth of brake fluid. All lines were clear brake fluid and pumped them about 6-9 times so I assumed that was enough but now I'm not sure.

Anybody have any thoughts?

i know right after you change brakes it take time to bed in the brakes. since it has been 100 miles i would bleed your brakes again and make sure there is no air in the lines.

Depends on what kind of miles that 100 consisted of. If 80 of them were highway...not much braking to be had.

Yea it was mostly highway but it was pretty busy time or day so I did do lots of stopping and slowing from 50-75 mph. 3 days later and my brakes still feel weak. I'm going to go back and drain out more brake fluid and will keep this updated.

You bled them wrong. You go from the farthest from the master cylinder to the closest. Also get a pressured bleeder if you can or take it where they can do it using a motive pressure bleeder. Run a full bottle of fluid through your system. When I did mine with a 2 person bleed, we did 7 pumps but did 3 - 4 cycles per wheel.

Bleed in the following order.
Right Rear
Left Rear
Right Front
Left Front

http://www.motiveproducts.com/

https://g35driver.com/forums/v36-diy...r-bleeder.html

http://my350z.com/forum/brakes-and-s...tem-bleed.html

Okay thanks for the help. Now in almost certain it's the brake fluid.

2 things:

- Hawk HPS pads do not have good initial bite. It's why I stopped using them on prior cars. They may have decent fade resistance but they are crappy in terms of bite, especially on first stops and in cold/wet weather. I've been much happier with Project Mu pads.

- The correct bleeding order, according to the FSM is Right rear brake → Left
front brake → Left rear brake → Right front brake

+1 Hawk HPS have a terrible initial bite.. I experienced the same thing. Unless you're going to the track and need fade resistence, stay with OEM. It's the best in terms of bite, modulation, and noise.

Damn I wish I read more into it and bought OEM, coulda saved 50$ as well.
Yea they definitely lack the initial bite, say I'm creeping off the brake and gas and press the brake firmly it takes longer than it should to stop.
I have to say though I'm pretty sure the car came with OEM when I bought it and I can't tell a big difference at all between the two.

I would have to agree on the HPS as well. I stopped putting them in my daily driver's because they need a little heat to really perform and seem to lack that cold initial bite feel.

If oyu go out and drive a bit aggressively, they should get better. Of course, that doesn't help you when you panic stop on cold brakes.

Of course, that's assuming nothing else is wrong with the brake system. If you give the pedal a quick double pump when stopping off the highway, does the brake pedal feel improve? If so, you def have air in the lines.

I just drove myself insane as I had a similar problem, it turned out to one of the calipers were defective and letting just a tiny bit of air into the system. Once I ripped off the calipers and replaced them, problem solved.

Sounds like you bled the brakes wrong and air is in the fluid system now. Get the motive brake bleeder, they make the whole process much easier.

As others have said even if the system is bled properly those HPS pads are not going to perform the same as OEM.