Need help with 80series brakes

[Big]

sounds like buggered hose's budging under pressure or failing..?.. I don't have any of that so would assume something is leaking..

[turoa]

Any chance you've figured out what the issue is yet?

Ive got a similar problem in mine. Brakes used to put you through the windscreen but now won't lock up and are a bit lack luster. Mine was originally drum rear so don't have a proportioning valve. Deglazed the pads and calipers don't seem to be seized. Checked the vacuum at the booster and that's ok, and don't think there's an issue with the master.

Next step for me I guess is to rebuild calipers, new rotors, new pads and hope for the best.

[Gardengnome]

Turoa,

As someone mentioned earlier check the brake hoses. They do degrade, are so often overlooked and you spend your right foot effort expanding the hose rather than moving callipers.

Brake hoses are a big thing on sport bikes and most hard riding pilots replace their front brake hoses with braided lines. Definitely no expansion of the hose and what you give you get at the calliper.

The brakes on my KZJ are a bit more spongy than what I would like but still work great. I have future plans to replace the lines with braided.

Best of luck.

[Petemcc]

I haven't fixed mine yet but have read a few bits on the net where they had the same symptoms and it was the booster but haven't seen any explainations why. I don't know enough about the boosters to know why but can only assume that the rod between the pedal and master plunger is in two parts with some sort of dampener in the middle that could be collapsing.

Seems weird but people that have said swapping booster worked had normally rebuilt everything else first.

I did adjust the booster connection onto the pedal to take up some slack which definitely helped. And locked up a couple of times but not consistent.

I'm going to try clamping flexible hoses to eliminate it to the top end then might try a spare booster I have.

Brakes suck!

[Clint]

Hey Pete, I have heard of worn out vacuum pumps giving brake issues on turbo diesels - might be another thing to check if you haven't already. Just about to swap an 80 series dual booster into my prado, should take the brakes from adequate to awesome I hope

Cheers
Clint

[Petemcc]

Hi Clint,

I would have thought that would just give you a stiffer pedal?

Cheers,
Pete

[Danjr]

I've also had crap brakes. They used to be good until I lifted it and changed the rear diff to a factory locker one that had drum brakes. After that, spongy and pedal would go to the floor. Bled them, rebuilt them (callipers and drums) and swapped booster all with no real result. Now I've bypassed the proportioning valve (I had extended it when I did the lift) and now they're substantially better. Still not throw you through the windscreen stuff but good enough. I've tested standing on the brakes in the wet and yes the rears lock up first so not ideal but rather that than what I had. Might need to put a new proportioning valve in there or a manual valve to adjust them back a little and get fronts locking first.

[Clint]

Hi Clint,

I would have thought that would just give you a stiffer pedal?

Cheers,
Pete

Yep, when there's not much vacuum. I think the problem can also be variable vacuum from the pump making troubleshooting confusing - this is just stuff I've read online while researching how to get my brakes set up right so take it with a grain of salt.

Cheers
Clint

[Petemcc]

I bit the bullet and got a new master cylinder which has fixed my brakes.

Cheers
Pete