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Old 05-02-2011, 07:19 AM   #1
68_Step
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Brake Adjustment Hole - 1978 K30 Dual wheel

I sure hope this is a silly question... The old brake drum had a hole (port?) in the front of the drum so you could adjust the brakes using the star-wheel; the new one does not. There is also not a hole in the backing plate either. Other than the extra set of wheel stud holes and lack of adjustment hole - the new one looks the same. Both have a max diameter of 11.21 they are the same height, and my wheel hub fits in perfectly. I also do not see knockout to punch it out either.
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Old 05-02-2011, 11:09 AM   #2
76stepsidechevy
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Re: Brake Adjustment Hole - 1978 K30 Dual wheel

Is it possible someone added the hole them self? My half ton has them too and it caught my eye when I had the wheels off the first time. The holes is mine dont look all that clean, almost like someone made them with a torch or something.
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Old 05-02-2011, 10:01 PM   #3
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Re: Brake Adjustment Hole - 1978 K30 Dual wheel

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Is it possible someone added the hole them self?
I do not think so, it should be there to adjust the brakes - least I hope so. I was wondering why the new one did not have one.
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Old 05-02-2011, 10:55 PM   #4
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Re: Brake Adjustment Hole - 1978 K30 Dual wheel

It just made me scratch my head for a bit, Ive always seen the holes in the backing plates on any other drum brakes ive worked on.
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Old 05-03-2011, 07:25 AM   #5
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Re: Brake Adjustment Hole - 1978 K30 Dual wheel

I have been scratching my head a lot on this brake job. The manual tells me to use the hole in the drum to back off the brakes, never noticed it was not there when I picked them up. Then I saw there was not one in the backing plate either... The day went down hill from there.
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Old 05-03-2011, 04:03 PM   #6
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Re: Brake Adjustment Hole - 1978 K30 Dual wheel

The new ones you got are for auto adjusting brakes. My 80 has them, I believe your 78 should too. Basicly you just need to set it as close as possible to where it needs to be, perferably not far enough over too far since it can't go back in, just out, then before you actually drive it anywhere drive it down an empty street and give it a couple good brake slams. It'll adjust itself correctly from there.
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Old 05-03-2011, 04:33 PM   #7
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Re: Brake Adjustment Hole - 1978 K30 Dual wheel

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The new ones you got are for auto adjusting brakes. My 80 has them, I believe your 78 should too. Basicly you just need to set it as close as possible to where it needs to be, perferably not far enough over too far since it can't go back in, just out, then before you actually drive it anywhere drive it down an empty street and give it a couple good brake slams. It'll adjust itself correctly from there.
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I thought you had to back up and hit the brakes hard for them to self adjust?
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Old 05-03-2011, 06:26 PM   #8
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Re: Brake Adjustment Hole - 1978 K30 Dual wheel

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Originally Posted by MadManAndrew View Post
The new ones you got are for auto adjusting brakes. My 80 has them, I believe your 78 should too. Basicly you just need to set it as close as possible to where it needs to be, perferably not far enough over too far since it can't go back in, just out, then before you actually drive it anywhere drive it down an empty street and give it a couple good brake slams. It'll adjust itself correctly from there.
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After a few years when I need to replace the shoes or turn the drum, how will I get the drum off? I thought I would need the adjustment hole to back off the brakes so I could then remove the drum.
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Old 05-03-2011, 08:54 PM   #9
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Re: Brake Adjustment Hole - 1978 K30 Dual wheel

No? The brake pads shouldn't be touching the drum unless you're hitting the brakes, the drum should always just slide right off. And Eyegore, yeah, you're correct, forgot that part.
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Old 05-04-2011, 09:00 AM   #10
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Re: Brake Adjustment Hole - 1978 K30 Dual wheel

I talked to the local auto parts store and they call the drum manufacturer and they said they stopped making 2 versions of that drum (one with the adjustment hole, the other without it) - they now only make the version that does NOT have the adjustment hole.

Do I need an adjustment hole in the drum or the backing plate? I thought I needed one for either the rough adjustment to start or to back off the shoes in an old drum...
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