Brakes????????

[sean210]

I was driving on the interstate today and I took the car out of gear
before I hit the brakes and the pedal slowly went to the floor.
It still slowed down but I had no pressure on the pedal.
I started thinking about it and I left it in gear the next time I hit the brakes
and it had pressure.

So the the problem with this is at idle there is no pressure on resistants in the
brake pedal at idle but there is at higher rpms?

I was thinking vacum but the only lines I know of on the booster are good.

Do anyone have a clue about what could cause this?

 

[AJ'S 88NA]

Could still be a vac leak, or a leak in the lines somewere. Might be the booster though. Have you changed fluid and blead the brakes lately?

 

[easternguy2005]

Down to the floor usually is a master cylinder leaking. Check the fluid level. I changed mine cause once and a while it would go to the floor and I was in denial not wanting to change it. It leaked into the cabin area BTW so there was nothing to see.
I can't figure it being a vacuum problem would cause the pedal to go down cause let's face it - it can't go down much before the car stops.

I bought a rebuilt one and it had the plunger installed backwards - so bought a dealer one and my brakes are sweet and I'm confident when I need 'em.

 

[sean210]

How much was the master cylinder?
I am going to try bleeding them tommorow.
the wierd thing is that the level is the same. as when I bought the car.

And no I have not changed the fluid. whats the easiest way to do that.

 

[easternguy2005]

M.C. was like 100 or so - dealer's isn't a rebuilt and I've read other posts saying the rebuilt lasted them a year and then started failing again.

Look for fluid leaking and/or hold the pedal down with steady pressure (not killing it of course) and see if it works its way to the floor. Usually it's at a stoplight holding the pedal down that you'll notice it sinking slowly. Its a closed hydraulic system so if the pedal is sinking (and it worked fine before) then thats the prob. I put in new calipers (dealer) as well cause I just want to do it once and right. One night after it was completed I had to stop in the rain and braced myself for the worst and the car stopped 3x faster than I would have ever imagined. The antilock has saved my butt at least twice too.

Incidentally the clutch M.C. failed on me too and dealer replaced that.

When you bleed the brakes start at the back passenger side (usa) and work your way closer so the last one is the front driver caliper.

You gotta verify that's the problem. Usually I'll let the problem get worse to be sure cause I don't want to have to do the work.

 

[subjug4tor]

My brakes have a similar but odd problem... I know that I have a slow leak somewhere, but I cant find it after searching for a hour.

When i pump the pedal with the car off, i can push it almost all the way to the floor with no resistance, but once i get it pushed almost all the way down, all the brakes still engage. The car drives and stops fine, and the pedal doesnt sink if im stopped at a light, it just takes almost all the way down to engage the brakes, and i have a tiny leak somewhere. could this be the MC?

 

[sean210]

That sounds like a squishy pedal. have you bleed them?
Usually air in the lines will do that.

Im going to have a couple people look at mine and hopefully the M.C.
is the problem.

 

[easternguy2005]

Well if you have a leak then you will lose fluid. Topping it up once every few months to accomodate brake pad wear is one thing....but if you are adding fluid like weekly then you got a leak.

That problem of it not engaging till the very bottom is usually associated with drum brakes that aren't adjusted but on the supra the pedal action is 4 wheel disc (handbrake is drum and not applicable here). If it feels spongy or pulls on a hard break then I would look at bleeding all the lines. If its engaging only on the bottom them the brake pedal to master cylinder (there;s a adjustable metal rod that goes from the pedal to the M.C.) could be out of adjustment - check the manual for that. Use your hand and 'feel' for when its actually pressing on the M.C. -

Like I said I've always waited till the M.C. is really on its way cause it doesn't get better...ever...only worse. Once you get to the stop light and have to pump them at 15 sec intervals....you know the deal then. Also noteworthy is that the rear brakes are activated first but there's a spring load on them. So after a certain amount of pressure the front start engaging and not much additional pressure goes to the back and then the antilock comes into play.

There's not much to the system and the M.C. usually is the first thing to go.

As far as vacuum assist - When that goes you have to press much harder on the pedal. If you drive the car on a flat area while coasting and shut the engine off and out of gear and apply brakes over and over lightly you'll notice it getting harder and harder to apply them.

Look inside the M.C. reservoir - There's probably alot of black 'dust' junk in there - thats M.C. wear. I actually took PIECES of rubber out of the Clutch M.C. and of course hoping for the best by turkey basting it out and flushing it only to have it fail a month later.

 

[subjug4tor]

Ive tried bleeding the brakes, bled them til new fluid came out, guess ill try it some more and see where that gets me, as well as checking the pedal adjustment. Really hope i dont have a bad MC...

 

[easternguy2005]

Dude thats the way I feel every time.....Hoping it ain't.....and it usually is. Its like a denial thing.....

Do yourself a favor though if you do have to change it get a dealer replacement this way you won't have to mess with it for a LONG time.

If you have to bleed the brakes then you gotta ask how did the air get there ? When you have a new car (like a mom) there is no brake bleeding needed. Air gets introduced because there's a leak or a crappy repair was done that left the air in there OR the fluid got so low that air got in.

Have you seen that section today on the 300Z brake calipers ? I'm not that hardcore - Just new dealer calipers and M.C. (even dealer pads all the way around) with a good bleed and my brakes are awesome.

Remember its a sealed hydraulic system.

 

[romaniello]

The brakes are there not only to protect you but also to protect those innocent people around you.
Don't waste time speculating and take it to a brake shop before you kill somebody.

 

[easternguy2005]

Yeah you don't want to be messing with brake problems obviously but going to a brake place gets real expensive.
They are in business to sell parts......and sell you parts they will !

Check this out:

http://www.ripoffreport.com/reports/0/069/RipOff0069579.htm

http://www.passatworld.com/forums/archive/index.php/t-93208.html

Obviously there are some good real shops out there but everyone is trying to make the mortgage payment.

I especially liked this one:

Yeah, on our 78 Impala, we had a problem with the brakes sinking to the floor. Took it to sears, and they came up with a $1,000+ estimate. When I said no way, they acted all shocked and said that they couldn't let me drive it this way and that it was a liability for them to let me leave. I then said that if they felt that way they should give me an honest estimate that fixes ONLY the broken part that is causing the brakes to go to the floor and NOT replace ever brake part on the car. Turns out it was a 2" hose and I got it fixed somewhere else for $49.95. Humm...$1,000-$50 - $950 that they tried to steal from me...

 

[sean210]

I was told by someone that I had to use dot4 brake fluid.
But I didnt think there was a such thing as dot4 .
What brake fluid am I supposed to use?
I tried to search but couldnt find it.

 

[tlo86]

dot 3 or 4 works fine.

a hairline crack will put air into the system (like a straw) i would check every line and every pad. ive seen air get into ABS systems as well. if a new master cyl is too much buy a rebuild kit.

 

[sean210]

my father in law works at napa so I got one for a discounted price.

Only 48 bucks.
I didnt know that there was a dot4

 

[gaboonviper85]

my brake master went on me...had almost the same issues...I bought a new brake master from a2motorsports for $60 ish...it was factory toyota part also.

 

[sean210]

Was it re-man Or brand new?

 

[IJ.]

Pedal height retention test:

Pump the pedal a few times with the engine off to exhaust the vacuum in the booster.

Hold constant pressure on the pedal.

It SHOULDN'T creep towards the floor.

If it does and there are no obvious leaks at the wheels it's usually a leaking master cylinder.

Biggest cause of this is old brake fluid as it's hygroscopic (meaning it attracts moisture)

After a year or 2 there's enough water in the fluid to lower it's boiling point and in hot weather you may experience brake failure, while all this is going on the bore of the master is rusting (iron masters) and this is where the creep comes in.

Feel the carpet below the master.

 

[gaboonviper85]

Was it re-man Or brand new?

bran spanking new! And took about 20min to instal with no bleeding needed!

 

[tok]

Had a similar issue even after installing a new MC. turned out to be the proportioning valve.