Please check the box next to the springs you need and quantity to either 2 or 4.
qty 4 will will send you 2 of each of the springs checked. If you need something
different please let us know in the special instructions during checkout.
For Help selecting your spring package email or call for assistance.
Technical Information on
Street Rod Suspensions
The following information is a general overview regarding the proper shock and
spring selection for your Street Rod. It is intended to offer a technical base from
which to design, redesign or troubleshoot suspensions. No matter how much you
think your car is like your buddy’s car, there will always exist differences in
geometry, weight, torque, horsepower, and more. Although recommendations
based off similar vehicles could get you close to what you want, we are confident
that by following the guidelines below and/or speaking with QA1 technicians, your
rod will ride as smooth as it looks.
Whether you are building a new car or updating your suspension, the chassis
design is the key to a solid foundation for your rod. Vehicles that are designed
with proper suspension geometry and a bind free suspension will tend to ride
and handle better for years to come. If you are in the process of updating your
suspension, take the time to inspect the entire suspension. At a minimum, you
should check the following key items: ball joints, tie rods, suspension bushings,
and all connecting points on the chassis. With today’s technology in shock
absorbers and coil springs, there is no reason for your ride to be uncomfortable.
At QA1, we have specially engineered shocks and springs to give you the ultimate
ride in rodding. With a little help and information from you, we can get your rod
driving and riding exactly as you want it. As a guide to choosing the correct
shock and/or coil-over spring, follow the steps below, according to your correct
application.
For non-coil-over suspensions, follow steps 1, 2, and 5
For independent coil-over suspensions, follow steps 1-7
For ladder bar and four-link suspensions, follow steps 1-7
1
Measure the lengths of the existing shock as fully compressed, fully extended
and ideal ride-height from the center of eyelet on the top and bottom. Also
measure your suspension travel. (See page 73 for instructions on these
measurements.)
2
Measure the bolt size that is used on the existing top and bottom shock mount.
3
Measure the angle of the existing shock versus the vertical.
4
Weigh the front half and the rear half of the car. This step is critical to
determine what spring weight should be used to provide the ideal ride quality.*
5
Reference pages 86 to 95 to determine the shocks that will fit your
application best.
6
Choose the appropriate spring length according to the application guide on
page 99.
7
Determine the motion ratio (see page 76) and choose spring rate accordingly.*
* If you are unable to gather this information, refer to the quick reference chart
that indicates "average car weights" found on page 99.
Mustang II Front-End Suspensions
With Mustang II style front-ends growing in popularity, the number of
manufacturers of these systems is also growing. There are several variations on
the design because of this, so it is extremely important to conduct all measurements
accurately. Following the steps below will assist you in determining the
correct shock and spring set-up.
For Mustang II coil-over front suspensions, follow steps 1-4
For Mustang II non coil-over front suspensions, follow steps 2-4
1
Weigh the front half of your street rod. This weight is needed to find the correct
spring rate to get your desired ride quality.
2
Measure the lengths of the existing shock as fully compressed, fully extended
and ideal ride-height. Also, measure your suspension travel. See page 73 for
instructions on these measurements.
3
Measure the bolt size used in the lower control arm. Different chassis builders
use one of three bolt sizes: 7/16", 1/2", or 5/8".
4
See pages 90 and 91 to determine the shock that will best fit your application.
QUICK TIPS
Suspension Clearance -
Always check the clearance on all suspension
arms, shocks and springs through the entire range of travel. Also check
shock mounting locations and configurations. The extra clearance through
the entire range of travel could determine whether or not the car handles and
rides correctly. Never use the shock as a limiter.
Bearing Maintenance -
The shock bearings should operate smoothly. Check
them for wear and fit. QA1 nyloy bearings offer smooth but firm operation. If
metal-to-metal bearings are used, have penetrating oil applied and then worked
in by hand for regular maintenance. Wipe the excess oil from the bearing when
finished so that it does not collect dirt.
Binding -
Check the entire suspension without springs and shocks for binding.
If the suspension binds in the normal operating range, fix or replace the problem
area. Binding and then freeing up in the typical suspension travel range will, in
effect, be adding spring rate at times and not adding it at others thereby making
the chassis inconsistent.
Frequently Asked Questions
What is better, a bearing mounted shock or a polyurethane
mounted shock?
Bearing mounted shocks provide the most bind free travel and allow the
shock to move through its travel without putting undue stress on the internal
components, typically providing longer shock life. Polyurethane is an
economical alternative to bearing mounts.
What does QA1 offer for Mustang II suspensions?
QA1 offers several Mustang II front end coil-over conversion systems, as well
as stock replacement shocks. All front end coil-over conversion systems include
(2) ride height adjustable shocks, (2) specially designed chrome plated conical
springs and mounting hardware. Mustang II Systems are available with polished
adjustable, anodized adjustable or economy polished and chrome plated shocks
depending on your preference. We also have a Mustang II system engineered for
drag racing (see pg. 70). The stock shocks are designed for Mustang II front
ends utilizing stock springs, lowering springs and even cut springs. See page 90
for more information.
When you turn the knob on a single adjustable shock, what
does it change?
Depending on what shock you have, turning the knob will either affect both
compression and rebound, or it will only affect the rebound of the shock. The
Ultra Ride
®, Street Star®, Mustang II coil-over, Mustang II stock replacement shocks,
and "R" Series drag racing shocks are all 12-position rebound adjustable.
Is there a difference between shock ride height and chassis
ride height?
Yes. In the street world, chassis ride height often comes down to the look. Does
it have the stance to make it “cool”? Shock ride height is a specified range that
is measured from mounting point to mounting point that the shock is designed
to work within under normal operating conditions. This measurement is taken or
set with the chassis ride set where it needs to be for the specific application. It
is designed to allow the shock enough travel in both directions so that the shock
will not top or bottom out.
What is spring rate?
Spring rate is the unit of measure in pounds it takes to compress a coil spring
an inch at a time (e.g. 250 lbs. per inch). For example, with a 250 lb. linear
spring, it takes 250 lbs. to compress the spring one inch, another 250 lbs. to
compress another inch, and so on. If you compress a 250 lb. spring two inches,
the load on the spring is 500 lbs., but the rate of the spring remains constant
at 250 lbs. per inch.
ECH: 952.985.5675 • ORDERS: 800.721.61 • www.qa1.net
Street Rod
Technical Information
Street Rod Spring Chart
SPRING
LENGTH 750-949 LBS 950-1149 LBS 1150-1324 LBS 1325-1524 LBS 1525-1749 LBS 1750 LBS +
Straight Axle
8” 200 225 250 275 325 450
9” 140 180 220 220 300 350
10” 115 125 150 200 250 300
12” 125 150 175 200 250 300
Independent Suspension
8” 300 325 450 550 600 CALL
9” 220 300 350 450 550 650
10” 175 225 275 350 450 600
SPRING
LENGTH 900-1099 LBS 1100-1249 LBS 1250-1449 LBS 1450-1599 LBS 1600-1899 LBS 1900 LBS +
Solid Rear Axle
8” 200 225 300 350 400 450
9” or 10” 115 200 225 250 275 350
12” 95 125 175 225 250 300
14” 105 125 150 175 225 275
Jaguar (IRS)
10” 115 140 200 250 250 275
Corvette (IRS) -
Ahead of Axle 10” 200 225 275 350 400 500
Corvette (IRS)
- Behind Axle 12” 95 125 150 225 275 300
The following charts provide general guidelines to
determine the approximate weight of the most
popular street rods. Of course, each car is different
so it is ideal to actually weigh the front half and the
rear half of your vehicle.
Average car weights listed are with driver,
automatic transmission, small block Chevrolet
V-8, full upholstery and all normal street
equipment (such as a spare tire and gas in the
tank). Fiberglass cars weigh the same as steel.
Stripped or lightened cars will weigh less.
Extra passengers will add to the weight.
Average Car Weights
Find the average weight of your car type here:
YEAR MODEL FRONT REAR
To ’27 Ford Coupe 1200 1300
’28-’31 Ford Coupe 1300 1400
’32-’34 Ford Coupe 1400 1600
’35-’38 Ford Coupe 1600 1700
’39-’40 Ford Coupe 1700 1800
’32-’38 Chev., Mopar Coupe 1500 1550
’39-’40 Chev., Mopar Coupe 1600 1600
’46-‘48 Ford 1700 1750
1948 Chev. Pickup 1950 1450
Adjust weight according to the following list of options:
OPTIONS FRONT REAR
Air conditioning +75 lbs. +25 lbs.
Sedan (4-door) +50 lbs. +125 lbs.
Sedan delivery +50 lbs. +200 lbs.
Roadster -50 lbs. -50 lbs.
Less fenders -100 lbs. -75 lbs.
Big-block V-8 +175 lbs. +25 lbs.
Other small block V-8’s +75 lbs. +25 lbs.