Alright, guys I need some help. I'm not to sure when it started doing it, but as it says in the title; my brake pedal drops to floor on very sharp left turns only with zero stopping power The brake pedal is fine during sharp right turns, and in a straight line driving around town. So far I have tried a couple things, but would like to hear your thoughts/input, or if any of you have experienced this issue. I'll list what I have I have tried below as well as the current status of the system.

Truck: 1992 Ford F350 4x4 7.5L 460

The Brake System: Everything is relatively new having been replaced this year. Master Cylinder, Brake Rotors, Brakes lines, Brake Pads.

What I've tried:

- Bleed the brake system (I've bled the system multiple times before trying anything below; did not fix it)

- Replaced Passenger Side Brake Line and bled the system. ( Did not fix it. Going to replace driver side Tuesday)

-Tightened wheel Bearings (Heard from a buddy that loose wheel bearings could mess with the caliper. Tightened both sides up; did not fix the problem).

So far that's what I've tried. I'm going to replace the driver side brake line Tuesday and bleed the system. If that doesn't work I'm going to try a Master Cylinder. Has anyone ever heard of or had such a problem? Everyone I tell hasn't heard of anything like this. Let me know.

 

Maybe you should have someone in the cab to turn the wheels while you watch. Get down there so you can get a good look. Take a peek under the hood too while they are in there. Make sure you don't get ran over though. The issue is not one I have ever heard of. Will be interesting to see whats up.

 

Turning left = swashing the fluid in the reservoir in a way that the M.C. inlet is exposed to air?
Just the first thing that came to mind.
Although that doesnt explain why it wont do it turning right.

 

Were the bearing loose? If so how loose?

 

Is it a hydroboost or vacuum boost system?

 

That was my 1st thought too. Low on fluid

 

That would be my guess, or something screwed up in the valving on the steering gear.

 

Do you have RABS on your truck?

 

Update: I did some work to the truck today, and I fixed it! You won't believe it. It was the sway bar. I put a lift on my truck a little while ago, and decided I wanted to re-install the front sway bar having ordered some extended links. I must have got the bracket for the sway bar backwards, or something, because somehow the caliper was contacting the sway bar. When I would cut the wheel to the left; the driver side caliper would contact the sway bar, and force the pistons back into the caliper. How that translates to the pedal going to the floor with no braking action escapes me, but for sure when I took off the sway bar the pedal went back to normal on sharp left turns.

 

Here's the Caliper with a shiny spot where the sway the bar rubbed into the caliper.

 

Glad it was that simple!!!!

 

I agree. If I didn't find that, I'd be out some money right now, because I was seriously considering a new Master Cylinder, and RABS valve if I didn't fix it yesterday.

 

I had a plastic bag fly up and melt to a rotor once.
Similar symptoms.
Glad you found it.