caliper bracket for LD to HD brakes

[808_c1500]

Wondering if the LD caliper brackets are the same for the HD calipers? I can't find any on rockauto to compare part numbers. I am converting from LD to HD brake 1.25" rotors and have the rotors, calipers, bearings, and spindle but don't know if my existing caliper bracket is compatible. thanks for oyur help in advanced.

 

[454cid]

Have you looked at your brakes yet? What vehicle do you have?

 

[Schurkey]

Define "LD" and "HD".

GM has more than half-a-dozen variations on the brake systems, depending on model year, vehicle, and options:

JN/JB1
JN/JB3
JN/JB5
JN/JB6
JN/JB/JD7
JB/JD8 single rear wheel
JB/JD8 dual rear wheel
JF9
And probably more that I haven't listed.

As asked already--WHAT VEHICLE are you working on, and what brakes did it come with?

What brakes are you trying to install that use caliper brackets that aren't integrated into the steering knuckle?

 

[808_c1500]

Define "LD" and "HD".

GM has more than half-a-dozen variations on the brake systems, depending on model year, vehicle, and options:

JN/JB1
JN/JB3
JN/JB5
JN/JB6
JN/JB/JD7
JB/JD8 single rear wheel
JB/JD8 dual rear wheel
JF9
And probably more that I haven't listed.

As asked already--WHAT VEHICLE are you working on, and what brakes did it come with?

What brakes are you trying to install that use caliper brackets that aren't integrated into the steering knuckle?

My truck is a 1991 c1500 regular cab. It came with the 1.0" thickness rotors on the front. These are commonly referred to as the Light Duty (LD)" brakes. I believe after 1992 (?) all c1500 trucks came with "Heavy Duty (HD)" rotors which were 1.25" thick. I am trying to convert over to the 1.25" rotors and found that I need the later model calipers, spindles (I'll be using drop spindles for the associated later model truck), and of course the thicker rotors.

What I am not certain on is if there is a caliper bracket needed maybe I messed up and don't even need a bracket because you say it could be part of the knuckle/spindle? I'm an idiot and need to crawl under the truck again and look more closely.

 

[454cid]

My truck is a 1991 c1500 regular cab. It came with the 1.0" thickness rotors on the front. These are commonly referred to as the Light Duty (LD)" brakes. I believe after 1992 (?) all c1500 trucks came with "Heavy Duty (HD)" rotors which were 1.25" thick. I am trying to convert over to the 1.25" rotors and found that I need the later model calipers, spindles (I'll be using drop spindles for the associated later model truck), and of course the thicker rotors.

What I am not certain on is if there is a caliper bracket needed maybe I messed up and don't even need a bracket because you say it could be part of the knuckle/spindle? I'm an idiot and need to crawl under the truck again and look more closely.

Our brakes don't use a separate bracket. I have no idea if you'll need new spindles/knuckles, as I don't have a 1/2 ton, or a truck old enough to have those brakes.

 

[Schurkey]

I did that same conversion on my truck except that mine is a K1500 instead of C1500. The JN3 brakes it came with were replaced with JN5 brakes. This happened kinda-sorta by mistake. I had a damaged steering knuckle, and happened to select an extended-cab truck at the Treasure Yard as a donor. When I got the parts home, I realized they were bigger/better/stronger than the stuff on my truck.

You need:
Calipers
Rotors
HUBS OR STEERING KNUCKLES on 4WD vehicles because the spacing is different. When it was me, I replaced the entire steering knuckle on both sides. But all you have to have are the hubs/bearings assemblies.
But I don't know how that works on the 2WD vehicles. Maybe the new rotors drop onto the original steering knuckles spindles--maybe not.

There are no separate caliper brackets--they're built-into the steering knuckle.

You also must upgrade the master cylinder and brake booster. The larger pistons on the calipers require more fluid, so the master cylinder bore is larger; and the bigger master cylinder requires a bigger booster to power it.

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Regular-cab trucks came with the crappy JN3 brakes, extended-cab trucks had the much-better JN5 (JB5 on newer vehicles--I don't know when the designation changed.) So if you find an extended-cab truck in the Treasure Yard, that should be an adequate donor vehicle. That's what I did. I just grabbed "everything" on the front suspension except the torsion bars; and used what I needed. Once I figured out I could upgrade the brakes in addition to replacing my damaged steering knuckle, I went back and grabbed the master and booster.

'Course, now I have "extra" control arms and CV axles; and the Treasure Yard brake hoses were already shot. But I used the calipers, rotors, steering knuckles/hubs/bearings, shocks, booster--and someday I'll install the Treasure Yard bump-stops. Naturally, the calipers were pulled apart for cleaning and inspection, and I don't remember if I used the Treasure Yard master cylinder, or turned it in as a "core" on a rebuilt. Kinda think I used it.

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Mind you, I had already gotten rid of the HORRIBLE 254mm (10 inch) leading/trailing shoe drum brakes at the rear, by replacing the axle with one from a 6-lug K2500 having the much-better 11.x Duo-Servo rear drums. Upgrading the front and rear has given me the equivalent of JN/JB6 brakes.

 

[808_c1500]

@Schurkey - Do you have more info on the correct master cylinder and brake booster needed? are you saying I need them from either the extended cab or the later models but still pre-1999?

 

[Schurkey]

The JN3 master had a 1" bore with a larger (36mm?) third chamber at the rear. The JN/JB5 or 6 master is 1 1/8" bore, and and even-bigger (40mm) third chamber.

You must be registered for see images attach

The photo comparison of the power boosters is in my previous post.

As I said...I'd be looking in the Treasure Yards for these parts, but any parts store should be able to get them if they're not already in stock. Just ask for parts for a same-model-year extended-cab; or for JN/JB5 brakes.