JB1 JB3 JB5 JD3 JD5 What is all this - The 1947 - Present Chevrolet & GMC Truck Message Board Network

jamon8 · 08-27-2006, 08:40 AM

I am putting a crossmember out of a 84 c-10 that had a 6.2 desiel into my 69 c-10 and I am wondering whick of these above codes would match up to the brakes

the brakes look kind of beefy and I can wait to see the difference in the discs vs the drums.

jamon8 · 08-27-2006, 12:17 PM

nobody knows about the brake codes

come on!

f.monroe · 08-27-2006, 12:33 PM

Look here . Click the correct suffix and you should find what you are after. Frank

http://www.73-87.com/chevy_ids/rpomenu2.htm

RyansToy · 07-09-2016, 02:43 PM

I have the same problem.

How do you figure out which booster to use?

I am putting a 1984 cross member from a C10 into my 69. had no intention to change the rear drums yet.

Any thoughts about JB3 vs JB5?

JB3 BRAKE, POWER, DISC/DRUM, 4600 LBS
JB5 BRAKE, POWER, DISC/DRUM, 6400 LBS

**hatzie** · 07-11-2016, 11:23 AM

JB3 has a single diaphragm booster
JB5 has a dual diaphragm booster and slightly larger (wider or larger dia) brake shoes.
http://67-72chevytrucks.com/vboard/s...d.php?t=203698

Keith Seymore · 07-12-2016, 09:08 AM

Quote:

Originally Posted by RyansToy

I have the same problem.

How do you figure out which booster to use?

I am putting a 1984 cross member from a C10 into my 69. had no intention to change the rear drums yet.

Any thoughts about JB3 vs JB5?

JB3 BRAKE, POWER, DISC/DRUM, 4600 LBS
JB5 BRAKE, POWER, DISC/DRUM, 6400 LBS

In this case I think bigger really is better.

I'd just opt for the JB5 system.

K

aggie91 · 07-12-2016, 11:38 AM

Quote:

Originally Posted by RyansToy

I have the same problem.

How do you figure out which booster to use?

I am putting a 1984 cross member from a C10 into my 69. had no intention to change the rear drums yet.

Any thoughts about JB3 vs JB5?

JB3 BRAKE, POWER, DISC/DRUM, 4600 LBS
JB5 BRAKE, POWER, DISC/DRUM, 6400 LBS

I agree with Keith. Go with the JB5 system.

BTW

JB3 is the 1" thick rotors
JB5 is the 1.25" thick rotors

**MikeB** · 07-12-2016, 04:09 PM

Quote:

Originally Posted by aggie91

BTW

JB3 is the 1" thick rotors
JB5 is the 1.25" thick rotors

And let me add that pads are the same, but calipers and spindles are different. Been there, done that.

Mattchu60 · 07-12-2016, 05:08 PM

I had a mix of JB3 and JB5 parts on my truck for some time. Had the thicker rotors (axle was from a 3/4 pickup) with the smaller pads and the JB3 calipers. It all fit fine. I also had the large 13" brake drums on the back.

Then a year later I updated to the JB5 calipers and larger pads and new JB5 rotors as the rotors that came with the axles were warped and shook when stopping.

I did keep the old JB3 Master Cylinder and it seems to work fine, not sure why the JB5 one is needed there, maybe someone can chime in on that. I know the booster is larger and the MC is a little bigger too.

Keith Seymore · 07-12-2016, 09:10 PM

Here are a couple representative brake system release charts (from 1974, and from 1987), which break down the systems by part number.

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

These are the charts the design engineers developed, and used as a reference when releasing the part numbers into the production and service database. All part number information flows from these.

K

**hatzie** · 07-13-2016, 07:14 AM

Quote:

Originally Posted by Mattchu60

I had a mix of JB3 and JB5 parts on my truck for some time. Had the thicker rotors (axle was from a 3/4 pickup) with the smaller pads and the JB3 calipers. It all fit fine. I also had the large 13" brake drums on the back.

Then a year later I updated to the JB5 calipers and larger pads and new JB5 rotors as the rotors that came with the axles were warped and shook when stopping.

I did keep the old JB3 Master Cylinder and it seems to work fine, not sure why the JB5 one is needed there, maybe someone can chime in on that. I know the booster is larger and the MC is a little bigger too.

The JB5 booster and larger diameter Master Cylinder is a worthwhile upgrade. It should reduce braking effort at the pedal.

stacey_65 · 07-13-2016, 10:41 AM

My truck has 1JJ5 heavy duty brakes RPO sticker in the glove box. It's a 85 c10 1/2 ton would that be JD5 brakes?

aggie91 · 07-13-2016, 11:57 AM

Quote:

Originally Posted by MikeB

And let me add that pads are the same, but calipers and spindles are different. Been there, done that.

Yes, I should have mentioned that about the spindles and calipers...Thanks!

Quote:

Originally Posted by stacey_65

My truck has 1JJ5 heavy duty brakes RPO sticker in the glove box. It's a 85 c10 1/2 ton would that be JD5 brakes?

Double check that code from the sticker in the glove box, it should only be 3 characters, not 4. My bet it is faded/damaged but actually is JD5...

Keith Seymore · 07-13-2016, 12:25 PM

Quote:

Originally Posted by aggie91

Double check that code from the sticker in the glove box, it should only be 3 characters, not 4. My bet it is faded/damaged but actually is JD5...

Many SPIDs have a dummy character, as a placeholder, which can be disregarded. It's a holdover from when the SPIDs contained ECL information, which fell into disuse.

Mine has a "9" in front of every code.

Quote:

Originally Posted by stacey_65

My truck has 1JJ5 heavy duty brakes RPO sticker in the glove box. It's a 85 c10 1/2 ton would that be JD5 brakes?

I'm not familiar with JJ5. You sure it's not J55?

Posting the '87 chart as a reference since I had it handy ('85 would be the same except for the C/K/R/V model designation).

JD3/JD5 is hydraboost; JB3/JB5 is vacuum. You then need to know your GVW in order to determine which system you have ("3" vs "5").

K

stacey_65 · 07-13-2016, 12:58 PM

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stacey_65 · 07-13-2016, 12:59 PM

Here is the glove box info. maybe you guys can help me figure it out.

Keith Seymore · 07-13-2016, 03:37 PM

Quote:

Originally Posted by stacey_65

Here is the glove box info. maybe you guys can help me figure it out.

From the powertrain chart below: 1985 C10703 w LE9 & MX1 & GU2 = 6100 lb GVW

From the brake system chart above: 6100 lb GVW= vacuum system = JB5 brakes.

Answer - JB5.

K

Keith Seymore · 07-13-2016, 03:38 PM

The option list and powertrain chart attached above are from the generic info packet located in the GM Heritage Center archive.

1985 Truck:
https://www.gmheritagecenter.com/doc...olet-Truck.pdf

K

stacey_65 · 07-13-2016, 04:21 PM

Thanks guys...........

Keith Seymore · 07-14-2016, 07:39 AM

Quote:

Originally Posted by stacey_65

Here is the glove box info. maybe you guys can help me figure it out.

Built in Flint, I see.

My guys may have installed your front fenders and pickup box.

K

aggie91 · 07-14-2016, 08:48 AM

learned something new. I have never seen the 4 digit RPO codes on the spids.

Nice to know that there is dummy character so that they are still the "normal" codes...

stacey_65 · 07-14-2016, 09:59 AM

It was strange for me as well. I have always seen 3 digit codes. That's why I came to you guys.

08-27-2006, 08:40 AM	#1
jamon8 Registered User Join Date: Apr 2006 Location: southern Il Posts: 335	JB1 JB3 JB5 JD3 JD5 What is all this I am putting a crossmember out of a 84 c-10 that had a 6.2 desiel into my 69 c-10 and I am wondering whick of these above codes would match up to the brakes the brakes look kind of beefy and I can wait to see the difference in the discs vs the drums.

08-27-2006, 12:17 PM	#2
jamon8 Registered User Join Date: Apr 2006 Location: southern Il Posts: 335	Re: JB1 JB3 JB5 JD3 JD5 What is all this nobody knows about the brake codes come on!

08-27-2006, 12:33 PM	#3
f.monroe Senior Member Join Date: May 2004 Location: Caldwell,Tx. Posts: 3,648	Re: JB1 JB3 JB5 JD3 JD5 What is all this Look here . Click the correct suffix and you should find what you are after. Frank http://www.73-87.com/chevy_ids/rpomenu2.htm __________________ Born and proudly residing in a Red State !

07-09-2016, 02:43 PM	#4
RyansToy Registered User Join Date: Aug 2015 Location: Nova Scotia Canada Posts: 145	Re: JB1 JB3 JB5 JD3 JD5 What is all this I have the same problem. How do you figure out which booster to use? I am putting a 1984 cross member from a C10 into my 69. had no intention to change the rear drums yet. Any thoughts about JB3 vs JB5? JB3 BRAKE, POWER, DISC/DRUM, 4600 LBS JB5 BRAKE, POWER, DISC/DRUM, 6400 LBS __________________ 1968 GMC truck 910 Trim (Canadian) 127" WB 3 on the Three Trans (Saginaw SM330) 250 ci L6 Engine HEI ignition (early 80s L6)

07-11-2016, 11:23 AM	#5
hatzie Moderator Join Date: Oct 2008 Location: Wentworth, NH Posts: 4,977	Re: JB1 JB3 JB5 JD3 JD5 What is all this JB3 has a single diaphragm booster JB5 has a dual diaphragm booster and slightly larger (wider or larger dia) brake shoes. http://67-72chevytrucks.com/vboard/s...d.php?t=203698 __________________ 1959 M35A2 LDT465-1D SOLD 1967 Dodge W200 B383, NP420/NP201 SOLD 1969 Dodge Polara 500 B383, A833 SOLD 1972 Ford F250 FE390, NP435/NP205 SOLD 1976 Chevy K20, 6.5L, NV4500/NP208 SOLD 1986 M1008 CUCV SOLD 2000 GMC C2500, TD6.5L, NV4500 2005 Chevy Silverado LS 2500HD 6.0L 4L80E/NP263 2009 Impala SS LS4 V8 RTFM... GM Parts Books, GM Schematics, GM service manuals, and GM training materials... 1973-1991 GM Light Truck Service, Unit/Overhaul, Wiring Manuals, Parts Books and Some 1968-1999 GM Service Training textbooks in PDF 1988-1998 GMT400 CK service manual project 1988-1993 GMT400 CK parts books. 1967-1972 GM Light, Medium, & Heavy Truck Service Manuals in PDF Please include at least the year and model in your threads. It'll be easier to answer your questions. And please let us know if and how your repairs were successful.

07-12-2016, 05:08 PM	#9
Mattchu60 Registered User Join Date: Jan 2014 Location: Swaledale, IA Posts: 485	Re: JB1 JB3 JB5 JD3 JD5 What is all this I had a mix of JB3 and JB5 parts on my truck for some time. Had the thicker rotors (axle was from a 3/4 pickup) with the smaller pads and the JB3 calipers. It all fit fine. I also had the large 13" brake drums on the back. Then a year later I updated to the JB5 calipers and larger pads and new JB5 rotors as the rotors that came with the axles were warped and shook when stopping. I did keep the old JB3 Master Cylinder and it seems to work fine, not sure why the JB5 one is needed there, maybe someone can chime in on that. I know the booster is larger and the MC is a little bigger too.

07-12-2016, 09:10 PM	#10
Keith Seymore Registered User Join Date: May 2009 Location: Motor City Posts: 9,226	Re: JB1 JB3 JB5 JD3 JD5 What is all this Here are a couple representative brake system release charts (from 1974, and from 1987), which break down the systems by part number. http://67-72chevytrucks.com/vboard/s...d.php?t=510519 These are the charts the design engineers developed, and used as a reference when releasing the part numbers into the production and service database. All part number information flows from these. K Attached Images __________________ 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/ Last edited by Keith Seymore; 07-13-2016 at 07:08 AM.

07-13-2016, 10:41 AM	#12
stacey_65 Registered User Join Date: Feb 2009 Location: Cleveland,Ga Posts: 42	Re: JB1 JB3 JB5 JD3 JD5 What is all this My truck has 1JJ5 heavy duty brakes RPO sticker in the glove box. It's a 85 c10 1/2 ton would that be JD5 brakes?

07-13-2016, 12:58 PM	#15
stacey_65 Registered User Join Date: Feb 2009 Location: Cleveland,Ga Posts: 42	Re: JB1 JB3 JB5 JD3 JD5 What is all this

07-13-2016, 12:59 PM	#16
stacey_65 Registered User Join Date: Feb 2009 Location: Cleveland,Ga Posts: 42	Re: JB1 JB3 JB5 JD3 JD5 What is all this Here is the glove box info. maybe you guys can help me figure it out.

07-13-2016, 03:38 PM	#18
Keith Seymore Registered User Join Date: May 2009 Location: Motor City Posts: 9,226	Re: JB1 JB3 JB5 JD3 JD5 What is all this The option list and powertrain chart attached above are from the generic info packet located in the GM Heritage Center archive. 1985 Truck: https://www.gmheritagecenter.com/doc...olet-Truck.pdf 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/

07-13-2016, 04:21 PM	#19
stacey_65 Registered User Join Date: Feb 2009 Location: Cleveland,Ga Posts: 42	Re: JB1 JB3 JB5 JD3 JD5 What is all this Thanks guys...........

07-14-2016, 08:48 AM	#21
aggie91 I'm just glad to be here! Join Date: Jan 2008 Location: Longview, TX Posts: 4,788	Re: JB1 JB3 JB5 JD3 JD5 What is all this learned something new. I have never seen the 4 digit RPO codes on the spids. Nice to know that there is dummy character so that they are still the "normal" codes... __________________ Karl 1965 Chevy Stepside(Grandpa's Old Blue) and (July 2015 Shop Build!)(2020, the Saga Continues) http://67-72chevytrucks.com/vboard/s...d.php?t=372424 The LST Challenge: http://67-72chevytrucks.com/vboard/s...=1#post7812257 Korbin's 1st Square: "Sunburn" http://67-72chevytrucks.com/vboard/s...d.php?t=418618 1985 GMC Sierra: "White Trash", Korbin's 2nd now... http://67-72chevytrucks.com/vboard/s...d.php?t=632305 Henry - 1984 Chevrolet, Owen's 1st Square

07-14-2016, 09:59 AM	#22
stacey_65 Registered User Join Date: Feb 2009 Location: Cleveland,Ga Posts: 42	Re: JB1 JB3 JB5 JD3 JD5 What is all this It was strange for me as well. I have always seen 3 digit codes. That's why I came to you guys.

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