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Since 1952

Magnum Axle 2870 1942-48 Ford 4 Inch Dropped I-Beam Axle

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Magnum Axle 2870 1942-48 Ford 4 Inch Dropped I-Beam Axle

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Q & A

What's in the Box

Fits 1942-1948 Ford passenger cars and works with a stock length spring. These 4" dropped axles accept 1937-48 Ford spindles and have 2-3/8" axle bosses for use in conjunction with the 1942-48 Ford wishbones utilizing the 2-3/8" dimension.  As such, they are not applicable to the 2-1/4" batwings used for the 4-bar or radius rod type suspension.  I-beam axles feature a one-piece design cast from high-strength 65-45-12 annealed ductile iron.

Axle measures 50" between kingpins and 40-5⁄8" wide between perch bolt center. Plain finish.

Caster Angle Illustration (GIF)

Leaf Spring Measuring Guide (Link)

Item Details

50-3/8" king pin centers
40-5/8" perch centers

Customer Reviews

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Product Q&A

4 questions : 4 answers

1 answers

do i need anything else to install on a 1947 mercury coupe? (brackets, etc?) is there a difference from this and part number 913-35109?

November 27, 2012

do i need anything else to install on a 1947 mercury coupe? (brackets, etc?) is there a difference from this and part number 913-35109?


November 27, 2012
To verify fit you will need to take some basic measurements to eliminate problems such as incorrect spring length. The kingpin centerline to kingpin centerline is 50 3/8” and the perch centers where the wishbones attach are 40 5/8”. The perch centers need to be close to insure your existing spring will work. From that standpoint if measurements are correct then all your components should swap over. The other axle you referenced under part number 91335109 is a hot rod version for spring over the top and not in front of the axle like your vehicle currently has. It is designed to be used with hair pin radius rods and will not work with your original wishbones. Without considerable modifications and a lot more parts the last axle would not be recommended for your application.
1 answers


April 17, 2011



April 19, 2011
This axle p/n 7022870 is for a 1942-48 ford passenger car and accepts 1937-48 ford spindles and have 2 ¼ axle bosses with a king pin centers of 50” and 40 5/8 perch centers if these measurements align with your Mercury then the axle should work if your mercury has a original straight axle this should work for you.
1 answers

Can this axle be welded? as adding brackets and/or bat wings for RR?

Boston MA
May 22, 2011

Can this axle be welded? as adding brackets and/or bat wings for RR?


May 23, 2011
This I beam axle is for the 42-48 Ford cars and is made of annealed ductile iron. This is similar to cast but improved for strength and durability. Designed to work with perch bolts for mounting of shackles, wishbones, etc. it is not designed to be welded on. If you desire to weld a bracket or arm on the axle we suggest a certified welder accustomed to welding dissimilar metals.
1 answers

What length spring should be used?

September 23, 2015

What length spring should be used?


September 25, 2015
The correct spring to use is p/n 58020374L
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You may also be interested in:

Posies Super Slide 2037-40L 35-40 Ford Leaf Spring-2 In. Drop
(Part #58020374L)

Achieve a smoother, more comfortable ride with one of Posies Super Slide™ springs! The ends of the spring leaves of a Super Slide™ spring have a unique "dimple" shape that retains a moly-nylon button which works as a dry lubricant to stop leaf-to-leaf interference. This freedom from friction lets the spring move more easily, thereby giving a softer, quieter ride.

  • 35-3/4" Reverse Eye
  • Made in the U.S.A. from high grade tempered steel
  • Reversed eyes for a 2" drop compared to stock
  • Get your ride lower without sacrificing ride comfort
  • Plain steel finish

Posies Spring Application Chart (GIF)

Leaf Spring Measuring Guide (Link)  

Item Details

Use with axle 7022850 and/or with axle 702280 using "split" wishbones or 4-bar kit 91639108
1941-48 Ford Crossmember
(Part #91657104)
                        Lowers 1941-48's by 3 inches, with no other changes. Direct bolt-in. All mounting holes match original frame.

This is a spring mount crossmember for a 2" spring. It is 29-1/4" wide, end to end, or 27-5/8" wide, hole to hole.

Warning: This crossmember does not work with a Ford Flathead Motor - there is no place for original motor mounts.

Speedway 1928-1948 Ford Forged Spindles Only
(Part #91632104)

These Speedway spindles are a one piece, drop forged design constructed of high strength 4140 steel, which makes them superior to original components. These spindles are modeled after the '37-'41 round-back design and use '37-'41 Ford kingpins. They  fit Ford axles from '28-'48 and can be used with period correct drum brakes or modern Speedway Motors disc brakes, but will not work with hubs from '28-'36.

  • Uses 1937-1941 kingpin kit
  • For Ford axles 1928-1948
  • Will not work with 1928-1936 Hubs

Be sure to include our kingpin kit (91032121) with these spindles.

Spindles also available in kit form with Standard or Deluxe kingpins.

Spindle Identification Guide (GIF)

910-32121 Instructions (PDF)

910-32122 Instructions (PDF)

Speedway 2 Inch Wide Nylon Spring Shackle Kit, Zinc
(Part #91033324-ZINC)

Fits front or rear springs. All measurements are width of spring. All nylon bushed shackles are 1-1/2" shackle bolt center to shackle bolt center.

Bushings are included. Bushing O.D. is 3/4".


Leaf Spring Measuring Guide (Link)