Brakes on '85 Chevy 1/2-ton

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  #1  
Old 07-05-03, 10:09 PM
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Brakes on '85 Chevy 1/2-ton

Help, please! In order to get the right brake parts for my '85 Chevrolet 1/2-ton pickup, my local AutoZone says there are two sizes of brakes - 11"x2" and 11&5/32"x2&3/4". The previous owner put shoes and drums of both sizes on the rear, and apparently mis-matched them as well. All I can give you to go on is the following - the VIN character for the brakes is E", indicating 6001-7000 lb. GVWR brakes. The sticker inside the glove compartment(COPO sticker?) indicates option J55 heavy duty power brakes. There is also in the glove compartment a camper loading information sticker, which has become illegibile over the years. The rear axle appears to be a 10-bolt, with a 2.73:1 gear ratio as indicated by the first glove-box sticker I mentioned. AutoZone tells me I have either the JB1 brakes (smaller) or the JB5 (larger). Since the characters on the sticker more closely match the JB5 designation, I want to believe I've got the bigger brakes. I just would like someone to confirm for me before I shell out for parts; I'd rather make as few trips as possible! Any and all input would be geatly appreciated! Thanks - Chris
 
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  #2  
Old 07-05-03, 10:49 PM
Joe_F
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The GM codes you gave don't have any boding to the option codes needed.....

I would assume EVERYTHING is wrong on the vehicle and if it were mine, I'd throw EVERYTHING out when you figure out what's really supposed to be in there. Dangerous to mix parts.

The brake code JB5 comes up with 6400 GVW braking range. I assumed the vehicle was an '85 C10 (2WD) with a 4.3 engine and Delco's website gave me:

AR 17449R SHOE KIT,RR BRK DURASTOP
11 X 2" BRKS
AR 17473R SHOE KIT,RR BRK DURASTOP
11 5/32 X 2 3/4
AR 14449R SHOE KIT,RR BRK(REMAN) DURASTOP
11 DD X 2 WIDTH
AR 14473R SHOE KIT,RR BRK(REMAN) DURASTOP
11 5/32 DD X 2 3/4 WIDTH


What that means in real terms is that industry #449R shoe (no matter who makes it) is 11x2 and #473R shoe is 11 5/32 x 2 3/4.

But looking up a brake drum for it, I believe I have found the answer...

02 177-370 DRUM,RR BRK
With RPO PWR BRK SYS(JB5)^(JD5) 11 X 2.75 BRK)(5 LUG
01 18B16 DRUM,RR BRK DURASTOP
11 X 2" BRAKES
AR 18B16 DRUM,RR BRK DURASTOP
5-5 HOLES & BOLT CIRCLE)(11 X 2" BRKS
01 18B29 DRUM,RR BRK DURASTOP
11 5/32 X 2 3/4" BRAKES
AR 18B29 DRUM,RR BRK DURASTOP
5-5 HOLES & BOLT CIRCLE)(11 5/32 DD X 2 3/4 WIDTH SHOE SIZE

That to me would indicate that JB5 is 11 5/32 by 2.75 (2 3/4).

Hence, I believe you have the "larger" of the two brakes.

Also, Delco DuraStop is really just Raybestos "PG" grade reboxed, so check the Raybestos website too.

BTW, COPO=Central Office Production Order.

Good luck...
 

Last edited by Joe_F; 07-05-03 at 11:14 PM.
  #3  
Old 07-05-03, 11:49 PM
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Thanks, Joe! I was (and am still) hoping that was the case - the bigger the brakes, the better I like it. The first sticker in the glovebox - IS that the COPO sticker? Seems with the listing of the options installed at build time, that would be what it is. Just curious... For clarification, the truck was built with the 305 v-8, not the 4.3l - my bad for leaving it out. It presently has an older-style small block, also courtesy of the previous owner. Oil dipstick tube installs in the block, not in the oilpan like on the correct engine. I'm HOPING I can make the thing go until I can secure an '85-vintage 350 and make it emissions legal while building in some performance. This forum will, as always, come in real handy during that phase of the truck's existence. Again, Joe, my thanks to you, and to anyone else who might have further insight into my situation. 'Til next time, - Chris
 
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Old 07-05-03, 11:58 PM
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Smacking forehead with open palm...

Oh, man! Joe, I meant to ask if you knew: why the discrepancy between the numbers on my truck ( VIN "E" and J55) and AutoZone's number (JB5)? Again, mostly just curious, but it DID seem kind of odd... Let me know what you think, and thanks again! - Chris
 
  #5  
Old 07-06-03, 01:31 AM
Joe_F
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Yes on the glovebox label. RPO, "SPID", COPO sticker, all refer to the "Option label" in one form or another.

The vin code E would be the position in the vin that determines the braking capacity based on original GVW of the vehicle.

J55 in my GM literature just says, "Braking system, Heavy Duty". Are you SURE no other codes are there? Any "J" codes are braking codes in GM.

How about checking the Raybestos website? The only other thing I can offer you is to check the GM parts literature/computer I have on Monday to see what they say there. Usually they have some clues as to how things are identified. Also, in the interim, go to www.acdelco.com as I did and look up various brake parts for it. Note how in the text they give clues and comments such as "5 lug wheels, 5.5" bolt pattern," etc, etc. Those might clue you into what you have there.

Is the vehicle a C10 (2WD) or a K10 (4WD). What #s are stamped on the power booster or master cylinder? Sometimes the GM parts literature will identify them in the text.
 
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Old 07-06-03, 07:47 AM
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It's a C10, Joe. Thanks for the input. On my next days off, I'm going to check the websites you listed and see what I find, but I'm willing to bet you've got me pointed in the right direction. I'll post back with findings. Thanks again - Chris
 
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Old 07-07-03, 11:25 AM
Joe_F
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Ok, I think I figured it out

J55 is a MERCHANDISING option. (Sales option).

Deep in the bowels of the #52R GM parts catalog for 1985 to 1991 trucks, there is a chart for brake specifications by year. J55 is shown as a merch. option next to JB5 and JB7.

JB7 is only for C20 models, this is a C10. If you look up a drum for a C10 in 1985, there are only two options, 11x2 and 11x2.75

Since J55 goes with JB5, parts for JB5 (power brakes) are 11x2.75. You did have J55 on your tag.

Hence I believe you have the 11x2.75 brakes and would need those parts .

Whew . Hope that helps.
 
  #8  
Old 07-07-03, 02:29 PM
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"Deep in the bowels..." Wow! It sounds like I never would have found the information on my own! Thanks, Joe. Your contributions to this forum are priceless. This will help me get one major part of this project finished. Thanks again, and keep up the good work. 'Til next time, - Chris
 
  #9  
Old 07-07-03, 04:48 PM
Joe_F
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Arrow

Most of the reference charts are buried deep in these parts catalogs, but something told me it was there, and sure enough it was .

I've often pointed a coworker (and they do this for a living) to those charts since I usually train our group on new parts software .
 
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