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Often while working on our automotive suspension systems, it becomes necessary to remove coil springs from the equation. This is the case any time you need to work on components that are loaded by the coil, such as a Macpherson strut, or control arm. These coils hold up hundreds of pounds of weight at each corner of the car, and as such are usually under a sizable load, even with the car's weight off of its wheels. This preload from other suspension components must be accounted for when removing coil springs from the suspension, and to this end, various types of coil spring compressors have been developed.

The main idea here is to draw the coils of the spring together tightly so that the preload from the suspension system is deferred to the compressor. This will allow the spring to be removed safely without risk of blasting out of it's mounts (if done properly). Not all coil springs are created equally, however, and different compressors are necessary for different types. We'll take a look at the main types most of us will see while working on European autos.



An External Coil Spring Compressor

Before we begin, I'd like to address a few notes about safety and tool maintenance. Before each usage, inspect the tool. If the tool looks questionable, has cracks, rust, or gouges, or if the action of the threaded shaft is not smooth and uniform, do NOT use the tool. The last thing you want is to learn the physics of a released spring the hard way. Once the spring is safely removed from the vehicle, gently unload the spring and remove the compressor. Keeping a compressed coil spring laying around while working is extremely dangerous, as anything could happen to damage the compressor and allow the spring to come loose. There are several videos online that demonstrate the extreme energy built up in a compressed spring - this is no matter to take lightly. Always keep the ends of the spring pointed in a safe direction and away from people at all times.


An internal coil spring comrpessorExternal Compressor

External spring compressors are generally used in a strut-type configuration where there may be a shaft or other obstruction running through the center of the spring. An external coil spring compressor usually comes with two devices that resemble C-clamps. They hook onto the spring from the outside and are tightened down with wrenches to load the spring. It's important that the clamps be placed with even spacing both around the coil, and down the length of the coil so that the spring does not tend to bend in any direction while compressing. A bend in the spring can load the clamps unevenly and cause damage or breakage to your equipment. Follow the tool manufacturer's recommendations on lubricating the threaded shafts of the clamps, and proper storage of the tool to avoid damage.


A klann-type internal coil spring compressor.Internal Compressor

Quite different than an external spring compressor, the internal compressor is used in situations where there is no obstruction to the center of the spring, and the tool can be successfully inserted and removed. The compressor consists of a jack-shaft with two threaded arms that grasp the spring and pull towards each other as the jack shaft is tightened. As with the external compressor, make sure that the arms are evenly spaced, both around the spring and along the spring, before tightening. Follow the tool manufacturer's recommendations on lubricating the jack-shaft, and proper storage of the tool to avoid damage.


Klann-type Compressor

I think that this type of compressor bears notice in this article, as it is used in several European autos. The Klann-type compressor is a type of coil spring compressor that involves plates and a telescoping jack-shaft. This tool is recommended or required for many high-tension spring applications. For example, my W124 Mercedes employs extremely high tension front coil springs. Unloaded, these springs are about as long as my arm, and they require an extremely strong and straight compressor in order to work with them safely. The tool also makes the job unbelievably easy and convenient. The point here is, there may be a special tool for working with the coils on your car, as there was with mine. A little research can save you a lot of trouble, and most importantly, help ensure your safety.

As with all DIY jobs, safety is step 1. A coil spring can be a very hazardous object if mishandled, so be sure you know what you are doing before attempting. If you don't feel comfortable doing the work yourself, have a qualified shop do it. I know that that statement will bother some on a DIY board, but I've seen too many cases where someone gets hurt because they don't want to admit that a certain job is out of their skill level. Changing coil springs is not a prestigious job, and if you get hurt doing it, you won't even have the satisfaction of getting a cool story out of it. As long as you are aware of the work you are doing, have the correct tools and use them correctly, the job can be done with relative ease.



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Written by :
Dan Bullmore

Dan Bullmore is a physicist and engineer from Houston, TX. Preferring the old to the new, Dan has owned many examples of Mercedes and Volvo vehicles and has devoted much of his time to maintaining and understanding them.

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