I’m at a loss with this too, but I’ve not been getting much sleep lately to thing this through, so I threw out the kitchen sink with the ABS.

A rear brake pull generally is a delayed pull, something I taught our guys to call a drift. You initiate the brake application and you feel the vehicle building up in pull, and can get pretty strong just like a front issue.

Pulls from the front axle are immediate. We have a high scrub radius so any imbalance or delay in application immediately tugs at the wheel. Usually air acts as an accumulator, making it take longer to achieve full clamping pressure, but once the air bubble compresses to the fluid pressure, it becomes even. Something hanging can cause that too, if it’s just quirky.

Just about all the friction materials sold for our truck is semi-metallic, so there’s a change in friction coefficient depending on temperature. With a slightly dragging pad against a rotor due to lack of retraction you can generate an imbalance of 75 to 100° that will be noticed as a pull. That can be immediate and will continue if not increase during the brake application. I posted some graphsabout that in the SD or Excirsion sections lately, if I find it I’ll edit it in to this.

So one thing you could do is go for a drive where you don’t have to apply the brakes often, put it in neutral and drift to a stop on the side of the road and shot the 4 rotors for temp. Any imbalance side to side would indicate a pad drag. You can also so the same on arun where you do apply the brakes often, then check all four. A dragging brake in this situation will also not let the rotor cool as well.

All of this stuff is what we would do on a test to find exactly what the cause was, but we were R&D and objective was to find the issue and document it no matter the time.

The ‘05+ TRW calipers have a history of causing pulls and drifts, without a definitive answer on the forums. Pad retraction from the rotors was enhanced from the prior design with the bracket spring clips, so that should not as much as a concern. Shouldn’t be.... But my career in brakes ended in ‘08 and we didn’t see the pull issue at that point, but that would be on the cusp of developing enough for a warranty concern.

So from my perspective there’s just a lot of things to check.

I forgot another point I was going to mention. With the earlier production design, we got into a pull issue we were not expecting back in 2001. Pulls were coming in high on warranty and what we found was the SD’s had a high scrub radius, so sensitive to friction side to side. Despite manufacturing the brake pads typical of the OE level, we had to ship pads by batch (batch to batch variability) and at the axle assembly plant the pads had to be installed by batch number. There was even a Ford TSB given so the service side would check batch numbers during corrective action. So with that wonderful experience every time I install pads I check for batch numbers. My old companies aftermarket side learned from this experience on these vehicles, and there was enough notice at the time that other companies aftermarket took notice as well. But stuff happens. That’s why the flip one pad might also help even if there’s not a temperature conditioning issue.

https://www.ford-trucks.com/forums/1...-replaced.html

You can’t do better with those spreads. So at this point there is no dragging of pads. But keep those temps written down, just in case sometime in the future you have a pull and need to temp check the rotors.