Homemade Coil Spring Compressors
| 01 April 2005
[The Pony Trick that follows can be considered dangerous because a compressed spring has a lot of stored energy. We don’t want anyone getting hurt so make sure you’re comfortable with containment of that energy before you use this Pony Trick. Evaluate the potential risks and if you don’t think it’s safe, don’t use the trick.- Ed.]
Sometimes you need to work on the front suspension of your first generation Mustang but the job requires that the front spring be compressed to “unload” the parts. For instance the Pony Trick in the March issue described how to lower the upper control arms à-la Shelby cars of the era. Part of the procedure included removal of the front spring. Without a doubt, the safest and best solution to spring compression is to compress it with a spring compressor and remove it from the vehicle. With the spring out of your way, access to the area is unimpeded and the stored energy in a compressed spring is not a safety issue because the spring is no longer there.
But in a pinch, if can’t get your hands on a spring compressor and you need to unload the front suspension, it’s possible to use the vehicle itself to compress the spring and leave it in place inside the shock tower. As you know, the spring is partially compressed when the tires are on the ground and the car is not jacked up. The trick is to prevent the spring from extending when the front of the car is jacked up and the tire is lifted off the ground. The tool for this trick is the shock absorber or an alternate tool made from a old shock absorber. Here’s how it works.
Before you begin to jack the car off the ground, disconnect the upper end of the shock from the tower bracket. Grasp the upper shock mount and extend the piston rod upward to the maximum as shown in the following drawing. Cut two sleeves, each 1½” long, from 7/16” ID pipe or thick-walled tubing. Slip the sleeves in place between the tower bracket and the ears of the upper shock mount. Attach the shock to the tower bracket by using two 5/16” x 2” bolts with the same thread pitch as the original bolts (some shock bolts are 18 pitch and some are 24 pitch). Tighten the bolts securely. DO NOT loosen or remove the nuts from the studs on the mounting plate at the bottom of the shock; the shock must remain securely attached to the spring seat. And DO NOT loosen or remove the bolts that attach the tower bracket to the top of the tower.
With the sleeves and shock securely in place, the car can be jacked up but the shock absorber will keep the spring from extending. You can remove the bolts that attach the lower spring seat to the upper control arm and free the suspension components so you can work on them.
An alternate tool to the one described above is pictured on the next page. Make the alternate tool by cutting the mounting plate from the bottom of an old shock absorber and welding it to an 18” length of 3/8” all-thread rod. To use the tool, remove the shock absorber from the car and bolt the tool securely in its place on the lower spring seat. Install and securely tighten the tower bracket.
Although not shown in the drawing, it’s suggested that an adapter plate should be made for the top of the tower bracket. Cut the plate from 1/8” steel flat-stock in a rectangular shape large enough to cover the top of the tower bracket. De-burr it and radius the corners to reduce the risk of injury and then drill two holes in the plate so it can be attached to the tower bracket using the bolts that attached the shock. Drill another hole at the center for the all-thread to pass through.
Place the adapter over top of the all-thread and bolt it securely to the top of the tower. Place a washer and nut on the all-thread and tighten the nut securely in place. When you jack up the car, the tool will prevent the spring from extending. This tool removes all possible slack and keeps the spring exactly at the length it was when the weight of the car had it compressed. An added benefit is the ability to compress the spring even further by having one or more people push down on the front of the car when the nut is being tightened on the all-thread. It’s also possible to compress the spring still further by additional tightening of the nut on the all-thread. If you compress the spring by tightening the nut, be careful to avoid stripping the threads. A couple drops of oil on the threads and a couple more between the nut and washer will help to prevent stripping.
Jack up the car and remove the lower spring seat from the upper control arm so you can go ahead with the repairs or modifications you had in mind.