Yeah, the "self-adjusting" feature (aka oxy-moron) on these brakes was finicky at best. My brakes always stopped straight and true, because I'm a tinkerer by nature and was literally under the truck adjusting them every couple of weeks when it was my daily driver.
And no, I'm NOT exaggerating. I was literally the joke of the neighborhood for years because they thought I must not be able to get anything right or get a vehicle that could run without me working on it constantly. Wrong! I just wanted it to be perfect.
And if you've ever made a panic stop in an otherwise straight braking Early Bronco, you'll know what I mean.%)
So yes, while some do adjust themselves like they're designed to, many don't. Hence most people's swap to discs. Not because they are more powerful (though they can be) but because they're easier to service and (if working properly) never need adjusting under normal use.
So on to your problem. Some possible causes of mild pulling:
1. Mis-adjusted brake shoes.
2. Contamination on one side.
3. Wheel bearing issue.
4. Suspension issue.
5. Tire wear.
6. Tire pressure
7. Tire failure (internally)
8. Something loose in the rear?
How bad is the pulling? Does it just gently shift the truck to one side? Or does it kind of yank the truck, and turn the steering wheel in your hands?
If no movement of the wheel, it's very possible that the pulling is from the rear. If the steering wheel moves noticeably in your hands, then it's likely in the front. The more pronounced the movement, the more likely it is to be the brakes than some of the other items I listed.
So first things first. Check the condition of the shoes in all four corners. If looking good, readjust them properly. The most important aspect of that is consistency. Consistent drag at all four corners, but side-to-side is most important.
Before inspecting them however, simply adjust them through the access ports on the back side. If this is all that's wrong, you'll be good to go.
If not, you'll need to inspect.
When checking the fronts, this requires removing the hub and bearings usually. This is a good thing if there's any doubt at all about the adjustment of them. Initially though, you could simply adjust the brakes through the access hole to avoid redoing the bearings, then test drive it to see if your pull is fixed. If so, you've just avoided re-adjusting the wheel bearings.
But don't put that project off forever. It's a good thing to know, and a good thing to get right.
Maybe even before you go in to do any of this other stuff though, check the air pressures in your tires and rotate them front to rear to see if it changes anything.
Also check for loose u-bolts and spring bolts. Neither of those are too likely, but are still definite possibilities.
Good luck.
Paul
