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Steering Box Info

Steering Box Ratios (from Dan Jones, m203253@ws2200.mdc.com)

------------------------------------------------------------

 Here's the info I promised on steering box codes. The chart was taken from the March 1993 issue of Mustang & Fords ("Steering Steady").

 I've also included some of my steering notes that may be of interest.

                                          Cheers, Dan Jones

Ford Steering Box Codes

 Long Shaft Boxes (HCC & HCA Prefix):

 Short Shaft Boxes (SMA & SMB Prefix):

* indicates special high performance applications such as GT, Boss, Mach 1, etc.

 - The steering boxes are identified by a tag attached to one of the steering box cover bolts.  Use the number of turns to verify ratio.

 - Early (64-70) Mustang power steering is of the non-integral, add-on assist type with a separate power cylinder and control valve.  There is no difference between the manual and power steering boxes, except for ratios. The fast ratio manual steering box is the same as the power steering box.

 - 1964-1970 Mustangs have two basic ratios:
1. 19.9:1 ratio, 4 5/8 turns lock-to-lock, used on all low performance manual steering cars.
2. 16:1 ratio, 3 3/4, used on all cars with power steering and on manual steering high performance cars (Shelbys, Bosses, GTs, Mach 1s, etc), optional?

 - 1964-1970 Mustangs have two shaft styles:
1. 1964 to early 1967 boxes are the long shaft style where the box and steering shaft form one unit.  There is no coupler, the shaft is one piece from the box to the steering wheel.
2. Late 1967 through 1970 are the short shaft style.  There is a couple between the box and the steering shaft.  This change was made to meet Federal Motor Vehicle Safety Standards (FMVSS) which required a collapsible steering column.  Sector shafts were either 1" or 1 1/8". There are four different '67-'70 short worms used (2 ratios, 2 sector shaft diameters).

 - The Ford steering box is internally (external housings are not shared) a GM Saginaw manual steering box.  Since the Ford steering boxes use Saginaw internals, many GM parts interchange and some can provide performance upgrades.

 - 1971-73 Mustangs with power steering use either a Saginaw or Ford integral power steering box.

 - 1971-1973 manual boxes used a differently shaped external casting with a 1 1/8" sector and 24:1 ratio.  There also used a slightly different frame mounting bolt pattern they won't interchange with 67-70 models.

 - The 71-73 worm and rack assembly is identical to the 70-82 Corvette piece.  The Corvette sector (GM P/N 7812838) and worm (GM P/N 7812942) will fit in 71-73 1 1/8" boxes if a new groove is scribed into the Ford pitman arm that corresponds with the index on the GM sector and if a Corvette coupler (GM P/N 7806391) is substituted for the Ford rag joint.  Provides 16:1 ratio rather 24:1 ratio.  Also the flat Ford-style sector shaft cover can be replaced with the 'Vette cover (GM P/N 7806748) which has an integral bushing that lends additional support to the sector shaft.  The outer rim of the bushing support must be turned down to fit in the Ford box.

 - In addition to using a fast ratio steering box, you can increase the steering rate by adding a Shelby quick steer kit (longer idler and pitman arms - What cars did these come from?).

Related Magazine Articles:

1. "Steering Steady", Mustang & Fords, March 1993
The article covers a Global West steering box rebuild.  Side articles explain how a recirculating ball steering box operates and provide a method for adjusting your steering box preload.  Also presented is a guide to identifying Ford steering box codes.

2. "Steerage Class", Mustang, February 1988
This article also covers a Global West steering box rebuild and provides a list of steering box part numbers that are still available (as of June 1987) from Ford.  The article also lists some parts interchanges and upgrades using GM parts.

3. "Pressure Sensitive", Super Ford, September 1993
This article describes a simple way to increase power steering feel on vehicles equipped with Ford's non-integral power steering.  The approach is to splice an adjustable valve in between the supply and return lines.  Adjusting the valve varies the amount of boost, increasing steering feel.