Trouble bleeding brakes (still spongy)

[CrUZida]

I'm pretty sure what you are describing there Placenta is a ripped seal in the master cylinder.

When you drive day-to-day for a few years you only use <50% of the pedal travel, so a whole heap of dirt builds up right where your foot stops.
And then when you go to bleed the system you put your foot to the ground, and the seal goes over this build up of dirt, and gets ripped.
Thus rendering your brakes useless.

I rebuilt the master cyl 6 months ago, so there would be negligible build up in that time.



And Stu, I'd have to take a few photos and do some photoshopping to show you how the caliper is internally.

[thechuckster]

peewee: sounds like wilbo's experience when he upgraded the jza61's brakes.

Bleeding them took ages, as did the bedding in of the (used) pads.

First drive on the newly-upgraded brakes was a bit of a disappointment - they're good now, but at first it was unable to lockup tyres - regardless of how hard you tried to pus hthe pedal thru the floor.

[fester]

Sometimes you just have to perservere. Had a Fiat years ago with standard brakes that was like that. Just rebuilt everything standard and took ages to get that last air bubble out as it must have ben clinging to the wall of the caliper or something.

Just bled heaps of times, went for several drives around the block to work them as hard as I could (luckily a nice quite area) then all of a sudden after heaps of tries, perfect.

Just to reinforce, when I bleed with the tube and bottle method (never any other way) I make sure the sequence EVERY time/pump is: crack nipple/pump and hold/close nipple/release pedal then repeat. I never release the pedal without closing the nipple regardless of how much fluid has gone through and it appears there is no way air could come back up the line.

[o_man_ra23]

fester, I tend to: pump, crack, tighten, release pedal. Gets a bit of ooomph into that first part of the squirt to help get dirt etc out. Another thing to maybe try is tap the calliper with a rubber mallet or the back of a plastic handled #3 point phillips head. Tends to loosen up any clinging air bubbles. Also, if the hole in your piston wall (where the bleed valve is fed from) isnt quite at dead top, then you will get a small air bubble and there is F all chance of gettin the bastard out. So you may need to revise your mounting position.

Cheers, Owen

[slide86]

does MZ10 have ABS?

[CrUZida]

Nah, only the MZ11 and MZ12's came with that option.

But through the use of a pair of linelockers, I have narrowed down the problem to air in the 2 front calipers.
Will try some bleeding tomorrow night.

[CrUZida]

Pics for you all to make your own minds up.
As you can see the bleeder is still the highest point on the caliper.

[allencr]

This has nothing to do with removing air, which by the way doesn't need the bleed at the very to, but it is nice to have it on the outside/non-feed half of the caliper.
Any idea where the port between the sides is at??? Top or bottom???
On the bottom does make it pretty tough to purge the outer half!


I'm concerned about the brake line going in. I hope that hose fitting has a 45 flare on it, and that the caliper body has the corrosponding 45 for it to seat on! I don't think the what looks like plumbers/teflon tape is going to do it for very long.

[jonra23]

Caliper orientation looks the goods, the connecting passage would be at the same end as the bleed nipple for obvious reasons.

I recon you are likely to have an airlock in the up loop of your new brake hoses, hook up clear plastic hose and bottle again, crack bleed nipple a fair bit ( full turn) and pump fairly vigourously on pedal to push a reasonable volume of fluid through.

Have to get enough volume going through to push bubble down the hose.

Had the same problem when sons A31 when putting R32GTR calipers on it.

regards
jon

[Squid]

We had exactly the same with a mates mini...

I have heard you can pressure bleed with a big syringe and suck it through, however for the cost and effort involved, we took it to a servo and got them to pressure bleed it for like $30.

[brett_celicacoupe]

i would suggest jacking up the LH rear side of the car to bleed the front RH calliper. you need to get that nipple as high up as possible.

it might need to be at least 300mm off the ground for this to work sucessfully though. also if you could park the car on a steep driveway...

i had dramas bleeding my hilux callipers.....i ended up lifting the other side of the car off the ground a foot or so. doing this with a combination of tapping the callipers with a hammer to release any bubbles (high frequency vibration). my brakes were spongy for a week until i gave it a final bleed after a weeks driving. if at all possible, driving on the road will help to get the bubbles to the top.....this is as long as there is adaquate brakes


if it still doesnt work, drop the callipers off and orientate them in the nissan-spec position and bleed

[JustCallMeOrlando]

I was looking bud, my caliper isn't on that much less on an angle. Perhaps pressure bleeding is the way to go if we have no love?

[o_man_ra23]

Just by looking, the ridges that would normally run vertically and carry the fluid are now at a 45 deg angle... which makes them no longer the highest point at each piston. You now have the possibility of trapping a small amount of air in each piston, which gives you 8 air bubbles to deal with. unbolt the bastards (dont pull off the disk tho) and rotate them round till their vertical and try again. tap with a mallet to be sure. IMHO, thats your problem. If i get really creative, tonight ill doctor your photos to show you what I mean, but I wouldnt bet on it.

Cheers, Owen

[takai]

Just by looking, the ridges that would normally run vertically and carry the fluid are now at a 45 deg angle... which makes them no longer the highest point at each piston. You now have the possibility of trapping a small amount of air in each piston, which gives you 8 air bubbles to deal with. unbolt the bastards (dont pull off the disk tho) and rotate them round till their vertical and try again. tap with a mallet to be sure. IMHO, thats your problem. If i get really creative, tonight ill doctor your photos to show you what I mean, but I wouldnt bet on it.

Cheers, Owen

Yeah, i was thinking exactly the same thing. Without having the connecting channels at the highest point in the cylinder you have effectively created an area where there can be multiple air bubbles.

As seen in this really hella dodgy photoshop image:


The areas in pink are your problem

*note* Picture not to size or scale, and i take no responsibility if the pictured caliper doesnt stop your car

[JustCallMeOrlando]

Perhaps if we can jack the back of the car up as per Brett's suggestion we can orientate the caliper enough? We had the front jacked up to do it, so you could get under it, but this would only compound the problem...