Back when the street rod industry was beginning to grow, front four-bar kits with Mustang steering for pre-1935 Fords were extremely popular. Although the Vega cross-steering arrangement ultimately came to be preferred, there are still many side-delivery 1965-70 Mustang boxes in use—and some of them are due to be replaced.

There were two basic styles of Mustang steering: the 1965-66 design, which had a one-piece steering shaft from the box to the wheel; and the late 1967-70 version with a short, splined steering shaft connected to a rag joint at the bottom of the column. (This change was made to comply with safety standards that required a collapsible steering column.) Sector shafts were either 1 or 1-1/8 inches. In addition, these steering boxes were produced with two steering ratios. The 19.9:1 (usually referred to as 20:1) with 4-5/8 turns lock to lock was used on low performance manual steering cars. A 16:1 ratio with 3-3/4 turns lock to lock was used on cars with power steering (the power steering was the linkage type rather than the integral style) and high-performance manual steering applications.

Understanding Steering Ratios

Our friends at Borgeson Universal Company explain steering ratios this way: "It's the relationship between input motion and output motion on the steering box. The ratio is expressed as 24:1, 22:1, 16:1, and so on. For example, in a 24:1 ratio box, the Pitman shaft rotates 1 degree for every 24 degrees of input shaft rotation. The higher the first number, the more input shaft rotation is required to get the same amount of output shaft rotation. Dividing the first number in the ratio by 4, gives the number of turns lock to lock.

"Steering speed can be adjusted by box ratio or Pitman arm length. The longer the Pitman arm, the quicker the steering will be. That is, a longer Pitman arm means less steering wheel movement is required to produce the same amount of front wheel movement. So if you are looking to speed up or slow down the steering, changing the Pitman arm is an easy way to do it.

"But keep in mind, a quicker ratio steering box will have fewer turns of the steering wheel lock-to-lock but this does have an effect on driveability. In manual steering applications a quick-ratio box, while enhancing the way the car feels at speed, will greatly increase steering effort during low speed and parking."

A Case in Point

Recently a good friend bought a 1932 Ford pickup with a Mustang box. The chassis was in excellent condition but the steering was in need of attention. An early style Mustang box had been used, the steering shaft had been cut off, and a U-joint and been pinned and welded in place. Not unusual in the 1970s, today there are better options to hook up steering columns that are readily available and safer—namely splined and double-D–style components.

Although Mustang boxes were popular, the real disadvantage to them is that in some cases interference between the left front wheel and the draglink increases the turning circle in that direction. However, when correctly installed, this style steering works quite well. Considering that fact, and to limit the amount of modification that would be needed to retrofit Vega-style cross steering, in this case the decision was made to fix what was there.

While one end of the worn-out steering U-joint was welded to the steering gear, the steering column end was a 1-inch DD that slipped in place and was secured with set screws, one of which went all the way through one side of the steering shaft and seated against the far inside surface of the U-joint. That meant the steering column could easily be used, but there was another concern. We wanted to use some sort of slip joint/isolator between the steering gear and the column. With the steering box mounted solidly to the frame and the steering column mounted to the body any flex between the two can put a strain on components and transfer vibration. That's also the reason manufacturers began to use rag joints between the steering gear and steering shaft.

To solve all the pickup's problems it was decided to install a reconditioned Mustang steering box from Borgeson Universal Company so a 1967-70 style, 16:1 box with a 1-inch sector shaft was procured (the 1-inch sector shaft allowed the existing Pitman arm to be reused). In addition a Borgeson Universal Company combination U-joint and vibration reducer was chosen for connect the box and the column. The result was better steering and a safer street rod.

SOURCE
Borgeson Universal
91 Technology Park Drive
Torrington
CT  06790
860-482-8283
https://www.borgeson.com