need some quick brake help - The 1947 - Present Chevrolet & GMC Truck Message Board Network

hotrod_991 · 01-10-2014, 12:15 AM

I Have a 77 heavy half and I am about to buy new rear wheel cylinders. They come in two sizes according to autozone website. I have the HD 1.25" brakes on the front so would that mean I would have the larger size wheel cylinder? I know the diffrence is in the size of the brake shoe or the drum. My drums have a Max Diameter stamped into them but not sure is that is the actual size i need. Any help is appreciated.

D13 · 01-10-2014, 11:39 AM

Measure the width of the rear pads. the big pads take the big cylinder. Base are 2", HD are 2 3/4".

Keith Seymore · 01-10-2014, 01:06 PM

Here's a link to the brake system release charts for '74 (and '87).

Find your model/option type on the chart and it will show you what wheel cylinder is required.

http://67-72chevytrucks.com/vboard/s...d.php?t=510519

These are the actual charts that we referred to in order to release parts for production.

K

Keith Seymore · 01-10-2014, 04:26 PM

Quote:

Originally Posted by hotrod_991

I Have a 77 heavy half and I am about to buy new rear wheel cylinders. They come in two sizes according to autozone website. I have the HD 1.25" brakes on the front so would that mean I would have the larger size wheel cylinder? I know the diffrence is in the size of the brake shoe or the drum. My drums have a Max Diameter stamped into them but not sure is that is the actual size i need. Any help is appreciated.

The "Max Diameter" is a reference to the largest diameter the drums can be safely turned before they must be scrapped. Doesn't have anything to do with the friction material, wheel cylinder or brake system info.

So - in looking at the '87 chart for a 10 series pickup ('cause it's a little easier to read) the 2" wide shoes take a 1.062 dia wheel cylinder (aka an inch and 1/16th) and the 2.75" wide shoes take a .9375" (aka 15/16ths of an inch) diameter wheel cylinder.

K

Houston Ben · 01-10-2014, 04:51 PM

I just did this, when you take the cylinder out it will tell you what size it is, then just go to AUTO ZONE or where ever and pick it up.

01-10-2014, 12:15 AM	#1
hotrod_991 Registered User Join Date: Jul 2009 Location: Thibodaux, LA Posts: 479	need some quick brake help I Have a 77 heavy half and I am about to buy new rear wheel cylinders. They come in two sizes according to autozone website. I have the HD 1.25" brakes on the front so would that mean I would have the larger size wheel cylinder? I know the diffrence is in the size of the brake shoe or the drum. My drums have a Max Diameter stamped into them but not sure is that is the actual size i need. Any help is appreciated. __________________ "Buckle up I wanna try somethin!!" "of course it will hold!, I welded it!" 1977 c10 under knife for full rebuild, 5.3l 4l60e drive rain swap, replacement frame and green repaint

01-10-2014, 11:39 AM	#2
D13 Registered User Join Date: Feb 2007 Location: Memphis MI Posts: 1,851	Re: need some quick brake help Measure the width of the rear pads. the big pads take the big cylinder. Base are 2", HD are 2 3/4". __________________ 1987 2 ton 1982 250/TH350 beater in progress Dad's 1981 3/4 L6 3 on tree posi and no options, awaiting restoration or scrapping Plus a mess o' tractors

01-10-2014, 01:06 PM	#3
Keith Seymore Registered User Join Date: May 2009 Location: Motor City Posts: 9,226	Re: need some quick brake help Here's a link to the brake system release charts for '74 (and '87). Find your model/option type on the chart and it will show you what wheel cylinder is required. http://67-72chevytrucks.com/vboard/s...d.php?t=510519 These are the actual charts that we referred to in order to release parts for production. K __________________ Chevrolet Flint Assembly 1979-1986 GM Full Size Truck Engineering 1986 - 2019 Intro from an Old Assembly Guy: http://67-72chevytrucks.com/vboard/s...d.php?t=342926 My Pontiac story: http://forums.maxperformanceinc.com/...d.php?t=560524 Chevelle intro: http://www.superchevy.com/features/s...hevy-chevelle/

01-10-2014, 04:51 PM	#5
Houston Ben Registered User Join Date: May 2013 Location: Houston Texas Posts: 713	Re: need some quick brake help I just did this, when you take the cylinder out it will tell you what size it is, then just go to AUTO ZONE or where ever and pick it up.



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