[plehmann]

Ok ladies and gents.....
Just got back form a rather successful tour round the Dobson, Mackauley, and Goodley river/valley systems from thursday last week...

Just been driving back from town and had to jump on the brakes pretty quick for someone that decided to turn right without indicating... sigh... no worries on the stopping bit ( well, as well as the brakes have preformed before... which were not very effective, never been able to lock the wheels)

BUT... next time I stopped I 'felt' something 'like a pop' for want of a better word through the pedal.... I did not hear anything and the brakes are now pretty much non existent... they start to bite and then the pedal continues to travel to the bottom with not very much happening on the stopping side of things....

There does not seem to be any visible leakages etc ... But when it comes to brakes I tend to leave that side of things to people that do brakes for their living if you get my drift....

Its one thing to be able to move forward but its another thing entirely to stop !!

So any ideas as to where to start on the fault finding.. My first thought is master cylinder.... ??!?!
Sigh... this money was earmarked for a snorkel.. bugger!!!:headwall:
I'm off to visit the search bar spanner in hand
Help!

 

[plehmann]

right............. Just been digging around and the brake fluid level is *just* below the Min line..on the master cylinder plastic overflow cup. It was above the line on thursday before I left... and I thought it had been dropping too so was keeping an eye on it. Shame I did not catch it this morning .arrrrg.

Found the leak... front left wheel and associated bits and bobs covered in brake fluid...
how damaging is the fluid... tarmac, wheels, suspension ?

Piers

 

[Canuck]

how damaging is the fluid... tarmac, wheels, suspension ?

It will eat through paint and certain plastics. It'll probably turn your pavement to mush if enough of it got on it. Clean everything down with a good degreaser. Allow it to dry. Then sand and touch up with anti rust spray paint were it has bubbled up or eaten the paint off. Brake fluid is not going to harm the metal.

 

[Somalian Bush Pig]

Plenty of water too, brake fluid is hydroscopic and effectively disperses in water.

 

[plehmann]

thanks as ever guys.. Just ordered a set of braided hoses from safe R Brakes on 87 Fitzgeral Ave, Christchurch ( for the NZ readers) for 90 +gst, Just got the wheel off and had a look after using a pressure washer on her straight away... looks like no harm done but the hose just above the metal crimped adapter going into the caliper split length-ways about 1 inch from the metal up the pipe... shame I just don't have the cash to do the whole lot, hey ho I'll look to put braided hoses on the rears next month after some more cash comes in.. .poor ol' dawg took the other lot(700$) and then had to be put to sleep (that was almost $400 for that sevice too) sigh money never stops gushing out.

hmmm while I think of it.... anybody know if the nut that attaches to the aluminium adapter at the top of the hose ( that is mounted to the stut assembly)from the steel tubing from the axel is a reverse thread?.. its stuck in there like nobodys business and the nut started to get rounded off so I stopped...

 

[FreddyN]

I doubt it's reverse threaded. Brake hoses/connectors etc are pretty standard. You might need a flare-nut spanner to get a grip without rounding the nut. Super Cheap Auto Chch had a cheap set (12-18mm or so) for about $20. If you wreck the nut, then a replacement nut isn't a problem, but you'd need to cut the flared end of the metal tubing, remove and replace the nut, then use a flaring tool to flare the end of the pipe.

 

[plehmann]

yeah I'm off there tomorrow... get the flare-nut spanner and then the new hoses.....

 

[FreddyN]

As the rubber hose you're taking off is stuffed and being replaced anyway, if the flare nut is really frozen, careful use of a blowtorch might just free it up.
Not sure, but you might find super-cheap has pre-made braided hoses in a selection of lengths. Otherwise there's BTNZ in Montreal St, opposite Repco, but back toward Moorhouse ave 100 metres.

 

[Captain Hook]

I doubt it's reverse threaded. Brake hoses/connectors etc are pretty standard. You might need a flare-nut spanner to get a grip without rounding the nut. Super Cheap Auto Chch had a cheap set (12-18mm or so) for about $20. If you wreck the nut, then a replacement nut isn't a problem, but you'd need to cut the flared end of the metal tubing, remove and replace the nut, then use a flaring tool to flare the end of the pipe.

Just make sure you use a double flaring tool. not the plumbing type.

 

[FreddyN]

I've got a (double) flaring tool here. If the OP needed to use it in Chch, he could PM me. From my experience using it (trailer hydraulic brakes), there's a bit of a knack getting the flare just right, first attempt will probably leak if you haven't done it before. A bit of practice with a some old or spare brake line isn't a bad idea.

 

[Iron Horse]

the brakes are now pretty much non existent... they start to bite and then the pedal continues to travel to the bottom with not very much happening on the stopping side of things....

Your rear brakes should be still working , you have another problem . Your master cylinder is a tandem type , when the front brakes fail the rear piston moves forward in the master cylinder bore and contacts the front piston which is the rear brakes . This keeps brakes working on one end of the vehicle no matter which end fails .

 

[plehmann]

FreddyN, Captain Hook...much thanks but the steel pipe was ok.. the flare spanner was an automotive one I hope the main problem turned out to be the drivers side bleed valve.. flicking welded tighter than a tight thing.. in the end I had to hammer on a ring spanner after the flare spanner had rounded the nut and the mole grips could not even get a decent enough purchase... heating and then cooling enabled me to finally break the seal and bleed the last caliper.. sheesh a swine of a job to do on your own in the glaring sun...

I dont think the breaks have been bled in er... forever... anyhow its all done now... next thing is to figure out why I had virtually no stopping power with the fronts outta action.. any ideas as to how to work out the load /proportioning vale .. the truck has had a 2" lift apparently.. came with it when I bought her...
thoughts ?

thanks again guys for the help/direction/support/guidance

yeah I thought so too.. but maybe the proportioning valve is not working?

 

[FreddyN]

I'm not sure what the proportioning valve position should be with no load - mine (not lifted) sits with the lever fully down, but no tension on it, so with load in the rear the lever will move up. The linkage and/or brackets should probably be modified if the truck is lifted.
As far as rear brakes go, then do you know if they're working? The sliders in the callipers are very prone to seizing - this happened to mine, but even when seized tight there's still enough action from them to polish rust off the rotor, and they seem to work if you jack a wheel and rotate it, and get someone to press the brake pedal. Only one of mine was seized - probably had been that way for years, my local workshop when doing WOF check just tested the brakes by driving round the block. It failed a WOF when put on rollers at a test station. With the rollers, they check L:R balance, but not front:rear balance, so if both are seized, they might both be hardly working, but may still pass the test for (IIRC <20%) variation in L:R balance. As the hand-brake is a transmission brake and very efficient when they test it, then they're not going to notice that the rear brakes are stuffed.
As well as freeing up the slider, I needed to remove the pistons and clean them up to get the rear brake balance within spec. Seal kits and replacement pistons are available from Supercheap at not too bad prices.

 

[Iron Horse]

I found a diagram of what happens in a tandem master cylinder when the front brakes fail due to fluid loss . The rear piston is the front brakes , the front piston is the rear brakes . Normally there is a gap between both pistons filled with fluid . When the brakes are applied , the front brakes are pressurised and then the fluid filled gap is pressurised which forces the rear brake piston forward . The front brakes must be applied first to prevent the rears locking up and sending the car into a sideways skid . When the fronts fail , the rear piston moves forward and physically contacts the front piston so that rear braking is still available .

 

[3VILC]

Also a handy feature of the safari is when the pads wear right down they actually fall out of the caliper! Shortly followed by the piston making a nice mess of the rotors.

 

[plehmann]

bloody great diagrams peeps!!! freddyN when you say down for the proportioning valve lever position .. you are saying that the lever should be closer to the ground.. mines been lifter 2" apparently..bilstein shocks and who know what springs... be good to know what the normal ride height is for a new safari on 275/70 r16 wheels....
Piers

 

[albundy]

I was always told that they should sit level, that was the correct adjustment. I have done this and the brakes seem to work fine. She pulled up pretty quickly when a bloody moped pulled out in front of me. He would have looked good under the front axle.
Al

 

[FreddyN]

When my SWB is unladen - nothing in the boot, then the lever on the proportioning valve sits loosely close to one end of it's travel - up. I just went out and checked it again, 'cause I've got 100kg or so of tools and junk in the back, and sure enough the lever has moved down a bit. So, as the diff centre moves up toward the chassis (ie with load in the back), tension on the spring is reduced, the lever moves down, and this increases bias to the rear brakes. If suspension is lifted, I suppose that unladen and on flat ground, you'd want to adapt the bracket(s) so it sits with only just no bias to rear brakes. But there's also a problem as with that lift, you'll probably have different/stiffer springs, and more suspension travel, so the valve, unless adjusted/adapted/checked isn't going to be "calibrated" to the suspension. But OTOH, if the suspension is stiffer than standard, then the "incorrect" bias will be on the safer side - less bias to the rear rather than too much - which risks rear wheel lockups.
The Haynes manual is useless - no information, just a suggestion that "in the event of poor braking performance" then get this adjusted by Nissan dealership. Perhaps a brake shop can help if you want to get really fussy on it, if they know what front:rear bias should be, laden and unladen. Perhaps someone in the suspension forum on this site can help more.