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#1607575 07/10/2026 7:17 PM
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'Bolter
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What size socket or wrench fits the big nut that holds the wheel cylinder to the backing plate? Asking for a friend. 😉. Actually, I injured myself trying to get it off with a crescent wrench. 😥
It’s been 20+ years since I worked on any drum brakes…. Thanks!


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Housekeeping (Moderator) Making a Stovebolt Bed & Paint and Body Shop Forums
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Actually that big nut is for the brake shoe anchor pin used for major adjustment (centering) of the shoes. It's a 15/16" hex. Wheel cylinders are secured by two 1/2" hex head bolts.
That's the sizes on my '51, which should have the same Bendix brakes as a 66 C10.
Crescent wrenches are known for drawing blood. frown


Kevin
1951 Chevy 3100 work truck
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1929 Ford pickup restored from the ground up. | 1929 Ford Special Coupe (First car)
Busting rust since the mid-60's
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'Bolter
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Frank was probably using a metric Crescent wrench.


'57 GMC 102, Original 347 V8, HydraMatic, 3.08 rear gear, added A/C, disk front brakes, HEI, AFB carb, '98 Honda Black Currant paint. T-boned and totaled 10/12
'52 GMC 152 Stake Bed, Original 228, SM420, added A/C, HEI, disk front brakes, '67 Chev 3.55 rear gear. Gets used as a real truck.
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Housekeeping (Moderator) Making a Stovebolt Bed & Paint and Body Shop Forums
Housekeeping (Moderator) Making a Stovebolt Bed & Paint and Body Shop Forums
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Originally Posted by Bill Hanlon
Frank was probably using a metric Crescent wrench.
Yeah, that. grin


Kevin
1951 Chevy 3100 work truck
Follow this saga in Project Journal
Photos
1929 Ford pickup restored from the ground up. | 1929 Ford Special Coupe (First car)
Busting rust since the mid-60's
If you're smart enough to take it apart, you darn well better be smart enough to put it back together.
Joined: Nov 2000
Posts: 1,969
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'Bolter
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Originally Posted by klhansen
Actually that big nut is for the brake shoe anchor pin used for major adjustment (centering) of the shoes. It's a 15/16" hex. Wheel cylinders are secured by two 1/2" hex head bolts.
That's the sizes on my '51, which should have the same Bendix brakes as a 66 C10.
Crescent wrenches are known for drawing blood. frown

Well, that makes sense. Thank you!


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'Bolter
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Originally Posted by klhansen
Actually that big nut is for the brake shoe anchor pin used for major adjustment (centering) of the shoes. It's a 15/16" hex. Wheel cylinders are secured by two 1/2" hex head bolts.
That's the sizes on my '51, which should have the same Bendix brakes as a 66 C10.
Crescent wrenches are known for drawing blood. frown

Well… that’s not correct. The rear wheel cylinders are attached by two bolts through the backing plate. But the front ones must be mounted by the anchor pin. And the hex measures 1.137”. So I guess a 1-3/16 socket will fit it. I will have to buy one.
Thanks for all suggestions. 😊
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Housekeeping (Moderator) Making a Stovebolt Bed & Paint and Body Shop Forums
Housekeeping (Moderator) Making a Stovebolt Bed & Paint and Body Shop Forums
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Frank, you are correct about the wheel cylinder mounting. I didn't look close enough when I checked on RockAuto for the wheel cylinders. Does the rear anchor pin that's separate from the wheel cylinder mounting use a 15/16" hex nut?

It seems like that front anchor pin mount would actually restrict the ability for it to move in relation to the backing plate. The hole in the '51 backing plate is elongated vertically to allow the anchor pin to move.

BTW, RockAuto has AC Delco wheel cylinders for about $12 each.


Kevin
1951 Chevy 3100 work truck
Follow this saga in Project Journal
Photos
1929 Ford pickup restored from the ground up. | 1929 Ford Special Coupe (First car)
Busting rust since the mid-60's
If you're smart enough to take it apart, you darn well better be smart enough to put it back together.
Joined: Nov 2000
Posts: 1,969
F
'Bolter
'Bolter
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Originally Posted by klhansen
Does the rear anchor pin that's separate from the wheel cylinder mounting use a 15/16" hex nut?

BTW, RockAuto has AC Delco wheel cylinders for about $12 each.

I don’t know about the rear nut. I haven’t worked on a rear brake on this truck yet.
Thanks for the tip on wheel cylinders at RockAuto!


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'Bolter
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I got it apart. And it’s not a nut, it’s the anchor pin. 6-pt impact socket, breaker bar and a generous cheater pipe got it out. It really helps to have the right tools.
Thanks for all responses.


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