I just finished installing my Stage 2 brake kit and everything seemed fine. That is until I got near the end of the bedding process. It quickly seemed to lose stopping power and the pedal got softer.

Before that, the pedal felt fine. Just seems like once it heated up, they lost power. I also did a few stops without holding the wheel and there is definitely a pull to the right, though it isn't severe. I also checked it for leaks and found none.

My thinking is that there may still be a little air in the lines somewhere and that might account for the pull and the premature fading. Any other ideas?

 

Air in system, bleed again and let us know if the results are the same

 

That was it. They seem much better now, but I'll probably put a few hundred miles on it and do it again. Since I had the calipers off for over a month, I had to plug the lines with rubber plugs. One of those came out unbeknownst to me and drained the master cylinder significantly.

I bled them 3 separate times over 3 days before the original post and no more air was coming out, but I figured driving it would move any additional air.

 

Well, I thought it was better. At normal braking forces they seem fine. It's once you try a hard stop that they suddenly no workey.

Last night I was driving spiritedly and tried to stop at a stop sign and the pedal was on the floor but the car wasn't stopping. I guess I have still have air in them.

I was rereading the service manual procedure and the first thing I noticed that I may have done wrong is that it claims you need to put the pedal down as far you can before you retighten the bleeder screw. When I was doing it, I had my girlfriend begin to apply pressure, then I would open the screw and allow the air/fluid out, tighten the bleeder screw and call to her to release. I was specifically timing it so that my part was done before she hit the floor with the pedal. Should what I was doing have prevented getting all the air out?

Secondly, the order stated in the manual it says "the front left, rear left, and front right tires, in that order." I was assuming that was a type and meant to say f/left, r/left, r/right, then f/right. Is that true? I had done it r/right, rear/left, f/right, then f/left. I thought you wanted to go from furthest to closest. What the manual claims isn't intuitive in any way. Why that order?

So, should I redo it with the first method of depressing the pedal fully and following the stated order (which is what exactly?) and would that give me a high chance for success?

Or should I get/will I need a power bleeder or vacuum bleeder? Which is better?

 

Get a motive power bleeder or a real pressure bleeder if you have a compressor available.

I never understood why after bleeding people don;t get in their car and test the pedal before getting it off the jackstands, putting the wheels on and driving. If the pedal is soft on the street it will be soft on the jackstands too! But it's a hell of a lot easier to bleed them again if it's still on the jack stands.

There is alot of air in there.

 

Thanks. I had wondered the same thing until I did it.

Just sitting in the car and pressing the brakes they feel hard as a rock. Even normal driving feels fine. It's hard or panic stops that really show there is still a problem.

 

i'm not sure if air in the system will cause the pedal to drop to the floor that fast, especially if under normal pedal forces it feels firm. almost sounds like fluid is going past the master cylinder.

typically air in the lines will be mushy at ALL times, not just panic stops.

i bled my miata by myself, just connecting a tube to the nipple and submersing the other end into a jar filled with brake fluid. then open the nipple and keep on pumping until clean fluid comes through.

your bleeding process sounds fine to me (can't help you on the bleed order though).

edit: oh yeah, the term "brake fade" usually refers to overheating the pads, not a soft brake pedal. during fade your pedal remains firm... you just don't slow down when you increase the pedal force.

 

ABS units are horrid about getting air in them that won't come out...though this doesn't sound like the issue at all. I'm thinking we have another problem. but I refuse to try diagnose this one w/out seeing the car.

 

julian - I didn't mean to give the impression that the pedal was soft. It doesn't feel soft, even on the panic stops, it just felt like I pressed it as far as it would go. The reason I'm using the term fade is because that's the closest thing I can come up with to describe it. The brakes are still working, even in the hard stops, just not nearly enough. It's like the caliper can't apply enough force to hold the rotor if the stop is too hard. I'm still stopping but the distances are more than they should be.

 

There are two types of fade. One related to fluid overheating or air being in the fluid. This will give you a soft pedal. The second kind of fade is a hard pedal fade where you have exceeded the operating temp of the brake pad. The pedal feels normal, but the brakes simply don't stop the car.

I don't know how much fluid you are bleeding, but it might take asa much as 1/2 a liter through each caliper to get it all out. If you let the master cylinder run low then you are re-introducing air into the system again.

 

air typically displays as a squishy pedal....which can be pumped up to a firm pedal (unless there's quite a bit of air)...In normal driving you shouldn't be able to create enough heat to boil brake fluid...esp during this part of the year (its cold).

however if your using old brake fluid that has been opened and re-closed, you could have water mixed in it...those 2 liquids have an affinity for one another.

also might be a vacuum problem...ie brake booster since you now say its not squishy, but no matter how hard you push it doesn't want to stop.

there are many things which this could be. I'm betting on loose nut behind the wrench, but that's just based on what I've seen in the past.

Which pad did you go with?

 

what pads do you have? and i hope they're not hawk hps. axxis ultimates will have better cold bite but they'll still fade at higher temps.

sounds like you need a pad with higher coefficient of friction. but pads with higher cof's usually need heat in them.

and fyi, re-reading your original post, you're supposed to feel that when you're at the end of the bedding in process. then you them cool and they should be good to go.

it either sounds like you overheated your pads or you pads just aren't aggressive enough for you. not sure what a stage 2 brake kit is... but remember a big brake kit doesn't decrease stopping distances. it has a higher heat sink capacity to handle increased heat. if a BBK adds more rotating mass your stopping distance will probably increase.

if you could lock the tires (or activate ABS) with your old braking system you needed stickier tires. hahaa

if you could overheat your pads with your old braking system, you need higher temp pads and/or cooling ducts. if those two didn't solve it, then you go to BBK.

 

ok so i was reading through the post.. one of the questions i had was if the lines were left open for a while... you may also want to bench bleed the master... it helps quite a bit.. Another thing is to get a true bleeded like jet had originally posted.. And if worse comes to worse you could always send it to nissan.

also have you possibly glazed the pads?
" What causes brake pad glazing?
Brake pad glazing is caused when the brake pad friction material is overheated.
This results in crystallized friction material on the pad surface and the brake disc.
Typical symptoms of glazed brake pads include: Poor stopping performance, vibration or brake judder, and cracks or fissures in the brake pad material.
Pad glazing is typically caused by operating the brake pads at a temperature above the specified temperature range of the friction material or not properly following the 'Bedding-in' instructions for the brake pads. Always follow the manufacturers brake pad bedding-in instructions and use a brake pad that has a temperature range that is sufficient for its intended use."

good luck and be safe..

 

They are in fact Hawk HPS. My second set. The first set worked fine.

 

one thing I've seen that has worked if there is some glazing is lightly sand off the surface of the pads...rebed...

edit: thought I should reiterate LIGHTLY. remember you are only taking the very top, thin layer off.

 

+1. get a power-air assisted bleeder.

Summit Racing has them for $80-

mushy / squishy lines = air.. try using a soft rubber mallet to knock the calipers to get air bubbles to come lose-. bleed from passenger rear , driver rear , passenger front, driver front, in that order.

make sure your gf is pressing all the way down and not modulating the pedal when bleeding.

 

any fix to this? im having sort of the same problem, the only difference is sometimes my pedal doesnt move at all and is rock hard but thats usally after boosting.