1stTruckGuy

So I bought a 14 FX4 back in August, and immediately had to replace my rear rotors since they were metal to metal and all grooved up. I was in a pinch and installed a cheap set of Detroit axle rotors and ceramic pads that came in a kit. My front rotors are drilled/slotted and were nice and smooth so I just did the pads with bosche extreme duty pads (semi metallic).

I'm wondering what the brake bias is like on these trucks, is the rear applied first under light brake pressure? Like when coasting gently to a stop, is that mostly rear brakes? Reason I ask is that type of gentle top of pedal pressure braking sucks. If I push harder into mid pedal, it slows down in a red hot hurry. This was disconcerting when towing my trailer as it felt like I couldn't stop unless I got heavy on the pedal.

I was thinking maybe I should replace the cheapo pads on the rear with a better pad to help breaking performance. I've also noticed the brakes kinda suck as far as bite until they get nice and warmed up. Those first few stops at cold start feel like the pedal moves but nothing bites. If I slam on the brakes when backing out of the driveway or at the stop sign at my first stop in the neighborhood, pedal moves but truck doesn't lurch tight like brakes are gripping hard. If that makes sense. And it's not my vaccum pump, it builds pedal vacuum right away at startup.

Once I've made a few hard stops, the brakes improve drastically (mid pedal performance is amazing) but light pedal pressure stopping never seems to get any better.

Spiky

As you must know, the front pads are twice the size of the rear, so that gives a natural bias. I don't think there is any valving with ABS. But the ABS will adjust at times on the fly if it senses slippage.

1stTruckGuy

I guess what I'm asking is do the rear pads engage first at light pressure? I know on my expedition I had to replace the rear pads at 75k miles but the fronts were still going strong when I sold it at 106k. I towed every summer with the expedition and it must be hard on rear pads. Usually the rears last far longer than fronts, on a car, that is.

Laminar

If someone put drilled/slotted rotors on front there's no telling what kind of pads they used. Maybe they thought they wanted performance pads without knowing anything about bite or operating temperature. There's a lot of marketing bs out there on brakes and people end up making compromises that they don't understand when they step away from OEM specs.

1stTruckGuy

I replaced whatever pads were on the front when I bought the truck with bosche extreme duty semi metallic pads. I left the rotors alone since they were not "warped" (a complete misnomer). I've got 4k miles on the new pads so I know they are bedded in. The rear pads and rotors were replaced but with cheap generic ceramic pads from Detroit axle. I've had good luck with their other parts but assume the pads are cheap junk due to them basically being free with the rotors.

MPETE

iTrader: (1)

I work for Ford parts dept. So my job is literally convincing people to buy OEM replacement parts. And I practice what I preach unless I simply do not have the money and something NEEDS to be purchased right now, I am buying OEM.
But OEM pads/rotors on 12th gen F150 I will never do again. I don't know what it is about them but the pad material transfer is TERRIBLE. I am on my fourth 12th gen truck, (2012 2wd 5.0 rcsb, 2011 4x4 5.0 scab 6.5, 2013 4x4 6.2 screw 6.5, 2013 4x4 5.0 screw 5.5) and every single one of them has had pad transfer issues causing pulsating feel trough the pedal. And if it was JUST ME, I would say ok, common denominator is me. But when thousands of customers, nationwide, have complained about the same issue, obviously there is something else at play here. But ya know what pad/rotor combination has not given me pad transfer issues? Powerstop. The Z36 pads DEFINITELY feel like the brake better. Whether they actually do or not, I don't know. But I've run both Z36 pads and Z23 pads, and I've used both the slotted/drilled rotors and the solid "stock replacement" rotors. So far neither scenario has given me the pulsing issue that stock pads/rotors have done. I have not used the Z36 pads on a solid rotor on an F150, but I have that exact setup on both my Jeep and my S10 and both work extremely well.

I'm glad to see people who know its not a warped rotor.
I am curious how you like the Semi-metallic pads? Do they put off a lot of dust? I've considered using them as well in the past but ended up going with the powerstop because I am familiar with them.

1stTruckGuy

They do put off lots of brake dust which I'm not a fan of. My understanding is ceramic must heat up before they provide their best stopping power. That is the trade off for low dust.

Spiky

I've been real happy with the Element3 pads.

For the original question, there shouldn't be any valving, meaning the 4 wheels should receive even pressure if the fluid is good and bled properly. Only the abs computer should modify that, and only when it senses a need. AFAIK.

Laminar

I'm seeing some references to a stepped master cylinder which, combined with different piston areas front and rear, would affect the overall bias. Also, in any tandem master cylinder setup, the location of the inlet port determines when fluid starts going to the calipers. If the inlet port spacing is slightly different front to rear, it can affect which axle gets pressure first.



From the service manual: