Both front brakes are dragging

[Schurkey]

Also, i am almost certain there’s not a spot on my backing plate to remove,
Unless a fella decides to literally cut a hole into it. Is that what they mean by “remove lanced area?”

There should be a defined, scored--partially stamped oval hole that can be whacked with a hammer and punch to create an actual hole. GM is too cheap to put a real hole in the backing plate, 'cause then they'd need a couple of five-cent rubber plugs; and nickels don't grow on trees at GM.

It is possible that there's no scored, partially-stamped area on your backing plates. Take another look right across from the star-wheel on the adjuster. I'm probably a dozen years away from owning leading-trailing shoe drum brakes on a GMT400 (still have 'em on a '98 Monte Carlo.) I'm kinda thinking there was no access hole for the adjuster on my '88 K1500 original rear brakes.

The rear brakes on the Monte looked like they had about five thousand miles worth of wear the last time I looked...at thirty-five thousand miles. Rear brakes aren't doing ****-all on that car.

It’s extremely frustrating that the manual gives a specific procedure which doesn’t match the reality at all in my case.

Yeah, the "official" service manuals have errors and omissions in them. They're still twenty times better than Chiltons/Clymers/etc., aftermarket "consumer-grade" manuals.

Anyhow, I’ll adjust them how schurkey said and see how it goes.

Please try. See what happens.

For reference, the rear drums should run hotter than the front because they do more braking right?

They typically do LESS braking, but they're also not as good as vented disc brakes at shedding heat. They tend to have more iron mass, so they're slower to heat up, but retain that heat longer.

Things might change if you have a heavy load in the bed.

 

[Road Trip]

Also, i am almost certain there’s not a spot on my backing plate to remove,
Unless a fella decides to literally cut a hole into it. Is that what they mean by “remove lanced area?”

It’s extremely frustrating that the manual gives a specific procedure which doesn’t match the reality at all in my case.

Most times this 'lanced' area is easy to see. Other times not so much. For example, here's one of the backing
plates off of my '99 C2500 in the blast cabinet for a long overdue refresh:

You must be registered for see images attach

NOTE: When I purchased the truck the appropriate star wheel adjuster opening was already removed on each side. However, since the backing plates
are symmetrical (so as to be usable on both LR & RR positions) the factory 'block-offs' for the adjustment hole that didn't line up remained in place.


This photo shows everything put back together. Look for the arrows showing that all 4 adjustment openings were open after the blast cab session:

You must be registered for see images attach

NOTE: At the time the picture was taken, Step #5 in Reply #37 has yet to be complied with. I needed (4) of these to finish the job: (Google rubber adj opening plugs)
If you can take a photo or two of the inboard side of your backing plates and share them with us it would help us figure out what's
up with the ability to service/adjust the rear brakes on your GMT400?

Just curious as to why people keep saying to adjust them this way,
Since in the manual it calls for that “20 click loosening after heavy drag has been achieved”

The General's Factory Service Manuals are frozen in time when they were published. Hard-won Experience
(Experience defined as the Knowledge you gained after you needed it) by mechanics before/during/after the books
were written may not match up exactly as to how the FSMs were written. (One of the goals of the FSMs is to provide
guidance in such a way so that 20 different dealer techs end up with a single desired outcome -- vs the same 20
dealer techs ending up with 20 different outcomes, spanning a range from unsafe to bad to good.)

EDIT: When I ask a mechanic how they perform a specific repair task, the ones that can tell me how the FSM
says to do it, and then they can explain why they do it a bit differently than the factory procedure? I am all ears. (!)
A reasoned approach, using the FSM as a starting point is always persuasive.

The way I read the factory manual is that the technical writers wanted to establish a clear starting point {heavy drag}
and then give the dealer dudes something they can count off. (loosen 20 clicks)

On the other hand, what Schurkey shared in Reply #38 is exactly how to go about sneaking up on the ideal brake
drum adjustment. I use the same method, especially applying/re-centering the shoes after the 1st adjustment
in order to get a more precise final setting. And achieving that light/whisper of a drag gives the best brake pedal while
at the same time minimizing the heat generated/fuel economy lost to the shoes dragging on the rotating drum surfaces.

Given the above, this is why I think that the General's FSMs combined with the hard-won experience freely shared in
the GMT400 forum = the best combo for those coming up to speed on how to keep these old brutes on the road
and earning their keep.

Hope this clarifies the situation you find yourself in. And if the adjustment holes weren't included in your backing plates,
then the only choice you have is to cycle the drums off & on in order to adjust the starwheel a few clicks at a time. A
lot more work, but doable. Again, a couple of sharp photos that you can take without disassembling anything would
be a big help for those of us trying to provide guidance remotely without guessing.

FWIW --

 

[Schurkey]

Keeping in mind that Duo-Servo drums have the adjuster--and therefore the access holes--at the bottom, as shown in the photos above.

Leading/Trailing drums have the adjuster between the wheel cylinder and the axle shaft, above the middle of the brake backing plate.

 

[Isaacmacleod]

I got the drums to an equal feeling slight drag on both sides

then after test drive,
One side would be slightly hotter than the other.

Finally after many attempts,
Including some single click adjustments on one side at a time,

I achieved a light drag that seems equal on both sides.
Just bought a temperature gun to verify.

 

[Isaacmacleod]

I had to readjust the parking brake cable by loosening the adjuster a TON,
since my shoes were now closer to my drums

 

[Schurkey]

The parking brake still applies enough to hold the vehicle...right?

 

[Isaacmacleod]

The parking brake still applies enough to hold the vehicle...right?

Yes, it does

I really did have to loosen my adjuster a lot to achieve “moderate drag”
with the parking brake lever pushed up to the specified hole for adjusting purposes.

I use the parking brake almost every time I park.

 

[Isaacmacleod]

I changed from ceramic to semi metallic pads on the front

the difference in heat is crazy.

Where before i couldn’t leave my finger on the front hub for more than a second or two,

Now with the semi metallic pads the front rotors reads about 80* F after a decent trip.