GQ Mav Front brake Issues...

[stewie81]

I believe I have posted similer Q but this is different...

Well after fitting my extended Brake lines after my lift I blead the brakes and all seemed fine But then,
On my way back to work i could smell brakes and when i pulled over the fronts were smoking they were Nearly on fire..

Now after Calling in a mate to look at it as well we took calipers off and made sure they were ok and checked obvious things but still issues..

When pushing the Piston back into the Caliper it goes in fine Until You push the brakes and bleed it up.. Then the pressure wont release out of the piston, Both sides on front.. Crack the bleed nipple and it compresses fine.

Just seems like the Front brakes are keeping presure and not releasing when you take foot off pedal..

My master cylinder is leaking where it mounts to booster. COULD this be the problem?? Could it not be releasing presure??

Also when bleeding the GQ brakes (all Disc's) is it just like normal? start L/R then R/R, L/F Then R/F? Furthest to closest... Do you touch the Load
sencing thing above diff? there was/is no air in system and we flushed the fluid.

SORRY for such a long post but it was the only way to really say what the problem is..

Cheers
STEWIE...

MERRY XMAS TO ALL!!!!

[patrol man]

sound like a block line, as i take it it was not like this before, pump up the brakes,check that the brakes stay on, then loosen the fitting at the master cylinder,recheck if brakes are still jamed on, if yes then loosen the bleder, recheck brakes, if not on now fault is in the line/hose. this will see if the problem is it the master cylinder or the line, have a good look at the line you just fitted, (and take the brake hose clamp off), cheers Phill.

[Hoonz]

calipers prolly need a rebuild .. the slides sound like they're getting stuck

[ozy1]

calipers prolly need a rebuild .. the slides sound like they're getting stuck

while this is a common prob of calipers slides needing a rebuild, its one hell of a coincidence that both siezed at once, might be a faulty brake line, you never know till you check,

[stewie81]

Thanks for the reply's so far Guys'S..

I like patrol man's idea will try that...

Also could be Calipers BUT we pulled them out stripped them down and looked fine we cleaned them up whilst they were out..

Cheers
Stewie..
MERRY XMAS!!

[Daisy]

Thanks for the reply's so far Guys'S..

I like patrol man's idea will try that...

Also could be Calipers BUT we pulled them out stripped them down and looked fine we cleaned them up whilst they were out..

Cheers
Stewie..
MERRY XMAS!!

when you put the calipers back together.. did you put grease inside the calliper sliders? as it helps with the retraction of pressure on the pad off the disc rotor?

[Hoonz]

calipers prolly need a rebuild .. the slides sound like they're getting stuck

while this is a common prob of calipers slides needing a rebuild, its one hell of a coincidence that both siezed at once, might be a faulty brake line, you never know till you check,

both my fronts went at the same time when i put new pads in ....
pushing the pistons in all the way to get the calipers back on with the new pads in ... went to bed in new pads .. hit the brakes .. brakes stuck on
cause the slides are in a new position with all the shit stuck in them
booom! over heated discs explode could be my random case

when i eventually get the sliding pin out of the caliper i'll do rebuild pics
after a week of trying and soaking its still stuck :| might be looking for a new caliper

[stewie81]

Just checking When you say Sliders you mean the part where the bolt goes in to with the little rubber boot? IF so then yes we Greased that up moves fine..

We checked the line that went in front ( original rear) and b4 i put it in it was not blocked or anything..

but seems lik Something is holding presure there Cause when you crack the Bleed nipple on calpier it spurts out like brakes are being Applied..

Cheers
Stewie..

[stewie81]

today I took it apart again checked the SLides. and they are good... Pistons on both sides are moving and clean...

When I Cracked the Nut on master Cylinder they ran free like they should...

Does this mean the prob is master Cyl.. Or could be more??

Cheers
sTeWiE..

[Daisy]

today I took it apart again checked the SLides. and they are good... Pistons on both sides are moving and clean...

When I Cracked the Nut on master Cylinder they ran free like they should...

Does this mean the prob is master Cyl.. Or could be more??

Cheers
sTeWiE..

If the master cyl is the problem - i have a fully reco'd master cylinder off my old GQ sittin in my garage - 140 for it.

TOM

[patrol man]

check that the free play in the pedal is set correctly, if it is to tight the master cylinder will not return all the way and hold the brakes on, cheers phill.

[marin]

when i eventually get the sliding pin out of the caliper i'll do rebuild pics
after a week of trying and soaking its still stuck :| might be looking for a new caliper

i found that an air fitting screwed straight into the back of the caliper and my sticky piston came straight out.

marin

[Hoonz]

the piston came out easy ... its the 2 sliding pins on either end of the caliper they are stuck solid i can't even knock them in with a hammer

[Daisy]

when i eventually get the sliding pin out of the caliper i'll do rebuild pics
after a week of trying and soaking its still stuck :| might be looking for a new caliper

thought you were puttin your twinpistons in??

[bowtie landie]

Code: Select all

[code][quote]We checked the line that went in front ( original rear) and b4 i put it in it was not blocked or anything.. [/quote]

The Nissans do have a longer brake hose on the rear than on the front however the block is also at 90 degrees to the front.

Whilst many people have successfully utilised the rear hose on the front, we have found cases where by twisting an old hose a quarter of a turn (90 degrees) it collapses the inside of the hose giving the same symptoms as you have described.

For that reason we have always fitted new hoses front and rear on any 4" plus suspension lift.

With a collapsed hose, the pedal pressure will force the hose to expand allowing fluid through and then collapse as soon as the pressure is released, stopping the fluid from returning.

Worth a try.

Peter K.[/url]

[stewie81]

OK UPDATE TIME...

I put in a Master cyl that i borrowed.. All brakes are good.. No Drag..

BUT.. no my pedal is only really firm at about 1.2inch from the floor..

Any ideas on this?
I blead the master to what i thought was ok b4 it went in.
Then the brake joint i just rang said blead it on the car.. Crack nuts on cyl after pump Ect.
But still no joy..

So they Do work and Great at that.. But pedal is now real low..

Cheers
Stewie.