Hilux disk brake upgrade - help needed

[Petemcc]

on my hilux I have mr2 rear callipers and v6 surf front callipers (the surf ones with the biggest pistons).

Now that I have it all plumbed up the brakes go to the floor. I have done heaps of bleeding and seem to have most of the air out. When rolling down the drive it will just hold its weight and come to a stop with the pedal on the floor. pumping up doesn't help when the engine is running. When the engine is off you can pump it up and then if you leave it for a minute it goes to the floor again.

3 options as I see it.

master cylinder buggered
air in the system still
master cylinder not enough volume for the new callipers.

What master have others used when doing this conversion on a ln106 or ln65? 80 series seems to be the go but I'm still a bit surprised that the standard one might not be up to it.

Cheers,
Pete

[J_Dub]

cant be of too much help but also when I was running all my stuff that you now have through the certifier who also builds toys, he mentioned how the factory brake booster and master cylinder setup simply will not cut it, as they are now required to do twice as much work as they originally were designed for.

cant remember what all the options were but he did say before you try anything else there was a valve of some sort that could be removed somewhere in the area of the master cylinder that feeds the lines that go to the rear, he said removing this valve helps to increase flow/travel to the rear which is required as they are now disks not drum.

sorry that's all I can remember, but im sure someone will get on board soon as this mod has been done many times

[keithal]

i beleive the 80 series master cylinder fits with a little bit of work and has a larger 1" bore

[Smurf]

FJ-80 Master Cylinder
The stock Hilux and Ithink Surf is tha same, master cylinder are designed for discs brakes up front and drums in the rear. It does not have a residual valve for use with rear disc brakes. Without a rear residual valve in the system the rear disc pads move away from teh disc after braking. This causes excess peddle travel the next time you step on the brakes. To solve this use a FJ80 brake master cylinder that is equipped with two residual valves, one for the front system and one for the rear. It's 1" bore size is larger than older 13/16" bore cylinders for more fluid volume, and bolts straight in

Copied from De-Ranged's 'Rear Disc Conversion for the Lemon' thread
http://www.offroadexpress.co.nz/Forums/ ... r+cylinder

I have used an 80 series master on my surf with Nissan rear calipers, works a treat.
Bolts straight in, you may need to re-bend one or two of the brake lines to get them to line up with the outlets on the master.

[shortylux]

Mine worked fine with a std surf master. I had Nissan rear calipers and std surf fronts. Did notice there was more pedal travel as the pads got older.

I believe that both the disc and drum setups have a residual pressure valve at the master cylinder, but one is about 3psi and the other is about 8psi. You could try unscrewing a front residual pressure valve (from a spare std master) and put that in place of your rear line.

Ultimately you do need more volume though, so 80 series or I think a supra master will work.

Few years since I did all this research, hence I'm a bit vague. Good luck.

[Petemcc]

Cheers for the info guys. I will go with a new fj80 master and probably a booster too if I can find one (apparently flip them upside down and they fit mint). I am not sure that my current master cylinder is wrong enough (to small and valving etc) to be causing all of my problems. It is possibly just buggered or I have a leak somewhere. Either way best I go to the 80 series one so may as well sort that first and see if it's still buggered.

Cheers,
Pete

[Crash bandicoot]

you'll be surprised, even toyota hilux clutch master cylinders are small.

when doing the Rb30 engine/box conversion on my lux we had to jimmy up a larger master cylinder to the firewall as the yota one was half the size of the nissan one...it only moved the nissan slave cylinder 10 odd mm

[smurf182]

cant remember what all the options were but he did say before you try anything else there was a valve of some sort that could be removed somewhere in the area of the master cylinder that feeds the lines that go to the rear, he said removing this valve helps to increase flow/travel to the rear which is required as they are now disks not drum.

The residual pressure valve is what you are thinking of, keeps a bit of pressure in the line so the drum shoe is nice and close to the drum. From what I understand, these are not required for discs, or at least a much lower pressure valve if one is used.

[mikeyt1689]

its a low possibility but i had similiar issues and sounds similar symptoms and had to replace everything check before spending lots like i did... First i had already replaced my master cylinder with a brand new one and bleed up the entire system.. still nothing so i pulled the calipers apart and replaced all the seals and 2 of the pistons... still no joy better but not on the road.... replaced the cylinders in the back on the drums so probably wont help you there but then after speaking to a mechanic looked over everything again and ended up replaced the rotors on front and drums(agian not applicable to you) as there was a 10mm taper from top to bottom on the rotors. dont know exactly what fixed it but seems to of been a combination of all. any way hope it helps

[bang-thud-thump]

Did you try bench bleeding the m/cyl then do the rest?

[mikeyt1689]

Did you try bench bleeding the m/cyl then do the rest?

if your asking me then yes the second time but is tru does help

[SamLogan]

i run a factory surf master on mine with mr2 calipers and no issues. you will actually find that the 1kz surf masters are 1" as well. buy a rebuild kit for 30 bucks from bnt and it should be fine.

Sam

[Petemcc]

Everything else is new so won't be buggered disks.

How do I bench bleed the master cylinder?

[kbushnz]

Easiest way to explain it...

[Petemcc]

Cool I'll give that a go.

Have just ordered a master from an 80 off http://www.partzonline.co.nz

Looks like a great website! Was cheaper than on my mates workshops trade account at appco.

Didn't try BNT but probably should have. They have been good to deal with lately. I won't check the BNT price haha. Might be less.

[Petemcc]

pretty sure I wrote about this in another post but to conclude rear callipers were on the wrong side so bleed nipple not at the top and air not getting out

[BlakeNZ]

Has anyone here upgraded their LN65 rotors (non vented) and calipers to the vented LN106 rotors and calipers? I'm told it only requires minor massaging to make fit. Is there a noticeable improvement in braking? And is it mandatory to also install the LN106 brake master cylinder at the same time , to compensate for the larger pistons in the calipers? From what i read, the LN65 master cylinder has a diameter of 20.64mm v LN106 at 23.81mm.

[bigstu]

Has anyone here upgraded their LN65 rotors (non vented) and calipers to the vented LN106 rotors and calipers? I'm told it only requires minor massaging to make fit. Is there a noticeable improvement in braking? And is it mandatory to also install the LN106 brake master cylinder at the same time , to compensate for the larger pistons in the calipers? From what i read, the LN65 master cylinder has a diameter of 20.64mm v LN106 at 23.81mm.

Have pmd u blake