Product Summary

Front Position, 5 on 4.75" Bolt Pattern, Natural

  • Easily installs 11" rotors and '78-up GM "Metric" calipers to your '37-'48 Ford passenger car spindles or '37-'47 Ford pickup spindles for increased stopping power
  • No machine work needed on round back spindle. Minimal modification on square back spindles
  • Includes new rotors and semi-metallic pads, new bearings and seals, new caliper bolts and calipers, along with caliper mounting brackets, bushings, hardware, and hoses
  • GM 5 x 4-3/4 inch bolt pattern rotor with 2.78-inch hub OD
  • Works with bolt-on steering arms or stock arms

Comes as a Kit

Key Specs

Bolt Pattern5 on 4.75"
Rotor Diameter11 Inch
Rotor TypeVented
Caliper PistonsOne

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Speedway Motors 91031946 Details

  • Works on all 1937-1948 car and 1937-1947 truck spindles
  • Brake kit fits 1937-1941 round back style spindle with zero modifications
  • Also fits 1942-1948 square back style spindles with minor grinding of the spindle
  • This kit works with both cast in and bolt-on steering arms without issue
  • Works perfectly with Speedway Motors spindles which utilize 1937-1941 round back styling
  • Disc brake style wheels are required for proper caliper clearance when upgrading from drum brakes
  • Single 2-3/8-inch piston GM-style "Metric"calipers use commonly available replacement pads
  • Street friendly organic brake pad compound for long pad and rotor life
  • Performance brake pad upgrades available separately for those wanting increased stopping power
  • Includes everything you need to convert from drum to disc brakes with all new parts
  • 11-inch vented rotors create superior stopping power to drums, especially for heavier cars
  • Rotors feature standard GM 5 on 4-3/4 wheel stud bolt pattern

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 complete disc brake conversion kit options with everything you need 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!

Everything You Need and Everything New

Time is our most precious commodity and something that we cannot ever obtain more of. So why waste your valuable time scouring parts stores, junkyards, and Internet forums for DIY "piece it together"disc brake conversion solutions that will only cause you frustration in the garage and lead to further delays and parts searching? Speedway Motors, a leader in street rod parts, understands how important your time is, which is why we have done all the time sensitive research and parts sourcing to build the most complete Model A brake upgrade with our straight axle drum to disc brake conversion kit package for early Ford spindles that works, is easy to install, and does not require you to mortgage a kidney just to buy it!

Our disc brake kit features 11-inch vented rotors that are paired with the popular 1978-1988 GM "Metric"single piston disc brake caliper. These calipers use a 2.375 (2-3/8-inch) diameter piston and offer excellent stopping power in a floating caliper design. We include standard organic brake pads, but the caliper can be upgraded with any D154 performance pad of your liking should you desire a bit more pad "bite"in your system. Also included in our kit are new brake fluid hoses, bearings, seals, dust caps, and all mounting hardware. This brake kit will add 8-1/4 inches overall to your straight axle's center-to-center distance of your king pins. 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 hub I.D. that is lug-centric for proper clearance.

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 1937-1941 Ford "round back"spindles. If you have the later 1942-1948 "square back"Ford 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 forged Ford round back spindles that include new king pins with installed bushings to help you finish your project. Do not forget your steering arms too, especially if you are using a drop axle, as aftermarket steering arms will save a lot of time and frustration in this regard.

An Easy DIY Installation You Can Complete in Your Home Garage

We have included everything you will need in our Ford straight axle disc brakes conversion kit, right down to the spindle nut with retainer and cotter pin, new bearings, brake hydraulic hoses, and more. With such a complete kit you will have your hot rod's front brakes upgraded and back on the road in no time. 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 a bearing 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 included brake hoses feature a 7/16-20 thread banjo bolt with sealing washers for the caliper end and standard 3/8-24 inverted female flare for the frame end and your 3/16-inch brake hard line. These brake hoses are 18 inches in length and should work for most applications. However, if you need a different length brake hose to clear four-link style front ends or prefer an AN hose with through-frame fluid line adapters, we have plenty of brake hose options available to suit your specific build style and clearance requirements. 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!


Speedway Motors 91031946 Specifications

MFG. Part #91031946
BrandSpeedway Motors
Bolt Pattern5 on 4.75"
Rotor Diameter11 Inch
Rotor TypeVented
Caliper PistonsOne
Caliper FinishNatural
Parking Brake ProvisionNo
Minimum Recommended Wheel Diameter15 Inch
Rotor ShapeRound
Hardware IncludedYes
Front Rotor IncludedYes
Front Rotor Diameter11 Inch
Front Caliper IncludedYes
Front Caliper Piston Quantity1
Front Caliper FinishNatural
Rear Caliper IncludedNo
Front Spindles IncludedNo
Master Cylinder IncludedNo
Brake Booster IncludedNo
Brake Hoses IncludedYes
Rear Rotor IncludedNo
Bore Size2.375"
Bolt Hole Pattern5x4-3/4
Race IncludedYes
Rotor Thickness1.00"
Stud Diameter.44"
Stud Length.94"
Thread Pitch7/16"-20
Centerline of Holes5.50"
Sold in QuantityKit
NotesIncludes rotors, bearings and seals, calipers, pads, brake hoses, brake tabs, and caliper brackets.
Front Suspension TypeStraight Axle
Rotor Material TypeCast Iron
Brake Hose MaterialRubber