Fastest Street Car Magazine Ford Galaxie

Be sure to pick up the August 2010 edition of Fastest Street Car Magazine and check out the tech article on Page 104. FSC installs a complete Spohn Performance rear suspension package on their 1966 Ford Galaxie project car.

They do a nice job covering the installation of the Ford Galaxie rear lower control arms, rear upper control arm and panhard bar track arm. To view a .pdf of the article click here.

Check out our full line up of suspension parts for the 1965-1974 Ford Galaxie at


Frequently Asked Questions about Polyurethane:

What is Polyurethane?

Polyurethane is a term used to describe a wide ranging family of elastomers (any compound exhibiting the characteristics of natural rubber; stretchy and elastic.). Poly meaning “many” and “urethane” the classification of the chemical structure. Polyurethane or urethane for short, is used as a solid cast material (bushings). Polyurethane can be as soft as a rubber band or as hard as plastic.

Is there a benefit over rubber?

Many advantages can be found over rubber. Depending on the formulation, urethane has a higher load-bearing capacity, greater tear strength, better compression set, greater abrasion resistance, tolerant to greases, oils and ozone and allows for more unique designs.

What’s the difference between rubber and urethane?

Rubber is the sap of trees found mostly in tropical climates. The sap is altered by mixtures of carbon (why it’s black) and mineral oils and various fillers. Polyurethane is completely chemical or man-made. Because rubber is a biodegradable product it is affected by ozone and will over time dry rot and degrade, while urethane will keep going and going.

How are urethanes rated?

There are approximately 20 categories in which urethanes are rated based on physical properties. The most common is hardness. Others include: abrasion resistance; compression set; tensile strength; tear strength; etc.

How are bushings manufactured?

Most all urethane bushings and mounts are manufactured from a two part liquid cast system. It basically constitutes a polyol or prepolymer and a curative. Much like epoxy, when the two are mixed together, they begin to harden and form a solid material. This mixture is poured into molds where it forms the bushing, mount or pad when it turns a hard solid.Other ways include injection of melted urethane pellets. This is accomplished much like plastic injection moldingwhere the pellets are melted and forced through a small opening into a closed mold cavity. Another way is to cast a solid round bar and then machine it to the desired shape.

Is there a difference between colors?

No. In most cases the color of the part has no relation to the hardness or other physical characteristic. The pigment used to color our urethane components is a paste-like product that is mixed into the urethane in quantities of about 2-4%. You have your choice between red or black colors.

Does urethane squeak?

In a word, no. Squeaking is caused by high frequency vibrations that can be heard rather than felt. It is usually caused by lack of lubrication, poor installation, incorrect part, urethane that may be too hard for the application. In sway bar mount applications, most squeaking comes from not cleaning the sway bar prior to installing the bushings and not using our “squeak proof” grease! Additionally, all our dynamic application bushings feature grooves or splines to hold in our waterproof, highly adhesive, high temperature and pressure grease.

Does urethane ride really hard (harsh)?

The original rubber bushing or mount was fairly soft which helped to attenuate noise and vibration that is generated by the tires and road surface. Increasing the hardness of the bushing either with harder rubber, urethane or even bronze, will allow more transmission of noise and vibration. Some manufacturers formulate the hardness and design to reduce this effect. A softer urethane bushing allows the vehicle to perform better without the harshness, even over the same hardness rubber piece.

Are all urethane bushings the same? Same material, same hardness?

No, no and no. Each manufacturer has their own idea as to the best way a bushing should be designed. We select materials based on physical performance and choose the right hardness for each application.

Can urethane be used for all types of vehicles?

Urethane can be formulated for anything from an MG to a Cadillac to a rough and ready 4X4 or lowered Honda street car.

Do I need special tools to install?

No. Installing urethane components requires no special tools. However, if unique tools and equipment are required due to the type of vehicle, you will need them in order to do a correct job.

Will I need to reuse my metal shells?

We have a complete shell program for most popular applications. Many of our control arm bushing kits come complete with a new shell. On some applications you will need to reuse the metal shell, so be very careful when removing it from the vehicle. The shells themselves are not a replacement item. If you do damage a shell during the removal procedure, you have a few choices: Obtain a used piece from a repair shop or salvage yard or purchase a new shell with rubber bushings from your local parts store.

Spohn Performance offers a complete selection of direct fit polyurethane bushings for a variety of car and truck applications as well as performance suspension components. Visit us on the web at

Tech Article: Suspension Alignment Settings Explained

Posted by Spohn Performance | 04/12/10 | Tagged 4. Technical Articles

In our new series of technical articles we will address some of the most common questions our technical support group receives on a regular basis. Please leave your comments below this post with any suggestions you’d like to see us cover in future technical articles. These articles are being written to benefit you, so your input is greatly appreciated. Remember that you can always find our technical resources in the future very easily through our searchable online FAQ/Knowledgebase located at

Tech Article: Suspension Alignment Settings Explained


Front End Camber Explained

Camber is the tilting of the wheels from the vertical when viewed from the front of the vehicle. When the wheels tilt outward at the top, the caster is positive (+). When the wheels tilt inward at the top, the camber is negative (-). The amount of tilt is measured in degrees from the vertical. Camber settings influence the directional control and the tire wear.

Too much positive camber will result in premature wear on the outside of the tire and cause excessive wear on the suspension parts. Too much negative camber will result in premature wear on the inside of the tire and cause excessive wear on the suspension parts.

Unequal side-to-side camber of 1 degree or more will cause the vehicle to pull or lead to the side with the most positive camber.


Front Caster Explained

Caster is the tilting of the uppermost point of the steering axis either forward or backward, when viewed from the side of the vehicle. A backward tilt is positive (+) and a forward tilt is negative (-). Caster influences directional control of the steering but does not affect the tire wear. Caster is affected by the vehicle height, therefore it is important to keep the body at its designed height, or correct the caster setting when altering the vehicle’s height. Overloading a vehicle or a weak or sagging rear spring will affect caster. When the rear of the vehicle is lower than it’s factory ride height, the front suspension moves to a more positive caster. If the rear of the vehicle is higher than it’s factory ride height, the front suspension moves to a less positive caster.

With too little positive caster, steering may be touchy at high speed and wheel returnability may be diminished when coming out of a turn. If one wheel has more positive caster than the other, that wheel will pull toward the center of the vehicle. This condition will cause the vehicle to pull or lead to the side with the least amount of positive caster.

Lead / Pull:

At a constant highway speed on a typical straight road, lead/pull is the amount of effort required at the steering wheel to maintain the vehicle’s straight path. Vehicles will tend to lead/pull in the direction of the road slope as part of normal operation. Lead/pull is usually caused by the following factors:

  • Road slope
  • Variability in tire construction
  • Wheel alignment (front cross caster and camber)
  • Unbalanced steering gear
  • Electronic Power Steering (EPS) steering position and torque sensors not calibrated correctly, if equipped.

Memory Steer:

Memory steer is when the vehicle wants to lead or pull in the direction the driver previously turned the vehicle. Additionally, after turning in the opposite direction, the vehicle will want to lead or pull in that direction.

Scrub Radius:

Ideally, the scrub radius is as small as possible. Noramlly the SAI angle and the centerline of the tire and the wheel intersect below the road surface, causing a positive (+) scrub radius. With struts, the SAI angle is much larger than the long arm/short arm type of front suspension. This allows the SAI angle to intersect the camber angle above the road surface, forming a negative (-) scrub radius. The smaller the scrub radius, the better the directional stability. Installing aftermarket wheels that have additional offset will dramatically increase the scrub radius. The newly installed wheels may cause the centerline of the tires to move further away from the spindle. This will increase the scrub radius.

A large amount of scrub radius can cause severe shimmy after hitting a bump. Four wheel drive vehicles with large tires use a steering damper to compensate for an increased scrub radius. Scrub radius is not directly measurable by the conventional methods. Scrub radius is projected geometrically by engineers during the design phase of the vehicle’s suspension system.


Setback applies to both the front and rear wheels. Setback is the amount that one wheel may be aligned behind the other wheel. Setback may be the result of a road hazard or a collision. The first clue is a caster difference from side-to-side of more than 1 degree.

Thrust Angles:

Thrust Angles Explained

The front wheels aim or steer the vehicle. The rear wheels control tracking. This tracking action relates to the thrust angle. The thrust angle is the path that the rear wheels take. Ideally, the thrust angle is geometrically aligned with the body centerline.

In the above illustration, toe-in is shown on the left rear wheel, moving the thrust line off center. The resulting deviation from the centerline is the thrust angle.

If the thrust angle is not set properly the vehicle may “dog track”, the steering wheel may not be centered or it could be perceived as a bent axle. Thrust angle can be checked during a wheel alignment.

Positive thrust angle means the thrust line is pointing to the right hand side of the vehicle. Negative thrust angle means the thrust line is pointing to the left hand side of the vehicle.

If the thrust angle is out of specification, moving the axle to body relationship will change the thrust angle reading. If the vehicle is out in the positive (+) direction, moving the right hand side forward and/or the left hand side rearward will move the thrust angle towards 0 degrees. If the vehicle is out in the negative (-) direction, moving the right hand side rearward and/or the left hand side forward will move the thrust angle towards zero degrees.


Toe Settings Explained

Toe is a measurement of how much the front and/or rear wheels are turned in or out from a straight-ahead position. When the wheels are turned in, toe is positive (+). When the wheels are turned out, toe is negative (-). The actual amount of toe is normally only a fraction of a degree. The purpose of toe is to ensure that the wheels roll parallel.

Sample Front End Alignment Specifications:

2010 Chevrolet Camaro SS

Camber: -0.8* (+/- 0.75*)
Cross Camber: (L-R): 0.00* (+/- 0.75*)
Caster: 6.6* (+/- 0.75*)
Cross Caster: 0.00* (+/- 0.75*)
Total Toe: +0.20* (+/- 0.20*)
Steering Wheel Angle: 0.00* (+/- 3.50*)