My brakes are stock, except they're equipped with Porterfields. I just got the rotors replaced a few months ago, and everything is in check.

Braking performance is really great on the freeway, I can go from 80-20ish in no time at all....but on the street, it is somewhat weak and unresponsive. Anyone know why? I've really analyzed this, and on all of the other cars I've tested, 97 Toyota Camry, 01 Ford Escape (rental car), 87 Corolla, 91 Previa (van), the brakes are very responsive. It seems that I just have to apply pressure and the brakes will do the rest for me. On my car, I feel like I have to gradually and continually press in the pedal. If I apply a certain pressure, I have to keep going in order to FULLY stop, or else I'll keep rolling.

I've had a few close calls too...I'm really hesitant to take my eyes off of the road even for a split second (like pressing the forward button on my head unit). Does anyone have any suggestions as to what it could be? Why are other cars' brakes much better than mine? Aren't 4 wheel disc brakes better than the 2disc/2drum type?

thanks

 

4 wheel discs are much better than than a rear drum setup. The way you described things leads me to two conclusions. The first one could be that on the highway, when you step on the brakes at high speed those Porterfield's heat up very quickly and stop better. On the street, they will take longer to reach their best operating temp. This may lead you to feel that you have to keep pressing more and more on the brake, because you essentially do. The other possibilty is that your master cylinder is starting to go and that's why you feel it start to bleed down. This most accurately describes what you experience on the street, but doesn't make much sense for your experience on the highway. It's kinda hard for me to guess anymore without driving your car.

One suggestion would be to swap an old set of brake pads back in and see how the car behaves. If you still have trouble stopping on the street, I'd look at the master cylinder.

 

The problem is that you have near racing grade brake pads and are using them normally. If you look at brake pad specs you can find coefficient of friction for the pads, normal is about 0.3, 0.5 is very high. I suspect you'll find the Porterfields are a little low unless hot - a racing pad characteristic, and a trade - off for very high performance. This is why you will see road race cars dragging their brakes on the pace lap - so the brakes work at the first corner.

 

Sounds like you got air in the system? I must say IMHO Maxima brakes are superior to the Camry of which I've driven several 4-cyl meaning ABS with rear drums. Maybe the dudes who did your brakes should bleed them, that would be my suggestion. Having to continually press is definitely not right. If the master cylinder goes that is also a symptom, but I'd try the bleeding process first. Good luck.

 

like the other person mentioned, your pads have a higher temp rating than stock so they require to be heated before they become effective. Stock organic pads are able to stop better when they're cold; aftermarket pads work better at slightly higher temps.

 

He needed to replace the MC, is there a way to put a "bigger" one on to create more system pressure? Or is there a inline booster that could be added to do this also?

I really want to get a better brake feel, but from what I have read..bb systems loose pedal feel. So I was thinking to boost the MC somehow...but my mechanical thinking is not what it needs to be to solve.

 

I've done a lot of brake fluid flushes already. And as for the racing brake pads problem...well, with OEM pads, I kinda had the same problem. I've had unresponsive brakes since I've gotten the car and I'm getting a little tired of it (and worried that I won't be so lucky next time.)

Other observations include:

-When I press the pedal I think I can actually feel the pad gripping on the rotor (its not silent like the other stock cars I've driven)

-My wheels are 16x7.5...very wide for a 16 inch wheel...and I have 225/55, which are slightly taller than recommended size. I've realized I should've have gotten 215/55 or 225/50. BUT, would the larger tire/wheel combo affect performance?

I guess since I've had the brake system checked numerous times, I'm suspecting it might be the wheels I have?..

 

That could be the problem. Did you notice it starting when you put these tires on? Maybe also at that size these tire/rim combination is heavier than stock as well? Try throwing your old stock tires/rims on there for a 20 minute drive or something and see if you notice a difference.

SuDZ

 

unfortunately I don't have tires on my stock steelies anymore.

But then again, I've read a lot of members not really noticing a brake perforamnce decrease when they upgrade to larger sized wheels.

 

Bigger tires and wheels shouldn't efect pedal feel at all. It may take slightly longer to stop the car because of the extra weight, but it shouldn't be that much more, we're probably talking less than a foot. If the pedal is sinking under a constant pressure and the system is well bled, you probably have a problem with the master cylinder. I'm not sure about options regarding putting in a bigger cylinder, but if you want increased feel a set of stainless steel brake lines does wonders for it.

 

What I notice a lot is brake performance on my car is inconsistent. Sometimes the car brakes really strong, like a brand new car would. Other times, it won't stop unless I continually apply pressure.

 

I forgot to mention...you know what else? It feels like whenever I have to brake to a stop, my car is nosediving. It seems like the front brakes are doing all of the work and the rears aren't doing anything.

help?