Ford Super Duty (1999-2016) :: Brakes Pulling To Left?

My Superduty has been pulling to the left when I hit the brakes for a few months now. In the past it's done it, like within a year or two after buying it brand-new off the lot, but that was because one brake pad had rusted itself to the bracket and was not doing a darn thing. Once or twice more, it was a stuck caliper pin, which was quite obvious when working on it.

Last year, around August, I replaced the rotors and pads with Advanced Auto parts stuff. Rotors are still great, pads look brand-new, and it wasn't pulling up until the past month or two.

But this most recent pulling has been a problem that I can't find. It's not the pins, it's not the pads, and now I find out, it wasn't the calipers

This past weekend I went so far as to replace the calipers with Napa rebuilt "semi-loaded" calipers (all hardware and pins and bracket, except for the pads) and pressure-bleed the entire system. The old fluid was green, not black, but now that it's been bled, the pedal is a bit firmer than it was.

I wasn't going to replace the calipers without checking them first, but I broke both bleed nipples off and I wasn't about to wrestle with an easy-out and try to get the darn things out. Per side, rebuilt caliper with hardware and bracket, can't go wrong. (Checking the calipers would have involved using a C-clamp to compress the caliper slightly, then backing off the C-clamp - if the pistons come back out a slight degree, they are free and the seals are still "grabby" and resilient).

While bleeding it, I saw a piece of black crud (rubber?) about 2-3mm in size come out of the left side. Didn't think much of it, figured it was just built up crud from somewhere.

Today, the first commute after doing the calipers and bleeding, it's still pulling just like it was before the calipers. However, I did notice at one point when I hit them, they pulled like they normally do, but seemed to go straight a few seconds into it. It does seem that if I keep my foot on the brake, the pulling is much less after the initial second or two, but if I stab them again, it pulls like crazy.

And by "pull" I mean the steering wheel actually moves in my hand. So with that in mind, it's actually a front-brake problem. If it was the rears, the wheel wouldn't pull like it does, and if it was something loose in the suspension, I would have found it already after checking everything, and it again, wouldn't pull the steering wheel like that.

Now, given that black piece of whatever that came out of the left side, I'm beginning to wonder... if it was rubber from the inside of the hose.

Is the right brake hose causing the pulling because it's coming apart just like the left one might be?

I've gone over and over this in my head this morning, and thought about the ABS unit possibly dumping pressure from the right because of a leaky valve (see side note below), but I would think that once the pedal stab was over, it would even out and not pull at all.

However, this thing pulls left quite a bit, even after the pedal has been held down for quite some time. Usually. Sometimes, it subsides and doesn't pull. But mostly it does no matter what I do, keep pressure on the pedal, let up and reapply, whatever.

Does this really sound like a bad hose? It's intermittent, but usually pulls like 90% of the time.

Side note: The ABS unit in my truck, and most Fords of the time (not sure about later than 2004 or so) is a Kelsey-Hayes three-channel unit like this:

Kelsey-Hayes RWAL Antilock Brakes

It's the same system found in Chevy Suburbans and light-trucks, which I have worked on before and know a bit about.

In my case, it can't be a dump valve leaking, because it would effect pedal-height and not PULL to one side like it does. The only way that could happen is if the isolation valve was closed, AND the dump valve were leaking at the same time.

I haven't, however, gotten the ABS to activate just to see if it changes anything. On my way home tonight I will see if I can find some dirt or sand and get it going