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Disc Brake Bracket Kit for 1937-48 Ford Spindles, Big GM Caliper
Disc Brake Bracket Kit for 1937-48 Ford Spindles, Big GM Caliper

Disc Brake Bracket Kit for 1937-48 Ford Spindles, Big GM Caliper

7.00" Centerline of Holes, .31" Material Thickness, Steel, Zinc Plated, Hardware Included

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Disc Brake Bracket Kit for 1937-48 Ford Spindles, Big GM Caliper
Disc Brake Bracket Kit for 1937-48 Ford Spindles, Big GM Caliper
Disc Brake Bracket Kit for 1937-48 Ford Spindles, Big GM Caliper
Disc Brake Bracket Kit for 1937-48 Ford Spindles, Big GM Caliper
Disc Brake Bracket Kit for 1937-48 Ford Spindles, Big GM Caliper
Disc Brake Bracket Kit for 1937-48 Ford Spindles, Big GM Caliper
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Part # 91631903
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MFG. Part #:
Centerline of Holes:
Material Thickness:
Material Type:
Zinc Plated
Hardware Included:
Sold in Quantity:
Includes brackets, hardware, seals, inner bearing cups and cones, and spacers.


  • Works on all 1937-1948 car and 1937-1947 truck spindles
  • Brackets fit 1942-1948 square back style spindles with zero modifications
  • Also fits 1937-1941 round back style spindle with minor grinding of the spindle
  • This kit works with both cast in and bolt-on steering arms without issue
  • Will work with Speedway Motors spindles if clearance is provided
  • Disc brake style wheels are required for proper caliper clearance when upgrading from drum brakes
  • Bracket kit designed to use customer supplied GM-style 1969-1977 "Midsize"calipers
  • Includes brackets, inner bearing races and bearings, spindle adapters, and mounting hardware
  • Customer must also supply 1969-1972 GM 11-inch vented rotors
  • Kit requires outer wheel bearings, spindle nut kit, and dust caps to complete installation
  • Brake hydraulic hoses and fittings not included

Add Disc Brakes to Your Straight Axle Hot Rod with Bolt-On Ease

We understand that the traditional straight axle hot rodder is going to want to keep the look of early Ford brakes and their finned drums on their Model A or 32 roadster if at all possible. However, we know there is a large base of builders that want their classic looks but with modern handling, braking, and comfort. Face it, if your hot rod is a miserable ride that will not stop you are not going to want to drive it. We get it. For those enthusiasts, a small amount of leeway in their hot rod's traditional looks is acceptable to make it a fun long-distance cruiser that can be safely operated in today's traffic. One of the top safety upgrades we see is updating these straight axle hot rods with front disc brake kits. Speedway Motors offers several disc brake conversion kit options to get the job done on your spindles, and if you do not have spindles for your hot rod straight axle setup, well, we have those as well!

Just The Basics to Make Your Brake Conversion Happen

Most of our straight axle disc brake kits ship complete with everything you need, but we know a lot of our customers have spare parts from previous builds or wish to make their disc brake upgrade stand out with custom calipers and rotors from alternative sources. Many have asked us to create a basic conversion kit with just the caliper adapter bracket and conversion hardware required. We have listened and this caliper bracket kit for 1969-1977 GM "Midsize"calipers on 1937-1948 Ford spindles is just the ticket. Why buy a complete kit when you are planning to upgrade to an aluminum caliper and a braided Teflon -3 AN brake hose for example? You are buying parts you will never use just to sit on a shelf in your garage forever. With our bracket kit you get just the specialized conversion parts you need and nothing more, leaving the rotor, caliper, brake hose, and so on up to you, saving you money.

The caliper mounting brackets provided fit '37-'48 Ford spindles and are quite stout to prevent any caliper flex during hard braking. They are direct fit to the 1942-1948 "square back"Ford spindles. If you have the earlier 1937-1941 Ford "round back"spindles this kit will still fit with some minor clearance work to the spindle to allow the caliper mounting bracket to properly seat to the spindle. And if you do not have any spindles at all for your project that is not a problem either, as we offer a beautiful set of forgedFord round back spindlesthat include new king pins with installed bushings to help you finish your project. Do not forget yoursteering armstoo, especially if you are using a drop axle, as aftermarket steering arms will save a lot of time and frustration in this regard. Also included in the kit is our machined spindle adapter, and conversion inner wheel bearing and race with spacers, plus mounting hardware for the caliper mounting bracket.

This bracket kit will add 8-1/4 inches overall to your straight axle's center-to-center distance of your king pins when used with the specified rotors and calipers. Meaning, if you are running a 48-inch axle, your overall width once installed will be 56-1/4 inches. This may be more or less than your current setup depending upon current brake package and wheel spacers. This kit requires a minimum of a 14-inch "disc brake" wheel, however we recommend a 15-inch wheel with a 2.80-inch hubI.D.that is lug-centric for proper clearance.

An Easy DIY Installation You Can Complete in Your Home Garage

To complete your installation, you will need the previously mentioned 1969-1977 GM "Midsize"calipers along with 1969-1972 GM 11-inch disc brake rotors. Standard replacement rotors use the GM 5x4-3/4 wheel stud pattern with GM spec 7/16-20 thread studs. In addition, you will need a pair ofouter wheel bearings, aspindle nut hardware kit,and a pair ofwheel dust caps.

The included inner bearing adapter that fits over the spindle requires a small press for installation (or you can heat it up to allow expansion and slip it on that way) and you will need to replace the inner bearing race in the included disc brake rotor with the new race provided. While there are several methods to install the supplied bearing race, the easiest way is with abearing race and seal driver. It is a very handy tool for removing and installing bearing races and bearing seals. Everything else in the kit will install with traditional hand tools any hot rodder will surely have in their toolbox.

The final piece of the installation puzzle will be your caliper's brake hoses. This kit does not include hoses because we offer so many options in SAE 7/16-20 fluid port threads. You will need to determine your overall hose length needed before you can order the correct brake hose for your installation. We offer plenty ofbrake hose optionsavailable to suit your specific build style and clearance requirements. Speedway Motors also offersthrough-frame fluid line adaptersthat may aid in routing your caliper fluid lines while providing a cleaner look that keeps your brake hoses away from your straight axle's front suspension.

Adding disc brakes to your pre-war straight axle hot rod has never been easier thanks to Speedway Motors and the value you get for your money means more budget left over for those T-bucket parts you need! Ordering our brake bracket kit provides just the essentials for your straight axle disc brake conversion and allows you to customize your front disc brake upgrade as you wish without wasting money or parts.


916-31903 Instructions (PDF)

Early Ford and GM Spindle Identification Chart (GIF)

Important Messages

  • Get FREE shipping when your order includes this item and exceeds $99! Ground shipping only in the contiguous US.
Some parts are not legal for use in California or other states with similar laws/regulations

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