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73-87 Chevy _ GMC Trucks => Engine/Drivetrain => Topic started by: Catrik on January 04, 2015, 04:33:50 am

Title: 86 K10 rear brake size
Post by: Catrik on January 04, 2015, 04:33:50 am

I need new rear brake cylinders. ACDelco has part# 18E112 for 11 x 2 and 18E1034 for 11-5/32 x 2-3/4 brakes. How do I know which one, other than measuring? and is that a brake shoe size or what?

Title: Re: 86 K10 rear brake size
Post by: Irish_Alley on January 04, 2015, 06:05:29 am

http://forum.73-87chevytrucks.com/smforum/index.php?topic=28592.0

Title: Re: 86 K10 rear brake size
Post by: Catrik on January 04, 2015, 10:38:25 am

Thanks, but where do I find the code? I dont see anything in my VIN/RPO sticker https://www.dropbox.com/s/q7pnt5z5ifx1o1m/IMG_20130529_054221.jpg?dl=0

I dont fully understand the page you linked. Is JB for front and JD for rear?
It lists "DISC/DRUM" or "DISC, DRUM", why the other have slash and other have comma? Does that mean fron/rear or front, rear?
I have 10-bolt rear so I must have JB5 or JB3?
But I have diesel and reservoir like in the above pic so I must have JD3/5/6?

"diesels and gas motors come with JD3, JD5, JD6 and JD7 (hydro boost)"
"JD5: Brake, Dual Power, Disc/Drum, 6,400 Lbs GVW (Dual Diaphragm Vacuum Booster)"


Confusing!

Title: Re: 86 K10 rear brake size
Post by: Irish_Alley on January 04, 2015, 01:55:47 pm

Don't pay no mind to the comma vs slash. Check your gvwr on the door and match that up with you master cylinder.

Title: Re: 86 K10 rear brake size
Post by: Irish_Alley on January 04, 2015, 02:00:12 pm

More than likely you have the jd3 being only a 1/2 ton their gvwr is normal under 6k

Title: Re: 86 K10 rear brake size
Post by: Captkaos on January 04, 2015, 05:23:22 pm

Based on the VIN I would suspect it was a JB5 based on the 4th digit.

Title: Re: 86 K10 rear brake size
Post by: Irish_Alley on January 04, 2015, 05:46:02 pm

Quote from: Captkaos on January 04, 2015, 05:23:22 pm

Based on the VIN I would suspect it was a JB5 based on the 4th digit.

Didn't even look at the rpo codes but captain might be right

Title: Re: 86 K10 rear brake size
Post by: Catrik on January 05, 2015, 09:01:57 am

I dont have the GVWR sticker anymore but registration papers say 2760kg which is 6085lbs so I guess that would make it JB5. I'll measure the rotor tomorrow to be sure. I tried to measure the brake shoes in the first place but the drum didnt come off without loosening parking brake cable and didn't feel like doing that in -20C  :D

Title: Re: 86 K10 rear brake size
Post by: Captkaos on January 05, 2015, 09:16:18 pm

The Brake GVWR is in the VIN...


http://www.73-87chevytrucks.com/techinfo/73-91VIN/1986truck.pdf



Unfortunately, the only way to know 30 years after it was built is to remove them and measure.