Offroad-Express

Hey guys im at the point were my Lux just needs to pass the brakes test section of the cert and im not happy with the way the brakes are working and want to sort it before taking it in.

A bit of history on the truck, its a 130 surf chassis with a lj78 prado front diff, its runs the factory 78 series Prado front calipers/vented rotors and ive fitted the Mr2 calipers on the back end with rear 78 series prado discs. Its got new pads and rotors all round and ive also fitted a brake booster and master cylinder from a 95 series Prado to cope with the disc/disc set-up i now have.

Ive fitted new copper brake hard lines and new flexi lines were needed and the brakes have been bleed propally aswell.

It doesnt help that im trying to get the brakes sweet running 35in simexs, i need to get the cert on my simexs as they are on my Beadlocks that i also need certed etc

Are the v6 surf calipers any better/bigger than the 78 prados and is the 80 series cruiser booster/master cylinder any better than the 95 series Prado one im using, the Prado one is a 1in bore and i thought if its good enought for a LWB kzn95 Prado then it should work on my 65 series Lux.

Also what normally happens when fitting a master cylinder with the bias built in to suit the rear brakes.? as ive still got the funny proportion valve set-up that the drum brake Surfs use.

It pulls a little to the left so ill rebuild the front calipers but first wanted to know if the v6 surfs ones are any better.

Cheers for any help its appreciated.

I have a KZJ78 LWB Prado running 35's and it pulls up fine.
So they work well.
The proportioning valve is really a load sensor which as the truck is weighted down it allows more brake pressure to the rear.
If you have lifted it it will need to be adjusted again so it allows the correct brake pressure to get by for normal unladen use.

Not sure if the Disc version is the same as the Drum ones.

Some of the guys will run soft pads for the cert so they really grab...
And change them later for something more longer lasting.

Calvin

kbushnz wrote:I have a KZJ78 LWB Prado running 35's and it pulls up fine.
So they work well.
The proportioning valve is really a load sensor which as the truck is weighted down it allows more brake pressure to the rear.
If you have lifted it it will need to be adjusted again so it allows the correct brake pressure to get by for normal unladen use.

Not sure if the Disc version is the same as the Drum ones.

Some of the guys will run soft pads for the cert so they really grab...
And change them later for something more longer lasting.

Calvin

Thanks for posting,

Yea that thinking ill throw in some softer pads, but ill double check that the booster is working propally first then maybe have a longer drive to bed things in better aswell.

Does anyone know if the booster and mastercylinder from a disc/disc 80 series is any better than the 95 series Prado one.? Ive heard/read that they are the same unit but no if this is 100% correct.

I was thinking i might need the extra vh44 booster but didnt think i would need it on a smaller hilux with bigger prado/cruiser braking componets already fitted.

And if anyone knows if the v6 surf calipers are better than the 71/78 series prado twin pots please let me no.

Cheers Hayden

4 pot surf calipers on it perhaps? could possibly bolt on
my ln130 has 4 pots on it, pulls up real nice, but thats with 31s..
im sure 35s wouldnt be too much for them either..

haydgq wrote:Hey guys im at the point were my Lux just needs to pass the brakes test section of the cert and im not happy with the way the brakes are working and want to sort it before taking it in.

A bit of history on the truck, its a 130 surf chassis with a lj78 prado front diff, its runs the factory 78 series Prado front calipers/vented rotors and ive fitted the Mr2 calipers on the back end with rear 78 series prado discs. Its got new pads and rotors all round and ive also fitted a brake booster and master cylinder from a 95 series Prado to cope with the disc/disc set-up i now have.

Ive fitted new copper brake hard lines and new flexi lines were needed and the brakes have been bleed propally aswell.

It doesnt help that im trying to get the brakes sweet running 35in simexs, i need to get the cert on my simexs as they are on my Beadlocks that i also need certed etc

Are the v6 surf calipers any better/bigger than the 78 prados and is the 80 series cruiser booster/master cylinder any better than the 95 series Prado one im using, the Prado one is a 1in bore and i thought if its good enought for a LWB kzn95 Prado then it should work on my 65 series Lux.

Also what normally happens when fitting a master cylinder with the bias built in to suit the rear brakes.? as ive still got the funny proportion valve set-up that the drum brake Surfs use.

It pulls a little to the left so ill rebuild the front calipers but first wanted to know if the v6 surfs ones are any better.

Cheers for any help its appreciated.

whats the issue, it dont stop?, pedal bloody hard?, back locking up?

clamp off rear lines see if it helps, same with front, get a feel for where the issue is, my vehicle had grief with rear lock up and not wantnig to stop, clamp the rear off and the front locked, you need to see if it is a proportioning issue,

readjust the rear valve and see if it helps, another vehicle i worked on had crap brakes, adjusted the valve a turn or two and the change was dramatic.

Cheers


Pedro

whats the issue, it dont stop?, pedal bloody hard?, back locking up?

clamp off rear lines see if it helps, same with front, get a feel for where the issue is, my vehicle had grief with rear lock up and not wantnig to stop, clamp the rear off and the front locked, you need to see if it is a proportioning issue,

readjust the rear valve and see if it helps, another vehicle i worked on had crap brakes, adjusted the valve a turn or two and the change was dramatic.

Cheers

Pedro[/quote]

The rear doesnt lock up its just front doesnt pull up hard like it should, we have adjusted the proportioning valve and the rears are working good but we just dont have enough grab from the front's.

getsum wrote:4 pot surf calipers on it perhaps? could possibly bolt on
my ln130 has 4 pots on it, pulls up real nice, but thats with 31s..
im sure 35s wouldnt be too much for them either..

Yea thats why im asking if the v6 surf calipers are any bigger/stronger or better than the Prado twin pots as they do bolt on but im not sure if i need them esp if they are no better than the Prado calipers ive already got eh.

The proportioning valve is designed to reduce brake pressure in the rear when the truck sits at "normal" ride height (no load) and increase it when its "sacked" down (heavy load). The thought behind that is that without load there is not much weight in the rear and it would be locking up all the time without load.

I found (double cab, 36 simex) that I could get rid of the valves altogether, just removed it and joined lines together. With the size and weight of the 36's I still couldn't get it to lock up but it had great stopping power after I removed it. I would be taking it out if I was you and give it a test, if you find there is now to much going to the rear and your locking the rear before the front you can get a valve to replace the proportioning valve which has a dial adjustment or 1-10 on it so you can fine tune exactly how much power you want to the rear. I think they are only about $120. Or you can get flast and get a remote one that has the valve and then you have a remote dial (via cable) in your cab so you can adjust it on the fly if you want.

Edit to add: sorry just read above post, sounds like you have the rear sorted?

i would always gor for 4 pots over twin pots...more even pad pressure to the disc on both pads as opposed to being pushed from one side, stil better than single pots

check the caliper slides on your prado calipers first you may have a sticky slide..

haydgq wrote:

whats the issue, it dont stop?, pedal bloody hard?, back locking up?

clamp off rear lines see if it helps, same with front, get a feel for where the issue is, my vehicle had grief with rear lock up and not wantnig to stop, clamp the rear off and the front locked, you need to see if it is a proportioning issue,

readjust the rear valve and see if it helps, another vehicle i worked on had crap brakes, adjusted the valve a turn or two and the change was dramatic.

Cheers

Pedro

The rear doesnt lock up its just front doesnt pull up hard like it should, we have adjusted the proportioning valve and the rears are working good but we just dont have enough grab from the front's.[/quote]


clamp rears off and see if the front improves if no change then booster VH44 should sort it,
if it changes then it is a proportioning valve issue,

and adjustable valves are allowed but cannot be accessed by the driver in the cab, has to be under the bonnet

cheers

pedro

getsum wrote:i would always gor for 4 pots over twin pots...more even pad pressure to the disc on both pads as opposed to being pushed from one side, stil better than single pots

check the caliper slides on your prado calipers first you may have a sticky slide..

Sorry i think im confused and ment to say Prado were 4 pots aswell, thanks for all the help guys and ill have a play with everything that was advised and see how we go.

Pedro wrote:

haydgq wrote:

whats the issue, it dont stop?, pedal bloody hard?, back locking up?

clamp off rear lines see if it helps, same with front, get a feel for where the issue is, my vehicle had grief with rear lock up and not wantnig to stop, clamp the rear off and the front locked, you need to see if it is a proportioning issue,

readjust the rear valve and see if it helps, another vehicle i worked on had crap brakes, adjusted the valve a turn or two and the change was dramatic.

Cheers

Pedro

The rear doesnt lock up its just front doesnt pull up hard like it should, we have adjusted the proportioning valve and the rears are working good but we just dont have enough grab from the front's.

clamp rears off and see if the front improves if no change then booster VH44 should sort it,
if it changes then it is a proportioning valve issue,

and adjustable valves are allowed but cannot be accessed by the driver in the cab, has to be under the bonnet

cheers

pedro[/quote]

Cheers for the help Pedro

have you tried a smaller set of tyres on it to see if it makes a big difference?

you could always take one caliper off,pull out the pads and get someone to SLOWLY push the pedal to see if all 4 pots move...could have a seized piston aswell..

then try the other side..lots of things to check....

new pads and rotors should be pulling up good...

good luck...

Get a vh44, you wont regret it, theyre about $430 trade from BNT (cheapest by far) but well worth it believe me. My truck has 1200kg over the front axle an 1000kg on the rear an without the vh44 it barely slows down, with it the certifier said he thinks it should pass (hasnt been for the full 5 stop brake test yet)

As for the pulling to one side under brakes, get a genuine kit from toyota, theyre the cheapest Ive found for caliper lits.

Fakey wrote:Get a vh44, you wont regret it, theyre about $430 trade from BNT (cheapest by far) but well worth it believe me. My truck has 1200kg over the front axle an 1000kg on the rear an without the vh44 it barely slows down, with it the certifier said he thinks it should pass (hasnt been for the full 5 stop brake test yet)

As for the pulling to one side under brakes, get a genuine kit from toyota, theyre the cheapest Ive found for caliper lits.

Cheers Fakey for the posts, im going to rebuild the calipers to make sure they are working 100% and also look into the vh44, do you have a close up pic of yours hooked up and fitted in your engine bay.?

Ive just read about a VH40 that is a little larger than a VH44 and designed for disk brakes, is your def a 44.? and have you fitted yours to the front brakes like what Sadam has done.? ive got a little hilux so fitting it in the engine bay might be a little difficult.

Cheers Hayden

haydgq wrote:

Fakey wrote:Get a vh44, you wont regret it, theyre about $430 trade from BNT (cheapest by far) but well worth it believe me. My truck has 1200kg over the front axle an 1000kg on the rear an without the vh44 it barely slows down, with it the certifier said he thinks it should pass (hasnt been for the full 5 stop brake test yet)

As for the pulling to one side under brakes, get a genuine kit from toyota, theyre the cheapest Ive found for caliper lits.

Cheers Fakey for the posts, im going to rebuild the calipers to make sure they are working 100% and also look into the vh44, do you have a close up pic of yours hooked up and fitted in your engine bay.?

Ive just read about a VH40 that is a little larger than a VH44 and designed for disk brakes, is your def a 44.? and have you fitted yours to the front brakes like what Sadam has done.? ive got a little hilux so fitting it in the engine bay might be a little difficult.

Cheers Hayden

if it has to go in it will fit!!!, i used a vh44 for the fronf of my rover, runnning 80 series brakes front and rear, work a treat, also fitted one to prado cuase it to, did not want to stop, worked well for that to, go 44 tried and tested.

pedro

I dunno the difference between them but the one howie stuck on my flatdeck is a VH40, its never been back through a brake test for cert coz the trucks been in bits for a while but it definately stops like a cut cat with it on, my trucks a bit heavier than yours, never weighed it but it'll be around 2.5-2.6 Ton. Has got the std front brakes with the VH40 (through front callipers only) and subaru callipers on the back

I would Imagine the diff between 40 an 44 would be the surface area of the diaphram so Id think the 44 would be slightly bigger. I havent got a close up pic but its much the same as saddams but mine faces the mastercylinder.
You can pretty much put it anywhere, under the dash? up by the headlight? the other side of the engine bay? where ever youve got room really
An yeah its plumbed into the front circuit only.

getsum wrote:have you tried a smaller set of tyres on it to see if it makes a big difference?

you could always take one caliper off,pull out the pads and get someone to SLOWLY push the pedal to see if all 4 pots move...could have a seized piston aswell..

then try the other side..lots of things to check....

new pads and rotors should be pulling up good...

good luck...

Yea its better with the 33's and im going to rebuild the calipers to make sure they are sweet and go from there, but the vh44 booster is looking good I can easily fit in on the other side of the engine bay but thought it had to be close to the factory master cylinder/booster.

Cheers Sadam for the pic and Pedro, fakey for the other advice on the vh boosters, ill rebuild the calipers then prob fit one, so they pretty much go inline from the front output of the factory master cylinder with the hard line before it tees off down to the front calipers.

Heres a pic of my engine bay and ive circled were i could fit the extra booster, is that distance going to matter or once its all bleed up it wont matter.?

Ive read some more and the vh40 is recommended for when you need more break force and is larger than the vh44 but are there different types designed for drums and discs.? I just wana make sure im getting the correct one.

Cheers Hayden

I went and had a look at google and probably found all the sites you saw, shit there is quite a difference in the output pressure between the VH40 and VH44

Yea and that chart says the vh44 is for drums only eh, so by the looks of that the vh40 has a bit more output pressure by quiet a large margin. so which do i get guys but even though that charts says the vh44 is for drums clearly many of you are using them in-line with discs.

go for the big one and dont go hitting the brake pedal too hard

Sadam_Husain wrote:go for the big one and dont go hitting the brake pedal too hard

Yea thats what im thinking Sadam, so urs is the vh40 eh.? you couldnt measure it for me please.? if its bigger than the 44 ill need to make some room. cheers

hey just a thought can they be fitted with the booster part down so the slave cylinder is facing up towards the bonnet or do they need to be upright as per a factory booster/master cylinder.? thanks Hayden

Should be ok as long as the bleed nipple is close to the highest point to make it easier to bleed.
One other thing is my one's vacuum line didnt like the heat from the headers an split causing the front brakes to lock on so I replaced the line with new hose an ill make a small heat shield for it. Just something to think about with your placement

awesome help guys thanks heaps.

Just to add to the mix, if you have power steering, why not go to hydroboost?
Get rid of the vacume booster and swap it for a hyraulic one.
Chevy trucks use them and they work well....And you still have room under the bonnet.The newer ones have an accumulator too so when the engine stops you get a few more assisted brake attempts just like a vac one.

Calvin