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Wilwood Superlite 4R Rear Disc Brake Kit - 12.88 inch Rotors, 76-77 Ford Bronco SKU: 140-13323N
Wilwood Superlite 4R Rear Disc Brake Kit - 12.88 inch Rotors, 76-77 Ford Bronco
Full description
Wilwood Rear Disc Brake Kit w/Parking Brake | 76-77 Bronco
For Large Bearing Axles with 11" x 2-1/4" Rear Drums — Requires 17"+ Wheels
Upgrade your Early Bronco rear brakes with the Wilwood Superlite 4R Big Rear Disc Brake Kit. This kit is perfect for high-performance builds and classic restorations alike. Whether you're hitting the trail or the highway, this system delivers powerful, balanced braking to complement your front big brake upgrade.
This kit features Wilwood's powerful four-piston Forged Narrow Superlite calipers, paired with large 12.88" rotors and high-performance BP-10 pads. It includes a neatly integrated internal parking brake system for clean looks and reliable hold. Plus, you can personalize your setup with optional caliper finishes and rotor designs to match your Bronco’s style.
Why Axle Identification Matters:
Before ordering, it’s critical to identify which rear axle you have. This ensures perfect fitment for your Wilwood brake kit! There were several rear axle options in the early Broncos. This kit is for a 1976-77 Ford Bronco large bearing axle with 11" x 2-1/4" rear drums.
Here’s how to check:
Step 1: Check for Large vs. Small Bearing
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Small Bearing: Smooth transition from axle tube to backing plate. If you measure the bearing diameter, it’s about 2.835" (just under 3").
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Large Bearing: Noticeable bulge where the axle tube meets the backing plate. Bearing diameter is about 3.150" (just over 3").
✔ This kit is for Large Bearing axles only.
Step 2: Check Your Brake Drum Size
Large bearing axles came in two versions:
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Medium Duty (1974–75): 10" brake drum — Not compatible, See #140-13664.
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66–75 Large Bearing: 11" x 1-3/4" brake drum — Not compatible, See # 140-13734.
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76–77 Large Bearing: Uses a wider 11" x 2-1/4" drum — This is the setup for this kit!
Quick Summary:
| Axle Type | Brake Drum Size | Fits This Kit? |
|---|---|---|
| Small Bearing | 10" | ❌ No |
| Medium Duty Large Bearing (74-75) | 10" | ❌ No |
| Large Bearing (66-75) | 11" x 1-3/4" | ❌ No |
| Large Bearing (76-77) | 11" x 2-1/4" | ✅ Yes |
Need more help - check the "Specs" section below for more info or give us a call. Our team is here to help!
Why You'll Love This Kit:
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Serious Stopping Power: 4-piston calipers and vented rotors keep your Bronco in control.
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Clean, Integrated Parking Brake: Hidden shoe system with strong holding power.
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Perfect for Custom Builds: Ready to match your high-performance front brakes.
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Customizable Options: Choose caliper finishes and rotor designs to suit your build.
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Precision Fit: Designed specifically for 76-77 Broncos with large bearing axles and 11" x 2-1/4" drums.
Important Fitment Note: This brake kit requires 17-inch or larger wheels for proper clearance.
Specifications:
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Calipers: 4-piston Superlite
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Rotors: 12.88" diameter, vented
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Mount Type: Radial mount
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Wheel Requirement: 17" or larger wheels
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Axle Flange Offset: 2.36"
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Parking Brake: Internal mechanical shoe
CAREFULLY CHOOSE THE RIGHT KIT
Let's cover some basics. The rear end refers to the entire rear axle assembly. The different parts of the rear end are the brakes, axles, axle housing, and the third member. The most common question we are asked is "How do I tell if I have a large or small bearing rear axle?" You can easily identify if you have large or small bearing axles by examining the ends of the axle housing.Photo 1 shows a small bearing axle housing. If you look close at the housing right where it meets the backing plate, there is no noticeable size increase where the axle bearing pocket is. Photo 2 and 3 show a large bearing axle housing and you can see a noticeable size increase where the axle housing meets the backing plate. If you have loose axles laying around, you can simply measure the outside diameter of the bearing. The small are 2.835" or just under 3" and the large are 3.150" or just over 3".
There are 4 different sets of rear axles that would have come stock in 66-77 Broncos. The original applications are as follows:
1. 66-75 small bearing,
2. 66-75 large bearing,
3. 74-75 medium duty large bearing, and
4. 76-77 large bearing.
Each of these sets have a driver and a passenger side axle. Each of these sets use corresponding backing plates and brake drums. The backing plates and drums are particular to each set and are not interchangeable with the exception of the 66-75 small bearing and 74-75 medium duty large bearing using the same brake drum.
So, how can you identify which large bearing set you have? it can be narrowed down this way: The inside diameter of the Bronco rear brake drum is approximately 10" or 11". So, if you have a large bearing and a 10" brake drum, you have what we call a 74-75 medium duty setup. That leaves us with the 66-75 large and 76-77 large. Both use an 11" brake drum. The 66-75 uses a narrower drum and corresponding brake shoes. We identify this as 11 X 1 3/4". The 76-77 uses an 11 X 2 1/4" drum and shoe. Note the difference in the backing plates * in photos 2 and 3. Photo 2 shows a 66-75 large bearing with 11 X 1 3/4" brakes. Photo 3 shows a 76-77 with 11 X 2 1/4" brakes. If you look close you can see the backing plate of the 66-75 appears wider. Please note that all of the original axle sets were 28 spline. See Photo 4. With an increase in spline count comes an increase in outside diameter of the axle and so you get an increase of strength. A very common upgrade is to install a set of 31 spline axles. All that is necessary to do this is a set of axles and a new differential and we would recommend a third member rebuild kit. 35 spline axles are another step up in the strength department but usually require a new differential housing. The 35 spline axle is common for the extreme rock crawlers.
The third member, also known as the differential housing, hogs head, and chunk, holds the differential, ring and pinion gears, and bearings. This is the part that bolts into the center of the axle housing. See photo 5. You have three choices of gear ratios that were stock. They would be 3.50 which is the most common, 4.11 and 4.56. There are many other ratios that can be used as well. The differential refers to the ring gear carrier and came stock either open or limited slip "posi" type. There are numerous upgrades such as Detroit Locker, ARB air locker, electric lockers, etc.
Instruction 1
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