For the brake genius out there.

[macca]

I have fitted new front pads and rear slave cylinders (drums on the rear).

I had to force the front pistons back to fit the new pads.

Now I have a soft pedal, long travel before the brakes start to work.

Pump the pedal and feels OK till next time.

Hold foot on pedal and it slowly goes to the floor.

We have bled the brakes twice including the proportion valve.

Any ideas what is playing up.

[93patrol]

Sounds like air still in the line. Start with the furtherest wheel away from the master cylinder left hand rear. Then RHR,LHF and finally RHF.

Are you using Dot 3 or Dot 4 fluid

[nissannewby]

Sounds like air still. What procedure are you using to bleed?

[NP99]

Have you started the bleed in the correct sequence? Starting from the nipple furthermost away from the master cylinder?

[macca]

LR, RR, LPV, LF & RF. 2 person, open pedal down, close pedal up. Thinking if it's air it would not firm after pumping the pedal.
Also the pedal going to the floor, could the master cylinder be leaking back past its piston.
I don't know if I have the wrong end of the stick.
It's doing my head in.

[macca]

Are you using Dot 3 or Dot 4 fluid

Just checked its Dot4

[pearcey]

Forget about the bleeding sequence as the master is split in to two separate systems and it doesn`t matter where you start.
What your problem sounds like is the master is bypassing to check this clamp the hoses going from the body to the DIFFS then see if the pedal slowly goes to the floor, if it does then the master needs to be replaced. If the pedal is solid then the master is OK. If OK release one clamp and check then reclamp and release the other clamp. This will tell you which end has the problem.
You can clamp the hoses off with a couple of G clamps BUT DO NOT clamp braided hoses.
Hope this helps

[macca]

Pearcey that sounds like a good way to fault find, that's what I will try tomorrow, report back with my findings. Thanks mate.

[pearcey]

Pearcey that sounds like a good way to fault find, that's what I will try tomorrow, report back with my findings. Thanks mate.
When bleeding the system, bench bleed the master or start at the master then go to any wheel it doesn`t matter which and with help get someone to push the pedal down then open the bleeder, then shut the bleeder, get the person to SLOWLY release the pedal TAKE FROM 5 to 10SECONDS wait a couple of seconds then have them depress the pedal again when they have depressed the pedal open the bleeder, repeat this until you have new fluid flowing at that bleeder. Do the same at each wheel and you should be successful. By pumping the pedal as most do can create problems where when the pedal is released fast air is drawn in past the cups in the wheel cylinders.
Any problems pm me, 45 years a brake specialist.

[pearcey]

Sorry macca I missed the 2000 posts as I just got back from Tas CONGRATS mate

[Old Wal]

Whilst certainly no expert on brakes I experienced a similar problem recently. I had new ( genuine - purchased from patrolapart ) master cylinder fitted by a "reputably" brake business in Wodonga as mine was weeping. Asked them to adjust rear brakes ( drum ) at the same time. Picked up my ute and pedal was going to floor but would firm up with constant use . Took it back & they re bleed system , assured me that they had gotten all air out. Still no good. Went back , they said master cylinder must be faulty. Clamped off brake hoses as pearcey suggested - at least they knew about that technique. Pedal was solid. They then seemed a little lost and proposed a major investigation ( at my expense ) which I declined. Took my ute to another brake guy & discussed problem with him. He mentioned the issue with air being drawn in past the cups but he said it could just be a brake shoe adjustment problem. Left my ute there & he re bleed brakes just to be sure - got " bugger all " air out . Adjusted rear brakes shoes and road tested - all GOOD. My brakes are fine now, probably better then they have been for ages. Needless to say I won't be using the other mob again. Anyway just my experience.

[macca]

Thanks Wal, I'll check the adjustment tomorrow too.

You guys have been a great help.

[NP99]

Whilst certainly no expert on brakes I experienced a similar problem recently. I had new ( genuine - purchased from patrolapart ) master cylinder fitted by a "reputably" brake business in Wodonga as mine was weeping. Asked them to adjust rear brakes ( drum ) at the same time. Picked up my ute and pedal was going to floor but would firm up with constant use . Took it back & they re bleed system , assured me that they had gotten all air out. Still no good. Went back , they said master cylinder must be faulty. Clamped off brake hoses as pearcey suggested - at least they knew about that technique. Pedal was solid. They then seemed a little lost and proposed a major investigation ( at my expense ) which I declined. Took my ute to another brake guy & discussed problem with him. He mentioned the issue with air being drawn in past the cups but he said it could just be a brake shoe adjustment problem. Left my ute there & he re bleed brakes just to be sure - got " bugger all " air out . Adjusted rear brakes shoes and road tested - all GOOD. My brakes are fine now, probably better then they have been for ages. Needless to say I won't be using the other mob again. Anyway just my experience.

Are they the mob near the railway line up the Bandiana end? The stuffed my tray back up years ago :(

[macca]

The clamp test had shown the problem is in the rears. On to something. Yeha

[macca]

Adjusted the rear shoes, only about 5 or 6 clicks.

Is a bit better, now I'm waiting for a hand to bleed the system again.

Pauly's out for the day and Dads deaf, daughters home but sleeping I'll get it done somehow. LOL

[Robo]

The valve above rear diff needs bleeding also.

[macca]

OK I now have a dilemma.

Engine off its great.
Engine on the pedal goes down heaps, 2nd pump its fine. Leave it of 5 second's the pedal goes down heaps again.

I have to wait for Pauly to get home to bleed it again...

[macca]

get someone to push the pedal down then open the bleeder, then shut the bleeder, get the person to SLOWLY release the pedal TAKE FROM 5 to 10SECONDS wait a couple of seconds then have them depress the pedal again when they have depressed the pedal open the bleeder, repeat this until you have new fluid flowing at that bleeder.

Right we have done this, problem still exists, clamped rear hose and it's gone. There must be something not right with one of the new rear slaves. I think...

[93patrol]

Adjust your rear drums up until there is constant scraping of the shoes on the drum or I was told adjust until it locks the wheel and then back it off until the wheel moves with moderate pressure but can hear the brake shoes on the drum

[nissannewby]

Are you blocking it before or after the LSV? I believe the LSV returns to the master so you could have a dodgy LSV (proportional valve)

[macca]

Adjust your rear drums up until there is constant scraping of the shoes on the drum or I was told adjust until it locks the wheel and then back it off until the wheel moves with moderate pressure but can hear the brake shoes on the drum

93 I have gone as far as I dare, I think its far enough the hub couldn't be turned but with the rim back on it turned with the motor and no excessive dragging noises.
The drums were a PITA to get off and trying to turn the drum is near impossible with the slippry diff. Will have another go in the morning when my work mate gets here. Backing the adjuster off concerns me, its a shizzen to get to.


Are you blocking it before or after the LSV? I believe the LSV returns to the master so you could have a dodgy LSV (proportional valve)

Yep NN the rubber hose to the diff all the rest are pipes.

[pearcey]

G`day macca.
I`m Not sure if the brakes can be adjusted with the drum on as it`s a long time since I`ve done a drum brake Patrol.
If not then you have to make sure that there is not a lip on the drum as this will cause all sorts of grief.
What I would do is drill a hole through the drum or the back plate to line up with the adjuster and put a rubber plug in it after the job is done.
Going by what you have said the adjustment would seem to be your problem.
To adjust it you should adjust the brakes up until they are looked solid then back them off until the wheel turns freely, but as said the LSD will give you some grief
To turn the drum use a long bar across the wheel studs and also you can do one with the opposite drum off the car, this will at least make one side easier.
Pity I`m in SA otherwise I`d help you out.
best of luck mate

[nissannewby]

93 I have gone as far as I dare, I think its far enough the hub couldn't be turned but with the rim back on it turned with the motor and no excessive dragging noises.
The drums were a PITA to get off and trying to turn the drum is near impossible with the slippry diff. Will have another go in the morning when my work mate gets here. Backing the adjuster off concerns me, its a shizzen to get to.



Yep NN the rubber hose to the diff all the rest are pipes.


Try putting the LSV to maximum and see what happens.

[macca]

Try putting the LSV to maximum and see what happens.

The pedal is firm when crimping the brake line after the LPV I assume that the valve is not the problem. This is a pain in the faarking ass.

[nissannewby]

The pedal is firm when crimping the brake line after the LPV I assume that the valve is not the problem. This is a pain in the faarking ass.

Sorry mate I misread your post getting a little tired.

[Old Wal]

Are they the mob near the railway line up the Bandiana end? The stuffed my tray back up years ago :(

Yes, that's them!

[NP99]

Yes, that's them!

Yep, stay clear of them. They wrecked my front end on my tray back, years ago!

[93patrol]

You might need to get your drums skimmed to take the lip off. If you haven't had this done before this would be your problem. To make it easier to remove the drum back your adjuster way off. Don't worry it's a pain in the arse but you won't break it.

[macca]

OK patrollers we have a solution to the problem.
Went to brake place this morning, the problem is a Nissan design fault.
As soon as I described what you had recommend I do he said is it a Patrol? Then showed me the problem and the fix.
The bleed port in the cylinder is not at the top so air can not get out when bleeding.
Either bend cylinder tubing to put it higher, a PITA. Or fill the top with rubber grease, the method I am going to try.
This may help others with an annoying spongy pedal.
Will try to get it done today and report back!

[macca]

Sorry, Pearcey there is a access to the adjustment it's a pain but I'm getting better at using it.
And 93 there is no lip fortunately, at least that's 1 less issue.

[93patrol]

Great outcome Macca at least you now have a solution to the problem. I am sure you are sick of working on your brakes by now

[Parksy]

Can you use a syringe and fill the slave via the bleed nipple?

[macca]

Can you use a syringe and fill the slave via the bleed nipple?

Parksy you could, just got to displace the air somehow. Just got it all back togeather, and bled , will adjust the shoes after we have a coffee. See how we go.

[Parksy]

Hmmm. I wonder if you can crimp the rubber hose and use a syringe to create a vacuum within the cylinder, then close bleed screw then undo the crimp. It works for filling in windscreen cracks. Just an idea.

[macca]

Well it's on the road, pedal is still spongy, bugger, like before but consistent.
No more pedal to the floor stuff.
So I'm happier today with this result. The wheels lock up with savage braking which is what I need.
The pic has a piece of wire through the nipple location, shows how much of an air filled void is not bled out.

[macca]

A big thank you to all that contributed to getting this thing working again, its been a pain in the butt but I'm a whole lot happier its working better.
Can not understand the design flaw though, very strange.

[NP99]

Are the GQ and GU cylinders the same or inter changeable?

[Alitis007]

While driving if you pump the brake pedal twice and hold down on the third pump does the brake pedal come up higher ?? To me most of your brake problems is the adjustment. Being and LSD drum brake system, lock the adjusters till the wheel cannot turn then back off 3 or 4 teeth of the adjuster on each wheel, when you rotate the wheels by hand you should hear a consistent scrape during a whole revolution. Brake adjustment should be made with wheels on DO NOT PUT A BAR ACROSS WHEEL STUDS UNLESS YOU WANT TO BREAK THEM OR DAMAGE THE THREADS as i seen someone recommend you do earlier.

When you bleed the brake fluid you should jack the back higher and have the side furthest away from the brake hose a bit higher, gravity bleeding gets most of the air out this way followed by pressure bleeding should see you have a great pedal.

[macca]

DO NOT PUT A BAR ACROSS WHEEL STUDS UNLESS YOU WANT TO BREAK THEM OR DAMAGE THE THREADS.

Yeah I figured that one out after the bar slipped and a big lump of me is now attached to the Nissan LOL bloody idiot me!! Where's them gloves, oh yeah right here beside me, FFS.

I am heading into town tomorrow night in it so will give it a work out, I'm sure I can get it better.

I will do as you say about the adjusting, Dad was here today and although appreciate what he did he is not strong enough to turn the wheel / tyre. Them diffs are tight buggers, no wonder everyone says they are the best.

Did the back up / nose down thing to get the cylinder level, bloody hell mate I have tried everything, it was driving me nuts.

Funny thing swearing with a gob full of a bullocky's worst didn't make any difference either!

Appreciate all the advice, every bit has contributed to getting me back on the road, the ute has been on the stands in the carport for 9 days today. I needed all the help you all gave me.

Thanks again team.

[Cuppa]

OK patrollers we have a solution to the problem.
Went to brake place this morning, the problem is a Nissan design fault.
As soon as I described what you had recommend I do he said is it a Patrol? Then showed me the problem and the fix.
The bleed port in the cylinder is not at the top so air can not get out when bleeding.



Hmmm, sounds like an opening for some enterprising company to produce or source aftermarket wheel cylinders with a bleed nipple which allows the air out!

[macca]

Hmmm, sounds like an opening for some enterprising company to produce or source aftermarket wheel cylinders with a bleed nipple which allows the air out!
The brake bloke said the army had Land Rovers with the same problem so they rigged up their winches and lifted the vehicle so the air could be bled out!.

[Robo]

Same idea as winch except, drive car up on ramps on right side only.
bleed left side the swap ramps to left side, and bleed right side.

Makes you wonder how Mr Nissan do it.

[93patrol]

Another option is to force fluid into the bleed nipple at the wheel cylinder and clamp the flexi hose at the diff and bleed it through your bias nipple. Use a squirts bottle with a rubber hose over the end of it. Might work



Disclaimer. This idea came to me at 4:30 am after a 12 hour nightshift on 1.5 hours sleep in the last 36

[pearcey]

If you put the wheel nuts back on the studs the bar will not slip off ,and if you can bend or break a stud then you should be in the worlds strongest mam comp
No trickery to the bleeding problem all you have to do is back the adjusters right off bleed then adjust the brakes.
With the brakes backed of the space in the cyl is so small that the air is displaced easily with fluid.

[Alitis007]

If you put the wheel nuts back on the studs the bar will not slip off ,and if you can bend or break a stud then you should be in the worlds strongest mam comp.

You still never put and bar across wheel stud, if you did that in any shop i know you'd be out the door quick smart. Its not hard to break wheels studs mate and you don't need to be the worlds strongest man either, i've broken tons of them when someone has cross threaded wheel nuts with my 900mm breaker bar. Anyway a proper brake adjustment is done by rotation of the wheel so without the wheel on how can you tell ??


How to know if your brakes are adjusted correctly:
Open rear diff center, the wheel rotates 1 revolution with a hard push
Lsd rear diff, the brake makes a consistent scrape on the drum during 1 complete revolution. In both cases the handbrake is disengaged.

[Cuppa]

No trickery to the bleeding problem all you have to do is back the adjusters right off bleed then adjust the brakes.
With the brakes backed of the space in the cyl is so small that the air is displaced easily with fluid.

Hi Pearcey, I understand the principle you are describing, but think I must be missing something. Firstly bear in mind I have never had my rear brakes apart, nor had need to bleed them myself. I also respect that you know what you are talking about when it comes to brakes, so I am not questioning your advice.

With the adjusters backed right off the wheel cylinder pistons will have moved inward reducing the internal space ... but..... when trying to bleed them wouldn’t pedal pressure simply result in pushing the pistons back out again? Is there some trick to prevent this ...... like placing something between the brake shoes & the drum or similar? Not sure if I’m being a bit thick.

Also, still wondering about a ‘better’ solution. When I was talking to Macca, I wondered aloud about the possibility of having the cylinders drilled & tapped in order to fit a bleed nipple on the top. Macca thought that there would likely be insufficient thickness of metal in the cylinder body to do this. A shame ‘cos I thought I was having a ‘Good Idea”. :icon_bonk:

How likely is it that there might be cylinders from another vehicle with suitably spaced mounting holes & a better placed bleed nipple? I have been trawling the net & have found many instances of others over the years who have suffered exactly the same difficulties as Macca, but no instances of the explanation he has found.
It’s hard to believe that no-one has found a bolt on solution to the standard ‘lack of feel’ Patrol brakes. I like many others was told by a Nissan dealer that they were designed that way on purpose because Nissan considered it safer in off road conditions! They even got me to sit in several other Patrols, all of which had similar feeling brakes, (& weren’t drum braked models).

To folks who have fitted braided lines to a Patrol, (particularly rear drum models) - did it make a significant difference to ‘feel’?

As things stand, I am not looking forward to ever having to bleed my brakes!

[threedogs]

would it be possible to run some brake line from each nipple to a central manifold
that will have one universal bleed point, easy enough imo

[jack]

I've followed this thread with interest, share your pain Macca as I had similar trouble finding a solution to wheel wobble many years ago. Very far from being an expert, I have changed, replaced, re-kitted many brake cylinders in the past. Really hope those times are well and truly behind me.

Also thought about a new bleed nipple on top of the cylinder as Cuppa mentioned but agree would be to thin to get a good thread to lock it considering the pressures involved as well. TD I don't think your idea of a central manifold would work either as the air trap is the issue and would still be above the bleed nipple.

Other than tipping the car almost on it's side to get the bleed nipple as the high point, it would be nice if it was possible to bleed the cylinder prior to installation (unfortunately that's not possible). Can't believe Nissan hasn't addressed this already!

[Robo]

simply tilt the car on ramps or the slope of a hill.
and bleed the lower side of car then swap and bleed lower side again.

Or can the cylinder be filled off the car and temporarily plugged to stop leak.
Install and bleed.

[pearcey]

G`day All
Cuppa to answer your question, it`s exactly what we want, that is for the cups to move out then when they return the agitation of the fluid drags the little air that is left in the cyl, out. One other way is to open the bleeder then stomp hard on the pedal shut the bleeder release the pedal SLOWLY and repeat as necessary.
This works ok on the rear brakes of the early MINI`s where the bleeder was placed in the bottom of the cyl.
Some times English engineering left something to be desired.

[Cuppa]

G`day All
Cuppa to answer your question, it`s exactly what we want, that is for the cups to move out then when they return the agitation of the fluid drags the little air that is left in the cyl, out.

That makes sense, allowing max movement of the cups. I can imagine in that scenario the 'timing' of opening the bleed nipple might be super critical, more so than in 'normal' bleeding procedure.

[threedogs]

When we bled the brakes after fitting new rotors and pad, the boys at TJM Coburg have a 4 into one system..
As in hooked up all four bleed nipple, took a couple of them to do it, as well. But the gravity system works best if you have the time

[macca]

Here's some more information.

Left photo, car is tilted 55degrees to get port to the very top.

Right photo, what Pearcy is talking about. Wrap the pistons with tie wire to bleed and carefully install then push the into correct position using brake pedal.

I like that best, not perfect but better. Add rubber grease and all air would be displaced.

Food for thought.

Now I have to knock dent out of the shed wall where I was hitting my head!

[nissannewby]

When we bled the brakes after fitting new rotors and pad, the boys at TJM Coburg have a 4 into one system..
As in hooked up all four bleed nipple, took a couple of them to do it, as well. But the gravity system works best if you have the time

Yours as you have just said is disc all round and does not have the problem these guys are having with their drums.

[macca]

Caught up with a mate last night, he is a mechanic at the local Nissan dealership.
They don't get to work on Patrols any more as most are a few years old and never get taken in for warrantee and services etc.
Showed him the slave cylinder and was amazed by the design, he did not know of the problem and had not heard anyone talk about it.
He was going to ask around and get back to me.
His dad is also a mechanic, although this was new to him, he said with something like this you compress the pistons together as Pearcy said then pump the pedal and hold it down hard to pressurise the system, release the bleeder and the force of fluid rushing in swirls the fluid and air out get "most" of the air. He had not done it but that was his solution.
Bugger of a thing

[Cuppa]

he did not know of the problem and had not heard anyone talk about it.


This is what really astonishes me. Will be interesting if he hears any more. It's hard to believe that the issue has gone unnoticed by Nissan. Would also be interesting to know if it's only a leafy GU issue, or other leafy models too.
Are there any ex Telstra mechanics here?

[timmay556]

Cant park the girl sideon on a hill? then do the final bleed?

[macca]

Cant park the girl sideon on a hill? then do the final bleed?

At 55 degrees, you are braver than me LOL
http://www.nissanpatrol.com.au/forums/attachment.php?attachmentid=46677&d=1404797356

[jack]

At 55 degrees, you are braver than me LOL

Chicken :oops:

[macca]

Chicken :oops:

book, book book book hell yeah

[FNQGU]

Ever get this sorted Macca?

[macca]

Yes I did the brake grease method, they work fine and the feel is better now that everything has bedded in.

Greenstuff front pads and slotted discs work well. Much improvement.