GQ Brake issues!!!! Help needed please

[panman]

Hi Just purchased my first 4x4, it's 95 wagon, when I bought it had spongy brakes! I thought no problem I can bleed them, I did no change.
OK must be master cylinder replaced it still the same.
Have removed all the callipers X4 blown them out no leaks none seized.
Not losing any fluid.
Have bleed them about 6 times now, missus on the brake pedal me underneath closing nipple before she comes off the pedal, still the same???????
The only thing I can think it could be is the Load Sensing Valve? it shows no sign of any leaks but could it have an internal fault??
If I anticipate braking ie 1 dab on the brake pedal and then push again the brakes work fine and it stops in a straight line.
Any advice would be very much appreciated.

[my third 256]

just remember to blead from back to front(longest distance to shortest)
gqs were a bit spongy you could try adjusting the load sensing valve at the bach of rear diff
have a read of this http://www.nissanpatrol.com.au/forums/showthread.php?3517-gq-brakes
also do a search with the box in the top right hand side just type in what your after

[panman]

Hi thanks for reply but all the books say bleed from furthest point to the shortest?? Didn't do a bench bleed on the master before I fitted it, how do you do one ?? What i did was fit master filled with fluid left overnight then pumped brake pedal till bubbles stopped from master cylinder then did the brakes.

[damaverick]

I second starting from wheel furthest from master cylinder and working your way to the closest. It's how I was taught and the GQ Manual agrees:

"Bleed air according to the following procedure:
L.S.V. air bleeder -> Left rear wheel cylinder -> Right rear wheel cylinder -> Left front caliper -> Right front caliper"

Panman, I read somewhere that worn wheel bearings can also affect your brakes. Try checking for free play. If nothing, maybe your brakes are just meant to be like that. After all it is an old car which weighs 3 tonnes. My brakes are terrible which is why I need to upgrade to twin piston calipers.

[timbar]

My brakes have always been spongy and i took it to a brake speciallist anf he told me thats as good as its gunna get ???

[BigRAWesty]

How's the clutch? Nice and soft? And does the engine still up a few rpm when engaging the AC?
If not it's possible a broken vacuum line for the assist?


Sent from a device which doesn't always agree with my thumbs...

[johno90]

As stated, Always bleed brakes from furtherest to closet to the master cylinder. on a side note the brakes in my 94 patrol are nice and hard.

[Morton]

mine were as you stated, I adjusted the Load Sensing Valve (or proportioning valve) as some call it, easiest way to check this is to use electrical ties & squeeze the spring together about 2-4 mm at a time & take it for a test run after, one or two small adjustments will show a significant change in braking, also check what fluid you are using, the wrong fluid will give a spongy feel, will be in the specs, always start bleeding at the furthest point. Just a point, whenever you lift a vehicle x 2 inches or more you need to adjust that valve spring, never let anyone tell you any different, otherwise it will be useless, you will find out the hardway in an emergency braking situation that your using your front brakes more than needed

[damaverick]

How does the handbrake on these baddies actually work? I assumed like most cars it had wheel cylinders underneath the rear discs which are triggered by a metal cable attached to the actual handbrake but they don't!

[my third 256]

brake drum on drive shaft just behind gear box

[Morton]

brakes fixed? what was the outcome

[JonnoD]

have you flushed the entire system as you could have some moisture in there or perhaps an air lock.

[melcor]

also check to make sure all the slide pins are working or your just flexing the calipers together , no amount of bleeding will firm it up..