Customer Appreciation Week 2026
Customer Appreciation Week 2026
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#91631903
Disc Brake Bracket Kit for 1937-48 Ford Spindles, Big GM Caliper
- Easily installs 11" rotors and '69-'77 mid-size GM single piston calipers to your '37-'48 Ford passenger car spindles or '37-'47 Ford pickup spindles
- No machine work needed on square back spindles (minor grinding on round back spindles), press on inner wheel bearing adapters included
$110.99
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Product Summary
7.00" Centerline of Holes, .31" Material Thickness
- Easily installs 11" rotors and '69-'77 mid-size GM single piston calipers to your '37-'48 Ford passenger car spindles or '37-'47 Ford pickup spindles
- No machine work needed on square back spindles (minor grinding on round back spindles), press on inner wheel bearing adapters included
- Bracket kit includes LH & RH caliper brackets, inner wheel bearings, bearing adapters, races, and hub seals along with caliper bracket hardware
- Same bracket kit as used in complete disc brake conversion kits 910-31942 and 910-31942D
- Works with bolt-on steering arms or stock arms
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Return PolicySpeedway Motors 91631903 Details
Speedway Motors 91631903 Details
- 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.
Charts
Guides & Documents
Speedway Motors 91631903 Specifications
Speedway Motors 91631903 Specifications
| KEY SPECS | |
|---|---|
| MFG. Part # | 91631903 |
| Brand | Speedway Motors |
| Material Type | Steel |
| Finish | Zinc Plated |
| GENERAL | |
| Centerline of Holes | 7.00" |
| Material Thickness | .31" |
| Hardware Included | Yes |
| Sold in Quantity | Kit |
| Notes | Includes brackets, hardware, seals, inner bearing cups and cones, and spacers. |
Ratings & Reviews
4.5
12 Reviews
Customers commend the disc brake mounting kit for its ease of installation and quality. Notably, the product suits various models, meeting users' needs effectively. Customers appreciate the kit's adaptability due to its provision for only the necessary parts. The kit is practical and delivers satisfactory performance. However, although instructions need improvement, customers' ability to troubleshoot testifies to the kit's usability and convenience. Some modification may be necessary for an optimal fit, reflecting the product's versatility. Notwithstanding, the kit receives consistent approval for its excellent functionality and quality.
Ratings & Reviews
4.5
12 Reviews
Customers commend the disc brake mounting kit for its ease of installation and quality. Notably, the product suits various models, meeting users' needs effectively. Customers appreciate the kit's adaptability due to its provision for only the necessary parts. The kit is practical and delivers satisfactory performance. However, although instructions need improvement, customers' ability to troubleshoot testifies to the kit's usability and convenience. Some modification may be necessary for an optimal fit, reflecting the product's versatility. Notwithstanding, the kit receives consistent approval for its excellent functionality and quality.
4.5
12 reviews
5
9
4
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3
1
2
1
1
0
Most Liked Positive Review
5.0
Good Product
They work Great but you do have to modify the spindle a bit.
Most Liked Negative Review
2.0
Good kit
The directions are bad, or I'm just stupid. The directions say to scribe a line and grind away the spindle to make the caliper fit, no mention of which way the bracket goes, I ended up grinding away on a brand new set of spindles (around the top of the king pin) only to realize I needed to flip the bracket around cause I had it on backwards and needed to grind away on the center section more towards the center.
Filter by Ratings
Yes I would buy again
5.0
3 years ago
Ted
Springfield Illinois.
Verified
Kit makes it easy to mount disc brakes on Ford spindles and proportioning valve balanced pressure between back drum and front disc. brakes.
Would Recommend
Nicely made
5.0
4 years ago
Eddies
Sauk Rapids MN
Verified
Everything I need. Already had the calipers and rotors. Able to get only what I needed.
Would Recommend
yes I woule buy this item again
5.0
8 years ago
Joe
Jax, AR
Verified
fit my needs perfectly
Would Recommend
Easy to install I would order again
5.0
9 years ago
Homeshopper
Gainesville ga
Verified
Used on 40 truck ratrod looks good
Would Recommend
Loved the ease of this kit
5.0
9 years ago
Calvin
Gainesville ga
Verified
Easy kit to use but I don't understand why no outer bearings
Would Recommend
I would buy this again
5.0
9 years ago
Tom
Edmond Oklahoma
Verified
I bought this kit. Very easy to install. Thanks you tech department for helping with installing. This kit looks so awsome
disk brake brackets
5.0
9 years ago
allworks
kern
Verified
look to be of good quality
Would Recommend
Good kit
2.0
10 years ago
Dirty 30 Model A
SF, SD
Verified
The directions are bad, or I'm just stupid. The directions say to scribe a line and grind away the spindle to make the caliper fit, no mention of which way the bracket goes, I ended up grinding away on a brand new set of spindles (around the top of the king pin) only to realize I needed to flip the bracket around cause I had it on backwards and needed to grind away on the center section more towards the center.
Would Not Recommend


This kits helps our street rod be safe w
5.0
11 years ago
Bajita
Laredo,Texas, usa
Verified
We will keep getting items from speedway for our project pickup.
Would Recommend
This is as pictured.
4.0
12 years ago
30ModelA
AZ
Verified
This is just what I needed for my 1930 model A, but needed some adjustments on one plate, and to fit the calipers from a 74 Chevy, I opened the ends by 100 thousands on each plate (50 thousands each side).
Would Recommend
Showing 10 of 12 reviews
Questions & Answers
Questions & Answers
4 Questions • 5 Answers
Slingshot steering arm Ok?
by Geo
• 8 years ago
1 answer
View Answer
What is the distance center to center of the caliper mounting holes?
by RJM
• 9 years ago
1 answer
View Answer
Will this bracket work with the calipers and rotor from your 91031909 kit? I bought that kit for the rotor bolt pattern but I would like to use this bracket instead of the one supplied.
by Jake
• 14 years ago
2 answers
View Answers
What is the hole measurement from center to center where the bracket mounts to the ford spindle.
by Max Marty
• 15 years ago
1 answer
View Answer
4 of 4 questions shown
Fitment
Fitment
1939-1948 Ford Deluxe
1941 Ford Model 11 A
1942 Ford Model 2 GA Special
1942 Ford Model 21 A Deluxe
1937 Ford Model 74
1937 Ford Model 78
1938 Ford Model 81 A
1938 Ford Model 82 A
1937-1947 Ford Sedan Delivery
1939-1940 Ford Standard
1941-1948 Ford Super Deluxe

