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© 1998-2008 Joe Weaver

 

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Although the above described suspension is ideal from a ride and tire wear standpoint during highway driving, it is less than desirable, perhaps evenwp3174e6da.gif dangerous during tight cornering at moderate to higher speeds. During a turn the center of gravity is shifted away from the direction of the turn in proportion to the tightness of the turn and the speed of the car -- the tighter the turn and the higher the speed the more the center of gravity will be displaced. For example during a sharp right turn the center of gravity shifts to the left causing the effect of more weight on the left tires than on the right ones which makes the car lower on the left side, thus compressing the left suspension. This is often referred to as body sway. As can be seen in the illustration to the right, if the suspension was designed so that the wheels were always aligned with the frame of the car as discussed above, when the car sways in a turn, the wheels, while still aligned with the frame, are no longer aligned perpendicularly with the road since the frame of the car is now at an angle to the road. Thus less tire tread is in contact with the road and the tire is now starting to ride on the sidewall. With the car now lower on the left, and centrifugal force trying to force the car left,  and the left tire now starting to ride on its left sidewall, it is easy to see that the car could easily roll over to the left.

 

To avoid roll-overs, especially in performance and sports cars, engineers try to design the suspension so that the tire maintains better alignment with wp3836206f.gif the road during cornering, which allows the tire tread to have better or full road contact even while the car body/frame sways (a good stabilizer bar -- sometimes called sway bar -- will help a great deal with this, but even with a good stabilizer bar the the car will sway to one degree or another during cornering). To accomplish this, since the suspension does not know whether the wheel is forced upward into the wheel well due to a bump in the road or due to sway from a turn, the engineers must design the suspension so that the bottom of the wheel is forced out and/or the top of the wheel is forced in whenever the wheel is forced up, regardless of the reason. As can be seen in the illustration to the right, even though the frame of the car is at an angle to the road, the tire is still perpendicular with the road and the tire tread is in full contact with the road. Since the tread is in full road contact a roll-over is much less likely.

 

While the suspension described above would be ideal for a sports car, it would be less than desirable for a highway car since wp8a238cb3.gif every bump the car encounters would cause the wheel to change angle with the road as can be seen in the illustration to the right. This would cause more tire wear than a design that keeps the wheels parallel to the frame during bumps. In addition, in these circumstances it can be seen that less tire tread is in contact with the road while going over bumps. This is not usually a problem from a control standpoint during straight forward driving, but can cause problems on washboard roads or otherwise very uneven road surfaces. All of this extra movement also has effect on the steering linkages which can cause a change in the right/left angle of the wheel with each bump which is referred to as "bump steer".  Engineers need to take all this and more into account in their design. And, as mentioned previously, a great deal of compromise usually takes place between ride, tire wear, highway use, cornering/ maneuvering ability, and cost of building and maintaining the vehicle. On our Falcons (and early Mustangs), Ford engineers decided the cars would generally be used for highway and around town use and took a "better ride" and  "cost effective" approach in their design.

 

 

 

General Overview

The front suspension, steering and front brakes on any car are highly interrelated and it is difficult to discuss one without mentioning the other. However, I will make the main focus of this series of web pages the front suspension alone. While they will be mentioned briefly here, I will cover steering and brakes in greater depth in other web pages.

Designing a front suspension for any car involves far more than is immediately obvious. The rear suspension on our Falcons is fairly straight forward and simple. Generally, it only needs to take into account up and down travel. The front suspension, on the other hand, must take several movements and handling characteristics into account when engineers start to design it. The ideal front suspension would be able to handle bumps and poor road conditions while maintaining optimal tire tread contact with the road during cornering and maneuvering, while also keeping an accurate alignment between both front wheels and with the rear wheels during straight driving as well as during turns. All the while giving a velvet smooth ride. Designing such a suspension can be a very daunting task for engineers and often, as with most other things in life, it involves a large degree of compromise. For example, if you want a suspension that handles well, you usually need to put up with a rougher ride and less than optimal tire wear. Conversely, if you want a velvety smooth ride and great highway tire wear you generally need to put up with less than optimal handling. A true high performance suspension will almost always cost considerably more and be more complex than a suspension that will simply  get the job done . Unfortunately, from a handling standpoint, Ford engineers seem to have taken the  get the job done attitude when designing our Falcon (and early Mustang) suspension systems. While they perform adequately in every-day around town and highway driving, they leave some to be desired on challenging roads and driving conditions, or when emergency maneuvering is required. Being aware of this, Carol Shelby came up with some modifications to our basic Falcon/Mustang V8 suspension system that improved the handling. The "Shelby Mod" changes the operating geometry of the upper and lower control arms and spindle while at the same time lowering the front end, both of which improve handling while maneuvering. Again, however, this modification does bring with it some downsides. This "Shelby Mod" will be discussed herein. Since the subject of this web site is restoration of a Falcon Sprint V8, the front suspension discussed here is obviously from a Falcon with a V8 engine, which differs to some degree from the suspension on six cylinder Falcons. However, even though the actual components are different in looks and strength, there are the same components on either car and the operation is the same on both models. As a result the general principles discussed herein for the V8 suspension will also apply to the suspension on six cylinder Falcons.

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Illustration from the 1964 Falcon Shop Manual

Used pursuant to permission granted by Ford Motor Company

The front suspension on our Falcons consists of the following: An upper control arm (red arrow in photo), a spindle (that the wpc6c98b60.jpg brake assembly & wheel/tire is mounted to -- blue arrow), lower control arm (green arrow),  a spring (not shown in this photo but it sits on the spring perch on the upper control arm where the red arrow is pointing to), and a shock absorber (also not shown in this photo but it mounts to the spring perch and rides inside the spring coils). In addition there is a stabilizer bar (not shown, sometimes referred to as a "sway bar") and a strut rod (yellow arrow). In order for the system to perform properly, all mounting and pivot points must be tight with no real play. From the factory, all the bushings for the mounting of the suspension parts were made of rubber so as to help cushion road bumps, but this also tends to introduce some sloppiness to the suspension and steering. Harder bushings made of Polygraphite are available from high performance suppliers which will improve handling, but which will also add some harshness to the ride. When performing a  from the ground up restoration one will tend to replace the entire front suspension (except for the spindle, strut rods, and stabilizer bar) with all new or reproduction parts. However, if the old parts (upper & lower control arms, stabilizer bar, strut rods, spindles and springs) are in good shape they can be cleaned up and refurbished with new integral parts (i.e. new rubber bushings, new ball joints, new pivot arm, etc.) and reused. For those who use their Falcons as daily drivers and their general concern is about mechanical soundness rather than returning parts to their original condition and appearance, the integral parts can simply be replaced as necessary without performing the cosmetic and restoration processes one does during a restoration. The assembly shown in this photo is exactly what it would have looked like brand new in 1964.

 

 

 

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This shows the entire front suspension and steering after removal from the car. The individual parts are highlighted in the right photo: Upper control arms (red), spindles with brake assembly attached (dark blue), lower control arms (green), strut rods (yellow), stabilizer bar (pink), springs -- sitting on the ground instead of on the upper arms (light blue), and steering components (brown).

Operation & Modifications

As discussed above, engineers design a front suspension differently for a sports car than they do for a luxury highway car. If a car were only to be driven on the highway and never need to deal with any real cornering, engineers would design the suspension so that the tire would stay parallel to the frame of the car as the wheel is forced up and down with road bumps as can be seen in the three illustrations below.

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The above four photos are of my '64 Sprint's suspension which were taken during disassembly after the spring, strut rod, and stabilizer bar were removed and show different amounts of front suspension compression. By looking at all four photos it is easy to see that the wheel maintains a position almost parallel to the frame of the car in its complete movement from full extension to full compression As discussed above this is generally fine for around town and highway use, but does not perform as well in tight cornering situations such as unexpectedly tight freeway off ramps, higher speed roads through mountainous terrain, or for higher performance sporty cars.

 

The Shelby Modification

When Carol Shelby was working on the Shelby Mustang he recognized that the car didn't corner as well as it could due to the geometry of wp62e8d65e.gif the front suspension. Since a complete redesign of the suspension would be very expensive, Shelby elected to simply change the geometry of the upper control arm (see illustration to the right). By lowering the mounting of the upper control arm to the frame, the operating angle of the upper arm was changed. In the illustration to the right, if the black arm represents the original "at rest" angle of the arm, when the arm is moved upward (due to a bump or a sway) to the height of the red arm, the amount the outer edge of the arm is moved inward in minimal (value A). However, if the arm angle is changed such that the new "at rest" angle of the arm is represented by the red arm in the illustration, then when the arm is forced up (due to a bump or a sway) to the height of the blue arm, then the outer edge of the arm is moved inward a great deal more (value B). As discussed above, doing this will help the wheel maintain better tread contact with the road during turn sway. This is how Carol Shelby improved the handling of the famous Shelby Mustang. Fortunately for Falcon owners, the Shelby Mustang has essentially the same suspension as a '64 or '65 Falcon, so the principles are the same for the Falcon. (Note on the blue arm in the illustration the angle of the ball joint stud -- this has been a cause of concern with the basic Shelby Mod and will be discussed later herein.)

 

In addition to better suspension geometry and tire tread contact with the road, lowering the mounting of the upper control arm also results in lowering the front end. Since the upper arm will pivot on the spring perch, physically moving the attach point of wpa6ceecbc.gif the upper control arm to a lower position on the frame will result in the outer edge of the upper arm moving upwards in relation to the frame. Since the outer edge of the upper control arm remains at a relatively constant height from the road (assuming constant tire inflation), if the outer edge of the arm moves upward in relation to the road, then the frame must drop in relation to the road. Thus, the entire front end of the car lowers. This also improves handling and cornering since lowering the center of gravity will make a car inherently more stable in turns and have less tendency toward rolling over.

 

The Shelby Mod calls for the upper control arm mounts to be lowered 1" and moved aft (toward the rear of the car) 1/8" (see wp86c08670.gif illustration). If you plan to make this modification these measurements must be exact! I have heard there are sources for a template for this mod but I have been unable to locate one myself. While you can make the measurements yourself and mark them directly on your car frame and drill from there, I recommend using a pre-drilled steel or stainless steel template since even a small error in measurement or drilling can either make mounting the arm in the new holes impossible or if it fits in the holes but they are otherwise out of alignment you will introduce undesirable handling qualities. If this happens on only one side of the car then you will have one wheel behaving differently than the other. This can result in something as simple as premature tire wear to as severe as loss of control of the car. A template makes much more sense. I would recommend finding a good reputable machine shop or fabricator to make one for you. (Note: the illustration to the right is not to scale and is for illustration purposes only -- do not attempt to print this out and use it as an accurate template for drilling.)

 

As alluded to above, the Shelby Mod is not without its concerns. While it does make the car handle much better, there are at least three down sides. The first and probably least concern is that many places refuse to even attempt to align a car that has been lowered or has had the front end otherwise modified; however, after quite a few phone calls I was able to find two or three places that would, but they told me up front that it would be on an hourly rate instead of their usual flat rate for an wp3646d66d.jpg alignment since it usually takes more time to get an accurate alignment after such modifications. As discussed above, a second, more major concern with the Shelby mod is the new angle of the ball joint stud to the arm when the arm is at the full up stop (hitting the frame bumper). At this angle the ball joint is near the limit of its travel. Some have felt that with the ball joint operating at or near its limit that it could eventually be stressed to the point of breaking and snapping off, which, of course, would likely cause loss of control of the car. In answer, several companies have introduced a kit to remedy the ball joint angle problem. The kit replaces the ball joint on the upper arm with a heavier duty one and the kit has a wedge that fits in between the upper arm and the ball joint that improves the operating angle of the ball joint with the arm at the new steeper angle. This wedge tapers from zero on the inside of the ball joint to 5/8" on the outside of the ball joint (see photo at left). To make up for the 5/8" width of the wedge the upper arm is lowered an additional 5/8" or 1 5/8" total and still 1/8" aft. The place I bought mine from calls the kit a "Negative Wedge Camber" kit and installation of this kit will be covered later in this series.

 

The third concern with these mods, especially the Negative Wedge Camber kit, is that with the arm at a steeper angle at rest, the outside edge of the arm wpfe16221f.gif is now much closer to the frame bumper and bottoming out becomes a fairly common occurrence rather than an occasional one. As can be seen in the illustration to the right, if the black arm represents the original design "at rest" angle, the distance from the top of the arm to the frame bumper is a fair distance and is represented by value A. As discussed above, when the arm is mounted lower on the frame it will pivot on the spring perch and force the outside edge of the arm upward as represented by the red arm in the illustration. Note the new distance between the red arm and the frame bumper is now much less than the original stock location and is represented by value B. (As a note, the blue arm in the illustration is simply to illustrate what would happen if you raised the mounting point of the upper arm instead of lowering it and to further illustrate that arm will pivot on the spring perch mount when the mounting point of the arm is moved.) As mentioned, the Shelby Mod lowers the arm one inch, but the Negative Wedge Camber kit lowers it 1 5/8" which raises the outer edge of the arm even more than the Shelby Mod. If you choose to do either of these mods make sure your frame bumpers are in good shape or when you do bottom out (which you will) your upper control arms will be hitting the frame directly. Replacing the bumpers (which will be covered later) is not difficult if you are doing this mod since the springs need to be removed during this procedure anyway.  An additional consideration if you decide to do either of these mods is to install heavy duty stiffer shock absorbers which will help to minimize bottoming out, albeit at some expense in ride comfort.

Should you modify your Falcon (or Mustang) in this manner? As with most things it depends on what you plan to do with your car and how you normally drive it. If you plan to race the car (race track type racing that is, not just straight ahead drag racing) then the decision would probably be a definite yes. If you are a very cautious, only around town and normal highway driver, then the decision most likely would be no. If you are an aggressive assertive driver who likes to go fast and take corners and off ramps at a quick pace, or one who is required to drive canyon-type roads regularly, then one of these mods is worth considering. Neither of these mods is "permanent". Other than drilling two additional holes in each of the shock towers no modification to the car itself is required and both of the procedures are completely reversible (except for the two drilled holes on each side that would be left after reversal of the mod, and even then the holes could be welded up later if desired).

A side benefit of either of these mods is that of aesthetics. Few will dispute the fact that a '64 or '65 Falcon looks like it sits nose high. It has always looked a bit funny to me. The lowering that happens when you do either of these mods improves the looks of the car, in my opinion, 100% or more. The car looks more like what one would have expected it to look like from the factory. It should be noted, however, that if you are looking to lower the car simply for aesthetics, "drop spindles" are available. These "drop spindles" simply raise the mounting location of the actual bearing spindle on the spindle proper which lowers the front end of the car without altering the operating geometry of the front suspension.

 

This is the end of the Front Suspension Edition

Part One

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Feel free to save this page to your computer for your personal use and future reference--no other use is authorized without prior written permission from me. All illustrations from the 1964 or 1965 Falcon Shop Manuals used pursuant to permission granted by Ford Motor Company. Disclaimer: This site is not intended to instruct or teach anyone in proper or safe methods of working on or maintaining any type of vehicle or use of any tool and the author takes no responsibility for the use of the information contained herein.

If you have comments or suggestions, email me at joe@joesfalcon.com

 

Front

Suspension

Part 1

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