No adjusting slot on drum backing plate
 

My rear drum brake backing plates don't have a slot in them for adjusting the brakes. Is this the norm for our trucks? I have had other vehicles that I had to back off the brakes through the slot to get the drum off. Hate to have a drum stuck and have no slot.

Re: No adjusting slot on drum backing plate
 

The knockout on these trucks is on the front of the drum (outside) instead of the rear backing plate. They are not punched very well and are a bear to knock out. It would be easier to take the drum off and drill them out....

LockDoc

Re: No adjusting slot on drum backing plate
 

Yup.

Re: No adjusting slot on drum backing plate
 

Will check that out, Thanks LockDoc

Re: No adjusting slot on drum backing plate
 

Just looked at the drums ( which I had off ), and there is not even a hint of a punch out. These are likely replacement drums. I was thinking of putting a hole in the backing plate that would fit one of those rubber plugs they sell.

Re: No adjusting slot on drum backing plate
 

I have never tried it but it should work. Let us know if you run into any problems with that.

LockDoc

Re: No adjusting slot on drum backing plate
 

My K20 still has original drums, also with no hint of a knockout. Finally drilled holes in the backing plates and put in rubber plugs a number of years ago. Works great!

Re: No adjusting slot on drum backing plate
 

Weird. I've punched literally hundreds of those knockouts out of drums and backing plates (trucks and cars). I guess the new stuff from Chinee isn't provided with that feature?

Re: No adjusting slot on drum backing plate
 

I just bought new drums for my 71 and they dont have knockouts. I'd be interested to see how you cut the holes in the backing plates. Drill holes on each side and then file out the middle?

Re: No adjusting slot on drum backing plate
 

Its called "Value Added Processing" another words you guessed it they cheapened up the parts by removing a critical step in the casting.

Value added What?

Re: No adjusting slot on drum backing plate
 

Stocker says his original drums has no slots, so there's more to the story than cheap and/or replacement drums. So my first ? Would be to stocker- how do u confirm your drums are original ? Stamped part # maybe. Facts first
.

Re: No adjusting slot on drum backing plate
 

Think I would drill two or three holes, and then dremel them out.

Re: No adjusting slot on drum backing plate
 

I have owned the truck since 1977 when it was 5 years old with about 50K miles. Pretty sure everything on the truck was factory original at that point, except the saddle tanks and rear bumper. If the drums had been changed before I got it, they would probably not be the same as whatever is available these days. :chevy:

Re: No adjusting slot on drum backing plate
 

I have a low mile 68 that has the knockouts outlined on drums. With under 40k , I am confident they are originals. Maybe later ones don’t have the markings for knockout.

Re: No adjusting slot on drum backing plate
 

Don't blast me for mentioning this, but don't our trucks have a self-adjusting rear drum brake set-up. A few 10 mph reverse blasts, then lock up the brakes is supposed to adjust the rears drums. Might be why we see so many back plates with no holes?

Re: No adjusting slot on drum backing plate
 

The problem is when you want to take the drums off, it is nice to be able to back off a little bit on the adjuster to free up the drum.

Re: No adjusting slot on drum backing plate
 

Yes, especially if the drums have worn enough that there's a ridge catching the shoes and preventing drum removal.

Also, those adjusters operate in a nasty environment and may not work anymore. With luck, they can be cleaned & lubed and continue doing their job.

Re: No adjusting slot on drum backing plate
 

No blasting here, you are 100% correct.

Re: No adjusting slot on drum backing plate
 

Cut in brake adjusting slots in my rear drum backing plates to fit the rubber plugs I bought. This is so I can adjust the brakes initially, or back them off if I need to take the drum off, and it won't come off.

Re: No adjusting slot on drum backing plate
 

:c2:

And you only have to do it once. It's worth all the sweat.