Rear Brakes 94 Terrano

[Keef]

Hey guys, need another set of eyes / brain on this one.

The short version:

got no rear brakes, have bled and replaced the brake master but still almost no brakes. Brake pedal pumps up firm when truck is off and kinda sinks to the floor under light pressure when truck is running.

The long version

Went to VTNZ to get a wof, failed due to weak brakes in the rear. went home, kicked the truck, bled the brakes and went back for a recheck.
Failed
the readings are equal but Low, and equal on front. Front brakes are strong
the truck had the brake master replaced when I bought it, never had a proper brake check I guess cause the thing doesn't feel any different. but I had noticed it locks up the fronts under heavy braking. and never the rears.
Replaced the brake master cause I figured the replacement might have been junk, turns out the replacement I got from repco is the same and although it feels a bit better, after bleeding it up I took it back for a recheck and failed again this time with almost no rear brakes at all. fronts still perfect.
I have no load sensing valve that I can see I've traced the brake lines, just a small block behind the drivers side front wheel and then a T on rear axle.
The rear brakes still bleed perfectly. Fluid is moving fine, I had thought I had a blockage. but now I am second guessing.

With the engine off, I can pump the pedal and get a very firm pedal, as soon as the engine starts it is soft, and if I pump like crazy I can get some pressure back but leave a foot on the pedal and it just goes down. Having never driven another terrano I don't know if this is normal pedal behavior.

when I pulled the line off the booster I did get a rush of air so it's holding pressure / vacuum I guess that means ??

I'm starting to wonder if I have the wrong vacuum pump on the alternator or all sorts of things really. getting to the point where I will find a wrecked one and start replacing everything which just sounds expensive.

[Crash bandicoot]

In Short...One of the seals in the master brake cylinder has packed up and F'd off for the new year.

The long version, the master cylinder has usually two or three(depends on model) out lets one for the front and one for the rear...obviously this means there are two sets of seals inside the master cylinder.

IT's not a bad idea really, if you split a line you only lose half your brakes, not all of them.

[Keef]

thanks for the reply.

before I changed the brake master I was getting 350/350 front and 50/70 on the rear thats on the vtnz brake test machine
bled it and the numbers all went up rear went to 80/90
still really poor rear brake performance.

now with the next cylinder on I initially had a reading similar on the rears then nothing.

I am strugling to believe it's 2 faulty brake masters. Started with crap rear now I have none.

have you got any other ideas ?

I might be doing something stupid, the truck is parked on a slope with the master cylinder high..might turn it around and rebleed in the morning.

[Keef]

I have the 3 port brake master if that helps, 1 goes to the rear the others appear for left and right.

[Sadam_Husain]

are the rear brakes disc or drum on those things?

[Keef]

hydraulic discs and cable drum for handbrake.

should I hear an air noise from inside the truck when I step on the pedal ? it doesn't sound like it's leaking, just sucking in air when i push the pedal in.

[Crash bandicoot]

The air noise is irrelevent at the mo, we'll get to that later as it only assists you in pushing the pedal, not fluid in motion.

terrano's have drum brake rear with a cable handbrake but still only has the one set of brake shoes inside each drum .

bleeding the brakes won't tell you if the seal in the master is incorrectly installed or damaged.

Another issue (and why i dont like VTNZ) is they don't inspect the brake lines when the brakes are in operation.

doing this allows the inspector to see any ballooning in the lines.

It isnt the brakes them selves as you would have a leaking/siezed slave cylinder and it would still operate one of the rear brakes.

When was the last time the rear brake shoes were changed?

[Keef]

thanks for replies,

the times time the vtnz man had the pedal firm up under foot they came on strong. So on random occasion, they work.

I have rear disks, and I checked the pads, they seemed fine.

There is also an independent cable driven hand brake which has shoes and the drum is built into the rear discs.

handbrake is awesome, I have no issues with the handbrake locking the rears up.

I wonder if I simply have too little vaccuum to operate the rears effectively.
the alternator could have a 70cc 50cc or 35cc vacuum pump on the back, what are the chances that was changed before I got it and could be a problem ?

[Crash bandicoot]

where's the head banging brick wall emocon when ya want it...oh there it is..




now. the standard terrano didn't have disc brakes. not even the face lift R50 terrano or 1998 facelift terrano II has disc brakes on the rear.

So if you have disc brakes on the back of your terrano, It's either not a terrano or you've got a pathfinder rear axle or pathfinder rear brakes which means you most likley have the wrong size slave cylinders compared to the master cylinder.

[Keef]

Thats confusing.
I'm looking at a wd21 service manual, there is a section for rear disks and a section for the model with hydraulic rear drums.

I don't really know how to tackle that.. last brake master cost me just under $200 special price.

Can someone recommend a garage to take it to so I can just get this thing matched up or do I just try a pathfinder brake master ?

NISSAN TERRANO 1994 R.3M-R is this a special model ?

[slide]

now. the standard terrano didn't have disc brakes. not even the face lift R50 terrano or 1998 facelift terrano II has disc brakes on the rear.

So if you have disc brakes on the back of your terrano, It's either not a terrano or you've got a pathfinder rear axle or pathfinder rear brakes which means you most likley have the wrong size slave cylinders compared to the master cylinder.

Ummm??? Where did you come up with that?
Have you ever looked under a 89-95 terrano?
Very rare for them to have drums. Only the c200 rear-diff type have drums. That only leaves 95odd percent with discs front and rear....

My suggestions;
Ignore vacuum issues. That has nothing to do with front/rear balance, only assists pushing down pedal. (also, when not driving you probably pushing the pedal down 5x harder to check for firmness that you ever would push it when driving)
Check rotors/ pads have 100% surface contacts.
If rotors worn badly (or rusted), then friction will be down. (also if linings contaminated (eg oil) or burnt)
Remove callipers, check slides free, and piston moves out freely if pedal depressed, and squeeze in easily.
You say fluid seems to flow freely- thats good.
I think you're correct saying no load sensing valve for terrano. So only possibility that remains is whether you have a navara master cylinder?
(they have drum rears, and proportioning valve, so possibly different m/c)
But no point spending heaps of time and money to get nowhere.
Might be worth taking to a garage (or brake specialist) You're in auckland right?
I'd have no idea where to go. Closest garage?

Hope that will help,
Nath

[hamboy]

These terrano rear brakes are a bastard at the best of times.
The import terrano has the disc/drum (pathfinder) setup from factory, so can sometimes be a bit of a task finding the right parts.
As crash said the master cylender might be wrong, maybe try bnt they seem to be able to find the right bits.
Also check your calipers as they can seize, i know it sounds wierd for both of them to do it, but stranger things have happend.

Cheers
Dan

[Keef]

thanks guys, popped in to my local supercheap and the manager looked things up on their computer, same part for terrano / pathfinder only difference we spotted was on the petrol version there are two versions of brake master one has a 15/16ths inch bore the other a 1 inch bore, he said that could be the one I need but I am not that keen to risk it.
I'm in Auckland, just querying a wrecker to see what they have that is the same as my setup, might go used and get it reco'd if it works out cheaper.

[Sadam_Husain]

sounds like you've got a few clues mate so battle on for a bit and as said above somewhere pull your back brakes apart and check the calliper pistons are working and not seized and the rotors and pads are all good to eliminate that as your problem then when its all got you beat you can look at taking it into the shop to get looked at?

Simon must be on holiday somewhere coz he hasnt popped in with all the terrano answers

[Keef]

thanks, yes will pull the brakes apart now and have a poke about, see what I can see.

[Keef]

took the other brake apart, put some more grease on the sliders but even before that they slide.
with a 1 man bleeder kit on the caliper I can push the piston back by hand and watch the fluid come out so calipers are receiving fluid and can slide.
The pads are not down to the wear indicator yet so I don't imagine they are too low.

I'm wondering if they could be contaminated ? rooted ? and doing a shit job now, I don't imagine they are so expensive to replace so I might go down that path.

thoughts anyone ?

[hamboy]

If you rekon the pads are a bit suspect just direct them at the bin and get some new ones, i think they were around 30 bucks from supa cheep.

[Keef]

new pads on the rear, and went to see a mate who had a theory that bleeding just with a hose into a container vs a 1 man bleeding kit would be the go.. I still have no rear brakes. We rebled the master and all 4 brakes. I have nothing in the rear according to the VTNZ machine occasionally they get up to about 50 then it just goes. Still sounds like an airlock ? yet we bled and bled..

it's starting to get me down..

[Keef]

If the truck has a leaking master when I got it and brake fluid leaked back on the booster and then ran down everywhere, would / could the booster be damaged ? There had been fluid all around and had eaten paint off the engine bay when I bought it.

But even with no booster assistance, I should have working brakes right ?

[Keef]

bled the rears again because I put the new pads in and figured why not. still the same, I can pump the pedal and make pressure when the engine is off. when I start the car the pedal will go to the firewall. still got working front brakes though. with the car running, I can pump quickly and build up pressure. but it goes pretty quickly. The booster is the original booster from when the original master failed and it has been repainted where the brake fluid ate the paint off it.

[kiwipete]

bled the rears again because I put the new pads in and figured why not. still the same, I can pump the pedal and make pressure when the engine is off. when I start the car the pedal will go to the firewall. still got working front brakes though. with the car running, I can pump quickly and build up pressure. but it goes pretty quickly. The booster is the original booster from when the original master failed and it has been repainted where the brake fluid ate the paint off it.

Can I suggest you double check all vacuum lines and hoses to be sure there are no splits in them where they plug in, especially these two areas. I had issues with lack of braking over the holidays and upon investigation I found the hoses had split where they plugged in, especially on the firewall connections. It may or may not help you?
http://i195.photobucket.com/albums/z218/kiwi_pete/Terrano%20Mods/20130106_143447_zps23362b3c.jpg

http://i195.photobucket.com/albums/z218/kiwi_pete/Terrano%20Mods/20130106_143457_zpsb5f50565.jpg

Bloody photobucket, pictures are too large?

[Keef]

Thanks Pete, I did notice and fix the split and loose hoses on the sensor below the vin plate, I will check the others, but question on vacuum leak, if I had vacuum leak, would my brakes not be harder to apply, where I get a hard pedal when pumped up with engine off that pretty much sinks to the firewall when the engine is started, indicating good vacuum ??

[Keef]

Tried a trick I read about, tapping the calipers with a soft faced hammer, did get more air out.but still don't think I have much in the way of rear brakes. I saw a master cylinder bleeding kit that screwed into the ports on the cylinder and allowed you to bleed the cylinder.and keep circulating fluid back into the master.

then read another article which i will do today. go to the pet shop, buy 30 or so feet or aquarium air line, clip a piece on each bleed nipple, put a cable tie on each so they don't fall off. dump the ends into the brake master, and start pumping... if I ran them all up past the windscreen, I would watch for air bubbles.

I'm convinced I have an air lock, and hope this will find it, doing it this way an can get an assistant to tap the calipers with a soft faced hammer to dislodge any trapped bubbles that might exist.

[Keef]

and now the brakes are worse.

I am admitting defeat and taking it to the doctor.

[Keef]

Genius.. the bleeding system for tricky brakes works.
real long 5mm clear vinyl hose from mitre10 from each bleed nipple to the resevoir on the master, with a couple mates gentle pedal pumping, one guy keeping the resevoir topped up and the hoses dipped in the fluid, the other keeping an eye under the vehicle and tapping on the calipers with a soft faced hammer did the trick.
I am now the owner of a nice shiny VTNZ wof.