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Tips for backing off drum brake

Old February 7th, 2016, 02:09 PM
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Tips for backing off drum brake

For 1970 Cutlass Rear Drum Brakes

As can be seen from the image I do not have a slot in my backing plate for backing off the brake adjuster. ( Reproduction kit from InLine Tube)
Aside from cutting a slot in the plate does anyone have any trick I can use to slack off the brake shoes?



Last edited by pcard; February 7th, 2016 at 02:32 PM. Reason: Clarification
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Old February 7th, 2016, 02:39 PM
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There is not an area that needs to be punched out?
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Old February 7th, 2016, 04:12 PM
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Hi Eric, I do not see one. Here is another angle:
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Old February 7th, 2016, 04:13 PM
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I do not have access to the car at the moment so have to rely on photos taken previously. There may be a notch but it is behind the centre line and I thought the slot was dead centre and just above the lower flange of the backing plate.

Last edited by pcard; February 7th, 2016 at 04:16 PM.
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Old February 7th, 2016, 04:20 PM
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Dremel cut a similar slot in the drum instead?
If you use a rubber plug to size the slot, you will have a ready solution for sealing it.

One of the problems with reproduction parts from ANY vendor is the lack of attention to detail... like, what if you need that access port someday?
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Old February 7th, 2016, 05:31 PM
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Take the wheels off, whack the drum up, down, pull off the drums. THEN mess with the slot. You have been in there before, right? No way you could have a ridge built that you couldn't get the drums off.
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Old February 7th, 2016, 06:35 PM
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I have also seen drums with the knock-out on them.
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Old February 7th, 2016, 07:28 PM
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It looks like there is a knockout on the bottom of the backing plate. Look at the pic in post #3.
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Old February 7th, 2016, 07:42 PM
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Eric: here is an image from the Inline Catalogue. I am not sure that the indentation in the centre is a knock-out.
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Old February 7th, 2016, 07:47 PM
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I'm just going by what I see in the picture in post #3. I may be wrong but it sure looks like a knockout there. You'll just have to wait and see.
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Old February 7th, 2016, 07:47 PM
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If there is no knock out then I will cut one out if I can't persuade the drum off gracefully. No big deal with an air tool.
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Old February 7th, 2016, 07:48 PM
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Thanks for working with me. I still want to make it out to Texas!
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Old February 7th, 2016, 07:50 PM
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The drum should still slide off. Come on down...
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Old February 7th, 2016, 07:57 PM
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Originally Posted by oldcutlass View Post
The drum should still slide off. Come on down...
X2.....the knockouts would be below the indentation to the LT or RT. Some drums also have knockouts, then you plug the hole. The knockouts are like on electrical outlet boxes.
Attached Files
File Type: pdf
backing plate.pdf (1.61 MB, 23 views)

Last edited by mrolds69; February 8th, 2016 at 12:27 PM.
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Old February 8th, 2016, 11:44 AM
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Thanks for that - I was going to ask for a schematic showing exactly where to cut the slots, but the diagrammes in the article give me what I need if I have to make the cut.
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Old February 8th, 2016, 12:29 PM
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Sure...glad to help. Rememember that side to side is different, the slot has to be where the "star" wheel is. That's why they show 2 knockouts.
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Old February 8th, 2016, 03:20 PM
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The 2016 Power Tour stops in I believe Grand Prarrie. I will be there, hoping to take the 64 F-85 Pro Touring car on its maiden voyage. Then up to OKC where the Tour ends. Sure be nice to get some of our Club locals out there to meet!!!
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Old February 8th, 2016, 03:23 PM
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MROLDS69 could be right Did you take the tire off yet? On my 67 the rear drums have the knockout not the backing plate.
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Old February 8th, 2016, 06:20 PM
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Going from the CSM in 70 the B and C body had the slot in the drum. The A body has it in the backing plate.
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