Cutting a Coil Spring
Lowering a car will result in lowering the center of gravity lessening roll and generally improving handling. There is a very inexpensive way of doing this and it involves cutting the coil springs on your cars suspension.
Many gasp in horror at the thought of cutting a coil spring. The reasoning goes something like this, “You use heat, that will ruin the temper and the spring will collapse.” Another angle, “The spring will not properly fit the pocket, and you won’t get full travel. These are misconceptions about what is being done from people who have never done it. Let’s examine the facts and look at the reasons and the proper way to do this modification.
My older brother was a not so elegant hot rodder who lowered his cars for appearance sake by “torching” the springs. He would run a cutting torch along one of the vertical set of coils of a coil spring while it was on the car, with weight on the wheels until the poor spring mostly collapsed. The result was a “slambed” ride with about an inch of suspension travel; not recommended. What he was doing was heating the spring steel until it became plastic, about 1800 deg F (orange yellow) while it was loaded. The weigh of the vehicle made it sag. The spring colapse and “springiness” on the heated side transferring the load to the half not heated.
Addressing the first issue of cutting the spring; namely temper, will not be affected for the portion of the coils left after cutting. That is because the uncut coils do not get hot enough to loose their set or temper if done correctly, and that is very easy to control. Springs are trimmed while unloaded and off of the car, using an oxy-acetylene cutting torch.
The second myth is that they will not fit the pocket and / or get full travel. Most stock springs can be trimmed a half coil to lower the car just enough for to improve handling. The spring must be LOCALLY heated a half coil below the cut so it can be bent to match the spring pocket.
Let’s look at each step and address the proper method to achieve a professional result.
1. CAUTION! Carefully remove the coil spring from the vehicle. Springs are under load, even when the car is jacked up. Carelessly releasing that load can result in serious injury.
Many shop manuals give you the step by step method to easily and safely remove the spring; follow the guidance! Study what is recommended for your car, and follow their directions. You may need a spring compressor to safely do this which is available from most tool rental shops.
2. Mark the spring one half coil directly across from the original end.
3. Cut the spring with an oxy acetylene torch on the mark.
4. Now locally heat the spring as shown, one half coil beyond where you just cut.
5. Quickly flip the spring and push the newly cut end against the shop floor to set the end so it will fit the pocket. Keep it vertical so the end forms flat for the pocket. DO NOT quench the spring in water, rather let it air cool slowly.
6. Give the spring a coat of paint and re-install per the shop manual taking care that you will once again be “loading” the spring with tension. CAUTION: Following the shop manuals instruction and using the proper tools is essential to safely installing the cut spring. You should re-align the front end since the lower ride height will affect alignment.
Once completed you will have a lower stance, lower center of gravity and improved cornering ability all at little or no cost.