WERNER1

Hey guys,.. I've basically got my 1990 GXE sold for 1500.00,... but,.. I went to bleed the brakes as they always seem to get spongy every few months or so (Actually the pedal has never been "hard"..) ... but after we bled them out,.. then we blew a rusted line to the right rear and had to splice in a piece,.. re-bled and it's still super smushy/spongy (?????).. thought it was maybe the MC,.. but upon further diagnosis we determined that the MC appeared to be fine - We clamped off the brake hoses near the wheel cylinders/calipers and the pedal wasn't budging. (??) .. with the rears unclamped and the fronts still clamped it was still real hard/stiff,... once the fronts were unclamped it got squishy again,(??)..

So it appears to be a problem in the front Calipers/lines (?)... we found a service type bulletin that said to run the caliper pistons almost all the way out and turn the calipers so that the pistons are facing down and the bleader screw is up,.. tap on the calipers and basically bleed it out that way,.. we sort of did all that,.. but still the same results...

I need this car GONE,.. and the buyer is waiting,.. but they're leaving Monday...SO, I'm in a bit of a crunch,.. Anybody who has any experience/info on this,.. well it'd be MUCH appreciated!!

Thanks in advance,
Rick

BenStoked

iTrader: (7)

something is wrong if you have to go back every few months for brake work.

if you haven't, check out pages 5-6, here:
http://www.nicoclub.com/FSM/maxima/1994/br.pdf
it doesn't seem right that you can clamp off the brake line to me, but I may be mistaken on that...

James92SE

iTrader: (31)

How are you bleeding them?

On the Maxima, for whatever reason, I've NEVER been able to use those "one man" vacuum bleeders. The brakes always felt spongy with those. I've always had to do it the messy way with a helper

Ben, they actually make brake hose clamps and they're aweeesome. I only discovered them a few years ago myself. You can clamp your brake hose, remove/screw with the caliper/whatever and put it all back together and you don't have to bleed it again. I wish I'd discovered them years and years ago

WERNER1

We're doing everything just like the manual,.. and using two guys,.. one pumping and holding,.. the other manning the bleeder screws,.. LR, RF, RR, LF,..

I'm about at my whits end on this one,.. I've been doing this stuff since I was a kid,.. and I'm 44 now, and I ain't never seen something like this,..

maximo018

iTrader: (6)

All I could tell you whether you want to believe it or not. Theres air somewhere in those lines they're just being a pain in the a$$ to bleed successfully. I think it has something to do with that distribution block that the MC has to pass through under the hood. Had the same problem with my clutch from that damn thing... so I bypassed it. Not saying you should do the same for your brakes but that might be the culprit.

akurtzer57

iTrader: (4)

Ya ive had some problems like that. I cracked the lines walked away for 30 min. Air worked itself way out. Don't have any leaks anywhere do you?

WERNER1

Yeah my "gut" is telling me it's air,.. but as much bleeding as we've done I find it hard to believe that there's still some air in there,.. I'll be getting back on it later this morning,.. fingers are crossed!

Thanks!

LvR

I suspect you guys read the recipe wrong and I would actually go exactly the opposite to that suggestion - if you can decrease the volume of the caliper cavity under controlled conditions then you are much more likely to get to the bottom of this all.

Pump and bleed to your heart's content and if you are happy that you have really done what you could start with THIS recipe. Make sure the MC is full

1. Remove the caliper from the bracket and don't disturb the piston (or then as little as possible) and clamp the brake line to the other front caliper. If however you have brand new pads, then you first must also first insert the pads in the removed caliper and have somebody push on the brake pedal so that the piston comes out as far as possible (don't do this with the disk between the pads - you want to have only the 2 pads in the caliper))

2. Turn it so that the banjo coupling from the master cylinder/brake line is at the top (vertically)

3. Release THAT coupling ONLY by about 2 full turns (leave the bleeder closed)

4. Now slowly force the piston back into the caliper until its about 5mm from being flush with the lip of the body of the cylinder it sits in and immediately close the banjo coupling securely ................... if you did it right, then you would have seen many bubbles and some brake fluid escaping from the released banjo coupling - soon as you reach that 5mm point close the banjo coupling - do not force it back deeper else you defeat the object of the exercise

5. Replace caliper on its bracket with the pads, pump the brake pedal vigorously, clamp the brake line at the caliper and go to the other front wheel and release its clamp.

6. Rinse and repeat with a full MC from step 1 to 5 WITHOUT TOUCHING THE BLEEDING NIPPLE OR PEDAL ON ANY CALIPER.

7. IF YOU DID IT RIGHT AND ENSURED THE MC STAYED FULL DURING ALL OF THE OPERATIONS, YOU SHOULD HAVE PROPER FRONT CALIPER ACTION WITH A HARD PEDAL NOW.

8. If you don't, start all over again and keep repeating the recipe till you DO get the trapped air out.

WERNER1

right on!,. thanks for that info,.. I'll try that today and hopefully get this thing taken care of...

What happens when you go further in than the "5mm",.. just curious?

My pads are wore a bit so I'm not sure what the thikness of two new pads would be,.. I'll probably just use a block of wood cut to that thickness in there when I push the pistons out(??)... I think the actual new pad "lining/material" is around 3/8" thick(?),.. and the then add the thickness of the metal of the pads,.. probably puts you at around 1- 1 1/4" (?) ..

Thanks,
Rick

WERNER1

Re-reading Step "1",.. you say not to disturb the pistons,.. but then goes on about using the pedal to push the pistons out as far as possible (?) --- I'm thinking that this "Far as possible" would be the pistons pushing the brake pads up against the far side of the caliper body,... ???

Thanks

LvR

"If however you have new pads ............. FIRST ........"

If you don't have new pads then its not necessary.

The basic idea is this: (Sorry didn't have a lot of time to explain before)

With the piston out of the cylinder, you have a bunch of fluid as well as air in the cylinder cavity - with older pads the default position of the piston already ensures you have a bunch of fluid and air to compress and expel when you force the piston back into the cylinder - with a set of new pads you will basically only have a small amount of fluid and lots of air in that cavity - hence my comment to first fill the cylinder with more fluid manually by extending the piston out of the cylinder. 5mm is an arbitrary point I have chosen simply to ensure that you have pressure on the piston while pushing it back into the cylinder at the time you close the banjo coupling - if you push it in further chances are you will lose the compression state of the cavity and defeat the object

WERNER1

Ok,.. did the procedure twice on both sides,.. no air what so ever,..

Now, what I did notice was that when the pedal is applied, the pistons do come out,.. but when you let off the pedal the pistons come back in ... a LOT!,.. so when you're just sitting with your foot off of the pedal there's like a total of a 1/4" of travel that the piston has to make up BEFORE it comes into contact with the pads/caliper,.. very strange...

I'm going to slap a new set of pads on there to take up the slack so that the piston can't back off as much,.. see if that helps.

Thanks!~

WERNER1

Put the new pads on, and that basically positioned the pistons all the way "in",.. so I've got brakes now,.. still a bit spongy, but I don't have to pump them up to hold,.. they grab now...

People are supposed to come over and test drive this evening ... here's a hope'n!!!

LvR

If the piston goes back in you have a funky MC ............. and its extremely dangerous