Upgrade from jn3 brakes?

[Burntoutaccountant]

I had a separate thread but figured this was the way to go.

I have a 89 k1500. I’ll be upgrading to hydroboost and a 1.25” master cylinder. I’ll also be upgrading the rear end from the 10 bolt to a 14 bolt.

Apparently I have the jn3 rotors and calipers. I measured the rotors and they’re approx 1” thick.

So my question is how do I upgrade to jb7 brakes? I think I need to upgrade the hub assembly as the knuckles are the same? Looking through rock auto, would I buy the hub and bearing assembly for the f44/ heavy duty suspension?

 

[GoToGuy]

Have you seen

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this page, and there are posts that already have the info your looking for, use search at top, take your time reading rather waiting on response if you prefer.

 

[HotWheelsBurban]

Why do you feel like you need JB7 brakes on a half ton? The JB 6 should be enough for a half ton pickup or Burb/SUV....
JB/JD 8 is what my one ton has, because it's built to haul 10,000 pounds.

 

[Burntoutaccountant]

Why do you feel like you need JB7 brakes on a half ton? The JB 6 should be enough for a half ton pickup or Burb/SUV....
JB/JD 8 is what my one ton has, because it's built to haul 10,000 pounds.

Eh I just like big brakes in all honesty.

After searching more it appears I should do jb6. So I guess back to the original question, it just bolts in after swapping the hub and bearings assembly?

I found this. Appears to be bolt in but looking for some quick confirmation so I can get parts ordered up.

JB3 with larger piston calipers?

I have a 90 K1500 RCSB and had a slight vibration under braking. Decided to just replace the braking system so ordered the 1" rotors, ACDelco calipers 743/744 non hd, and pads to go with it. After pulling the wheel off, I saw that it had the HD calipers 745/746, but still had 1" rotors. Will I...

www.gmt400.com

 

[Schurkey]

Upgrading JN3 to JN/JB6 is EASY on a 4WD. Not as easy on a 2WD. Adding hydroboost would be more-challenging but still do-able at greater expense and significantly more effort.

My '88 K1500 got upgraded from JN3 to JN6 almost by accident. I replaced a crappy worn-out 10-bolt axle and leading-trailing shoe drums with a 14-bolt semi-float with the 11.x drums, stolen from a light-duty K2500. That took care of the rear brakes.

Some years later, I broke a ball-joint stud due to a damaged steering knuckle. Got the whole front suspension from a random Treasure-Yard vehicle about to be crushed. That was the one I was directed to, as the owner wanted anything salvageable taken from that truck. Happened to be an extended-cab. The extended-cab trucks got JN5 brakes, exactly the same as JN6 up front and on the firewall--but still cursed with the crappy 254mm leading-trailing shoe drums in back.

At that time, I didn't know the difference. Took the whole suspension home. Wasn't until I compared rotors on the replacement steering knuckle that the light dawned on me. Ended up replacing both steering knuckles, (along with the matching "used" hubs) replacing the broken ball joint, used the bigger-piston calipers to go with the wider rotors. Then I had to drive back to the Treasure Yard to get the bigger brake booster and bigger master cylinder to go with the bigger caliper pistons.

You find the right "donor" vehicle, (light-duty K2500 with JB/JN6 and correct gear ratio) you could take everything you need from one unit except the Hydroboost--rear axle with 11.x drums, master and booster, and steering knuckles/hubs/rotors/calipers. Even if there's excess wear or deterioration to certain parts, you'd be able to turn them in for "core charge" to get rebuilt items--master cylinder, booster, calipers, etc.

Be sure to get the correct gear ratio on that axle.

Converting to hydroboost is covered in other threads.

 

[Burntoutaccountant]

Upgrading JN3 to JN/JB6 is EASY on a 4WD. Not as easy on a 2WD. Adding hydroboost would be more-challenging but still do-able at greater expense and significantly more effort.

My '88 K1500 got upgraded from JN3 to JN6 almost by accident. I replaced a crappy worn-out 10-bolt axle and leading-trailing shoe drums with a 14-bolt semi-float with the 11.x drums, stolen from a light-duty K2500. That took care of the rear brakes.

Some years later, I broke a ball-joint stud due to a damaged steering knuckle. Got the whole front suspension from a random Treasure-Yard vehicle about to be crushed. That was the one I was directed to, as the owner wanted anything salvageable taken from that truck. Happened to be an extended-cab. The extended-cab trucks got JN5 brakes, exactly the same as JN6 up front and on the firewall--but still cursed with the crappy 254mm leading-trailing shoe drums in back.

At that time, I didn't know the difference. Took the whole suspension home. Wasn't until I compared rotors on the replacement steering knuckle that the light dawned on me. Ended up replacing both steering knuckles, (along with the matching "used" hubs) replacing the broken ball joint, used the bigger-piston calipers to go with the wider rotors. Then I had to drive back to the Treasure Yard to get the bigger brake booster and bigger master cylinder to go with the bigger caliper pistons.

You find the right "donor" vehicle, (light-duty K2500 with JB/JN6 and correct gear ratio) you could take everything you need from one unit except the Hydroboost--rear axle with 11.x drums, master and booster, and steering knuckles/hubs/rotors/calipers. Even if there's excess wear or deterioration to certain parts, you'd be able to turn them in for "core charge" to get rebuilt items--master cylinder, booster, calipers, etc.

Be sure to get the correct gear ratio on that axle.

Converting to hydroboost is covered in other threads.

I’ll just be buying new. I actually work as a service advisor and get discounts on stuff especially compared to retail. Just needed to confirm once the hub is switched it bolts in.

So parts I need are jb6 calipers, rotors, and pads. Then the f44 hub and bearing assembly.

Will this clear a 16” wheel? I guess offset is another question there too.

 

[Schurkey]

I’ll just be buying new. I actually work as a service advisor and get discounts on stuff especially compared to retail. Just needed to confirm once the hub is switched it bolts in.

Is this archaic stuff available "new"? I'd be kinda surprised, at least from GM.

"New" aftermarket is likely, though.

So parts I need are jb6 calipers, rotors, and pads.

Up front, and on the firewall, JB5 or JB6 is the same stuff.

JB5 has the crappy rear brakes, though.

I used my nearly-worn-out JN3 pads to scuff the rust off of the Treasure Yard rotors. Same pad, different spring clip on the back of the inboard pad, to fit the smaller piston in the JN3 caliper. Then I put "new" pads on after the rotors were appropriately polished.

Then the f44 hub and bearing assembly.

I don't know about F44. Maybe, maybe not. You order what came with an extended-cab instead of a regular-cab for an '88, and you should get the correct parts.

Will this clear a 16” wheel? I guess offset is another question there too.

My truck has 16" wheels. Currently GM aluminum, but I've used the OEM steel-wheel spare on the front.