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Toyota Proportioning Valve

Discussion in '40- & 55-Series Tech' started by atazman, Feb 19, 2006.

  1. atazman

    atazman Regular Member

    Messages:
    174
    Location:
    Pleasanton, Ca
    I just completed a rear disc brake conversion on my 76 FJ-40 (using the Monte Carlo clipers). Like many of you, I'm experiencing premature rear brake lock-up. It's beautiful under normal braking, but if I had to stop under a real emergency, I'm sure the rear would lock up. Right now.....I'm using the stock Toyota proportioning valve. Obviously, I want safer brakes if I can get them.

    I have spent hours on the "search" feature, and conclude that adding an adjustable proportioning valve might/might not solve my problem. So here is my question......

    Has anyone taken the stock Toyota proportioning valve apart to see if it can be shimmed (or probably shims taken out) to decrease pressure to the rear brakes? Any advice here?
  2. nuclearlemon

    nuclearlemon not an addict Moderator

    Messages:
    14,309
    Location:
    meh-ico, colorado
    76 had front disc rear drums which is why they had to have a prop valve (different valving between the two. the prop valve isn't hooked to both sections either. fronts are a seperate section than rears.

    also, did you remove the check valve on the master (for the rears...where brake line comes into master)?
  3. Bret

    Bret New Member

    Messages:
    1,816
    My 76 with the monte rear brakes still locks up under hard braking when empty. Thats with a max'd out wilwood proportioning valve. My next step is to try the 4-runner front calipers to try to even out the bite. After that I may try switching to a different master.

    I have heard there are 2 different sized monte-carlo calipers, do you know if you have the larger or smaller?

    There was a thread awhile back that talked about this a bit too.
  4. lone gunman

    lone gunman New Member

    Messages:
    1,389
    Location:
    granite falls WA.
    Did you check the sticky up above ? the one on FJ40 and 45 F A Q about 3/4 of the way down you will find all sorts of info on this.

    on my 76 FJ40 i have the FZJ80 master (w/out anti lock brakes) bolted to my factory vacum canister and eliminated the factory valves below the old master cylinder and run the 4 runner calipers and in the rear i run the cady eldorado calipers (same as monte but with e-brake) and it brakes great at hi speed or at laest so far no problems and i have had this set up for over 2 years now. and no proportioning valve at all. maybe i am just lucky i dont know.

    good luck!
    frank
  5. nuclearlemon

    nuclearlemon not an addict Moderator

    Messages:
    14,309
    Location:
    meh-ico, colorado
    i run 60 calipers in front and monte carlo calipers in back and a wilwood proportioning valve that's been sitting on my workbench for five years. no problems at all.
  6. atazman

    atazman Regular Member

    Messages:
    174
    Location:
    Pleasanton, Ca
    Thanks, everyone, for your comments.....

    Yes, Lone Gunman....I did read those FAQ you referred me to. Reading all that is where i formed my opinion that an adjustable proportioning valve may not get me to where I want to be.

    Bret....My Monte calipers are the 2 1/2" diameter single piston. I "guess" that they are the small ones. By the way......by the looks of your Cruiser, mine has a twin.

    Nuclearlemon........No, I did not remove the check valve in the port to the rear brakes. I thought I would try things first to see the reaction. After my trial run, the rotors were a normal "hot to the touch", but they were rotating freely. I thought maybe the check valve would keep pressure on them, and cause them to drag. No drag whatsoever after several trial panic stops from speeds at about 30 mph. I have not tried a panic stop from 70 mph yet (kinda scared to try it).

    I guess no one has "messed around" with the Toyota proportional valve??

    Another question is whether anyone has installed one of those proportional valves from a pickup that automatically adjusts the rear brake pressure based on the shift of weight to the front end? I'd like to find out more about this as a possible remedy.

    By the way.....I took a little different approach to the brackets holding the calipers in place. I left my old backing plate on, cut out slots for the calipers, and welded "ears" onto the backing plate for the caliper bolts. Using this method I did not have to dis-assemble my full floater. Made the installation quite simple.

    All comments welcome.
  7. Fman

    Fman Regular Member

    Messages:
    201
    Location:
    Roseville
    One other fix is to install a 1994 Toyota V6 Pickup Master Cylinder set up for 4 wheel disc brakes. Its a direct bolt on application, you only have to grind down the pushrod to relieve some pressure from your break pedal. The cost is about $65-$70 (Autozone).

    Just a thought.....

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