Anybody know when they started to put rear disc brakes on the 4runners. Here's my problem. I have a 84 4 runner that i put rear discs on> I ran monte carlo front calipars and a fj-80 master cylinder. They have pressure when the trucks off but when you start it they go to the floor. I have switched out the power brake booster with one from my 89 toyota truck but it didn't seem to work. Any ideas???? anyways getting back to my original question I fiqured if I can get a booster from a late model 4 runner with factory discs that might help??? But I don't know when they switched and if this would help my problem???

Might need a new master cyl. My bro put rear discs on his runner. Since discs take more fluid, the pedal traveled further than normal. Old m/c had corossion further in, so it tore up the seals. It had worked fine before the swap, but once he bought a new m/c it worked fine again. Make sense?

I have had similiar issue once I did my disc brake swap a year ago. What I found from searching the BB was that the monte carlo front calipars need the bleeder elevated up to bleed to get all the air out. Once I bleed them this way I could lock up my 35 mtr and my pedal was a lot firmer.

You've got air. Get the thing set nose down and bleed some more. Also, when you did the swap did you bypass the rear load valve? If not, its a good time to do it.

I'm sure i've got the air out I've been through 3 large bottles of brake fluid and when you crack the bleeders it shoots out a steady stream with no hickups. I've tried two mc's one used and one new and that didn't seem to help?

You've got air. Get the thing set nose down and bleed some more.

Since you tried two different master cylinders, listen to Rat~Man. Check out the Toyota FAQ's for the Rear Disc Brake FAQ section and find the picture of the Monte Carlo caliper showing how if you don't mount it with the bleeder in the correct position, it is almost impossible to blee all the air out of the caliper.

Edit: http://www.pirate4x4.com/forum/showpost.php?p=3141588&postcount=8

Check this post for the caliper pic to show how the caliper should be mounted.