How do I measure my rear brake ?! - The 1947 - Present Chevrolet & GMC Truck Message Board Network

**Nima** · 05-27-2005, 12:23 AM

Hi eveherybody:
As some of you may know, I will change my front brakes to disck soon. The only part which is missing is booster,mc and pp valve. When I look at the different websites, some of them ask for 13 or 11 inch rear brake. How do you measure that? is it the diameter of the drum? if yes, the diameter inside (after taking the drum off) or outside? By the way mine is C20, maybe they just come with 13"? Thanks.

68LSS1 · 05-27-2005, 03:34 AM

I think when dealing with drums it's the internal diameter of the drum. When dealing with rotors it is just the diameter of the rotor.

3 on the tree · 05-27-2005, 08:18 PM

Size should be stamped into the brake drum: something like Max Diameter 11.03 in. kShould be stamped on the flat face of the drum.

OhioDan · 05-28-2005, 02:49 AM

When I did mine, I had to measure the length and width of the lining on the brake shoe. Some are 11" X 2", and some are 13" X 2 1/2". Hope this helps?

**Nima** · 05-28-2005, 03:50 PM

Thanks guys. any info helps.

05-27-2005, 12:23 AM	#1
Nima Blue 67 Join Date: Apr 2004 Location: Western WA Posts: 1,178	How do I measure my rear brake ?! Hi eveherybody: As some of you may know, I will change my front brakes to disck soon. The only part which is missing is booster,mc and pp valve. When I look at the different websites, some of them ask for 13 or 11 inch rear brake. How do you measure that? is it the diameter of the drum? if yes, the diameter inside (after taking the drum off) or outside? By the way mine is C20, maybe they just come with 13"? Thanks.

05-27-2005, 03:34 AM	#2
68LSS1 Registered User Join Date: Dec 2002 Location: Tampa Posts: 1,191	I think when dealing with drums it's the internal diameter of the drum. When dealing with rotors it is just the diameter of the rotor. __________________ '68 Short Step LS1/T56, Hydratech, Fatman Fabrications Stage III, Baer, Hot Rods to Hell, US Body, S&W, etc

05-28-2005, 02:49 AM	#4
OhioDan Registered User Join Date: Apr 2002 Location: New Carlisle, Ohio,USA Posts: 1,404	When I did mine, I had to measure the length and width of the lining on the brake shoe. Some are 11" X 2", and some are 13" X 2 1/2". Hope this helps? __________________ LIFE AIN'T EASY WHEN YER FAT AND GREASY! GMC= Got More Class! 1970 GMC LWB, Fleetside, 350/4spd, Flowmaster "40's", 2002 GMC 16" Rallies, cowl hood,and added a bunch of options that weren't there when I started.

05-27-2005, 08:18 PM	#3
3 on the tree Registered User Join Date: Oct 2004 Posts: 393	Size should be stamped into the brake drum: something like Max Diameter 11.03 in. kShould be stamped on the flat face of the drum.

05-28-2005, 03:50 PM	#5
Nima Blue 67 Join Date: Apr 2004 Location: Western WA Posts: 1,178	Thanks guys. any info helps.



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