DrKlop

iTrader: (3)

I took my car to the autocross event (it's not hard on the brakes but I did "apply" them) last Saturday, and on the way back I noticed that my brake pedal became sort off too firm, and at the same time very imprecise. (it still hasn't changed) It feels like there's a bottle of soda stuck behind the pedal.

Do you guys have any idea of what could be causing this?

A few more things that might help identify the problem:

* I have done 4 emergency style stops from 45 to 0 mph this week (just for testing purposes) and two times the brakes did not work as good as they should have. (the car stopped 15 - 20 feet further than I expected)

* After trying to slow down from 90 to about 50 I started feeling the burning smell, apparently, coming from the brake pads. The brakes did not fade.

* About a month ago I did some spirited back road driving, and the brakes started fading MUCH earlier than I expected.

* My rotors are slightly gouged.

Thanks in advance!

steven88

iTrader: (28)

hmm...so your pedal is becoming stiff? but how is the overall braking of the car? the smell you described seems normal if u ask me...anytime i brake real hard...or any other people i talk to...they experience a burnt smell...and thats just the brakes if u ask me...

subscribing for some answers as well...

DrKlop

iTrader: (3)

Basically all this week the pedal feels very stiff regardless of how long I have been driving, but the brakes do seem to slow the car down... (most of the time, at least)

LA02MAX

iTrader: (3)

you might want to take off your pads and see if one of the pistons is jammed in too far or something. that definitely does not sound like normal brake wear if you ask me. And yes, the burning smell is normal when applying them at 90mph...

DrKlop

iTrader: (3)

Thanks, I'm ganna take off the wheels and check all 4 brakes this coming weekend.

Should I check any other parts of the braking system?

Is it possible that my gouged rotors have something to do with this? I'm pretty much a noob in troubleshooting brakes related problems.

ghostrider17

iTrader: (6)

My rotors are gouged too, and I have heard of many others this happens to. I don't know if this is symptomatic of "warped rotors" but I think it's not helping. I may try to remove my pads and put them on a Stationary belt sander to remove any grooving that has developed (hawk hps).

I've never found a happy medium with my brakes and longevity. I seem to get about 5k miles on the rotors before they start to "warp". I literally have two sets of rotors that I turn whenever one goes bad now, and am going to swap-out the frozen rotors that I have on right now, which have, btw - already been turned once since installing 15k ago.

9DTALON

iTrader: (1)

I would say to inspect the rotors for rust and uneven wear. I've seen MANY A33B max's at the dealership here that have some very unusual wear on the rotors. The inside faces especially tend to rust around the outer and inner edges of the face leaving only a small band of smooth rotor in the middle. I have to imagine that this scenario has the car stopping very unevenly. Anyways good luck.

LA02MAX

iTrader: (3)

the gouges in the rotors that you're talking about are from the pad material building up in certain places. Did you ever bed in your brakes when you first got them? The uneven transfer of pad material to the rotor face is what most people feel when vibration is present under braking; not warped rotors...you might want to take a quick look at both your pads and your calipers...

Larrio Motors

iTrader: (23)

bad pedal feel is usually attributed primarily to the fluid. I'd recommend bleeding the brakes and replacing the fluid with some higher performance ones.

Your current brake fluid might have been in the car so long that the moisture lowered the boiling point of the fluid.

DrKlop

iTrader: (3)

To be honest, I never had to change the brake pads on this car yet. Apparently, they were changed with the original Nissan pads right before I bought the car. BTW, I don't have any vibration when the brakes are pressed.

Hm... interesting enough it all started 9 months ago, when I asked my mechanic to change my brake fluid. Before that, my brakes worked just fine. After he put the new fluid int (Valvoline Synpower) the brake pedal started behaving sorta different from time to time. Once I had to make an evasive manual at a very high speed and when I pressed the pedal the car started pulling to the side.

After a couple of weeks it all went away. I have done a million of emergency stops and evasive maneuver and the brakes worked just fine.

And now, it is all coming back!!!

Larrio Motors

iTrader: (23)

just do it as preventative maintenance anyways. And then see if the problem goes away

BlackBIRDVQ

iTrader: (15)

Brake booster went bad. If this where a honda I would tell you to also check if the vacuum check valve is working properly- inline the vacuum line to the booster. Here is a simple test for ya....

Unhook the big black vacuum hose from the booster, and go drive the car carefully, what do the brakes feel like ? If they feel no diff..... you need a booster, if the problem got worse you need a booster.

DrKlop

iTrader: (3)

Thanks! My car is parked on a hill so instead of disconnecting the hose I just put it in neutral with the engine off, let it start rolling, and pressed the brakes.

It felt like the problem I have got amplified. So you think my brake booster is going bad? Should I even bother doing all other stuff now like checking the caliper pistons?

Forgot to mention: (if that makes any difference) I asked my mechanic to bleed the brakes right before the auto-x and according to him, there were no air bubbles.

Edit: one more thing, if you press the brake pedal when the engine is running (brake booster connected,) the pedal will go 1/4 of the way down normally, and then if you still keep you foot on the brakes the pedal will continue going down VERY slowly.

irish44j

iTrader: (38)

if the stiffness is variable, it's a dead ringer for either the master cylinder or the slave cylinder going bad. I had the "inconsistent stiff pedal" on my integra, and I ended up replacing the slave cylinder to fix the problem.

Air bubbles do not cause the pedal to get stiffer...just the opposite.


that...or you really DO have a bottle wedged under the clutch pedal

DrKlop

iTrader: (3)

that's what I thought before I started this thread (slave or master cylinders,) just didn't want to bias conversation towards my own opinion. Take a look at how I edited my previous post (probably after you started typing yours.) I heard somewhere that if the brake pressure changes when you keep the pedal pressed there's a problem with a master cylinder.

Is there any way to test it?

super6

iTrader: (5)

id say the same, master cylinder, but ive never heard these symptoms before. it does sound like one of the pistons is siezed, but siezed in the open position, which i never heard of happening before.

BTW, what is a brake booster anyway?? where is it and what does it do?

DrKlop

iTrader: (3)

The basic idea is that it makes in easier to slow the car dow when the engine is running. Here's some more info: http://auto.howstuffworks.com/power-brake.htm

BlackBIRDVQ

iTrader: (15)

Ahhh so you JUST had brakes bleed at a mechanic..... BINGO check for loose bleeder screws. Rebleed the brakes before you start repleacing the brake booster. Its kinda PITA to remove out of the car. When I did the last 5spd swap from Auto for a .org member I removed the booster out of the car to get the hard line installed for the clutch properly....

irish44j

iTrader: (38)

Mike, how would that cause a stiff pedal? Typically introducing air into the system (via a loose bleeder screw) would cause just the opposite...

BlackBIRDVQ

iTrader: (15)

It wouldn't cause a stiff pedal, but I would still check it all out....

I have had my $$$ on the booster since I read his 1st post bout it.

9DTALON

iTrader: (1)

Slow sinking pedal is a sure thing for a master cylinder. The uneven stopping is also contributing. Hard pedal feel??? But a sinking pedal with steady pressure is definately a master cylinder. And what ware you guys talking about slave cylinders for, I though this was a brake issue not a clutch issue.