Product Summary

Universal Fit, 5.25" Centerline of Holes, Steel

  • Economical brake bracket kit for machined '49-'54 Chevy car spindles
  • Your spindles must be machined or use our reproduction forged spindles
  • Uses 9 1/4" Mustang rotors (available in Ford and GM bolt patterns) with common GM Metric calipers
  • Customer must supply their own rotors, calipers, brake hoses, and bearings/races to complete brake kit
  • Perfect starting point for light weight hot rod disc brake needs

Comes as a Kit

Key Specs

MFG. Part #91631950
BrandSpeedway Motors
Material TypeSteel
FinishZinc Plated

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Speedway Motors 91631950 Details

  • Works on all 1949-1954 GM car spindles that have been machined per the included instructions
  • For straight axle hot rod builds only, not for use on 1949-1954 GM car use
  • This kit will not work with stock steering arms, you must use aftermarket arms
  • Not for use with 1949-1954 GM truck spindles
  • Will work with Speedway Motors forged 1949-1954 GM car spindles with no machining required
  • Disc brake style wheels are required for proper caliper clearance when upgrading from drum brakes
  • Bracket kit designed to use customer supplied GM-style 1978-1988 "Metric"calipers
  • Includes brackets and mounting hardware only
  • Customer must also supply 1974-1978 Ford Mustang II 9-1/4 inch vented rotors
  • Kit requires inner and outer wheel bearings/races, 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 mounting hardware required. We have listened and this caliper bracket kit for 1978-1988 GM "Metric"calipers on 1949-1954 GM car 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.

These brackets are a direct fit to GM 1949-1954 car spindles but will not work with same year GM truck spindles. Machine work is required to resize the inner and outer bearing surfaces of the spindle pin, shorten the spindle pin, and rethread the retaining nut threads to properly use original spindles with this brake kit. An inner bearing and seal adapter (Speedway PN 91009300, Qty 2) will also be required to be welded in place to properly space the rotor. If you do not have the means to machine and weld your original spindles for your project, or you do not have any original spindles to use that is not a problem either, as we offer a beautiful set of forgedGM 1949-1954 car spindlesthat include new king pins with installed bushings that are already modified for our brake kits to help you finish your project. Because the original GM steering arms will not work for a straight axle conversion you will need to update to one of our GM spindlesteering armstoo, especially if you are using a drop axle, as aftermarket steering arms will save a lot of time and frustration in this regard.

This bracket kit will add 8-1/2 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 56-1/2 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 13-inch wheel; however, we recommend at least a 14-inch wheel with a 2.60-inch hub I.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 1978-1988 GM "Metric"calipers along with 1974-1978 Ford Mustang II 9.25-inch disc brake rotors. Standard replacement rotors use the Ford 5x4-1/2 wheel stud pattern with 1/2-20 thread studs, but we offer the same disc brake rotor in the GM 5x4-3/4 pattern with 7/16-20 thread studs as well. In addition, you will need a pair of inner and outer wheel bearings/races with seals, a spindle nut hardware kit, and a pair of wheel dust caps to complete the kit.

You will need to replace the inner and outer wheel bearing races installed in the disc brake rotors you purchase with the new races we specified above for this kit. While there are several methods to install the bearing races, 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.


Speedway Motors 91631950 Specifications

MFG. Part #91631950
BrandSpeedway Motors
Material TypeSteel
FinishZinc Plated
Centerline of Holes5.25"
Thread Pitch7/16"-20
Material Thickness.31"
Hardware IncludedYes
Sold in QuantityKit
NotesIncludes brackets and hardware only