Brake Tech, what do all the numbers mean..

[Captkaos]

I started a new tech thread at the following link.  http://forum.73-87chevytrucks.com/smforum/index.php?topic=28592

If anyone finds more brake info on the forum or something to add reply to here and I will merge it all..

[Captkaos]

This is what I have in that so far...  Thanks to bd and others for reminding and asking..

There are 2 style calipers and rotors on these trucks after 1980,  Standard 1" and HD 1.5"  They don't interchange.

For 1/2 Tons..
JB1 - manual brakes, 1" rotors
JB3 = power brakes, 1" rotors
JB5 = power brakes, 1.25" rotors

JB1 BRAKE, MANUAL, DISC/DRUM, 4300 LBS
JB3 BRAKE, POWER, DISC/DRUM, 4600 LBS
JB5 BRAKE, POWER, DISC/DRUM, 6400 LBS
JB6 BRAKE, POWER, DISC, DRUM 7200 LBS
JB7 BRAKE, POWER, DISC, DRUM 8400 L85
JB8 8RAKE, POWER, DISC, DRUM 10000 LBS

The only rear ends that have 13" brakes are the JB7 and JB8 brakes on a 14 bolt full float.

10 or 12 bolt [rear axles] had either 11.15" x 2.75" for the JB5 or 11.15" x 2" for the JB3.


diesels come with JD3, JD5, JD6 and JD7
gassers come with  JB3, JB5, JB6 and JB7
now here's the kicker for gassers if its a plastic reservoir its a  JB3, JB5 or JB6
if its a cast reservoir its a JB7

If your a gasser you dont need this info but if its a Diesel then read on
if you reservoir looks like this


then you have a JD3, JD5 or JD6
if it looks like this

then its a JD7

JD7 (for diesles) and JB7 (for gassers) use the same cylinder
other than that gassers use plastic besides the JB7

[cvbear]

thanks, that kind of information is great. 
were JB5 rotors 1.25 or 1.5?
Also, it might be worthwhile to note that what is on the truck now, especially with parts that could have been expected to be replaced at least once by now, may be different than what was there when it left the factory.
Thanks again for putting this information together.

[Irish_Alley]

This is what I have in that so far...  Thanks to bd and others for reminding and asking..

There are 2 style calipers and rotors on these trucks after 1980,  Standard 1" and HD 1.5"  They don't interchange.

For 1/2 Tons..
JB1 - manual brakes, 1" rotors
JB3 = power brakes, 1" rotors
JB5 = power brakes, 1.25" rotors

JB1 BRAKE, MANUAL, DISC/DRUM, 4300 LBS
JB3 BRAKE, POWER, DISC/DRUM, 4600 LBS
JB5 BRAKE, POWER, DISC/DRUM, 6400 LBS
JB6 BRAKE, POWER, DISC, DRUM 7200 LBS
JB7 BRAKE, POWER, DISC, DRUM 8400 L85
JB8 8RAKE, POWER, DISC, DRUM 10000 LBS

The only rear ends that have 13" brakes are the JB7 and JB8 brakes on a 14 bolt full float.

10 or 12 bolt [rear axles] had either 11.15" x 2.75" for the JB5 or 11.15" x 2" for the JB3.


diesels come with JD3, JD5, JD6 and JD7
gassers come with  JB3, JB5, JB6 and JB7
now here's the kicker for gassers if its a plastic reservoir its a  JB3, JB5 or JB6
if its a cast reservoir its a JB7

If your a gasser you dont need this info but if its a Diesel then read on
if you reservoir looks like this


then you have a JD3, JD5 or JD6
if it looks like this

then its a JD7

JD7 (for diesles) and JB7 (for gassers) use the same cylinder
other than that gassers use plastic besides the JB7