Brake Pedal to the Floor! (1 Viewer)

[JAX 1988 FJ62]

On my newly acquired FJ62, the brake pedal goes pretty much straight to the floor and there is almost no stopping power. With the car off, the pedal is pretty firm, but as soon as you start the car, the pedal goes to the floor.

I bled the brakes twice using the old fashioned (pump, pump, hold) method and that didn’t seem to make any difference. And yes, we followed the proper order and bled the LSPV as well.

After going through that twice, I figured the master cylinder was bad and so I ordered new and replaced that. Bench bled the master cylinder, then installed it on the truck, and then bled the lines the old fashioned way again. Still zero difference! The pedal goes to the floor and I have no stopping power.

I decided to use a vacuum bleeder today (just to be sure) and that made no difference either.

I’m looking for any help/direction on what to check next. There are no visible leaks anywhere and I’m not losing fluid. Thoughts??

 

[Gimme a 60]

Try bleeding directly at your proportioning valve.


It’s good to check for small leaks.

 

[Dr. John]

So...where is the fluid going when you press the pedal. Since the truck is fairly new to you, I'd check for a missing brake pad (or shoe), or maybe even a rotor. I vaguely remember a possible issue with position of the MC piston...If it's not correct, fluid will just recirculate to the MC reservoir. Good luck.

 

[Godwin]

Two things, one is that you replaced the master cylinder and you need to make sure that the brake booster rod is properly adjusted. Second is to adjust the rear brake cylinders, if not adjusted the shoes will not contact the drum well and you'll have a soft brake pedal.

 

[duncanrm]

I'm with @Godwin - well adjusted rears are essential. As a test you can clamp off the rear soft line from body to diff - if that immediately gives you an excellent pedal you'll know where the problem is.

 

[JAX 1988 FJ62]

Two things, one is that you replaced the master cylinder and you need to make sure that the brake booster rod is properly adjusted. Second is to adjust the rear brake cylinders, if not adjusted the shoes will not contact the drum well and you'll have a soft brake pedal.

I forgot to mention it, but I did adjust the brake booster push rod when replacing the master cylinder.

I will research and try adjusting the rear brake cylinders. Thanks.

 

[JAX 1988 FJ62]

I'm with @Godwin - well adjusted rears are essential. As a test you can clamp off the rear soft line from body to diff - if that immediately gives you an excellent pedal you'll know where the problem is.

@duncanrm I love the idea for this test. Do you happen to have a picture of where to clamp? Also, clamping the line will not damage it?
Thanks!

 

[duncanrm]

@duncanrm I love the idea for this test. Do you happen to have a picture of where to clamp? Also, clamping the line will not damage it?
Thanks!

Sorry no photo.. but go to the rear diff, you'll find a rubber hose that comes down from the body to the drivers side of the diff and then splits into two hard brake lines. it can be safely clamped without fear of damaging it if you dont go overboard on the force. Dont be tempted to drive with the rear line clamped off, I did this once and found that fluid is forced through the clamp eventually and cant get back - locking on the rear brakes.

 

[JAX 1988 FJ62]

Sorry no photo.. but go to the rear diff, you'll find a rubber hose that comes down from the body to the drivers side of the diff and then splits into two hard brake lines. it can be safely clamped without fear of damaging it if you dont go overboard on the force. Dont be tempted to drive with the rear line clamped off, I did this once and found that fluid is forced through the clamp eventually and cant get back - locking on the rear brakes.

Perfect, thank you for the clarification. I’ll definitely give that a try.

In my research, I also found that you may need to add a spacer on the rear axle for the LSPV since the PO installed an OME lift. Appears to be a 3” lift and there is no spacer on the rear axle. Seems to be a common issue and fix? Likely going to give that a shot as well.

 

[JAX 1988 FJ62]

Added a spacer for the LSPV on the rear axle and adjusted the rear drums quite a bit and the brakes are good! Thanks all!