Troubles on my SFA's brakes

GeorgeJvR · Post by **GeorgeJvR** » Mon May 03, 2010 7:44 am

Every now and then the brakes get quite hard as if the vacume is gone, i've fitted a Gearmax diff lock, but can't find any leaks on the vacume pipes. Please help.

Silinders has new kits, new load sensor, rear drums skimed with new shoes,Front discs skimed and shoes matched.
I also replaced the valve that operate the vacume for the diff lock.

zepplin · Post by **zepplin** » Mon May 03, 2010 9:16 am

The only part of the whole system you haven't replaced seems to be the rubber pad on the pedal.
Try that!!!

GeorgeJvR · Post by **GeorgeJvR** » Mon May 03, 2010 10:02 am

zepplin wrote:The only part of the whole system you haven't replaced seems to be the rubber pad on the pedal.
Try that!!!

Undersand why i'm so frustrated?

Mr_B · Post by **Mr_B** » Mon May 03, 2010 10:23 am

Is it not possible that the issue is in the brake master cylinder??

Mr B

GeorgeJvR · Post by **GeorgeJvR** » Mon May 03, 2010 10:39 am

Mr_B wrote:Is it not possible that the issue is in the brake master cylinder??

Mr B

Thanks MR-B
At this stage i'm out of options any sugestions??

Where is all the pros.

Post by **Mud Dog** » Mon May 03, 2010 11:19 am

George, it's quite probable that you have a vacuum leak since as you say the problem is intermittent. The diff-loc system should be separate of the brake system. Also physically check the metal vacuum reservoir (behind the master cyl.) for pin-prick rust holes. Just go over your hoses (look for perishing) and connection clamps to eliminate other leak possibilities.

GeorgeJvR · Post by **GeorgeJvR** » Mon May 03, 2010 11:42 am

Mud Dog wrote:George, it's quite probable that you have a vacuum leak since as you say the problem is intermittent. The diff-loc system should be separate of the brake system. Also physically check the metal vacuum reservoir (behind the master cyl.) for pin-prick rust holes. Just go over your hoses (look for perishing) and connection clamps to eliminate other leak possibilities.

MD My diff lock's vacuum is conected to the vacuum pipe between the Master cyl and the motor by a T pice. where els can i conect the vacuum?

Post by **Mud Dog** » Mon May 03, 2010 12:08 pm

GeorgeJvR wrote:
Mud Dog wrote:George, it's quite probable that you have a vacuum leak since as you say the problem is intermittent. The diff-loc system should be separate of the brake system. Also physically check the metal vacuum reservoir (behind the master cyl.) for pin-prick rust holes. Just go over your hoses (look for perishing) and connection clamps to eliminate other leak possibilities.
MD My diff lock's vacuum is conected to the vacuum pipe between the Master cyl and the motor by a T pice. where els can i conect the vacuum?

That should be fine, but do you have a seperate vacuum reservoir for the difflock? Also, where is the valve that activates the difflock situated? To my mind it should be immediately after the reservoir or immediately after the "T" piece if there is no reservoir. That valve should then act as the 'separator' between the two systems. Imagine if you damaged / ripped the vacuum line in the bush or over an obstacle .... your brakes would immediately go for a ball of chalk.

A vacuum leak is not so easy to find ... a pressure leak is easier.

Toybox · Post by **Toybox** » Mon May 03, 2010 12:44 pm

I had an odd vacuum problem with my brakes a while back, perhaps its a similar situation...

My rear locker was also tee'd off the brake vacuum line. What solved it eventually was installing a two 1-way valves after the tee piece. 1 for the locker, and 1 for the brake. This way if the locker vacuum line gets torn it shouldn't effect the brakes, and it helps hold vacuum in the master at low revs....

Post by **Mud Dog** » Mon May 03, 2010 12:54 pm

Good idea!

Mr_B · Post by **Mr_B** » Mon May 03, 2010 1:26 pm

Vacuum leaks really suck!

GeorgeJvR · Post by **GeorgeJvR** » Mon May 03, 2010 1:46 pm

Toybox wrote:I had an odd vacuum problem with my brakes a while back, perhaps its a similar situation...

My rear locker was also tee'd off the brake vacuum line. What solved it eventually was installing a two 1-way valves after the tee piece. 1 for the locker, and 1 for the brake. This way if the locker vacuum line gets torn it shouldn't effect the brakes, and it helps hold vacuum in the master at low revs....

Toybox
What 1-way valves did u use, and where can i buy them, Midas/ Autozone?
the valve at the d/lock and the Master, witch way does it work?
This is a new one for me.

Toybox · Post by **Toybox** » Mon May 03, 2010 2:10 pm

I needed 2 different sizes because of the 2 different size hoses. The one from the tee to the brake booster can be sources from a golf or a sentra. The lux's originally have one in-line along the firewall but mine was missing...

The one I used for the locker was much smaller and I picked it up from the local brake/diff place.

If you don't mind shooting me a PM this eve to remind me, and I'll take some pics...

Toybox · Post by **Toybox** » Mon May 03, 2010 6:01 pm

Okay here's that foto I promised:

See the little brass goodie, and the black valve? Those are the one way valves I mentioned....

GeorgeJvR · Post by **GeorgeJvR** » Tue May 04, 2010 7:34 am

Toybox

Corect me if i'm wrong;

The vacume pipe comes from the motor then the T
One pipe to the master with a valve alowing suction towards the motor,
the other pipe with a valve alowing suction towards the motor, where after the pipe runs to the D/Lock (selector).

Toybox · Post by **Toybox** » Tue May 04, 2010 8:27 am

Edzackery!

Engine - Tee piece - 1 way valve - brake booster
- 1 way valve - D/lock

GeorgeJvR · Post by **GeorgeJvR** » Tue May 04, 2010 8:41 am

Thanks i'll see who can help me in this smal Town

GeorgeJvR · Post by **GeorgeJvR** » Thu Jun 03, 2010 3:33 pm

OK I'm getting realy frustrated now :evil: :evil: :evil: :evil:

Normal braking when stopping in a "no emergancy mode" / slowing down to a full stop no problem even when i slowly pushes the brake till the wheels lock (front and rear)

BUT

WHEN Mr taxi or who so ever whants to test my brakes, drives up in front of the hilux, and forces me to do a "NOOD STOP"
the rear brakes think they are on holliday only the front brakes works
On gravel road i forcefully stopped in quite a hurry , front brakes locks rear brakes nothing0 rear brakes

On a slow steddy brake "on grave road" till the wheels lock all the 4 wheels locks.
:evil: :evil: :evil: :evil:

PLEEEZZZ HELP

GeorgeJvR · Post by **GeorgeJvR** » Thu Jun 03, 2010 3:35 pm

I've bloked off my difflock vacume for now, still the same.

Mr_B · Post by **Mr_B** » Thu Jun 03, 2010 4:00 pm

Is it not possible that the rear brake load proportioning valve is to blame?

GeorgeJvR · Post by **GeorgeJvR** » Thu Jun 03, 2010 4:09 pm

Mr_B wrote:Is it not possible that the rear brake load proportioning valve is to blame?

Been replaced twice

I'm thinking when they have fitted the load sensor the two line were swoped "the supply and the return" any idea what will happen if it's swopped?

Mr_B · Post by **Mr_B** » Thu Jun 03, 2010 4:26 pm

If your bakkie has a raised suspension or body lift, then the arm of the load proportioning valve must be lengthen to compensate...

Take a look here SifuLux(Andrew) posted pics of the mod he did to correct:

viewtopic.php?f=136&t=520&start=20" onclick="window.open(this.href);return false;

Mr B

Post by **Mud Dog** » Thu Jun 03, 2010 4:35 pm

There is no return ... it's not a looped system. There is on 'in' and two 'outs' (one to each wheel).

GeorgeJvR · Post by **GeorgeJvR** » Fri Jun 04, 2010 7:31 am

Andy
i got a print out fron Toyota showing there are one supply from the front of the master to a T (A & B) A to the one front wheel, B to another T (C & D) C to the other front wheel, D to the Load sensor.The second pipe from the side of the master goes to the Load sensor. From the Load sensor there are a single supply to a T that supplies the two rear wheels.???????????

Gunta · Post by **Gunta** » Fri Jun 04, 2010 8:17 am

George I had a similar problem, Check the length of the load arm. I had to extend it to stop the rear brakes locking up. The other thing to check is if the pedal is hard you might have to much play on your rear brake shoe's. Adjust the rear shoe's to take up the slack.
Just another stupid question, have you checked to see if you have vacuum on the pipe?

GeorgeJvR · Post by **GeorgeJvR** » Fri Jun 04, 2010 8:30 am

(Just another stupid question, have you checked to see if you have vacuum on the pipe?) Yes.

They adjust the rear brakes abit more but i'm thinking that the brakes will start locking again, un der normal braking?

gompie · Post by **gompie** » Fri Jun 04, 2010 8:37 am

George , ek het n plan, knip die agter briek pypies af en blok hulle.

sterkte, ongelukkig is dit nie my sterk punt nie.

Gunta · Post by **Gunta** » Fri Jun 04, 2010 9:02 am

George, have you adjusted the load arm yet? That will deffinitely stop the rear wheels from locking up.

GeorgeJvR · Post by **GeorgeJvR** » Fri Jun 04, 2010 9:39 am

Gunta wrote:George, have you adjusted the load arm yet? That will deffinitely stop the rear wheels from locking up.

Mark

normal braking all 4 wheels brakes good, rear brakes slightly more but that is with the load arm not even toutchung the load sensor ( as if no load )

Speady / Emergency brake Front wheels locks and 0 brakes at the back

Gunta · Post by **Gunta** » Fri Jun 04, 2010 10:38 am

Sounds like you might have air in the system. Have you bled the rear brakes? When you bleed, open the niple under pressure and see how fast and how much fluid comes out.
It seems to me that under pressure the brake fluid is not getting there in volume. Check for kinks in the pipes that might restrict the flow as well.
Another thing to do is change the seals and check the piston (for pitting)on the rear brakes.

GeorgeJvR · Post by **GeorgeJvR** » Fri Jun 04, 2010 11:09 am

Gunta wrote:Sounds like you might have air in the system. Have you bled the rear brakes? When you bleed, open the niple under pressure and see how fast and how much fluid comes out.
It seems to me that under pressure the brake fluid is not getting there in volume. Check for kinks in the pipes that might restrict the flow as well.
Another thing to do is change the seals and check the piston (for pitting)on the rear brakes.

Mark I've replaced the rear brake selinder kits
when bleeding the brakes the flued is plenty.

May be i should start replacing the pipes?

Gunta · Post by **Gunta** » Fri Jun 04, 2010 11:48 am

Have you replaced your master cylinder? Something does not make sense there, If you hit the brakes hard are you pushing in the clutch? You should not push in the clutch when you brake. If the rear wheels are locking up without pushing the clutch then the problem can only be between the load shaft and the load sensor. Try adjusting the load arm to the longest setting you can and then test it again. If it is to high only the front brakes will work, but then you can start adjusting it slowly down until the rear brakes brake without locking.
Have you lengthened the load shaft? if not that will be your problem.

Post by **Mud Dog** » Fri Jun 04, 2010 11:51 am

GeorgeJvR wrote:Andy
i got a print out fron Toyota showing there are one supply from the front of the master to a T (A & B) A to the one front wheel, B to another T (C & D) C to the other front wheel, D to the Load sensor.The second pipe from the side of the master goes to the Load sensor. From the Load sensor there are a single supply to a T that supplies the two rear wheels.???????????

Correct. There are no return lines.

I also think your problem lies with a faulty or poorly set load proportioning valve. Under normal braking you might be assuming that the rear brakes are working properly whereas they may in fact not be, which then only becomes apparent under heavy breaking when the front wheels lock (the rear still not having adequate brake pressure). Why not take it to a testing centre and let them assess the actual effectiveness on all wheels. It won't cost you much but at least you will have a clearer indication of what could be wrong. They may even pin point your problem for you. Brake performance is a major safety issue, and it's vital that you get it sorted.

GeorgeJvR · Post by **GeorgeJvR** » Fri Jun 04, 2010 12:06 pm

Andy
On gravel road doing 60 to 80KM/H braking and slowing down till a save speed to force the brake pedal,
then all 4 wheels lock???????????????????
But jumping on the brakes as if its an emergency only front 2 wheels lock?????????

How can i test the Load sensor?

GeorgeJvR · Post by **GeorgeJvR** » Fri Jun 04, 2010 12:14 pm

Alright this is it for today speak to you all again on monday,
Maybe i'll have good news.

Scooter · Post by **Scooter** » Fri Jun 04, 2010 12:25 pm

I suggest anyone who has time this weekend whilst driving try and perform an emergency stop and table the results here.

To me if the brakes work under normal circumstances and only the rear is not locking up in a emergency it sounds normal i.e the only time my rear wheels lock is when I dont want them to :wth: and then I know they need adjustment

In emergency stopping the pressure exerted on the pedal will mostly affect the front brakes because of the shorter lines.
Of course the increased pressure burst might be affecting the rear cylinders adversely.

IMO you don't have a problem, you have a SFA

that is to say that the brakes on these trucks never work like your dads BMW but they work a dam site better than the old Datsun 1400 or Beetle, drums all round.

Just another thought, when you jump on the brakes all the weight is shifted to the front of the vehicle thus lifting the rear and that could cause the LPV to think there is no weight at the back. Try the same stop in reverse and see what happens

Maybe Im braking the wrong caliper but they are just thoughts.

GeorgeJvR · Post by **GeorgeJvR** » Mon Jun 07, 2010 7:39 am

Thanks Scott
i'll try the reverse one later today.

Seems i was wrong on the brake lines;
(Andy
i got a print out fron Toyota showing there are one supply from the front of the master to a T (A & B) A to the one front wheel, B to another T (C & D) C to the other front wheel, D to the Load sensor.
"The second pipe from the side of the master goes to the Load sensor) THIS IS ALSO A SUPPLY" .
From the Load sensor there are a single supply to a T that supplies the two rear wheels.???????????)

GeorgeJvR · Post by **GeorgeJvR** » Mon Jun 07, 2010 7:48 am

OK I'm going to try and get the Load sensor replaced today (The work shop had the 2 supply lines swoped anddon't know if that might have stuffed up the valve "under warentee")

If that aint working .....Well this is the plan;

Supply from the front of the master to T(1) (A & B) A to the one front wheel, B to T(2) (C & D) C to the other front wheel, D to T(3). The second pipe from the side of the master goes to T(4). From T(5) there are a single supply to T(6) that supplies the two rear wheels.???????????

GeorgeJvR · Post by **GeorgeJvR** » Mon Jun 07, 2010 10:57 am

?????

GeorgeJvR · Post by **GeorgeJvR** » Tue Jun 08, 2010 2:05 pm

Has anyone bypassed a load sensor on a SFA hilux?

Gunta · Post by **Gunta** » Wed Jun 09, 2010 6:53 am

I would not do that, the rear needs to adjust itself when loaded and that would remove it. Are you sure its the load sensor thats not working and not just an adjustment?

GeorgeJvR · Post by **GeorgeJvR** » Wed Jun 09, 2010 7:39 am

Mark I've adjusted the load sensor, the thingy on the diff where u adjust the Load sensor were extended by +/- 100mm or more can't remember. even if I tied the horisontal rod from the loadsensor to the chassis with a cabletie the brakes are the same.
I'm taking my trailer to the test station today if all goes well, I'll soma ask them to test the hilux's brakes. Doubt they check it on a emergentcy stop, will see.

Gunta · Post by **Gunta** » Wed Jun 09, 2010 8:16 am

I extended mine by 100mm as well, but I found I only needed about 20mm. So maybe sheck where it is and if its to high takee it down untill the brakes lock and then adjust up untill it grabs without locking.

GeorgeJvR · Post by **GeorgeJvR** » Wed Jun 09, 2010 8:33 am

Just help me here; If it's adjusted up it will be as if the vhehicle is loaded - more braking power?
If it's adjusted down it will be as if the vhehicle is not loaded - less braking power?

Gunta · Post by **Gunta** » Wed Jun 09, 2010 9:47 am

No The other way round. Less braking power the higher you go up.

GeorgeJvR · Post by **GeorgeJvR** » Wed Jun 09, 2010 10:20 am

Gunta wrote:No The other way round. Less braking power the higher you go up.

Mark are you sure cause if u load the vehicle the Diff gets closer to the chassis therefor the beam from the loadsensor moves up to create more brakes at the back? and down lfor less brakes

Here are the testing station report;
when i aply the brakes slowly.
Left front 3.0 Right front 3.1
Left rear 1.2

Right rear 3.1
Hand brake.
Left rear 1.3

Right rear 3.0

Now fast braking;
Left front 3.0 Right front 3.1
Left rear 0.0

Right rear 0.0

Back to the work shop it is.

Maddoglips · Post by **Maddoglips** » Wed Jun 09, 2010 10:35 am

George

With out been a pain, check the master cylinder and not the compensating valve.

If I remeber, There's 2 sets of seals/washers in it, 1 for front and 1 for back. Maybe under emergency braking they are allowing fluid past due to wear on them.

But under normal/slow braking, they hold up.

If you think of it like a rubber plunger for the drains

if you push it slowly it forces the water forwards in front of the rubber, but if you push it too hard and quick the rubber flips back on itself allowing the water past the sides and in turn doing nothing.

I hope I'm not waisting your time if you've checked this :roll: just trying to help, as if you have no leaks/air in the system, it has to be in the master as it is what controls the pressure increase to the front and back.

Zane

Gunta · Post by **Gunta** » Wed Jun 09, 2010 11:07 am

George, I had mine set at the top and I had no brakes at the back. When I set it to the lowest point the rear locked up everytime I touched the brakes. So I asume that when you set it higher it opens the valve and there is less pressure at the back resulting in less braking. Try setting it at the lowest point and take a drive and see what happens.

Maddoglips · Post by **Maddoglips** » Wed Jun 09, 2010 11:34 am

GeorgeJvR wrote:
Gunta wrote:No The other way round. Less braking power the higher you go up.
Mark are you sure cause if u load the vehicle the Diff gets closer to the chassis therefor the beam from the loadsensor moves up to create more brakes at the back? and down lfor less brakes

Here are the testing station report;
when i aply the brakes slowly.
Left front 3.0 Right front 3.1
Left rear 1.2 Right rear 3.1
Hand brake.
Left rear 1.3 Right rear 3.0

George, looking at the above reading in red, your handbrake is a mechanical brake so with it being low on the left side, this tells me there's some more adjustment needed on the pads to bring it into range of the right side. If you get this close on the mechanical setup, it'll help with the braking already when applying slowly, as it should then be 3.0+- both sides on the rear.

The below makes me more convinced then that the prob lies in the front by the master, as how could the load compensating valve relieve all pressure to zero on fast braking?
Now fast braking;
Left front 3.0 Right front 3.1
Left rear 0.0 Right rear 0.0

Back to the work shop it is.

GeorgeJvR · Post by **GeorgeJvR** » Wed Jun 09, 2010 12:09 pm

Zane thanks there are two supplies to the load sensor 1 the same that supply the front wheels the other is the rear one on the master. do you think that the fluid returns through the (rear Supply on the master) back to the reservoir? But surely then the front brakes also won't brake. :? :?

Mark thanks will check into it

(George, looking at the above reading in red, your handbrake is a mechanical brake so with it being low on the left side, this tells me there's some more adjustment needed on the pads to bring it into range of the right side. If you get this close on the mechanical setup, it'll help with the braking already when applying slowly, as it should then be 3.0+- both sides on the rear.

Correct will do the adjustments tomorrow.

The below makes me more convinced then that the prob lies in the front by the master, as how could the load compensating valve relieve all pressure to zero on fast braking?_

Yes but if the front brakes are 100%
Left front 3.0 Right front 3.1 (fast or slow braking) then the loadsensor surely gets the same pressure as it is one supply from the front of the Master to a T pice, one to the Left front wheel the other to a second T pice from there one to the right front wheel the other to the load sensor

Again thanks for all the input.

Post by **CasKru** » Wed Jun 09, 2010 12:31 pm

Disconnect the vacuum pipe from the master cylinder. Start the engine and test to see what kind of vacuum is being generated by putting your finger over the open end of the pipe.

When the engine is at idle it will generate more vacuum than at top revs. If you have a leak in the system (tear in the diaphragm in the brake booster or in the pipes) at low RPM the engine might be able to still produce enough vacuum to assist but if at speed the leaks are to big and the engine does not produce enough vacuum.

If the booster is working correctly, it should have no noticable effect on the engine, but if it is leaking, it will cause big problems. Use the following procedure to check yours.

Things you need to test:

* Vacuum guage
* Cap for vacuum port on the intake manifold
* Friend to work brake pedal
* Pencil and paper

Procedure:

Hook up the vac guage. Start the engine. Note the reading. This is your "base" reading.

Stop the engine, disconnect the booster vacuum line and cap the port on the manifold. Start the engine, look at the guage. If this reading is substantally higher than the base, you have a leak in the system, probably in the lines leading to the booster.

Stop the engine, remove and test the one-way valve (should be able to blow into it one way but not the other). Air should only pass in the direction indicated by the arrow printed on the top of the valve (make sure to reinstall it in the correct direction).

Reconnect the one way valve and vacuum line to the manifold and start the engine. Watch the vac guage as a friend depresses the brake pedal. It should dip as the pedal is depressed and return to the base reading. If it drops slowly, but returns, you have a blockage/collapse in the vac line. If it falls and does not return, you have a torn diaphram in the booster. Especially indicative of a torn diaphram is a hissing when the pedal is depressed.

Post by **CasKru** » Wed Jun 09, 2010 12:36 pm

GeorgeJvR wrote:Zane thanks there are two supplies to the load sensor 1 the same that supply the front wheels the other is the rear one on the master. do you think that the fluid returns through the (rear Supply on the master) back to the reservoir? But surely then the front brakes also won't brake. :? :?

Mark thanks will check into it

(George, looking at the above reading in red, your handbrake is a mechanical brake so with it being low on the left side, this tells me there's some more adjustment needed on the pads to bring it into range of the right side. If you get this close on the mechanical setup, it'll help with the braking already when applying slowly, as it should then be 3.0+- both sides on the rear.

Correct will do the adjustments tomorrow.

The below makes me more convinced then that the prob lies in the front by the master, as how could the load compensating valve relieve all pressure to zero on fast braking?_

Yes but if the front brakes are 100%
Left front 3.0 Right front 3.1 (fast or slow braking) then the loadsensor surely gets the same pressure as it is one supply from the front of the Master to a T pice, one to the Left front wheel the other to a second T pice from there one to the right front wheel the other to the load sensor

Again thanks for all the input.

Keep in mind that the brakes have to separate channels. The right front and left rear works on one and the front left and right rear works on the other. This is built in redundancy should you loose one of the brake lines. On the master cylinder you also have two or more separate compartments each with it's own set of valves. It could be that only one of these are leaking and causing your problem.

Maddoglips · Post by **Maddoglips** » Wed Jun 09, 2010 1:03 pm

CasKru wrote:Keep in mind that the brakes have to separate channels. The right front and left rear works on one and the front left and right rear works on the other. This is built in redundancy should you loose one of the brake lines. On the master cylinder you also have two or more separate compartments each with it's own set of valves. It could be that only one of these are leaking and causing your problem.

Cassie

This is exactly what I'm trying to get at

, sorry but the brain and fingers don't always work in harmony

.

Standard as I recall is you have the front circuit and then rear with 1 resivoir serving both. now if the seal/plunger for the rear is damaged/worn it'll/can cause this type of behaviour.

I'm going to check my van this evening, try and see what I have as a setup but almost positive it's front and rear apart.

GeorgeJvR · Post by **GeorgeJvR** » Wed Jun 09, 2010 1:16 pm

Zane thanks i'll apreciate if u can verify it for me, cause the Toyota print out differs from u, any chance the setup was changed along the line on the SFAs?

GeorgeJvR · Post by **GeorgeJvR** » Wed Jun 09, 2010 1:18 pm

Cassie wher can I find this any specific description for the Midas / Autozone guys?
* Vacuum guage
* Cap for vacuum port on the intake manifold

Post by **CasKru** » Wed Jun 09, 2010 1:35 pm

Vacuum:
http://www.fingerprintsolutions.co.za/vdo.htm" onclick="window.open(this.href);return false;
http://www.autostyle.co.za/prodview.php?prod_id=15012" onclick="window.open(this.href);return false;

Cap:
You can use anything that will seal the port. Depending on the size but I would probably make a cone shaped plug by squirting some silicon into a cone shaped something and let it dry.

Maddoglips · Post by **Maddoglips** » Wed Jun 09, 2010 1:42 pm

George

Now that all at my work think I'm looney for lying under my van in the rain this is how mine is.

From the front of the Master Cyl, it goes out to a T and then to the left and right front. Circuit 1

At the right front there is a T which then goes to the rear comp valve.

From the rear of the Master Cyl it goes straight to the comp valve. Circuit 2

At the comp Valve, it has the direct in and the "in" from the front circuit and then the 1 out to the rear brakes left and right.

So my thinking is, the front has the 60% braking as standard and the line which then goes direct to the rear is the 40% all from the master cyl.

The fact that the front is T'd to the rear, tells me that when loaded, and the comp valve is automatically adjusted by the rod, it actually opens/allows some of the pressure from the front brake lines in to assist with the braking, therefore allowing an increase in the breaking pressure to the wheels at the back compensating for the load.( I'm under correction here, but this is how I see it, trying to get a machi to confirm or deny if I'm right.)

So I still get back to that I think the masters seals have started to collapse.

How the master works, it has fluid in front of the plunger when not applied, when you apply the pedal, it thencompress the fluid in front of it, causing the pressure in the lines, it also has bypass chambers that then allows excess fluid to enter at the rear of the seals to prevent the fluid been pushed out of the resivior and if these seals are worn, it'll collapse allowing the seals to open and allow fluid past them and not through the intended ports thus not allowing the sytem to build up the pressure in the front of the plunger. Note. If at some stage, dirt has entered the chamber in front of the seals, and blocked abit of the bypass, this additional presure will also collapse the seals which can cause this. So if you do by a seal kit and replace them, make sure all the holes are clear

Sorry if this isn't making sense, but it's hard to put to keyboard what I'm thinking.

Zane

GeorgeJvR · Post by **GeorgeJvR** » Wed Jun 09, 2010 3:05 pm

Zane thanks i get that but would that not meen that when the loadsensor is opened (under load) the front and rear brakes both has 50/50 brakes thus if the fluid bypass', the rear as well as the front brakes will be efected?
At this stage only the front wheels brake in an emergency brake (if the load sensor is open / loaded, "even if closed")

I'm starting to feel somewhat stupid

Post by **CasKru** » Wed Jun 09, 2010 3:12 pm

George... quick simple question... did you adjust the rear brakes so that you can feel it when you turn the wheel by hand?

GeorgeJvR · Post by **GeorgeJvR** » Wed Jun 09, 2010 4:01 pm

Cassie it was done by a local Brake and clutch workshop didn't have the time to do it my self but as this mornings tests shows the rear left needs adjusting.

I found a Auto gage vacuum gage at a lockal eccesory shop R120.00

I'll do some vacuum testing to night and take the hilux back to the work shop tomorrow morning.