 
             
|
| STREET ROD SHOCKS - How To |
| HOW TO MEASURE
YOUR VEHICLE |
| Using the compressed and extended lengths
taken from existing shocks may not be the most accurate for your
vehicle. Set the vehicle at the desired ride height and measure
from the center of the upper shock mount to the center of the
lower shock mount to determine the length of shock needed. This
method of measuring shock lengths works with both coil-over and
non coil-over applications. If a measurement should fall between
shock lengths, choose the shock that gives you the most compression
(in) travel. Refer to the charts on the following pages for our
shock lengths to fit your application. |
| HOW
TO SELECT PROPER SPRING RATE |
| We have compiled a list of the most commonly used vehicles and accessories used in the Street Rod Industry. If you do not have the use of scales, a more accurate selection of spring rates will be made available to you by our tech staff to assist in helping select the "perfect" set-up on your vehicle. If you use scales, remember to add any additional loading such as trailers, extra persons, etc. to your rear weight. Also, always keep the vehicle level while using the scales. Use the Coil-Over Spring Rate Chart on the following page to select the correct shock and spring combination. |
| SHOCK
TRAVEL |
 Do you know how much shock travel your vehicle has? For a simple way to check it, place a plastic wire tie around your shock shaft as tightly as possible. Be sure the tie is next to the head of the shock. Drive your vehicle over different types of roads. Measure how much the tie has move up the shock shaft.
Do not jack the vehicle up. On a coil-over
or leaf spring vehicle, if there is very little movement, you
are too stiff. If the tie is way up the shock shaft, you are
too soft.
|
| ANGLE CORRECTION FACTOR FOR COIL OVER SHOCKS |
When mounting coil-over shocks measure the degree of angle and use the chart to find your angle correction factor (ACF). Then divide the desired spring rate (DSR) by the angel correction factor (ACF) and the result will be the actual correct spring rate (CSR) that you need.
| Angle |
10º |
15º |
20º |
25º |
30º |
35º |
40º |
45º |
| ACF |
.96 |
.93 |
.88 |
.82 |
.75 |
.66 |
.59 |
.50 |
 EXAMPLE:
- Your desired spring rate (DSR) is 200 lbs.
- Your shock will mount at a 20 degree angle.
- The table above shows that the angle correction factor (ACF) is .88
- Divide the .88 into the desired rate. 200 ÷ .88 = 227.3
- The 227.3 represents the amount of spring needed at 20º of angle to equal the desired rate of 200 lbs. per inch.
- Or you can use the Pro Shocks Coil Over Mounting Angle Calculator.
Mathematical Formula:
DSR ÷ ACF = CSR
|
| AVERAGE STREET ROD WEIGHTS |
| YEAR |
CAR |
FRONT WEIGHT |
REAR WEIGHT |
| -27 |
Ford Coupe |
1200 |
1300 |
| 28-31 |
Ford Coupe |
1350 |
1400 |
| 32-34 |
Ford Coupe |
1400 |
1600 |
| 35-38 |
Ford Coupe |
1600 |
1700 |
| 39-40 |
Ford Coupe |
1700 |
1800 |
| 40-48 |
Ford Coupe |
1750 |
1700 |
| 32-38 |
Chevrolet, Plymouth & Dodge Coupe |
1500 |
1550 |
| 39-40 |
Chevrolet, Plymouth & Dodge Coupe |
1600 |
1600 |
| 40-48 |
Chevrolet, Plymouth & Dodge Coupe |
1700 |
1600 |
OPTIONS
add or subtract to above weight |
FRONT WEIGHT |
REAR WEIGHT |
| 4-Door Sedan |
0 |
+125 |
| Sedan Delivery |
+50 |
+200 |
| Roadster |
-50 |
-50 |
| Less Fenders |
-100 |
-75 |
| Air Conditioning |
+75 |
+25 |
| Big Block Engine |
+175 |
+25 |
| Ford, Chevrolet, Small Block |
+ 75 |
+ 25 |
| A-Model with Side or Rear Tanks |
|
-125 |
|
|
